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rocksdb/db/db_impl.cc
Siying Dong aaf9c6203c [RocksDB][Performance Branch]Iterator Cleanup method only tries to find obsolete files if it has the last reference to a version 
Summary: When deconstructing an iterator, no need to check obsolete file if it doesn't hold last reference of any version.

Test Plan: make all check

Reviewers: haobo, igor, dhruba, kailiu

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D14595
2013-12-11 13:59:43 -08:00

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// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "db/db_impl.h"
#include <algorithm>
#include <climits>
#include <cstdio>
#include <set>
#include <stdexcept>
#include <stdint.h>
#include <string>
#include <unordered_set>
#include <vector>
#include "db/builder.h"
#include "db/dbformat.h"
#include "db/db_iter.h"
#include "db/filename.h"
#include "db/log_reader.h"
#include "db/log_writer.h"
#include "db/memtable.h"
#include "db/memtable_list.h"
#include "db/merge_context.h"
#include "db/merge_helper.h"
#include "db/prefix_filter_iterator.h"
#include "db/table_cache.h"
#include "db/table_properties_collector.h"
#include "db/transaction_log_impl.h"
#include "db/version_set.h"
#include "db/write_batch_internal.h"
#include "port/port.h"
#include "rocksdb/compaction_filter.h"
#include "rocksdb/db.h"
#include "rocksdb/env.h"
#include "rocksdb/merge_operator.h"
#include "rocksdb/statistics.h"
#include "rocksdb/status.h"
#include "rocksdb/table.h"
#include "port/port.h"
#include "table/block.h"
#include "table/block_based_table_factory.h"
#include "table/merger.h"
#include "table/two_level_iterator.h"
#include "util/auto_roll_logger.h"
#include "util/build_version.h"
#include "util/coding.h"
#include "util/hash_skiplist_rep.h"
#include "util/logging.h"
#include "util/mutexlock.h"
#include "util/perf_context_imp.h"
#include "util/stop_watch.h"
namespace rocksdb {
void dumpLeveldbBuildVersion(Logger * log);
// Information kept for every waiting writer
struct DBImpl::Writer {
Status status;
WriteBatch* batch;
bool sync;
bool disableWAL;
bool done;
port::CondVar cv;
explicit Writer(port::Mutex* mu) : cv(mu) { }
};
struct DBImpl::CompactionState {
Compaction* const compaction;
// If there were two snapshots with seq numbers s1 and
// s2 and s1 < s2, and if we find two instances of a key k1 then lies
// entirely within s1 and s2, then the earlier version of k1 can be safely
// deleted because that version is not visible in any snapshot.
std::vector<SequenceNumber> existing_snapshots;
// Files produced by compaction
struct Output {
uint64_t number;
uint64_t file_size;
InternalKey smallest, largest;
SequenceNumber smallest_seqno, largest_seqno;
};
std::vector<Output> outputs;
std::list<uint64_t> allocated_file_numbers;
// State kept for output being generated
unique_ptr<WritableFile> outfile;
unique_ptr<TableBuilder> builder;
uint64_t total_bytes;
Output* current_output() { return &outputs[outputs.size()-1]; }
explicit CompactionState(Compaction* c)
: compaction(c),
total_bytes(0) {
}
// Create a client visible context of this compaction
CompactionFilter::Context GetFilterContext() {
CompactionFilter::Context context;
context.is_full_compaction = compaction->IsFullCompaction();
return context;
}
};
// Fix user-supplied options to be reasonable
template <class T, class V>
static void ClipToRange(T* ptr, V minvalue, V maxvalue) {
if (static_cast<V>(*ptr) > maxvalue) *ptr = maxvalue;
if (static_cast<V>(*ptr) < minvalue) *ptr = minvalue;
}
Options SanitizeOptions(const std::string& dbname,
const InternalKeyComparator* icmp,
const InternalFilterPolicy* ipolicy,
const Options& src) {
Options result = src;
result.comparator = icmp;
result.filter_policy = (src.filter_policy != nullptr) ? ipolicy : nullptr;
ClipToRange(&result.max_open_files, 20, 1000000);
ClipToRange(&result.write_buffer_size, ((size_t)64)<<10,
((size_t)64)<<30);
ClipToRange(&result.block_size, 1<<10, 4<<20);
// if user sets arena_block_size, we trust user to use this value. Otherwise,
// calculate a proper value from writer_buffer_size;
if (result.arena_block_size <= 0) {
result.arena_block_size = result.write_buffer_size / 10;
}
result.min_write_buffer_number_to_merge = std::min(
result.min_write_buffer_number_to_merge, result.max_write_buffer_number-1);
if (result.info_log == nullptr) {
Status s = CreateLoggerFromOptions(dbname, result.db_log_dir, src.env,
result, &result.info_log);
if (!s.ok()) {
// No place suitable for logging
result.info_log = nullptr;
}
}
if (result.block_cache == nullptr && !result.no_block_cache) {
result.block_cache = NewLRUCache(8 << 20);
}
result.compression_per_level = src.compression_per_level;
if (result.block_size_deviation < 0 || result.block_size_deviation > 100) {
result.block_size_deviation = 0;
}
if (result.max_mem_compaction_level >= result.num_levels) {
result.max_mem_compaction_level = result.num_levels - 1;
}
if (result.soft_rate_limit > result.hard_rate_limit) {
result.soft_rate_limit = result.hard_rate_limit;
}
if (result.compaction_filter) {
Log(result.info_log, "Compaction filter specified, ignore factory");
}
if (result.prefix_extractor) {
// If a prefix extractor has been supplied and a HashSkipListRepFactory is
// being used, make sure that the latter uses the former as its transform
// function.
auto factory = dynamic_cast<HashSkipListRepFactory*>(
result.memtable_factory.get());
if (factory &&
factory->GetTransform() != result.prefix_extractor) {
Log(result.info_log, "A prefix hash representation factory was supplied "
"whose prefix extractor does not match options.prefix_extractor. "
"Falling back to skip list representation factory");
result.memtable_factory = std::make_shared<SkipListFactory>();
} else if (factory) {
Log(result.info_log, "Prefix hash memtable rep is in use.");
}
}
if (result.wal_dir.empty()) {
// Use dbname as default
result.wal_dir = dbname;
}
// -- Sanitize the table properties collector
// All user defined properties collectors will be wrapped by
// UserKeyTablePropertiesCollector since for them they only have the
// knowledge of the user keys; internal keys are invisible to them.
auto& collectors = result.table_properties_collectors;
for (size_t i = 0; i < result.table_properties_collectors.size(); ++i) {
assert(collectors[i]);
collectors[i] =
std::make_shared<UserKeyTablePropertiesCollector>(collectors[i]);
}
// Add collector to collect internal key statistics
collectors.push_back(
std::make_shared<InternalKeyPropertiesCollector>()
);
return result;
}
CompressionType GetCompressionType(const Options& options, int level,
const bool enable_compression) {
if (!enable_compression) {
// disable compression
return kNoCompression;
}
// If the use has specified a different compression level for each level,
// then pick the compresison for that level.
if (!options.compression_per_level.empty()) {
const int n = options.compression_per_level.size() - 1;
// It is possible for level_ to be -1; in that case, we use level
// 0's compression. This occurs mostly in backwards compatibility
// situations when the builder doesn't know what level the file
// belongs to. Likewise, if level_ is beyond the end of the
// specified compression levels, use the last value.
return options.compression_per_level[std::max(0, std::min(level, n))];
} else {
return options.compression;
}
}
DBImpl::DBImpl(const Options& options, const std::string& dbname)
: env_(options.env),
dbname_(dbname),
internal_comparator_(options.comparator),
options_(SanitizeOptions(
dbname, &internal_comparator_, &internal_filter_policy_, options)),
internal_filter_policy_(options.filter_policy),
owns_info_log_(options_.info_log != options.info_log),
db_lock_(nullptr),
mutex_(options.use_adaptive_mutex),
shutting_down_(nullptr),
bg_cv_(&mutex_),
mem_rep_factory_(options_.memtable_factory.get()),
mem_(new MemTable(internal_comparator_, mem_rep_factory_,
NumberLevels(), options_)),
logfile_number_(0),
tmp_batch_(),
bg_compaction_scheduled_(0),
bg_flush_scheduled_(0),
bg_logstats_scheduled_(false),
manual_compaction_(nullptr),
logger_(nullptr),
disable_delete_obsolete_files_(false),
delete_obsolete_files_last_run_(options.env->NowMicros()),
purge_wal_files_last_run_(0),
last_stats_dump_time_microsec_(0),
default_interval_to_delete_obsolete_WAL_(600),
stall_level0_slowdown_(0),
stall_memtable_compaction_(0),
stall_level0_num_files_(0),
stall_level0_slowdown_count_(0),
stall_memtable_compaction_count_(0),
stall_level0_num_files_count_(0),
started_at_(options.env->NowMicros()),
flush_on_destroy_(false),
stats_(options.num_levels),
delayed_writes_(0),
storage_options_(options),
bg_work_gate_closed_(false),
refitting_level_(false) {
mem_->Ref();
env_->GetAbsolutePath(dbname, &db_absolute_path_);
stall_leveln_slowdown_.resize(options.num_levels);
stall_leveln_slowdown_count_.resize(options.num_levels);
for (int i = 0; i < options.num_levels; ++i) {
stall_leveln_slowdown_[i] = 0;
stall_leveln_slowdown_count_[i] = 0;
}
// Reserve ten files or so for other uses and give the rest to TableCache.
const int table_cache_size = options_.max_open_files - 10;
table_cache_.reset(new TableCache(dbname_, &options_,
storage_options_, table_cache_size));
versions_.reset(new VersionSet(dbname_, &options_, storage_options_,
table_cache_.get(), &internal_comparator_));
dumpLeveldbBuildVersion(options_.info_log.get());
options_.Dump(options_.info_log.get());
char name[100];
Status st = env_->GetHostName(name, 100L);
if (st.ok()) {
host_name_ = name;
} else {
Log(options_.info_log, "Can't get hostname, use localhost as host name.");
host_name_ = "localhost";
}
last_log_ts = 0;
LogFlush(options_.info_log);
}
DBImpl::~DBImpl() {
std::vector<MemTable*> to_delete;
to_delete.reserve(options_.max_write_buffer_number);
// Wait for background work to finish
if (flush_on_destroy_ && mem_->GetFirstSequenceNumber() != 0) {
FlushMemTable(FlushOptions());
}
mutex_.Lock();
shutting_down_.Release_Store(this); // Any non-nullptr value is ok
while (bg_compaction_scheduled_ ||
bg_flush_scheduled_ ||
bg_logstats_scheduled_) {
bg_cv_.Wait();
}
mutex_.Unlock();
if (db_lock_ != nullptr) {
env_->UnlockFile(db_lock_);
}
if (mem_ != nullptr) {
delete mem_->Unref();
}
imm_.UnrefAll(&to_delete);
for (MemTable* m: to_delete) {
delete m;
}
LogFlush(options_.info_log);
}
// Do not flush and close database elegantly. Simulate a crash.
void DBImpl::TEST_Destroy_DBImpl() {
// ensure that no new memtable flushes can occur
flush_on_destroy_ = false;
// wait till all background compactions are done.
mutex_.Lock();
while (bg_compaction_scheduled_ ||
bg_flush_scheduled_ ||
bg_logstats_scheduled_) {
bg_cv_.Wait();
}
// Prevent new compactions from occuring.
bg_work_gate_closed_ = true;
const int LargeNumber = 10000000;
bg_compaction_scheduled_ += LargeNumber;
mutex_.Unlock();
LogFlush(options_.info_log);
// force release the lock file.
if (db_lock_ != nullptr) {
env_->UnlockFile(db_lock_);
}
log_.reset();
versions_.reset();
table_cache_.reset();
}
uint64_t DBImpl::TEST_Current_Manifest_FileNo() {
return versions_->ManifestFileNumber();
}
Status DBImpl::NewDB() {
VersionEdit new_db(NumberLevels());
new_db.SetComparatorName(user_comparator()->Name());
new_db.SetLogNumber(0);
new_db.SetNextFile(2);
new_db.SetLastSequence(0);
const std::string manifest = DescriptorFileName(dbname_, 1);
unique_ptr<WritableFile> file;
Status s = env_->NewWritableFile(manifest, &file, storage_options_);
if (!s.ok()) {
return s;
}
file->SetPreallocationBlockSize(options_.manifest_preallocation_size);
{
log::Writer log(std::move(file));
std::string record;
new_db.EncodeTo(&record);
s = log.AddRecord(record);
}
if (s.ok()) {
// Make "CURRENT" file that points to the new manifest file.
s = SetCurrentFile(env_, dbname_, 1);
} else {
env_->DeleteFile(manifest);
}
return s;
}
void DBImpl::MaybeIgnoreError(Status* s) const {
if (s->ok() || options_.paranoid_checks) {
// No change needed
} else {
Log(options_.info_log, "Ignoring error %s", s->ToString().c_str());
*s = Status::OK();
}
}
const Status DBImpl::CreateArchivalDirectory() {
if (options_.WAL_ttl_seconds > 0 || options_.WAL_size_limit_MB > 0) {
std::string archivalPath = ArchivalDirectory(options_.wal_dir);
return env_->CreateDirIfMissing(archivalPath);
}
return Status::OK();
}
void DBImpl::PrintStatistics() {
auto dbstats = options_.statistics.get();
if (dbstats) {
Log(options_.info_log,
"STATISTCS:\n %s",
dbstats->ToString().c_str());
}
}
void DBImpl::MaybeDumpStats() {
if (options_.stats_dump_period_sec == 0) return;
const uint64_t now_micros = env_->NowMicros();
if (last_stats_dump_time_microsec_ +
options_.stats_dump_period_sec * 1000000
<= now_micros) {
// Multiple threads could race in here simultaneously.
// However, the last one will update last_stats_dump_time_microsec_
// atomically. We could see more than one dump during one dump
// period in rare cases.
last_stats_dump_time_microsec_ = now_micros;
std::string stats;
GetProperty("rocksdb.stats", &stats);
Log(options_.info_log, "%s", stats.c_str());
PrintStatistics();
}
}
// Returns the list of live files in 'sst_live' and the list
// of all files in the filesystem in 'all_files'.
// no_full_scan = true -- never do the full scan using GetChildren()
// force = false -- don't force the full scan, except every
// options_.delete_obsolete_files_period_micros
// force = true -- force the full scan
void DBImpl::FindObsoleteFiles(DeletionState& deletion_state,
bool force,
bool no_full_scan) {
mutex_.AssertHeld();
// if deletion is disabled, do nothing
if (disable_delete_obsolete_files_) {
return;
}
bool doing_the_full_scan = false;
// logic for figurint out if we're doing the full scan
if (no_full_scan) {
doing_the_full_scan = false;
} else if (force || options_.delete_obsolete_files_period_micros == 0) {
doing_the_full_scan = true;
} else {
const uint64_t now_micros = env_->NowMicros();
if (delete_obsolete_files_last_run_ +
options_.delete_obsolete_files_period_micros < now_micros) {
doing_the_full_scan = true;
delete_obsolete_files_last_run_ = now_micros;
}
}
// get obsolete files
versions_->GetObsoleteFiles(&deletion_state.sst_delete_files);
// store the current filenum, lognum, etc
deletion_state.manifest_file_number = versions_->ManifestFileNumber();
deletion_state.log_number = versions_->LogNumber();
deletion_state.prev_log_number = versions_->PrevLogNumber();
if (!doing_the_full_scan && !deletion_state.HaveSomethingToDelete()) {
// avoid filling up sst_live if we're sure that we
// are not going to do the full scan and that we don't have
// anything to delete at the moment
return;
}
// don't delete live files
deletion_state.sst_live.assign(pending_outputs_.begin(),
pending_outputs_.end());
versions_->AddLiveFiles(&deletion_state.sst_live);
if (doing_the_full_scan) {
// set of all files in the directory
env_->GetChildren(dbname_, &deletion_state.all_files); // Ignore errors
//Add log files in wal_dir
if (options_.wal_dir != dbname_) {
std::vector<std::string> log_files;
env_->GetChildren(options_.wal_dir, &log_files); // Ignore errors
deletion_state.all_files.insert(
deletion_state.all_files.end(),
log_files.begin(),
log_files.end()
);
}
}
}
// Diffs the files listed in filenames and those that do not
// belong to live files are posibly removed. Also, removes all the
// files in sst_delete_files and log_delete_files.
