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Refactor ArenaWrappedDBIter into separate files (#5801) 

Summary:
Move definition and implementation for ArenaWrappedDBIter into its own .h/.cc files. Also, change inlining of functions to better comply with the Google C++ style guide.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5801

Test Plan: make check

Differential Revision: D17371012

Pulled By: anand1976

fbshipit-source-id: c1361abc2851575111e357a63d88be3b3d6cb341
This commit is contained in:
anand76 2019-09-13 13:48:04 -07:00 committed by Facebook Github Bot
parent 6a171724b7
commit 83a6a614e9
15 changed files with 550 additions and 498 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
CMakeLists.txt
View File

@ -481,6 +481,7 @@ set(SOURCES
cache/clock_cache.cc
cache/lru_cache.cc
cache/sharded_cache.cc
db/arena_wrapped_db_iter.cc
db/builder.cc
db/c.cc
db/column_family.cc

1
TARGETS
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@ -108,6 +108,7 @@ cpp_library(
"cache/clock_cache.cc",
"cache/lru_cache.cc",
"cache/sharded_cache.cc",
"db/arena_wrapped_db_iter.cc",
"db/builder.cc",
"db/c.cc",
"db/column_family.cc",

106
db/arena_wrapped_db_iter.cc Normal file
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@ -0,0 +1,106 @@
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root 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/arena_wrapped_db_iter.h"
#include "memory/arena.h"
#include "rocksdb/env.h"
#include "rocksdb/iterator.h"
#include "rocksdb/options.h"
#include "table/internal_iterator.h"
#include "table/iterator_wrapper.h"
#include "util/user_comparator_wrapper.h"
namespace rocksdb {
Status ArenaWrappedDBIter::GetProperty(std::string prop_name,
std::string* prop) {
if (prop_name == "rocksdb.iterator.super-version-number") {
// First try to pass the value returned from inner iterator.
if (!db_iter_->GetProperty(prop_name, prop).ok()) {
*prop = ToString(sv_number_);
}
return Status::OK();
}
return db_iter_->GetProperty(prop_name, prop);
}
void ArenaWrappedDBIter::Init(Env* env, const ReadOptions& read_options,
const ImmutableCFOptions& cf_options,
const MutableCFOptions& mutable_cf_options,
const SequenceNumber& sequence,
uint64_t max_sequential_skip_in_iteration,
uint64_t version_number,
ReadCallback* read_callback, DBImpl* db_impl,
ColumnFamilyData* cfd, bool allow