// It is not necessary to hold the mutex when invoking this method.
void DBImpl::PurgeObsoleteFiles(DeletionState& state) {
// free pending memtables
for (auto m : state.memtables_to_free) {
delete m;
}
// check if there is anything to do
if (!state.all_files.size() &&
!state.sst_delete_files.size() &&
!state.log_delete_files.size()) {
return;
}
// this checks if FindObsoleteFiles() was run before. If not, don't do
// PurgeObsoleteFiles(). If FindObsoleteFiles() was run, we need to also
// run PurgeObsoleteFiles(), even if disable_delete_obsolete_files_ is true
if (state.manifest_file_number == 0) {
return;
}
uint64_t number;
FileType type;
std::vector<std::string> old_log_files;
// Now, convert live list to an unordered set, WITHOUT mutex held;
// set is slow.
std::unordered_set<uint64_t> live_set(state.sst_live.begin(),
state.sst_live.end());
state.all_files.reserve(state.all_files.size() +
state.sst_delete_files.size());
for (auto file : state.sst_delete_files) {
state.all_files.push_back(TableFileName("", file->number).substr(1));
delete file;
}
state.all_files.reserve(state.all_files.size() +
state.log_delete_files.size());
for (auto filenum : state.log_delete_files) {
if (filenum > 0) {
state.all_files.push_back(LogFileName("", filenum).substr(1));
}
}
// dedup state.all_files so we don't try to delete the same
// file twice
sort(state.all_files.begin(), state.all_files.end());
auto unique_end = unique(state.all_files.begin(), state.all_files.end());
for (size_t i = 0; state.all_files.begin() + i < unique_end; i++) {
if (ParseFileName(state.all_files[i], &number, &type)) {
bool keep = true;
switch (type) {
case kLogFile:
keep = ((number >= state.log_number) ||
(number == state.prev_log_number));
break;
case kDescriptorFile:
// Keep my manifest file, and any newer incarnations'
// (in case there is a race that allows other incarnations)
keep = (number >= state.manifest_file_number);
break;
case kTableFile:
keep = (live_set.find(number) != live_set.end());
break;
case kTempFile:
// Any temp files that are currently being written to must
// be recorded in pending_outputs_, which is inserted into "live"
keep = (live_set.find(number) != live_set.end());
break;
case kInfoLogFile:
keep = true;
if (number != 0) {
old_log_files.push_back(state.all_files[i]);
}
break;
case kCurrentFile:
case kDBLockFile:
case kIdentityFile:
case kMetaDatabase:
keep = true;
break;
}
if (!keep) {
if (type == kTableFile) {
// evict from cache
table_cache_->Evict(number);
}
std::string fname = ((type == kLogFile) ? options_.wal_dir : dbname_) +
"/" + state.all_files[i];
Log(options_.info_log,
"Delete type=%d #%lu",
int(type),
(unsigned long)number);
Status st;
if (type == kLogFile && (options_.WAL_ttl_seconds > 0 ||
options_.WAL_size_limit_MB > 0)) {
st = env_->RenameFile(fname,
ArchivedLogFileName(options_.wal_dir, number));
if (!st.ok()) {
Log(options_.info_log,
"RenameFile logfile #%lu FAILED -- %s\n",
(unsigned long)number, st.ToString().c_str());
}
} else {
st = env_->DeleteFile(fname);
if (!st.ok()) {
Log(options_.info_log, "Delete type=%d #%lu FAILED -- %s\n",
int(type), (unsigned long)number, st.ToString().c_str());
}
}
}
}
}
// Delete old info log files.
size_t old_log_file_count = old_log_files.size();
// NOTE: Currently we only support log purge when options_.db_log_dir is
// located in `dbname` directory.
if (old_log_file_count >= options_.keep_log_file_num &&
options_.db_log_dir.empty()) {
std::sort(old_log_files.begin(), old_log_files.end());
size_t end = old_log_file_count - options_.keep_log_file_num;
for (unsigned int i = 0; i <= end; i++) {
std::string& to_delete = old_log_files.at(i);
// Log(options_.info_log, "Delete type=%d %s\n",
// int(kInfoLogFile), to_delete.c_str());
env_->DeleteFile(dbname_ + "/" + to_delete);
}
}
PurgeObsoleteWALFiles();
LogFlush(options_.info_log);
}
void DBImpl::DeleteObsoleteFiles() {
mutex_.AssertHeld();
DeletionState deletion_state;
FindObsoleteFiles(deletion_state, true);
PurgeObsoleteFiles(deletion_state);
}
// 1. Go through all archived files and
// a. if ttl is enabled, delete outdated files
// b. if archive size limit is enabled, delete empty files,
// compute file number and size.
// 2. If size limit is enabled:
// a. compute how many files should be deleted
// b. get sorted non-empty archived logs
// c. delete what should be deleted
void DBImpl::PurgeObsoleteWALFiles() {
bool const ttl_enabled = options_.WAL_ttl_seconds > 0;
bool const size_limit_enabled = options_.WAL_size_limit_MB > 0;
if (!ttl_enabled && !size_limit_enabled) {
return;
}
int64_t current_time;
Status s = env_->GetCurrentTime(&current_time);
if (!s.ok()) {
Log(options_.info_log, "Can't get current time: %s", s.ToString().c_str());
assert(false);
return;
}
uint64_t const now_seconds = static_cast<uint64_t>(current_time);
uint64_t const time_to_check = (ttl_enabled && !size_limit_enabled) ?
options_.WAL_ttl_seconds / 2 : default_interval_to_delete_obsolete_WAL_;
if (purge_wal_files_last_run_ + time_to_check > now_seconds) {
return;
}
purge_wal_files_last_run_ = now_seconds;
std::string archival_dir = ArchivalDirectory(options_.wal_dir);
std::vector<std::string> files;
s = env_->GetChildren(archival_dir, &files);
if (!s.ok()) {
Log(options_.info_log, "Can't get archive files: %s", s.ToString().c_str());
assert(false);
return;
}
size_t log_files_num = 0;
uint64_t log_file_size = 0;
for (auto& f : files) {
uint64_t number;
FileType type;
if (ParseFileName(f, &number, &type) && type == kLogFile) {
std::string const file_path = archival_dir + "/" + f;
if (ttl_enabled) {
uint64_t file_m_time;
Status const s = env_->GetFileModificationTime(file_path,
&file_m_time);
if (!s.ok()) {
Log(options_.info_log, "Can't get file mod time: %s: %s",
file_path.c_str(), s.ToString().c_str());
continue;
}
if (now_seconds - file_m_time > options_.WAL_ttl_seconds) {
Status const s = env_->DeleteFile(file_path);
if (!s.ok()) {
Log(options_.info_log, "Can't delete file: %s: %s",
file_path.c_str(), s.ToString().c_str());
continue;
}
continue;
}
}
if (size_limit_enabled) {
uint64_t file_size;
Status const s = env_->GetFileSize(file_path, &file_size);
if (!s.ok()) {
Log(options_.info_log, "Can't get file size: %s: %s",
file_path.c_str(), s.ToString().c_str());
return;
} else {
if (file_size > 0) {
log_file_size = std::max(log_file_size, file_size);
++log_files_num;
} else {
Status s = env_->DeleteFile(file_path);
if (!s.ok()) {
Log(options_.info_log, "Can't delete file: %s: %s",
file_path.c_str(), s.ToString().c_str());
continue;
}
}
}
}
}
}
if (0 == log_files_num || !size_limit_enabled) {
return;
}
size_t const files_keep_num = options_.WAL_size_limit_MB *
1024 * 1024 / log_file_size;
if (log_files_num <= files_keep_num) {
return;
}
size_t files_del_num = log_files_num - files_keep_num;
VectorLogPtr archived_logs;
AppendSortedWalsOfType(archival_dir, archived_logs, kArchivedLogFile);
if (files_del_num > archived_logs.size()) {
Log(options_.info_log, "Trying to delete more archived log files than "
"exist. Deleting all");
files_del_num = archived_logs.size();
}
for (size_t i = 0; i < files_del_num; ++i) {
std::string const file_path = archived_logs[i]->PathName();
Status const s = DeleteFile(file_path);
if (!s.ok()) {
Log(options_.info_log, "Can't delete file: %s: %s",
file_path.c_str(), s.ToString().c_str());
continue;
}
}
}
// If externalTable is set, then apply recovered transactions
// to that table. This is used for readonly mode.
Status DBImpl::Recover(VersionEdit* edit, MemTable* external_table,
bool error_if_log_file_exist) {
mutex_.AssertHeld();
assert(db_lock_ == nullptr);
if (!external_table) {
// We call CreateDirIfMissing() as the directory may already exist (if we
// are reopening a DB), when this happens we don't want creating the
// directory to cause an error. However, we need to check if creating the
// directory fails or else we may get an obscure message about the lock
// file not existing. One real-world example of this occurring is if
// env->CreateDirIfMissing() doesn't create intermediate directories, e.g.
// when dbname_ is "dir/db" but when "dir" doesn't exist.
Status s = env_->CreateDirIfMissing(dbname_);
if (!s.ok()) {
return s;
}
s = env_->LockFile(LockFileName(dbname_), &db_lock_);
if (!s.ok()) {
return s;
}
if (!env_->FileExists(CurrentFileName(dbname_))) {
if (options_.create_if_missing) {
// TODO: add merge_operator name check
s = NewDB();
if (!s.ok()) {
return s;
}
} else {
return Status::InvalidArgument(
dbname_, "does not exist (create_if_missing is false)");
}
} else {
if (options_.error_if_exists) {
return Status::InvalidArgument(
dbname_, "exists (error_if_exists is true)");
}
}
// Check for the IDENTITY file and create it if not there
if (!env_->FileExists(IdentityFileName(dbname_))) {
s = SetIdentityFile(env_, dbname_);
if (!s.ok()) {
return s;
}
}
}
Status s = versions_->Recover();
if (s.ok()) {
SequenceNumber max_sequence(0);
// Recover from all newer log files than the ones named in the
// descriptor (new log files may have been added by the previous
// incarnation without registering them in the descriptor).
//
// Note that PrevLogNumber() is no longer used, but we pay
// attention to it in case we are recovering a database
// produced by an older version of rocksdb.
const uint64_t min_log = versions_->LogNumber();
const uint64_t prev_log = versions_->PrevLogNumber();
std::vector<std::string> filenames;
s = env_->GetChildren(options_.wal_dir, &filenames);
if (!s.ok()) {
return s;
}
uint64_t number;
FileType type;
std::vector<uint64_t> logs;
for (size_t i = 0; i < filenames.size(); i++) {
if (ParseFileName(filenames[i], &number, &type)
&& type == kLogFile
&& ((number >= min_log) || (number == prev_log))) {
logs.push_back(number);
}
}
if (logs.size() > 0 && error_if_log_file_exist) {
return Status::Corruption(""
"The db was opened in readonly mode with error_if_log_file_exist"
"flag but a log file already exists");
}
// Recover in the order in which the logs were generated
std::sort(logs.begin(), logs.end());
for (size_t i = 0; i < logs.size(); i++) {
s = RecoverLogFile(logs[i], edit, &max_sequence, external_table);
// The previous incarnation may not have written any MANIFEST
// records after allocating this log number. So we manually
// update the file number allocation counter in VersionSet.
versions_->MarkFileNumberUsed(logs[i]);
}
if (s.ok()) {
if (versions_->LastSequence() < max_sequence) {
versions_->SetLastSequence(max_sequence);
}
SetTickerCount(options_.statistics.get(), SEQUENCE_NUMBER,
versions_->LastSequence());
}
}
return s;
}
Status DBImpl::RecoverLogFile(uint64_t log_number,
VersionEdit* edit,
SequenceNumber* max_sequence,
MemTable* external_table) {
struct LogReporter : public log::Reader::Reporter {
Env* env;
Logger* info_log;
const char* fname;
Status* status; // nullptr if options_.paranoid_checks==false or
// options_.skip_log_error_on_recovery==true
virtual void Corruption(size_t bytes, const Status& s) {
Log(info_log, "%s%s: dropping %d bytes; %s",
(this->status == nullptr ? "(ignoring error) " : ""),
fname, static_cast<int>(bytes), s.ToString().c_str());
if (this->status != nullptr && this->status->ok()) *this->status = s;
}
};
mutex_.AssertHeld();
// Open the log file
std::string fname = LogFileName(options_.wal_dir, log_number);
unique_ptr<SequentialFile> file;
Status status = env_->NewSequentialFile(fname, &file, storage_options_);
if (!status.ok()) {
MaybeIgnoreError(&status);
return status;
}
// Create the log reader.
LogReporter reporter;
reporter.env = env_;
reporter.info_log = options_.info_log.get();
reporter.fname = fname.c_str();
reporter.status = (options_.paranoid_checks &&
!options_.skip_log_error_on_recovery ? &status : nullptr);
// We intentially make log::Reader do checksumming even if
// paranoid_checks==false so that corruptions cause entire commits
// to be skipped instead of propagating bad information (like overly
// large sequence numbers).
log::Reader reader(std::move(file), &reporter, true/*checksum*/,
0/*initial_offset*/);
Log(options_.info_log, "Recovering log #%lu",
(unsigned long) log_number);
// Read all the records and add to a memtable
std::string scratch;
Slice record;
WriteBatch batch;
MemTable* mem = nullptr;
if (external_table) {
mem = external_table;
}
while (reader.ReadRecord(&record, &scratch) && status.ok()) {
if (record.size() < 12) {
reporter.Corruption(
record.size(), Status::Corruption("log record too small"));
continue;
}
WriteBatchInternal::SetContents(&batch, record);
if (mem == nullptr) {
mem = new MemTable(internal_comparator_, mem_rep_factory_,
NumberLevels(), options_);
mem->Ref();
}
status = WriteBatchInternal::InsertInto(&batch, mem, &options_);
MaybeIgnoreError(&status);
if (!status.ok()) {
break;
}
const SequenceNumber last_seq =
WriteBatchInternal::Sequence(&batch) +
WriteBatchInternal::Count(&batch) - 1;
if (last_seq > *max_sequence) {
*max_sequence = last_seq;
}
if (!external_table &&
mem->ApproximateMemoryUsage() > options_.write_buffer_size) {
status = WriteLevel0TableForRecovery(mem, edit);
if (!status.ok()) {
// Reflect errors immediately so that conditions like full
// file-systems cause the DB::Open() to fail.
break;
}
delete mem->Unref();
mem = nullptr;
}
}
if (status.ok() && mem != nullptr && !external_table) {
status = WriteLevel0TableForRecovery(mem, edit);
// Reflect errors immediately so that conditions like full
// file-systems cause the DB::Open() to fail.
}
if (mem != nullptr && !external_table) {
delete mem->Unref();
}
return status;
}
Status DBImpl::WriteLevel0TableForRecovery(MemTable* mem, VersionEdit* edit) {
mutex_.AssertHeld();
const uint64_t start_micros = env_->NowMicros();
FileMetaData meta;
meta.number = versions_->NewFileNumber();
pending_outputs_.insert(meta.number);
Iterator* iter = mem->NewIterator();
const SequenceNumber newest_snapshot = snapshots_.GetNewest();
const SequenceNumber earliest_seqno_in_memtable =
mem->GetFirstSequenceNumber();
Log(options_.info_log, "Level-0 table #%lu: started",
(unsigned long) meta.number);
Status s;
{
mutex_.Unlock();
s = BuildTable(dbname_, env_, options_, storage_options_,
table_cache_.get(), iter, &meta,
user_comparator(), newest_snapshot,
earliest_seqno_in_memtable, true);
LogFlush(options_.info_log);
mutex_.Lock();
}
Log(options_.info_log, "Level-0 table #%lu: %lu bytes %s",
(unsigned long) meta.number,
(unsigned long) meta.file_size,
s.ToString().c_str());
delete iter;
pending_outputs_.erase(meta.number);
// Note that if file_size is zero, the file has been deleted and
// should not be added to the manifest.
int level = 0;
if (s.ok() && meta.file_size > 0) {
edit->AddFile(level, meta.number, meta.file_size,
meta.smallest, meta.largest,
meta.smallest_seqno, meta.largest_seqno);
}
CompactionStats stats;
stats.micros = env_->NowMicros() - start_micros;
stats.bytes_written = meta.file_size;
stats.files_out_levelnp1 = 1;
stats_[level].Add(stats);
return s;
}
Status DBImpl::WriteLevel0Table(std::vector<MemTable*> &mems, VersionEdit* edit,
uint64_t* filenumber) {
mutex_.AssertHeld();
const uint64_t start_micros = env_->NowMicros();
FileMetaData meta;
meta.number = versions_->NewFileNumber();
*filenumber = meta.number;
pending_outputs_.insert(meta.number);
const SequenceNumber newest_snapshot = snapshots_.GetNewest();
const SequenceNumber earliest_seqno_in_memtable =
mems[0]->GetFirstSequenceNumber();
Version* base = versions_->current();
base->Ref(); // it is likely that we do not need this reference
Status s;
{
mutex_.Unlock();
std::vector<Iterator*> list;
for (MemTable* m : mems) {
Log(options_.info_log,
"Flushing memtable with log file: %lu\n",
(unsigned long)m->GetLogNumber());
list.push_back(m->NewIterator());
}
Iterator* iter = NewMergingIterator(env_, &internal_comparator_, &list[0],
list.size());
Log(options_.info_log,
"Level-0 flush table #%lu: started",
(unsigned long)meta.number);
// We skip compression if universal compression is used and the size
// threshold is set for compression.
bool enable_compression = (options_.compaction_style
!= kCompactionStyleUniversal ||
options_.compaction_options_universal.compression_size_percent < 0);
s = BuildTable(dbname_, env_, options_, storage_options_,
table_cache_.get(), iter, &meta,
user_comparator(), newest_snapshot,
earliest_seqno_in_memtable, enable_compression);
LogFlush(options_.info_log);
delete iter;
Log(options_.info_log, "Level-0 flush table #%lu: %lu bytes %s",
(unsigned long) meta.number,
(unsigned long) meta.file_size,
s.ToString().c_str());
mutex_.Lock();
}
base->Unref();
// re-acquire the most current version
base = versions_->current();
// There could be multiple threads writing to its own level-0 file.
// The pending_outputs cannot be cleared here, otherwise this newly
// created file might not be considered as a live-file by another
// compaction thread that is concurrently deleting obselete files.
// The pending_outputs can be cleared only after the new version is
// committed so that other threads can recognize this file as a
// valid one.
// pending_outputs_.erase(meta.number);
// Note that if file_size is zero, the file has been deleted and
// should not be added to the manifest.
int level = 0;
if (s.ok() && meta.file_size > 0) {
const Slice min_user_key = meta.smallest.user_key();
const Slice max_user_key = meta.largest.user_key();
// if we have more than 1 background thread, then we cannot
// insert files directly into higher levels because some other
// threads could be concurrently producing compacted files for
// that key range.
if (base != nullptr && options_.max_background_compactions <= 1 &&
options_.compaction_style == kCompactionStyleLevel) {
level = base->PickLevelForMemTableOutput(min_user_key, max_user_key);
}
edit->AddFile(level, meta.number, meta.file_size,
meta.smallest, meta.largest,
meta.smallest_seqno, meta.largest_seqno);
}
CompactionStats stats;
stats.micros = env_->NowMicros() - start_micros;
stats.bytes_written = meta.file_size;
stats_[level].Add(stats);
return s;
}
Status DBImpl::FlushMemTableToOutputFile(bool* madeProgress,
DeletionState& deletion_state) {
mutex_.AssertHeld();
assert(imm_.size() != 0);
if (!imm_.IsFlushPending(options_.min_write_buffer_number_to_merge)) {
Log(options_.info_log, "FlushMemTableToOutputFile already in progress");
Status s = Status::IOError("FlushMemTableToOutputFile already in progress");
return s;
}
// Save the contents of the earliest memtable as a new Table
uint64_t file_number;
std::vector<MemTable*> mems;
imm_.PickMemtablesToFlush(&mems);
if (mems.empty()) {
Log(options_.info_log, "Nothing in memstore to flush");
Status s = Status::IOError("Nothing in memstore to flush");
return s;
}
// record the logfile_number_ before we release the mutex
// entries mems are (implicitly) sorted in ascending order by their created
// time. We will use the first memtable's `edit` to keep the meta info for
// this flush.
MemTable* m = mems[0];
VersionEdit* edit = m->GetEdits();
edit->SetPrevLogNumber(0);
// SetLogNumber(log_num) indicates logs with number smaller than log_num
// will no longer be picked up for recovery.
edit->SetLogNumber(
mems.back()->GetNextLogNumber()
);
std::vector<uint64_t> logs_to_delete;
for (auto mem : mems) {
logs_to_delete.push_back(mem->GetLogNumber());
}
// This will release and re-acquire the mutex.
Status s = WriteLevel0Table(mems, edit, &file_number);
if (s.ok() && shutting_down_.Acquire_Load()) {
s = Status::IOError(
"Database shutdown started during memtable compaction"
);
}
// Replace immutable memtable with the generated Table
s = imm_.InstallMemtableFlushResults(
mems, versions_.get(), s, &mutex_, options_.info_log.get(),
file_number, pending_outputs_, &deletion_state.memtables_to_free);
if (s.ok()) {
if (madeProgress) {
*madeProgress = 1;
}
MaybeScheduleLogDBDeployStats();
if (!disable_delete_obsolete_files_) {
// add to deletion state
deletion_state.log_delete_files.insert(
deletion_state.log_delete_files.end(),
logs_to_delete.begin(),
logs_to_delete.end());
}
}
return s;
}
void DBImpl::CompactRange(const Slice* begin, const Slice* end,
bool reduce_level, int target_level) {
int max_level_with_files = 1;
{
MutexLock l(&mutex_);
Version* base = versions_->current();
for (int level = 1; level < NumberLevels(); level++) {
if (base->OverlapInLevel(level, begin, end)) {
max_level_with_files = level;
}
}
}
TEST_FlushMemTable(); // TODO(sanjay): Skip if memtable does not overlap
for (int level = 0; level < max_level_with_files; level++) {
TEST_CompactRange(level, begin, end);
}
if (reduce_level) {
ReFitLevel(max_level_with_files, target_level);
}
LogFlush(options_.info_log);
}
// return the same level if it cannot be moved
int DBImpl::FindMinimumEmptyLevelFitting(int level) {
mutex_.AssertHeld();
int minimum_level = level;
for (int i = level - 1; i > 0; --i) {
// stop if level i is not empty
if (versions_->NumLevelFiles(i) > 0) break;
// stop if level i is too small (cannot fit the level files)
if (versions_->MaxBytesForLevel(i) < versions_->NumLevelBytes(level)) break;
minimum_level = i;
}
return minimum_level;
}
void DBImpl::ReFitLevel(int level, int target_level) {
assert(level < NumberLevels());
MutexLock l(&mutex_);
// only allow one thread refitting
if (refitting_level_) {
Log(options_.info_log, "ReFitLevel: another thread is refitting");
return;
}
refitting_level_ = true;
// wait for all background threads to stop
bg_work_gate_closed_ = true;
while (bg_compaction_scheduled_ > 0 || bg_flush_scheduled_) {
Log(options_.info_log,
"RefitLevel: waiting for background threads to stop: %d %d",
bg_compaction_scheduled_, bg_flush_scheduled_);
bg_cv_.Wait();
}
// move to a smaller level
int to_level = target_level;
if (target_level < 0) {
to_level = FindMinimumEmptyLevelFitting(level);
}
assert(to_level <= level);
if (to_level < level) {
Log(options_.info_log, "Before refitting:\n%s",
versions_->current()->DebugString().data());
VersionEdit edit(NumberLevels());
for (const auto& f : versions_->current()->files_[level]) {
edit.DeleteFile(level, f->number);
edit.AddFile(to_level, f->number, f->file_size, f->smallest, f->largest,
f->smallest_seqno, f->largest_seqno);
}
Log(options_.info_log, "Apply version edit:\n%s",
edit.DebugString().data());
auto status = versions_->LogAndApply(&edit, &mutex_);
Log(options_.info_log, "LogAndApply: %s\n", status.ToString().data());
if (status.ok()) {
Log(options_.info_log, "After refitting:\n%s",
versions_->current()->DebugString().data());
}
}
refitting_level_ = false;
bg_work_gate_closed_ = false;
}
int DBImpl::NumberLevels() {
return options_.num_levels;
}
int DBImpl::MaxMemCompactionLevel() {
return options_.max_mem_compaction_level;
}
int DBImpl::Level0StopWriteTrigger() {
return options_.level0_stop_writes_trigger;
}
Status DBImpl::Flush(const FlushOptions& options) {
Status status = FlushMemTable(options);
return status;
}
SequenceNumber DBImpl::GetLatestSequenceNumber() const {
return versions_->LastSequence();
}
Status DBImpl::GetUpdatesSince(SequenceNumber seq,
unique_ptr<TransactionLogIterator>* iter) {
RecordTick(options_.statistics.get(), GET_UPDATES_SINCE_CALLS);
if (seq > versions_->LastSequence()) {
return Status::IOError("Requested sequence not yet written in the db");
}
// Get all sorted Wal Files.
// Do binary search and open files and find the seq number.
std::unique_ptr<VectorLogPtr> wal_files(new VectorLogPtr);
Status s = GetSortedWalFiles(*wal_files);
if (!s.ok()) {
return s;
}
s = RetainProbableWalFiles(*wal_files, seq);
if (!s.ok()) {
return s;
}
iter->reset(
new TransactionLogIteratorImpl(options_.wal_dir,
&options_,
storage_options_,
seq,
std::move(wal_files),
this));
return (*iter)->status();
}
Status DBImpl::RetainProbableWalFiles(VectorLogPtr& all_logs,
const SequenceNumber target) {
long start = 0; // signed to avoid overflow when target is < first file.
long end = static_cast<long>(all_logs.size()) - 1;
// Binary Search. avoid opening all files.
while (end >= start) {
long mid = start + (end - start) / 2; // Avoid overflow.
SequenceNumber current_seq_num = all_logs.at(mid)->StartSequence();
if (current_seq_num == target) {
end = mid;
break;
} else if (current_seq_num < target) {
start = mid + 1;
} else {
end = mid - 1;
}
}
size_t start_index = std::max(0l, end); // end could be -ve.
// The last wal file is always included
all_logs.erase(all_logs.begin(), all_logs.begin() + start_index);
return Status::OK();
}
bool DBImpl::CheckWalFileExistsAndEmpty(const WalFileType type,
const uint64_t number) {
const std::string fname = (type == kAliveLogFile) ?
LogFileName(options_.wal_dir, number) :
ArchivedLogFileName(options_.wal_dir, number);
uint64_t file_size;
Status s = env_->GetFileSize(fname, &file_size);
return (s.ok() && (file_size == 0));
}
Status DBImpl::ReadFirstRecord(const WalFileType type, const uint64_t number,
WriteBatch* const result) {
if (type == kAliveLogFile) {
std::string fname = LogFileName(options_.wal_dir, number);
Status status = ReadFirstLine(fname, result);
if (!status.ok()) {
// check if the file got moved to archive.
std::string archived_file =
ArchivedLogFileName(options_.wal_dir, number);
Status s = ReadFirstLine(archived_file, result);
if (!s.ok()) {
return Status::IOError("Log File has been deleted: " + archived_file);
}
}
return Status::OK();
} else if (type == kArchivedLogFile) {
std::string fname = ArchivedLogFileName(options_.wal_dir, number);
Status status = ReadFirstLine(fname, result);
return status;
}
return Status::NotSupported("File Type Not Known: " + std::to_string(type));
}
Status DBImpl::ReadFirstLine(const std::string& fname,
WriteBatch* const batch) {
struct LogReporter : public log::Reader::Reporter {
Env* env;
Logger* info_log;
const char* fname;
Status* status; // nullptr if options_.paranoid_checks==false
virtual void Corruption(size_t bytes, const Status& s) {
Log(info_log, "%s%s: dropping %d bytes; %s",
(this->status == nullptr ? "(ignoring error) " : ""),
fname, static_cast<int>(bytes), s.ToString().c_str());
if (this->status != nullptr && this->status->ok()) *this->status = s;
}
};
unique_ptr<SequentialFile> file;
Status status = env_->NewSequentialFile(fname, &file, storage_options_);
if (!status.ok()) {
return status;
}
LogReporter reporter;
reporter.env = env_;
reporter.info_log = options_.info_log.get();
reporter.fname = fname.c_str();
reporter.status = (options_.paranoid_checks ? &status : nullptr);
log::Reader reader(std::move(file), &reporter, true/*checksum*/,
0/*initial_offset*/);
std::string scratch;
Slice record;
if (reader.ReadRecord(&record, &scratch) && status.ok()) {
if (record.size() < 12) {
reporter.Corruption(
record.size(), Status::Corruption("log record too small"));
return Status::IOError("Corruption noted");
// TODO read record's till the first no corrupt entry?
}
WriteBatchInternal::SetContents(batch, record);
return Status::OK();
}
return Status::IOError("Error reading from file " + fname);
}
struct CompareLogByPointer {
bool operator() (const unique_ptr<LogFile>& a,
const unique_ptr<LogFile>& b) {
LogFileImpl* a_impl = dynamic_cast<LogFileImpl*>(a.get());
LogFileImpl* b_impl = dynamic_cast<LogFileImpl*>(b.get());
return *a_impl < *b_impl;
}
};
Status DBImpl::AppendSortedWalsOfType(const std::string& path,
VectorLogPtr& log_files, WalFileType log_type) {
std::vector<std::string> all_files;
const Status status = env_->GetChildren(path, &all_files);
if (!status.ok()) {
return status;
}
log_files.reserve(log_files.size() + all_files.size());
VectorLogPtr::iterator pos_start;
if (!log_files.empty()) {
pos_start = log_files.end() - 1;
} else {
pos_start = log_files.begin();
}
for (const auto& f : all_files) {
uint64_t number;
FileType type;
if (ParseFileName(f, &number, &type) && type == kLogFile){
WriteBatch batch;
Status s = ReadFirstRecord(log_type, number, &batch);
if (!s.ok()) {
if (CheckWalFileExistsAndEmpty(log_type, number)) {
continue;
}
return s;
}
uint64_t size_bytes;
s = env_->GetFileSize(LogFileName(path, number), &size_bytes);
if (!s.ok()) {
return s;
}
log_files.push_back(std::move(unique_ptr<LogFile>(new LogFileImpl(
number, log_type, WriteBatchInternal::Sequence(&batch), size_bytes))));
}
}
CompareLogByPointer compare_log_files;
std::sort(pos_start, log_files.end(), compare_log_files);
return status;
}
void DBImpl::TEST_CompactRange(int level, const Slice* begin,const Slice* end) {
assert(level >= 0);
InternalKey begin_storage, end_storage;
ManualCompaction manual;
manual.level = level;
manual.done = false;
manual.in_progress = false;
// For universal compaction, we enforce every manual compaction to compact
// all files.
if (begin == nullptr ||
options_.compaction_style == kCompactionStyleUniversal) {
manual.begin = nullptr;
} else {
begin_storage = InternalKey(*begin, kMaxSequenceNumber, kValueTypeForSeek);
manual.begin = &begin_storage;
}
if (end == nullptr ||
options_.compaction_style == kCompactionStyleUniversal) {
manual.end = nullptr;
} else {
end_storage = InternalKey(*end, 0, static_cast<ValueType>(0));
manual.end = &end_storage;
}
MutexLock l(&mutex_);
// When a manual compaction arrives, temporarily throttle down
// the number of background compaction threads to 1. This is
// needed to ensure that this manual compaction can compact
// any range of keys/files. We artificialy increase
// bg_compaction_scheduled_ by a large number, this causes
// the system to have a single background thread. Now,
// this manual compaction can progress without stomping
// on any other concurrent compactions.
const int LargeNumber = 10000000;
const int newvalue = options_.max_background_compactions-1;
bg_compaction_scheduled_ += LargeNumber;
while (bg_compaction_scheduled_ > LargeNumber) {
Log(options_.info_log, "Manual compaction request waiting for background threads to fall below 1");
bg_cv_.Wait();
}
Log(options_.info_log, "Manual compaction starting");
while (!manual.done) {
while (manual_compaction_ != nullptr) {
bg_cv_.Wait();
}
manual_compaction_ = &manual;
if (bg_compaction_scheduled_ == LargeNumber) {
bg_compaction_scheduled_ = newvalue;
}
MaybeScheduleFlushOrCompaction();
while (manual_compaction_ == &manual) {
bg_cv_.Wait();
}
}
assert(!manual.in_progress);
// wait till there are no background threads scheduled
bg_compaction_scheduled_ += LargeNumber;
while (bg_compaction_scheduled_ > LargeNumber + newvalue) {
Log(options_.info_log, "Manual compaction resetting background threads");
bg_cv_.Wait();
}
bg_compaction_scheduled_ = 0;
}
Status DBImpl::FlushMemTable(const FlushOptions& options) {
// nullptr batch means just wait for earlier writes to be done
Status s = Write(WriteOptions(), nullptr);
if (s.ok() && options.wait) {
// Wait until the compaction completes
s = WaitForFlushMemTable();
}
return s;
}
Status DBImpl::WaitForFlushMemTable() {
Status s;
// Wait until the compaction completes
MutexLock l(&mutex_);
while (imm_.size() > 0 && bg_error_.ok()) {
bg_cv_.Wait();
}
if (imm_.size() != 0) {
s = bg_error_;
}
return s;
}
Status DBImpl::TEST_FlushMemTable() {
return FlushMemTable(FlushOptions());
}
Status DBImpl::TEST_WaitForFlushMemTable() {
return WaitForFlushMemTable();
}
Status DBImpl::TEST_WaitForCompact() {
// Wait until the compaction completes
// TODO: a bug here. This function actually does not necessarily
// wait for compact. It actually waits for scheduled compaction
// OR flush to finish.
MutexLock l(&mutex_);
while ((bg_compaction_scheduled_ || bg_flush_scheduled_) &&
bg_error_.ok()) {
bg_cv_.Wait();
}
return bg_error_;
}
void DBImpl::MaybeScheduleFlushOrCompaction() {
mutex_.AssertHeld();
if (bg_work_gate_closed_) {
// gate closed for backgrond work
} else if (shutting_down_.Acquire_Load()) {
// DB is being deleted; no more background compactions
} else {
bool is_flush_pending =
imm_.IsFlushPending(options_.min_write_buffer_number_to_merge);
if (is_flush_pending &&
(bg_flush_scheduled_ < options_.max_background_flushes)) {
// memtable flush needed
bg_flush_scheduled_++;
env_->Schedule(&DBImpl::BGWorkFlush, this, Env::Priority::HIGH);
}
if ((manual_compaction_ ||
versions_->NeedsCompaction() ||
(is_flush_pending && (options_.max_background_flushes <= 0))) &&
bg_compaction_scheduled_ < options_.max_background_compactions) {
// compaction needed, or memtable flush needed but HIGH pool not enabled.
bg_compaction_scheduled_++;
env_->Schedule(&DBImpl::BGWorkCompaction, this, Env::Priority::LOW);
}
}
}
void DBImpl::BGWorkFlush(void* db) {
reinterpret_cast<DBImpl*>(db)->BackgroundCallFlush();
}
void DBImpl::BGWorkCompaction(void* db) {
reinterpret_cast<DBImpl*>(db)->BackgroundCallCompaction();
}
Status DBImpl::BackgroundFlush(bool* madeProgress,
DeletionState& deletion_state) {
Status stat;
while (stat.ok() &&
imm_.IsFlushPending(options_.min_write_buffer_number_to_merge)) {
Log(options_.info_log,
"BackgroundCallFlush doing FlushMemTableToOutputFile, flush slots available %d",
options_.max_background_flushes - bg_flush_scheduled_);
stat = FlushMemTableToOutputFile(madeProgress, deletion_state);
}
return stat;
}
void DBImpl::BackgroundCallFlush() {
bool madeProgress = false;
DeletionState deletion_state(options_.max_write_buffer_number);
assert(bg_flush_scheduled_);
MutexLock l(&mutex_);
Status s;
if (!shutting_down_.Acquire_Load()) {
s = BackgroundFlush(&madeProgress, deletion_state);
if (!s.ok()) {
// Wait a little bit before retrying background compaction in
// case this is an environmental problem and we do not want to
// chew up resources for failed compactions for the duration of
// the problem.
bg_cv_.SignalAll(); // In case a waiter can proceed despite the error
Log(options_.info_log, "Waiting after background flush error: %s",
s.ToString().c_str());
mutex_.Unlock();
LogFlush(options_.info_log);
env_->SleepForMicroseconds(1000000);
mutex_.Lock();
}
}
// If !s.ok(), this means that Flush failed. In that case, we want
// to delete all obsolete files and we force FindObsoleteFiles()
FindObsoleteFiles(deletion_state, !s.ok());
// delete unnecessary files if any, this is done outside the mutex
if (deletion_state.HaveSomethingToDelete()) {
mutex_.Unlock();
PurgeObsoleteFiles(deletion_state);
mutex_.Lock();
}
bg_flush_scheduled_--;
if (madeProgress) {
MaybeScheduleFlushOrCompaction();
}
bg_cv_.SignalAll();
}
void DBImpl::TEST_PurgeObsoleteteWAL() {
PurgeObsoleteWALFiles();
}
void DBImpl::BackgroundCallCompaction() {
bool madeProgress = false;
DeletionState deletion_state(options_.max_write_buffer_number);
MaybeDumpStats();
MutexLock l(&mutex_);
// Log(options_.info_log, "XXX BG Thread %llx process new work item", pthread_self());
assert(bg_compaction_scheduled_);
Status s;
if (!shutting_down_.Acquire_Load()) {
s = BackgroundCompaction(&madeProgress, deletion_state);
if (!s.ok()) {
// Wait a little bit before retrying background compaction in
// case this is an environmental problem and we do not want to
// chew up resources for failed compactions for the duration of
// the problem.
bg_cv_.SignalAll(); // In case a waiter can proceed despite the error
Log(options_.info_log, "Waiting after background compaction error: %s",
s.ToString().c_str());
mutex_.Unlock();
LogFlush(options_.info_log);
env_->SleepForMicroseconds(1000000);
mutex_.Lock();
}
}
// If !s.ok(), this means that Compaction failed. In that case, we want
// to delete all obsolete files we might have created and we force
// FindObsoleteFiles(). This is because deletion_state does not catch
// all created files if compaction failed.
FindObsoleteFiles(deletion_state, !s.ok());
// delete unnecessary files if any, this is done outside the mutex
if (deletion_state.HaveSomethingToDelete()) {
mutex_.Unlock();
PurgeObsoleteFiles(deletion_state);
mutex_.Lock();
}
bg_compaction_scheduled_--;
MaybeScheduleLogDBDeployStats();
// Previous compaction may have produced too many files in a level,
// So reschedule another compaction if we made progress in the
// last compaction.
if (madeProgress) {
MaybeScheduleFlushOrCompaction();
}
bg_cv_.SignalAll();
}
Status DBImpl::BackgroundCompaction(bool* madeProgress,
DeletionState& deletion_state) {
*madeProgress = false;
mutex_.AssertHeld();
// TODO: remove memtable flush from formal compaction
while (imm_.IsFlushPending(options_.min_write_buffer_number_to_merge)) {
Log(options_.info_log,
"BackgroundCompaction doing FlushMemTableToOutputFile, compaction slots "
"available %d",
options_.max_background_compactions - bg_compaction_scheduled_);
Status stat = FlushMemTableToOutputFile(madeProgress, deletion_state);
if (!stat.ok()) {
return stat;
}
}
unique_ptr<Compaction> c;
bool is_manual = (manual_compaction_ != nullptr) &&
(manual_compaction_->in_progress == false);
InternalKey manual_end;
if (is_manual) {
ManualCompaction* m = manual_compaction_;
assert(!m->in_progress);
m->in_progress = true; // another thread cannot pick up the same work
c.reset(versions_->CompactRange(m->level, m->begin, m->end));
if (c) {
manual_end = c->input(0, c->num_input_files(0) - 1)->largest;
} else {
m->done = true;
}
Log(options_.info_log,
"Manual compaction at level-%d from %s .. %s; will stop at %s\n",
m->level,
(m->begin ? m->begin->DebugString().c_str() : "(begin)"),
(m->end ? m->end->DebugString().c_str() : "(end)"),
(m->done ? "(end)" : manual_end.DebugString().c_str()));
} else if (!options_.disable_auto_compactions) {
c.reset(versions_->PickCompaction());
}
Status status;
if (!c) {
// Nothing to do
Log(options_.info_log, "Compaction nothing to do");
} else if (!is_manual && c->IsTrivialMove()) {
// Move file to next level
assert(c->num_input_files(0) == 1);
FileMetaData* f = c->input(0, 0);
c->edit()->DeleteFile(c->level(), f->number);
c->edit()->AddFile(c->level() + 1, f->number, f->file_size,
f->smallest, f->largest,
f->smallest_seqno, f->largest_seqno);
status = versions_->LogAndApply(c->edit(), &mutex_);
VersionSet::LevelSummaryStorage tmp;
Log(options_.info_log, "Moved #%lld to level-%d %lld bytes %s: %s\n",
static_cast<unsigned long long>(f->number),
c->level() + 1,
static_cast<unsigned long long>(f->file_size),
status.ToString().c_str(),
versions_->LevelSummary(&tmp));
versions_->ReleaseCompactionFiles(c.get(), status);
*madeProgress = true;
} else {
MaybeScheduleFlushOrCompaction(); // do more compaction work in parallel.
CompactionState* compact = new CompactionState(c.get());
status = DoCompactionWork(compact, deletion_state);
CleanupCompaction(compact, status);
versions_->ReleaseCompactionFiles(c.get(), status);
c->ReleaseInputs();
*madeProgress = true;
}
c.reset();
if (status.ok()) {
// Done
} else if (shutting_down_.Acquire_Load()) {
// Ignore compaction errors found during shutting down
} else {
Log(options_.info_log,
"Compaction error: %s", status.ToString().c_str());
if (options_.paranoid_checks && bg_error_.ok()) {
bg_error_ = status;
}
}
if (is_manual) {
ManualCompaction* m = manual_compaction_;
if (!status.ok()) {
m->done = true;
}
// For universal compaction:
// Because universal compaction always happens at level 0, so one
// compaction will pick up all overlapped files. No files will be
// filtered out due to size limit and left for a successive compaction.
// So we can safely conclude the current compaction.
//
// Also note that, if we don't stop here, then the current compaction
// writes a new file back to level 0, which will be used in successive
// compaction. Hence the manual compaction will never finish.
if (options_.compaction_style == kCompactionStyleUniversal) {
m->done = true;
}
if (!m->done) {
// We only compacted part of the requested range. Update *m
// to the range that is left to be compacted.
m->tmp_storage = manual_end;
m->begin = &m->tmp_storage;
}
m->in_progress = false; // not being processed anymore
manual_compaction_ = nullptr;
}
return status;
}
void DBImpl::CleanupCompaction(CompactionState* compact, Status status) {
mutex_.AssertHeld();
if (compact->builder != nullptr) {
// May happen if we get a shutdown call in the middle of compaction
compact->builder->Abandon();
compact->builder.reset();
} else {
assert(compact->outfile == nullptr);
}
for (size_t i = 0; i < compact->outputs.size(); i++) {
const CompactionState::Output& out = compact->outputs[i];
pending_outputs_.erase(out.number);
// If this file was inserted into the table cache then remove
// them here because this compaction was not committed.
if (!status.ok()) {
table_cache_->Evict(out.number);
}
}
delete compact;
}
// Allocate the file numbers for the output file. We allocate as
// many output file numbers as there are files in level+1.
// Insert them into pending_outputs so that they do not get deleted.
void DBImpl::AllocateCompactionOutputFileNumbers(CompactionState* compact) {
mutex_.AssertHeld();
assert(compact != nullptr);
assert(compact->builder == nullptr);
int filesNeeded = compact->compaction->num_input_files(1);
for (int i = 0; i < filesNeeded; i++) {
uint64_t file_number = versions_->NewFileNumber();
pending_outputs_.insert(file_number);
compact->allocated_file_numbers.push_back(file_number);
}
}
// Frees up unused file number.
void DBImpl::ReleaseCompactionUnusedFileNumbers(CompactionState* compact) {
mutex_.AssertHeld();
for (const auto file_number : compact->allocated_file_numbers) {
pending_outputs_.erase(file_number);
// Log(options_.info_log, "XXX releasing unused file num %d", file_number);
}
}
Status DBImpl::OpenCompactionOutputFile(CompactionState* compact) {
assert(compact != nullptr);
assert(compact->builder == nullptr);
uint64_t file_number;
// If we have not yet exhausted the pre-allocated file numbers,
// then use the one from the front. Otherwise, we have to acquire
// the heavyweight lock and allocate a new file number.
if (!compact->allocated_file_numbers.empty()) {
file_number = compact->allocated_file_numbers.front();
compact->allocated_file_numbers.pop_front();
} else {
mutex_.Lock();
file_number = versions_->NewFileNumber();
pending_outputs_.insert(file_number);
mutex_.Unlock();
}
CompactionState::Output out;
out.number = file_number;
out.smallest.Clear();
out.largest.Clear();
out.smallest_seqno = out.largest_seqno = 0;
compact->outputs.push_back(out);
// Make the output file
std::string fname = TableFileName(dbname_, file_number);
Status s = env_->NewWritableFile(fname, &compact->outfile, storage_options_);
if (s.ok()) {
// Over-estimate slightly so we don't end up just barely crossing
// the threshold.
compact->outfile->SetPreallocationBlockSize(
1.1 * versions_->MaxFileSizeForLevel(compact->compaction->output_level()));
CompressionType compression_type = GetCompressionType(
options_, compact->compaction->output_level(),
compact->compaction->enable_compression());
compact->builder.reset(
GetTableBuilder(options_, compact->outfile.get(), compression_type));
}
LogFlush(options_.info_log);
return s;
}
Status DBImpl::FinishCompactionOutputFile(CompactionState* compact,
Iterator* input) {
assert(compact != nullptr);
assert(compact->outfile);
assert(compact->builder != nullptr);
const uint64_t output_number = compact->current_output()->number;
assert(output_number != 0);
// Check for iterator errors
Status s = input->status();
const uint64_t current_entries = compact->builder->NumEntries();
if (s.ok()) {
s = compact->builder->Finish();
} else {
compact->builder->Abandon();
}
const uint64_t current_bytes = compact->builder->FileSize();
compact->current_output()->file_size = current_bytes;
compact->total_bytes += current_bytes;
compact->builder.reset();
// Finish and check for file errors
if (s.ok() && !options_.disableDataSync) {
if (options_.use_fsync) {
StopWatch sw(env_, options_.statistics.get(),
COMPACTION_OUTFILE_SYNC_MICROS);
s = compact->outfile->Fsync();
} else {
StopWatch sw(env_, options_.statistics.get(),
COMPACTION_OUTFILE_SYNC_MICROS);
s = compact->outfile->Sync();
}
}
if (s.ok()) {
s = compact->outfile->Close();
}
compact->outfile.reset();
if (s.ok() && current_entries > 0) {
// Verify that the table is usable
Iterator* iter = table_cache_->NewIterator(ReadOptions(),
storage_options_,
output_number,
current_bytes);
s = iter->status();
delete iter;
if (s.ok()) {
Log(options_.info_log,
"Generated table #%lu: %lu keys, %lu bytes",
(unsigned long) output_number,
(unsigned long) current_entries,
(unsigned long) current_bytes);
}
}
return s;
}
Status DBImpl::InstallCompactionResults(CompactionState* compact) {
mutex_.AssertHeld();
// paranoia: verify that the files that we started with
// still exist in the current version and in the same original level.
// This ensures that a concurrent compaction did not erroneously
// pick the same files to compact.
if (!versions_->VerifyCompactionFileConsistency(compact->compaction)) {
Log(options_.info_log, "Compaction %d@%d + %d@%d files aborted",
compact->compaction->num_input_files(0),
compact->compaction->level(),
compact->compaction->num_input_files(1),
compact->compaction->level() + 1);
return Status::IOError("Compaction input files inconsistent");
}
Log(options_.info_log, "Compacted %d@%d + %d@%d files => %lld bytes",
compact->compaction->num_input_files(0),
compact->compaction->level(),
compact->compaction->num_input_files(1),
compact->compaction->level() + 1,
static_cast<long long>(compact->total_bytes));
// Add compaction outputs
compact->compaction->AddInputDeletions(compact->compaction->edit());
const int level = compact->compaction->level();
for (size_t i = 0; i < compact->outputs.size(); i++) {
const CompactionState::Output& out = compact->outputs[i];
compact->compaction->edit()->AddFile(
(options_.compaction_style == kCompactionStyleUniversal) ?
level : level + 1,
out.number, out.file_size, out.smallest, out.largest,
out.smallest_seqno, out.largest_seqno);
}
return versions_->LogAndApply(compact->compaction->edit(), &mutex_);
}
//
// Given a sequence number, return the sequence number of the
// earliest snapshot that this sequence number is visible in.
// The snapshots themselves are arranged in ascending order of
// sequence numbers.
// Employ a sequential search because the total number of
// snapshots are typically small.
inline SequenceNumber DBImpl::findEarliestVisibleSnapshot(
SequenceNumber in, std::vector<SequenceNumber>& snapshots,
SequenceNumber* prev_snapshot) {
SequenceNumber prev __attribute__((unused)) = 0;
for (const auto cur : snapshots) {
assert(prev <= cur);
if (cur >= in) {
*prev_snapshot = prev;
return cur;
}
prev = cur; // assignment
assert(prev);
}
Log(options_.info_log,
"Looking for seqid %lu but maxseqid is %lu",
(unsigned long)in,
(unsigned long)snapshots[snapshots.size()-1]);
assert(0);
return 0;
}
Status DBImpl::DoCompactionWork(CompactionState* compact,
DeletionState& deletion_state) {
assert(compact);
int64_t imm_micros = 0; // Micros spent doing imm_ compactions
Log(options_.info_log,
"Compacting %d@%d + %d@%d files, score %.2f slots available %d",
compact->compaction->num_input_files(0),
compact->compaction->level(),
compact->compaction->num_input_files(1),
compact->compaction->level() + 1,
compact->compaction->score(),
options_.max_background_compactions - bg_compaction_scheduled_);
char scratch[256];
compact->compaction->Summary(scratch, sizeof(scratch));
Log(options_.info_log, "Compaction start summary: %s\n", scratch);
assert(versions_->NumLevelFiles(compact->compaction->level()) > 0);
assert(compact->builder == nullptr);
assert(!compact->outfile);
SequenceNumber visible_at_tip = 0;
SequenceNumber earliest_snapshot;
SequenceNumber latest_snapshot = 0;
snapshots_.getAll(compact->existing_snapshots);
if (compact->existing_snapshots.size() == 0) {
// optimize for fast path if there are no snapshots
visible_at_tip = versions_->LastSequence();
earliest_snapshot = visible_at_tip;
} else {
latest_snapshot = compact->existing_snapshots.back();
// Add the current seqno as the 'latest' virtual
// snapshot to the end of this list.
compact->existing_snapshots.push_back(versions_->LastSequence());
earliest_snapshot = compact->existing_snapshots[0];
}
// Is this compaction producing files at the bottommost level?
bool bottommost_level = compact->compaction->BottomMostLevel();
// Allocate the output file numbers before we release the lock
AllocateCompactionOutputFileNumbers(compact);
// Release mutex while we're actually doing the compaction work
mutex_.Unlock();
const uint64_t start_micros = env_->NowMicros();
unique_ptr<Iterator> input(versions_->MakeInputIterator(compact->compaction));
input->SeekToFirst();
Status status;
ParsedInternalKey ikey;
std::string current_user_key;
bool has_current_user_key = false;
SequenceNumber last_sequence_for_key __attribute__((unused)) =
kMaxSequenceNumber;
SequenceNumber visible_in_snapshot = kMaxSequenceNumber;
std::string compaction_filter_value;
std::vector<char> delete_key; // for compaction filter
MergeHelper merge(user_comparator(), options_.merge_operator.get(),
options_.info_log.get(),
false /* internal key corruption is expected */);
auto compaction_filter = options_.compaction_filter;
std::unique_ptr<CompactionFilter> compaction_filter_from_factory = nullptr;
if (!compaction_filter) {
auto context = compact->GetFilterContext();
compaction_filter_from_factory =
options_.compaction_filter_factory->CreateCompactionFilter(context);
compaction_filter = compaction_filter_from_factory.get();
}
for (; input->Valid() && !shutting_down_.Acquire_Load(); ) {
// Prioritize immutable compaction work
// TODO: remove memtable flush from normal compaction work
if (imm_.imm_flush_needed.NoBarrier_Load() != nullptr) {
const uint64_t imm_start = env_->NowMicros();
LogFlush(options_.info_log);
mutex_.Lock();
if (imm_.IsFlushPending(options_.min_write_buffer_number_to_merge)) {
FlushMemTableToOutputFile(nullptr, deletion_state);
bg_cv_.SignalAll(); // Wakeup MakeRoomForWrite() if necessary
}
mutex_.Unlock();
imm_micros += (env_->NowMicros() - imm_start);
}
Slice key = input->key();
Slice value = input->value();
if (compact->compaction->ShouldStopBefore(key) &&
compact->builder != nullptr) {
status = FinishCompactionOutputFile(compact, input.get());
if (!status.ok()) {
break;
}
}
// Handle key/value, add to state, etc.
bool drop = false;
bool current_entry_is_merging = false;
if (!ParseInternalKey(key, &ikey)) {
// Do not hide error keys
// TODO: error key stays in db forever? Figure out the intention/rationale
// v10 error v8 : we cannot hide v8 even though it's pretty obvious.
current_user_key.clear();
has_current_user_key = false;
last_sequence_for_key = kMaxSequenceNumber;
visible_in_snapshot = kMaxSequenceNumber;
} else {
if (!has_current_user_key ||
user_comparator()->Compare(ikey.user_key,
Slice(current_user_key)) != 0) {
// First occurrence of this user key
current_user_key.assign(ikey.user_key.data(), ikey.user_key.size());
has_current_user_key = true;
last_sequence_for_key = kMaxSequenceNumber;
visible_in_snapshot = kMaxSequenceNumber;
// apply the compaction filter to the first occurrence of the user key
if (compaction_filter &&
ikey.type == kTypeValue &&
(visible_at_tip || ikey.sequence > latest_snapshot)) {
// If the user has specified a compaction filter and the sequence
// number is greater than any external snapshot, then invoke the
// filter.
// If the return value of the compaction filter is true, replace
// the entry with a delete marker.
bool value_changed = false;
compaction_filter_value.clear();
bool to_delete =
compaction_filter->Filter(compact->compaction->level(),
ikey.user_key, value,
&compaction_filter_value,
&value_changed);
if (to_delete) {
// make a copy of the original key
delete_key.assign(key.data(), key.data() + key.size());
// convert it to a delete
UpdateInternalKey(&delete_key[0], delete_key.size(),
ikey.sequence, kTypeDeletion);
// anchor the key again
key = Slice(&delete_key[0], delete_key.size());
// needed because ikey is backed by key
ParseInternalKey(key, &ikey);
// no value associated with delete
value.clear();
RecordTick(options_.statistics.get(), COMPACTION_KEY_DROP_USER);
} else if (value_changed) {
value = compaction_filter_value;
}
}
}
// If there are no snapshots, then this kv affect visibility at tip.
// Otherwise, search though all existing snapshots to find
// the earlist snapshot that is affected by this kv.
SequenceNumber prev_snapshot = 0; // 0 means no previous snapshot
SequenceNumber visible = visible_at_tip ?
visible_at_tip :
findEarliestVisibleSnapshot(ikey.sequence,
compact->existing_snapshots,
&prev_snapshot);
if (visible_in_snapshot == visible) {
// If the earliest snapshot is which this key is visible in
// is the same as the visibily of a previous instance of the
// same key, then this kv is not visible in any snapshot.
// Hidden by an newer entry for same user key
// TODO: why not > ?
assert(last_sequence_for_key >= ikey.sequence);
drop = true; // (A)
RecordTick(options_.statistics.get(), COMPACTION_KEY_DROP_NEWER_ENTRY);
} else if (ikey.type == kTypeDeletion &&
ikey.sequence <= earliest_snapshot &&
compact->compaction->IsBaseLevelForKey(ikey.user_key)) {
// For this user key:
// (1) there is no data in higher levels
// (2) data in lower levels will have larger sequence numbers
// (3) data in layers that are being compacted here and have
// smaller sequence numbers will be dropped in the next
// few iterations of this loop (by rule (A) above).
// Therefore this deletion marker is obsolete and can be dropped.
drop = true;
RecordTick(options_.statistics.get(), COMPACTION_KEY_DROP_OBSOLETE);
} else if (ikey.type == kTypeMerge) {
// We know the merge type entry is not hidden, otherwise we would
// have hit (A)
// We encapsulate the merge related state machine in a different
// object to minimize change to the existing flow. Turn out this
// logic could also be nicely re-used for memtable flush purge
// optimization in BuildTable.
merge.MergeUntil(input.get(), prev_snapshot, bottommost_level,
options_.statistics.get());
current_entry_is_merging = true;
if (merge.IsSuccess()) {
// Successfully found Put/Delete/(end-of-key-range) while merging
// Get the merge result
key = merge.key();
ParseInternalKey(key, &ikey);
value = merge.value();
} else {
// Did not find a Put/Delete/(end-of-key-range) while merging
// We now have some stack of merge operands to write out.
// NOTE: key,value, and ikey are now referring to old entries.
// These will be correctly set below.
assert(!merge.keys().empty());
assert(merge.keys().size() == merge.values().size());
// Hack to make sure last_sequence_for_key is correct
ParseInternalKey(merge.keys().front(), &ikey);
}
}
last_sequence_for_key = ikey.sequence;
visible_in_snapshot = visible;
}
#if 0
Log(options_.info_log,
" Compact: %s, seq %d, type: %d %d, drop: %d, is_base: %d, "
"%d smallest_snapshot: %d level: %d bottommost %d",
ikey.user_key.ToString().c_str(),
(int)ikey.sequence, ikey.type, kTypeValue, drop,
compact->compaction->IsBaseLevelForKey(ikey.user_key),
(int)last_sequence_for_key, (int)earliest_snapshot,
compact->compaction->level(), bottommost_level);
#endif
if (!drop) {
// We may write a single key (e.g.: for Put/Delete or successful merge).
// Or we may instead have to write a sequence/list of keys.
// We have to write a sequence iff we have an unsuccessful merge
bool has_merge_list = current_entry_is_merging && !merge.IsSuccess();
const std::deque<std::string>* keys = nullptr;
const std::deque<std::string>* values = nullptr;
std::deque<std::string>::const_reverse_iterator key_iter;
std::deque<std::string>::const_reverse_iterator value_iter;
if (has_merge_list) {
keys = &merge.keys();
values = &merge.values();
key_iter = keys->rbegin(); // The back (*rbegin()) is the first key
value_iter = values->rbegin();
key = Slice(*key_iter);
value = Slice(*value_iter);
}
// If we have a list of keys to write, traverse the list.
// If we have a single key to write, simply write that key.
while (true) {
// Invariant: key,value,ikey will always be the next entry to write
char* kptr = (char*)key.data();
std::string kstr;
// Zeroing out the sequence number leads to better compression.
// If this is the bottommost level (no files in lower levels)
// and the earliest snapshot is larger than this seqno
// then we can squash the seqno to zero.
if (options_.compaction_style == kCompactionStyleLevel &&
bottommost_level && ikey.sequence < earliest_snapshot &&
ikey.type != kTypeMerge) {
assert(ikey.type != kTypeDeletion);
// make a copy because updating in place would cause problems
// with the priority queue that is managing the input key iterator
kstr.assign(key.data(), key.size());
kptr = (char *)kstr.c_str();
UpdateInternalKey(kptr, key.size(), (uint64_t)0, ikey.type);
}
Slice newkey(kptr, key.size());
assert((key.clear(), 1)); // we do not need 'key' anymore
// Open output file if necessary
if (compact->builder == nullptr) {
status = OpenCompactionOutputFile(compact);
if (!status.ok()) {
break;
}
}
SequenceNumber seqno = GetInternalKeySeqno(newkey);
if (compact->builder->NumEntries() == 0) {
compact->current_output()->smallest.DecodeFrom(newkey);
compact->current_output()->smallest_seqno = seqno;
} else {
compact->current_output()->smallest_seqno =
std::min(compact->current_output()->smallest_seqno, seqno);
}
compact->current_output()->largest.DecodeFrom(newkey);
compact->builder->Add(newkey, value);
compact->current_output()->largest_seqno =
std::max(compact->current_output()->largest_seqno, seqno);
// Close output file if it is big enough
if (compact->builder->FileSize() >=
compact->compaction->MaxOutputFileSize()) {
status = FinishCompactionOutputFile(compact, input.get());
if (!status.ok()) {
break;
}
}
// If we have a list of entries, move to next element
// If we only had one entry, then break the loop.
if (has_merge_list) {
++key_iter;
++value_iter;
// If at end of list
if (key_iter == keys->rend() || value_iter == values->rend()) {
// Sanity Check: if one ends, then both end
assert(key_iter == keys->rend() && value_iter == values->rend());
break;
}
// Otherwise not at end of list. Update key, value, and ikey.
key = Slice(*key_iter);
value = Slice(*value_iter);
ParseInternalKey(key, &ikey);
} else{
// Only had one item to begin with (Put/Delete)
break;
}
}
}
// MergeUntil has moved input to the next entry
if (!current_entry_is_merging) {
input->Next();
}
}
if (status.ok() && shutting_down_.Acquire_Load()) {
status = Status::IOError("Database shutdown started during compaction");
}
if (status.ok() && compact->builder != nullptr) {
status = FinishCompactionOutputFile(compact, input.get());
}
if (status.ok()) {
status = input->status();
}
input.reset();
CompactionStats stats;
stats.micros = env_->NowMicros() - start_micros - imm_micros;
if (options_.statistics.get()) {
options_.statistics.get()->measureTime(COMPACTION_TIME, stats.micros);
}
stats.files_in_leveln = compact->compaction->num_input_files(0);
stats.files_in_levelnp1 = compact->compaction->num_input_files(1);
int num_output_files = compact->outputs.size();
if (compact->builder != nullptr) {
// An error occurred so ignore the last output.
assert(num_output_files > 0);
--num_output_files;
}
stats.files_out_levelnp1 = num_output_files;
for (int i = 0; i < compact->compaction->num_input_files(0); i++)
stats.bytes_readn += compact->compaction->input(0, i)->file_size;
for (int i = 0; i < compact->compaction->num_input_files(1); i++)
stats.bytes_readnp1 += compact->compaction->input(1, i)->file_size;
for (int i = 0; i < num_output_files; i++) {
stats.bytes_written += compact->outputs[i].file_size;
}
LogFlush(options_.info_log);
mutex_.Lock();
stats_[compact->compaction->output_level()].Add(stats);
// if there were any unused file number (mostly in case of
// compaction error), free up the entry from pending_putputs
ReleaseCompactionUnusedFileNumbers(compact);
if (status.ok()) {
status = InstallCompactionResults(compact);
}
VersionSet::LevelSummaryStorage tmp;
Log(options_.info_log,
"compacted to: %s, %.1f MB/sec, level %d, files in(%d, %d) out(%d) "
"MB in(%.1f, %.1f) out(%.1f), read-write-amplify(%.1f) "
"write-amplify(%.1f) %s\n",
versions_->LevelSummary(&tmp),
(stats.bytes_readn + stats.bytes_readnp1 + stats.bytes_written) /
(double) stats.micros,
compact->compaction->output_level(),
stats.files_in_leveln, stats.files_in_levelnp1, stats.files_out_levelnp1,
stats.bytes_readn / 1048576.0,
stats.bytes_readnp1 / 1048576.0,
stats.bytes_written / 1048576.0,
(stats.bytes_written + stats.bytes_readnp1 + stats.bytes_readn) /
(double) stats.bytes_readn,
stats.bytes_written / (double) stats.bytes_readn,
status.ToString().c_str());
return status;
}
namespace {
struct IterState {
port::Mutex* mu;
Version* version;
std::vector<MemTable*> mem; // includes both mem_ and imm_
DBImpl *db;
};
static void CleanupIteratorState(void* arg1, void* arg2) {
IterState* state = reinterpret_cast<IterState*>(arg1);
DBImpl::DeletionState deletion_state(state->db->GetOptions().
max_write_buffer_number);
state->mu->Lock();
for (unsigned int i = 0; i < state->mem.size(); i++) {
MemTable* m = state->mem[i]->Unref();
if (m != nullptr) {
deletion_state.memtables_to_free.push_back(m);
}
}
if (state->version->Unref()) {
// fast path FindObsoleteFiles
state->db->FindObsoleteFiles(deletion_state, false, true);
}
state->mu->Unlock();
state->db->PurgeObsoleteFiles(deletion_state);
delete state;
}
} // namespace
Iterator* DBImpl::NewInternalIterator(const ReadOptions& options,
SequenceNumber* latest_snapshot) {
IterState* cleanup = new IterState;
mutex_.Lock();
*latest_snapshot = versions_->LastSequence();
// Collect together all needed child iterators for mem
std::vector<Iterator*> list;
mem_->Ref();
list.push_back(mem_->NewIterator(options));
cleanup->mem.push_back(mem_);
// Collect together all needed child iterators for imm_
std::vector<MemTable*> immutables;
imm_.GetMemTables(&immutables);
for (unsigned int i = 0; i < immutables.size(); i++) {
MemTable* m = immutables[i];
m->Ref();
list.push_back(m->NewIterator(options));
cleanup->mem.push_back(m);
}
// Collect iterators for files in L0 - Ln
versions_->current()->AddIterators(options, storage_options_, &list);
Iterator* internal_iter =
NewMergingIterator(env_, &internal_comparator_, &list[0], list.size());
versions_->current()->Ref();
cleanup->mu = &mutex_;
cleanup->db = this;
cleanup->version = versions_->current();
internal_iter->RegisterCleanup(CleanupIteratorState, cleanup, nullptr);
mutex_.Unlock();
LogFlush(options_.info_log);
return internal_iter;
}
Iterator* DBImpl::TEST_NewInternalIterator() {
SequenceNumber ignored;
return NewInternalIterator(ReadOptions(), &ignored);
}
int64_t DBImpl::TEST_MaxNextLevelOverlappingBytes() {
MutexLock l(&mutex_);
return versions_->MaxNextLevelOverlappingBytes();
}
Status DBImpl::Get(const ReadOptions& options,
const Slice& key,
std::string* value) {
return GetImpl(options, key, value);
}
Status DBImpl::GetImpl(const ReadOptions& options,
const Slice& key,
std::string* value,
bool* value_found) {
Status s;
StopWatch sw(env_, options_.statistics.get(), DB_GET);
StopWatchNano snapshot_timer(env_, false);
StartPerfTimer(&snapshot_timer);
SequenceNumber snapshot;
std::vector<MemTable*> to_delete;
to_delete.reserve(options_.max_write_buffer_number);
mutex_.Lock();
if (options.snapshot != nullptr) {
snapshot = reinterpret_cast<const SnapshotImpl*>(options.snapshot)->number_;
} else {
snapshot = versions_->LastSequence();
}
MemTable* mem = mem_;
MemTableList imm = imm_;
Version* current = versions_->current();
mem->Ref();
imm.RefAll();
current->Ref();
// Unlock while reading from files and memtables
mutex_.Unlock();
bool have_stat_update = false;
Version::GetStats stats;
// Prepare to store a list of merge operations if merge occurs.
MergeContext merge_context;
// First look in the memtable, then in the immutable memtable (if any).
// s is both in/out. When in, s could either be OK or MergeInProgress.
// merge_operands will contain the sequence of merges in the latter case.
LookupKey lkey(key, snapshot);
BumpPerfTime(&perf_context.get_snapshot_time, &snapshot_timer);
if (mem->Get(lkey, value, &s, merge_context, options_)) {
// Done
RecordTick(options_.statistics.get(), MEMTABLE_HIT);
} else if (imm.Get(lkey, value, &s, merge_context, options_)) {
// Done
RecordTick(options_.statistics.get(), MEMTABLE_HIT);
} else {
StopWatchNano from_files_timer(env_, false);
StartPerfTimer(&from_files_timer);
current->Get(options, lkey, value, &s, &merge_context, &stats,
options_, value_found);
have_stat_update = true;
BumpPerfTime(&perf_context.get_from_output_files_time, &from_files_timer);
RecordTick(options_.statistics.get(), MEMTABLE_MISS);
}
StopWatchNano post_process_timer(env_, false);
StartPerfTimer(&post_process_timer);
mutex_.Lock();
if (!options_.disable_seek_compaction &&
have_stat_update && current->UpdateStats(stats)) {
MaybeScheduleFlushOrCompaction();
}
MemTable* m = mem->Unref();
imm.UnrefAll(&to_delete);
current->Unref();
mutex_.Unlock();
// free up all obsolete memtables outside the mutex
delete m;
for (MemTable* v: to_delete) delete v;
LogFlush(options_.info_log);
// Note, tickers are atomic now - no lock protection needed any more.
RecordTick(options_.statistics.get(), NUMBER_KEYS_READ);
RecordTick(options_.statistics.get(), BYTES_READ, value->size());
BumpPerfTime(&perf_context.get_post_process_time, &post_process_timer);
return s;
}
std::vector<Status> DBImpl::MultiGet(const ReadOptions& options,
const std::vector<Slice>& keys,
std::vector<std::string>* values) {
StopWatch sw(env_, options_.statistics.get(), DB_MULTIGET);
StopWatchNano snapshot_timer(env_, false);
StartPerfTimer(&snapshot_timer);
SequenceNumber snapshot;
std::vector<MemTable*> to_delete;
to_delete.reserve(options_.max_write_buffer_number);
mutex_.Lock();
if (options.snapshot != nullptr) {
snapshot = reinterpret_cast<const SnapshotImpl*>(options.snapshot)->number_;
} else {
snapshot = versions_->LastSequence();
}
MemTable* mem = mem_;
MemTableList imm = imm_;
Version* current = versions_->current();
mem->Ref();
imm.RefAll();
current->Ref();
// Unlock while reading from files and memtables
mutex_.Unlock();
bool have_stat_update = false;
Version::GetStats stats;
// Contain a list of merge operations if merge occurs.
MergeContext merge_context;
// Note: this always resizes the values array
int numKeys = keys.size();
std::vector<Status> statList(numKeys);
values->resize(numKeys);
// Keep track of bytes that we read for statistics-recording later
uint64_t bytesRead = 0;
BumpPerfTime(&perf_context.get_snapshot_time, &snapshot_timer);
// For each of the given keys, apply the entire "get" process as follows:
// First look in the memtable, then in the immutable memtable (if any).
// s is both in/out. When in, s could either be OK or MergeInProgress.
// merge_operands will contain the sequence of merges in the latter case.
for (int i=0; i<numKeys; ++i) {
merge_context.Clear();
Status& s = statList[i];
std::string* value = &(*values)[i];
LookupKey lkey(keys[i], snapshot);
if (mem->Get(lkey, value, &s, merge_context, options_)) {
// Done
} else if (imm.Get(lkey, value, &s, merge_context, options_)) {
// Done
} else {
current->Get(options, lkey, value, &s, &merge_context, &stats, options_);
have_stat_update = true;
}
if (s.ok()) {
bytesRead += value->size();
}
}
// Post processing (decrement reference counts and record statistics)
StopWatchNano post_process_timer(env_, false);
StartPerfTimer(&post_process_timer);
mutex_.Lock();
if (!options_.disable_seek_compaction &&
have_stat_update && current->UpdateStats(stats)) {
MaybeScheduleFlushOrCompaction();
}
MemTable* m = mem->Unref();
imm.UnrefAll(&to_delete);
current->Unref();
mutex_.Unlock();
// free up all obsolete memtables outside the mutex
delete m;
for (MemTable* v: to_delete) delete v;
LogFlush(options_.info_log);
RecordTick(options_.statistics.get(), NUMBER_MULTIGET_CALLS);
RecordTick(options_.statistics.get(), NUMBER_MULTIGET_KEYS_READ, numKeys);
RecordTick(options_.statistics.get(), NUMBER_MULTIGET_BYTES_READ, bytesRead);
BumpPerfTime(&perf_context.get_post_process_time, &post_process_timer);
return statList;
}
bool DBImpl::KeyMayExist(const ReadOptions& options,
const Slice& key,
std::string* value,
bool* value_found) {
if (value_found != nullptr) {
// falsify later if key-may-exist but can't fetch value
*value_found = true;
}
ReadOptions roptions = options;
roptions.read_tier = kBlockCacheTier; // read from block cache only
auto s = GetImpl(roptions, key, value, value_found);
// If options.block_cache != nullptr and the index block of the table didn't
// not present in block_cache, the return value will be Status::Incomplete.
// In this case, key may still exist in the table.
return s.ok() || s.IsIncomplete();
}
Iterator* DBImpl::NewIterator(const ReadOptions& options) {
SequenceNumber latest_snapshot;
Iterator* iter = NewInternalIterator(options, &latest_snapshot);
iter = NewDBIterator(
&dbname_, env_, options_, user_comparator(), iter,
(options.snapshot != nullptr
? reinterpret_cast<const SnapshotImpl*>(options.snapshot)->number_
: latest_snapshot));
if (options.prefix) {
// use extra wrapper to exclude any keys from the results which
// don't begin with the prefix
iter = new PrefixFilterIterator(iter, *options.prefix,
options_.prefix_extractor);
}
return iter;
}
const Snapshot* DBImpl::GetSnapshot() {
MutexLock l(&mutex_);
return snapshots_.New(versions_->LastSequence());
}
void DBImpl::ReleaseSnapshot(const Snapshot* s) {
MutexLock l(&mutex_);
snapshots_.Delete(reinterpret_cast<const SnapshotImpl*>(s));
}
// Convenience methods
Status DBImpl::Put(const WriteOptions& o, const Slice& key, const Slice& val) {
return DB::Put(o, key, val);
}
Status DBImpl::Merge(const WriteOptions& o, const Slice& key,
const Slice& val) {
if (!options_.merge_operator) {
return Status::NotSupported("Provide a merge_operator when opening DB");
} else {
return DB::Merge(o, key, val);
}
}
Status DBImpl::Delete(const WriteOptions& options, const Slice& key) {
return DB::Delete(options, key);
}
Status DBImpl::Write(const WriteOptions& options, WriteBatch* my_batch) {
StopWatchNano pre_post_process_timer(env_, false);
StartPerfTimer(&pre_post_process_timer);
Writer w(&mutex_);
w.batch = my_batch;
w.sync = options.sync;
w.disableWAL = options.disableWAL;
w.done = false;
StopWatch sw(env_, options_.statistics.get(), DB_WRITE);
MutexLock l(&mutex_);
writers_.push_back(&w);
while (!w.done && &w != writers_.front()) {
w.cv.Wait();
}
if (w.done) {
return w.status;
}
// May temporarily unlock and wait.
Status status = MakeRoomForWrite(my_batch == nullptr);
uint64_t last_sequence = versions_->LastSequence();
Writer* last_writer = &w;
if (status.ok() && my_batch != nullptr) { // nullptr batch is for compactions
// TODO: BuildBatchGroup physically concatenate/copy all write batches into
// a new one. Mem copy is done with the lock held. Ideally, we only need
// the lock to obtain the last_writer and the references to all batches.
// Creation (copy) of the merged batch could have been done outside of the
// lock protected region.
WriteBatch* updates = BuildBatchGroup(&last_writer);
// Add to log and apply to memtable. We can release the lock
// during this phase since &w is currently responsible for logging
// and protects against concurrent loggers and concurrent writes
// into mem_.
{
mutex_.Unlock();
const SequenceNumber current_sequence = last_sequence + 1;
WriteBatchInternal::SetSequence(updates, current_sequence);
int my_batch_count = WriteBatchInternal::Count(updates);
last_sequence += my_batch_count;
// Record statistics
RecordTick(options_.statistics.get(),
NUMBER_KEYS_WRITTEN, my_batch_count);
RecordTick(options_.statistics.get(),
BYTES_WRITTEN,
WriteBatchInternal::ByteSize(updates));
if (options.disableWAL) {
flush_on_destroy_ = true;
}
BumpPerfTime(&perf_context.write_pre_and_post_process_time,
&pre_post_process_timer);
if (!options.disableWAL) {
StopWatchNano timer(env_);
StartPerfTimer(&timer);
status = log_->AddRecord(WriteBatchInternal::Contents(updates));
if (status.ok() && options.sync) {
if (options_.use_fsync) {
StopWatch(env_, options_.statistics.get(), WAL_FILE_SYNC_MICROS);
status = log_->file()->Fsync();
} else {
StopWatch(env_, options_.statistics.get(), WAL_FILE_SYNC_MICROS);
status = log_->file()->Sync();
}
}
BumpPerfTime(&perf_context.write_wal_time, &timer);
}
if (status.ok()) {
StopWatchNano write_memtable_timer(env_, false);
StartPerfTimer(&write_memtable_timer);
status = WriteBatchInternal::InsertInto(updates, mem_, &options_, this,
options_.filter_deletes);
BumpPerfTime(&perf_context.write_memtable_time, &write_memtable_timer);
if (!status.ok()) {
// Panic for in-memory corruptions
// Note that existing logic was not sound. Any partial failure writing
// into the memtable would result in a state that some write ops might
// have succeeded in memtable but Status reports error for all writes.
throw std::runtime_error("In memory WriteBatch corruption!");
}
SetTickerCount(options_.statistics.get(),
SEQUENCE_NUMBER, last_sequence);
}
StartPerfTimer(&pre_post_process_timer);
LogFlush(options_.info_log);
mutex_.Lock();
if (status.ok()) {
versions_->SetLastSequence(last_sequence);
}
}
if (updates == &tmp_batch_) tmp_batch_.Clear();
}
if (options_.paranoid_checks && !status.ok() && bg_error_.ok()) {
bg_error_ = status; // stop compaction & fail any further writes
}
while (true) {
Writer* ready = writers_.front();
writers_.pop_front();
if (ready != &w) {
ready->status = status;
ready->done = true;
ready->cv.Signal();
}
if (ready == last_writer) break;
}
// Notify new head of write queue
if (!writers_.empty()) {
writers_.front()->cv.Signal();
}
BumpPerfTime(&perf_context.write_pre_and_post_process_time,
&pre_post_process_timer);
return status;
}
// REQUIRES: Writer list must be non-empty
// REQUIRES: First writer must have a non-nullptr batch
WriteBatch* DBImpl::BuildBatchGroup(Writer** last_writer) {
assert(!writers_.empty());
Writer* first = writers_.front();
WriteBatch* result = first->batch;
assert(result != nullptr);
size_t size = WriteBatchInternal::ByteSize(first->batch);
// Allow the group to grow up to a maximum size, but if the
// original write is small, limit the growth so we do not slow
// down the small write too much.
size_t max_size = 1 << 20;
if (size <= (128<<10)) {
max_size = size + (128<<10);
}
*last_writer = first;
std::deque<Writer*>::iterator iter = writers_.begin();
++iter; // Advance past "first"
for (; iter != writers_.end(); ++iter) {
Writer* w = *iter;
if (w->sync && !first->sync) {
// Do not include a sync write into a batch handled by a non-sync write.
break;
}
if (!w->disableWAL && first->disableWAL) {
// Do not include a write that needs WAL into a batch that has
// WAL disabled.
break;
}
if (w->batch != nullptr) {
size += WriteBatchInternal::ByteSize(w->batch);
if (size > max_size) {
// Do not make batch too big
break;
}
// Append to *reuslt
if (result == first->batch) {
// Switch to temporary batch instead of disturbing caller's batch
result = &tmp_batch_;
assert(WriteBatchInternal::Count(result) == 0);
WriteBatchInternal::Append(result, first->batch);
}
WriteBatchInternal::Append(result, w->batch);
}
*last_writer = w;
}
return result;
}
// This function computes the amount of time in microseconds by which a write
// should be delayed based on the number of level-0 files according to the
// following formula:
// if n < bottom, return 0;
// if n >= top, return 1000;
// otherwise, let r = (n - bottom) /
// (top - bottom)
// and return r^2 * 1000.
// The goal of this formula is to gradually increase the rate at which writes
// are slowed. We also tried linear delay (r * 1000), but it seemed to do
// slightly worse. There is no other particular reason for choosing quadratic.
uint64_t DBImpl::SlowdownAmount(int n, int top, int bottom) {
uint64_t delay;
if (n >= top) {
delay = 1000;
}
else if (n < bottom) {
delay = 0;
}
else {
// If we are here, we know that:
// level0_start_slowdown <= n < level0_slowdown
// since the previous two conditions are false.
float how_much =
(float) (n - bottom) /
(top - bottom);
delay = how_much * how_much * 1000;
}
assert(delay <= 1000);
return delay;
}
// REQUIRES: mutex_ is held
// REQUIRES: this thread is currently at the front of the writer queue
Status DBImpl::MakeRoomForWrite(bool force) {
mutex_.AssertHeld();
assert(!writers_.empty());
bool allow_delay = !force;
bool allow_hard_rate_limit_delay = !force;
bool allow_soft_rate_limit_delay = !force;
uint64_t rate_limit_delay_millis = 0;
Status s;
double score;
while (true) {
if (!bg_error_.ok()) {
// Yield previous error
s = bg_error_;
break;
} else if (
allow_delay &&
versions_->NumLevelFiles(0) >=
options_.level0_slowdown_writes_trigger) {
// We are getting close to hitting a hard limit on the number of
// L0 files. Rather than delaying a single write by several
// seconds when we hit the hard limit, start delaying each
// individual write by 0-1ms to reduce latency variance. Also,
// this delay hands over some CPU to the compaction thread in
// case it is sharing the same core as the writer.
mutex_.Unlock();
uint64_t delayed;
{
StopWatch sw(env_, options_.statistics.get(), STALL_L0_SLOWDOWN_COUNT);
env_->SleepForMicroseconds(
SlowdownAmount(versions_->NumLevelFiles(0),
options_.level0_slowdown_writes_trigger,
options_.level0_stop_writes_trigger)
);
delayed = sw.ElapsedMicros();
}
RecordTick(options_.statistics.get(), STALL_L0_SLOWDOWN_MICROS, delayed);
stall_level0_slowdown_ += delayed;
stall_level0_slowdown_count_++;
allow_delay = false; // Do not delay a single write more than once
mutex_.Lock();
delayed_writes_++;
} else if (!force &&
(mem_->ApproximateMemoryUsage() <= options_.write_buffer_size)) {
// There is room in current memtable
if (allow_delay) {
DelayLoggingAndReset();
}
break;
} else if (imm_.size() == options_.max_write_buffer_number - 1) {
// We have filled up the current memtable, but the previous
// ones are still being compacted, so we wait.
DelayLoggingAndReset();
Log(options_.info_log, "wait for memtable compaction...\n");
uint64_t stall;
{
StopWatch sw(env_, options_.statistics.get(),
STALL_MEMTABLE_COMPACTION_COUNT);
bg_cv_.Wait();
stall = sw.ElapsedMicros();
}
RecordTick(options_.statistics.get(),
STALL_MEMTABLE_COMPACTION_MICROS, stall);
stall_memtable_compaction_ += stall;
stall_memtable_compaction_count_++;
} else if (versions_->NumLevelFiles(0) >=
options_.level0_stop_writes_trigger) {
// There are too many level-0 files.
DelayLoggingAndReset();
Log(options_.info_log, "wait for fewer level0 files...\n");
uint64_t stall;
{
StopWatch sw(env_, options_.statistics.get(),
STALL_L0_NUM_FILES_COUNT);
bg_cv_.Wait();
stall = sw.ElapsedMicros();
}
RecordTick(options_.statistics.get(), STALL_L0_NUM_FILES_MICROS, stall);
stall_level0_num_files_ += stall;
stall_level0_num_files_count_++;
} else if (
allow_hard_rate_limit_delay &&
options_.hard_rate_limit > 1.0 &&
(score = versions_->MaxCompactionScore()) > options_.hard_rate_limit) {
// Delay a write when the compaction score for any level is too large.
int max_level = versions_->MaxCompactionScoreLevel();
mutex_.Unlock();
uint64_t delayed;
{
StopWatch sw(env_, options_.statistics.get(),
HARD_RATE_LIMIT_DELAY_COUNT);
env_->SleepForMicroseconds(1000);
delayed = sw.ElapsedMicros();
}
stall_leveln_slowdown_[max_level] += delayed;
stall_leveln_slowdown_count_[max_level]++;
// Make sure the following value doesn't round to zero.
uint64_t rate_limit = std::max((delayed / 1000), (uint64_t) 1);
rate_limit_delay_millis += rate_limit;
RecordTick(options_.statistics.get(),
RATE_LIMIT_DELAY_MILLIS, rate_limit);
if (options_.rate_limit_delay_max_milliseconds > 0 &&
rate_limit_delay_millis >=
(unsigned)options_.rate_limit_delay_max_milliseconds) {
allow_hard_rate_limit_delay = false;
}
mutex_.Lock();
} else if (
allow_soft_rate_limit_delay &&
options_.soft_rate_limit > 0.0 &&
(score = versions_->MaxCompactionScore()) > options_.soft_rate_limit) {
// Delay a write when the compaction score for any level is too large.
// TODO: add statistics
mutex_.Unlock();
{
StopWatch sw(env_, options_.statistics.get(),
SOFT_RATE_LIMIT_DELAY_COUNT);
env_->SleepForMicroseconds(SlowdownAmount(
score,
options_.soft_rate_limit,
options_.hard_rate_limit)
);
rate_limit_delay_millis += sw.ElapsedMicros();
}
allow_soft_rate_limit_delay = false;
mutex_.Lock();
} else {
unique_ptr<WritableFile> lfile;
MemTable* memtmp = nullptr;
// Attempt to switch to a new memtable and trigger compaction of old.
// Do this without holding the dbmutex lock.
assert(versions_->PrevLogNumber() == 0);
uint64_t new_log_number = versions_->NewFileNumber();
mutex_.Unlock();
{
EnvOptions soptions(storage_options_);
soptions.use_mmap_writes = false;
DelayLoggingAndReset();
s = env_->NewWritableFile(
LogFileName(options_.wal_dir, new_log_number),
&lfile,
soptions
);
if (s.ok()) {
// Our final size should be less than write_buffer_size
// (compression, etc) but err on the side of caution.
lfile->SetPreallocationBlockSize(1.1 * options_.write_buffer_size);
memtmp = new MemTable(
internal_comparator_, mem_rep_factory_, NumberLevels(), options_);
}
}
mutex_.Lock();
if (!s.ok()) {
// Avoid chewing through file number space in a tight loop.
versions_->ReuseFileNumber(new_log_number);
assert (!memtmp);
break;
}
logfile_number_ = new_log_number;
log_.reset(new log::Writer(std::move(lfile)));
mem_->SetNextLogNumber(logfile_number_);
imm_.Add(mem_);
if (force) {
imm_.FlushRequested();
}
mem_ = memtmp;
mem_->Ref();
Log(options_.info_log,
"New memtable created with log file: #%lu\n",
(unsigned long)logfile_number_);
mem_->SetLogNumber(logfile_number_);
force = false; // Do not force another compaction if have room
MaybeScheduleFlushOrCompaction();
}
}
return s;
}
Env* DBImpl::GetEnv() const {
return env_;
}
const Options& DBImpl::GetOptions() const {
return options_;
}
bool DBImpl::GetProperty(const Slice& property, std::string* value) {
value->clear();
MutexLock l(&mutex_);
Slice in = property;
Slice prefix("rocksdb.");
if (!in.starts_with(prefix)) return false;
in.remove_prefix(prefix.size());
if (in.starts_with("num-files-at-level")) {
in.remove_prefix(strlen("num-files-at-level"));
uint64_t level;
bool ok = ConsumeDecimalNumber(&in, &level) && in.empty();
if (!ok || (int)level >= NumberLevels()) {
return false;
} else {
char buf[100];
snprintf(buf, sizeof(buf), "%d",
versions_->NumLevelFiles(static_cast<int>(level)));
*value = buf;
return true;
}
} else if (in == "levelstats") {
char buf[1000];
snprintf(buf, sizeof(buf),
"Level Files Size(MB)\n"
"--------------------\n");
value->append(buf);
for (int level = 0; level < NumberLevels(); level++) {
snprintf(buf, sizeof(buf),
"%3d %8d %8.0f\n",
level,
versions_->NumLevelFiles(level),
versions_->NumLevelBytes(level) / 1048576.0);
value->append(buf);
}
return true;
} else if (in == "stats") {
char buf[1000];
uint64_t total_bytes_written = 0;
uint64_t total_bytes_read = 0;
uint64_t micros_up = env_->NowMicros() - started_at_;
// Add "+1" to make sure seconds_up is > 0 and avoid NaN later
double seconds_up = (micros_up + 1) / 1000000.0;
uint64_t total_slowdown = 0;
uint64_t total_slowdown_count = 0;
uint64_t interval_bytes_written = 0;
uint64_t interval_bytes_read = 0;
uint64_t interval_bytes_new = 0;
double interval_seconds_up = 0;
// Pardon the long line but I think it is easier to read this way.
snprintf(buf, sizeof(buf),
" Compactions\n"
"Level Files Size(MB) Score Time(sec) Read(MB) Write(MB) Rn(MB) Rnp1(MB) Wnew(MB) RW-Amplify Read(MB/s) Write(MB/s) Rn Rnp1 Wnp1 NewW Count Ln-stall Stall-cnt\n"
"--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------\n"
);
value->append(buf);
for (int level = 0; level < NumberLevels(); level++) {
int files = versions_->NumLevelFiles(level);
if (stats_[level].micros > 0 || files > 0) {
int64_t bytes_read = stats_[level].bytes_readn +
stats_[level].bytes_readnp1;
int64_t bytes_new = stats_[level].bytes_written -
stats_[level].bytes_readnp1;
double amplify = (stats_[level].bytes_readn == 0)
? 0.0
: (stats_[level].bytes_written +
stats_[level].bytes_readnp1 +
stats_[level].bytes_readn) /
(double) stats_[level].bytes_readn;
total_bytes_read += bytes_read;
total_bytes_written += stats_[level].bytes_written;
snprintf(
buf, sizeof(buf),
"%3d %8d %8.0f %5.1f %9.0f %9.0f %9.0f %9.0f %9.0f %9.0f %10.1f %9.1f %11.1f %8d %8d %8d %8d %8d %9.1f %9lu\n",
level,
files,
versions_->NumLevelBytes(level) / 1048576.0,
versions_->NumLevelBytes(level) /
versions_->MaxBytesForLevel(level),
stats_[level].micros / 1e6,
bytes_read / 1048576.0,
stats_[level].bytes_written / 1048576.0,
stats_[level].bytes_readn / 1048576.0,
stats_[level].bytes_readnp1 / 1048576.0,
bytes_new / 1048576.0,
amplify,
// +1 to avoid division by 0
(bytes_read / 1048576.0) / ((stats_[level].micros+1) / 1000000.0),
(stats_[level].bytes_written / 1048576.0) /
((stats_[level].micros+1) / 1000000.0),
stats_[level].files_in_leveln,
stats_[level].files_in_levelnp1,
stats_[level].files_out_levelnp1,
stats_[level].files_out_levelnp1 - stats_[level].files_in_levelnp1,
stats_[level].count,
stall_leveln_slowdown_[level] / 1000000.0,
(unsigned long) stall_leveln_slowdown_count_[level]);
total_slowdown += stall_leveln_slowdown_[level];
total_slowdown_count += stall_leveln_slowdown_count_[level];
value->append(buf);
}
}
interval_bytes_new = stats_[0].bytes_written - last_stats_.bytes_new_;
interval_bytes_read = total_bytes_read - last_stats_.bytes_read_;
interval_bytes_written = total_bytes_written - last_stats_.bytes_written_;
interval_seconds_up = seconds_up - last_stats_.seconds_up_;
snprintf(buf, sizeof(buf), "Uptime(secs): %.1f total, %.1f interval\n",
seconds_up, interval_seconds_up);
value->append(buf);
snprintf(buf, sizeof(buf),
"Compaction IO cumulative (GB): "
"%.2f new, %.2f read, %.2f write, %.2f read+write\n",
stats_[0].bytes_written / (1048576.0 * 1024),
total_bytes_read / (1048576.0 * 1024),
total_bytes_written / (1048576.0 * 1024),
(total_bytes_read + total_bytes_written) / (1048576.0 * 1024));
value->append(buf);
snprintf(buf, sizeof(buf),
"Compaction IO cumulative (MB/sec): "
"%.1f new, %.1f read, %.1f write, %.1f read+write\n",
stats_[0].bytes_written / 1048576.0 / seconds_up,
total_bytes_read / 1048576.0 / seconds_up,
total_bytes_written / 1048576.0 / seconds_up,
(total_bytes_read + total_bytes_written) / 1048576.0 / seconds_up);
value->append(buf);
// +1 to avoid divide by 0 and NaN
snprintf(buf, sizeof(buf),
"Amplification cumulative: %.1f write, %.1f compaction\n",
(double) total_bytes_written / (stats_[0].bytes_written+1),
(double) (total_bytes_written + total_bytes_read)
/ (stats_[0].bytes_written+1));
value->append(buf);
snprintf(buf, sizeof(buf),
"Compaction IO interval (MB): "
"%.2f new, %.2f read, %.2f write, %.2f read+write\n",
interval_bytes_new / 1048576.0,
interval_bytes_read/ 1048576.0,
interval_bytes_written / 1048576.0,
(interval_bytes_read + interval_bytes_written) / 1048576.0);
value->append(buf);
snprintf(buf, sizeof(buf),
"Compaction IO interval (MB/sec): "
"%.1f new, %.1f read, %.1f write, %.1f read+write\n",
interval_bytes_new / 1048576.0 / interval_seconds_up,
interval_bytes_read / 1048576.0 / interval_seconds_up,
interval_bytes_written / 1048576.0 / interval_seconds_up,
(interval_bytes_read + interval_bytes_written)
/ 1048576.0 / interval_seconds_up);
value->append(buf);
// +1 to avoid divide by 0 and NaN
snprintf(buf, sizeof(buf),
"Amplification interval: %.1f write, %.1f compaction\n",
(double) interval_bytes_written / (interval_bytes_new+1),
(double) (interval_bytes_written + interval_bytes_read) /
(interval_bytes_new+1));
value->append(buf);
snprintf(buf, sizeof(buf),
"Stalls(secs): %.3f level0_slowdown, %.3f level0_numfiles, "
"%.3f memtable_compaction, %.3f leveln_slowdown\n",
stall_level0_slowdown_ / 1000000.0,
stall_level0_num_files_ / 1000000.0,
stall_memtable_compaction_ / 1000000.0,
total_slowdown / 1000000.0);
value->append(buf);
snprintf(buf, sizeof(buf),
"Stalls(count): %lu level0_slowdown, %lu level0_numfiles, "
"%lu memtable_compaction, %lu leveln_slowdown\n",
(unsigned long) stall_level0_slowdown_count_,
(unsigned long) stall_level0_num_files_count_,
(unsigned long) stall_memtable_compaction_count_,
(unsigned long) total_slowdown_count);
value->append(buf);
last_stats_.bytes_read_ = total_bytes_read;
last_stats_.bytes_written_ = total_bytes_written;
last_stats_.bytes_new_ = stats_[0].bytes_written;
last_stats_.seconds_up_ = seconds_up;
return true;
} else if (in == "sstables") {
*value = versions_->current()->DebugString();
return true;
} else if (in == "num-immutable-mem-table") {
*value = std::to_string(imm_.size());
return true;
}
return false;
}
void DBImpl::GetApproximateSizes(
const Range* range, int n,
uint64_t* sizes) {
// TODO(opt): better implementation
Version* v;
{
MutexLock l(&mutex_);
versions_->current()->Ref();
v = versions_->current();
}
for (int i = 0; i < n; i++) {
// Convert user_key into a corresponding internal key.
InternalKey k1(range[i].start, kMaxSequenceNumber, kValueTypeForSeek);
InternalKey k2(range[i].limit, kMaxSequenceNumber, kValueTypeForSeek);
uint64_t start = versions_->ApproximateOffsetOf(v, k1);
uint64_t limit = versions_->ApproximateOffsetOf(v, k2);
sizes[i] = (limit >= start ? limit - start : 0);
}
{
MutexLock l(&mutex_);
v->Unref();
}
}
inline void DBImpl::DelayLoggingAndReset() {
if (delayed_writes_ > 0) {
Log(options_.info_log, "delayed %d write...\n", delayed_writes_ );
delayed_writes_ = 0;
}
}
Status DBImpl::DeleteFile(std::string name) {
uint64_t number;
FileType type;
WalFileType log_type;
if (!ParseFileName(name, &number, &type, &log_type) ||
(type != kTableFile && type != kLogFile)) {
Log(options_.info_log, "DeleteFile %s failed.\n", name.c_str());
return Status::InvalidArgument("Invalid file name");
}
Status status;
if (type == kLogFile) {
// Only allow deleting archived log files
if (log_type != kArchivedLogFile) {
Log(options_.info_log, "DeleteFile %s failed.\n", name.c_str());
return Status::NotSupported("Delete only supported for archived logs");
}
status = env_->DeleteFile(options_.wal_dir + "/" + name.c_str());
if (!status.ok()) {
Log(options_.info_log, "DeleteFile %s failed.\n", name.c_str());
}
return status;
}
int level;
FileMetaData metadata;
int maxlevel = NumberLevels();
VersionEdit edit(maxlevel);
DeletionState deletion_state;
{
MutexLock l(&mutex_);
status = versions_->GetMetadataForFile(number, &level, &metadata);
if (!status.ok()) {
Log(options_.info_log, "DeleteFile %s failed. File not found\n",
name.c_str());
return Status::InvalidArgument("File not found");
}
assert((level > 0) && (level < maxlevel));
// If the file is being compacted no need to delete.
if (metadata.being_compacted) {
Log(options_.info_log,
"DeleteFile %s Skipped. File about to be compacted\n", name.c_str());
return Status::OK();
}
// Only the files in the last level can be deleted externally.
// This is to make sure that any deletion tombstones are not
// lost. Check that the level passed is the last level.
for (int i = level + 1; i < maxlevel; i++) {
if (versions_->NumLevelFiles(i) != 0) {
Log(options_.info_log,
"DeleteFile %s FAILED. File not in last level\n", name.c_str());
return Status::InvalidArgument("File not in last level");
}
}
edit.DeleteFile(level, number);
status = versions_->LogAndApply(&edit, &mutex_);
FindObsoleteFiles(deletion_state, false);
} // lock released here
LogFlush(options_.info_log);
if (status.ok()) {
// remove files outside the db-lock
PurgeObsoleteFiles(deletion_state);
}
return status;
}
void DBImpl::GetLiveFilesMetaData(std::vector<LiveFileMetaData> *metadata) {
MutexLock l(&mutex_);
return versions_->GetLiveFilesMetaData(metadata);
}
Status DBImpl::GetDbIdentity(std::string& identity) {
std::string idfilename = IdentityFileName(dbname_);
unique_ptr<SequentialFile> idfile;
const EnvOptions soptions;
Status s = env_->NewSequentialFile(idfilename, &idfile, soptions);
if (!s.ok()) {
return s;
}
uint64_t file_size;
s = env_->GetFileSize(idfilename, &file_size);
if (!s.ok()) {
return s;
}
char buffer[file_size];
Slice id;
s = idfile->Read(file_size, &id, buffer);
if (!s.ok()) {
return s;
}
identity.assign(id.ToString());
// If last character is '\n' remove it from identity
if (identity.size() > 0 && identity.back() == '\n') {
identity.pop_back();
}
return s;
}
// Default implementations of convenience methods that subclasses of DB
// can call if they wish
Status DB::Put(const WriteOptions& opt, const Slice& key, const Slice& value) {
WriteBatch batch;
batch.Put(key, value);
return Write(opt, &batch);
}
Status DB::Delete(const WriteOptions& opt, const Slice& key) {
WriteBatch batch;
batch.Delete(key);
return Write(opt, &batch);
}
Status DB::Merge(const WriteOptions& opt, const Slice& key,
const Slice& value) {
WriteBatch batch;
batch.Merge(key, value);
return Write(opt, &batch);
}
DB::~DB() { }
Status DB::Open(const Options& options, const std::string& dbname, DB** dbptr) {
*dbptr = nullptr;
EnvOptions soptions;
if (options.block_cache != nullptr && options.no_block_cache) {
return Status::InvalidArgument(
"no_block_cache is true while block_cache is not nullptr");
}
DBImpl* impl = new DBImpl(options, dbname);
Status s = impl->env_->CreateDirIfMissing(impl->options_.wal_dir);
if (!s.ok()) {
delete impl;
return s;
}
s = impl->CreateArchivalDirectory();
if (!s.ok()) {
delete impl;
return s;
}
impl->mutex_.Lock();
VersionEdit edit(impl->NumberLevels());
s = impl->Recover(&edit); // Handles create_if_missing, error_if_exists
if (s.ok()) {
uint64_t new_log_number = impl->versions_->NewFileNumber();
unique_ptr<WritableFile> lfile;
soptions.use_mmap_writes = false;
s = options.env->NewWritableFile(
LogFileName(impl->options_.wal_dir, new_log_number),
&lfile,
soptions
);
if (s.ok()) {
lfile->SetPreallocationBlockSize(1.1 * options.write_buffer_size);
edit.SetLogNumber(new_log_number);
impl->logfile_number_ = new_log_number;
impl->log_.reset(new log::Writer(std::move(lfile)));
s = impl->versions_->LogAndApply(&edit, &impl->mutex_);
}
if (s.ok()) {
impl->mem_->SetLogNumber(impl->logfile_number_);
impl->DeleteObsoleteFiles();
impl->MaybeScheduleFlushOrCompaction();
impl->MaybeScheduleLogDBDeployStats();
}
}
impl->mutex_.Unlock();
if (options.compaction_style == kCompactionStyleUniversal) {
int num_files;
for (int i = 1; i < impl->NumberLevels(); i++) {
num_files = impl->versions_->NumLevelFiles(i);
if (num_files > 0) {
s = Status::InvalidArgument("Not all files are at level 0. Cannot "
"open with universal compaction style.");
break;
}
}
}
if (s.ok()) {
*dbptr = impl;
} else {
delete impl;
}
return s;
}
Snapshot::~Snapshot() {
}
Status DestroyDB(const std::string& dbname, const Options& options) {
const InternalKeyComparator comparator(options.comparator);
const InternalFilterPolicy filter_policy(options.filter_policy);
const Options& soptions(SanitizeOptions(
dbname, &comparator, &filter_policy, options));
Env* env = soptions.env;
std::vector<std::string> filenames;
std::vector<std::string> archiveFiles;
std::string archivedir = ArchivalDirectory(dbname);
// Ignore error in case directory does not exist
env->GetChildren(dbname, &filenames);
if (dbname != soptions.wal_dir) {
std::vector<std::string> logfilenames;
env->GetChildren(soptions.wal_dir, &logfilenames);
filenames.insert(filenames.end(), logfilenames.begin(), logfilenames.end());
archivedir = ArchivalDirectory(soptions.wal_dir);
}
if (filenames.empty()) {
return Status::OK();
}
FileLock* lock;
const std::string lockname = LockFileName(dbname);
Status result = env->LockFile(lockname, &lock);
if (result.ok()) {
uint64_t number;
FileType type;
for (size_t i = 0; i < filenames.size(); i++) {
if (ParseFileName(filenames[i], &number, &type) &&
type != kDBLockFile) { // Lock file will be deleted at end
Status del;
if (type == kMetaDatabase) {
del = DestroyDB(dbname + "/" + filenames[i], options);
} else if (type == kLogFile) {
del = env->DeleteFile(soptions.wal_dir + "/" + filenames[i]);
} else {
del = env->DeleteFile(dbname + "/" + filenames[i]);
}
if (result.ok() && !del.ok()) {
result = del;
}
}
}
env->GetChildren(archivedir, &archiveFiles);
// Delete archival files.
for (size_t i = 0; i < archiveFiles.size(); ++i) {
if (ParseFileName(archiveFiles[i], &number, &type) &&
type == kLogFile) {
Status del = env->DeleteFile(archivedir + "/" + archiveFiles[i]);
if (result.ok() && !del.ok()) {
result = del;
}
}
}
// ignore case where no archival directory is present.
env->DeleteDir(archivedir);
env->UnlockFile(lock); // Ignore error since state is already gone
env->DeleteFile(lockname);
env->DeleteDir(dbname); // Ignore error in case dir contains other files
env->DeleteDir(soptions.wal_dir);
}
return result;
}
//
// A global method that can dump out the build version
void dumpLeveldbBuildVersion(Logger * log) {
Log(log, "Git sha %s", rocksdb_build_git_sha);
Log(log, "Compile time %s %s",
rocksdb_build_compile_time, rocksdb_build_compile_date);
}
} // namespace rocksdb
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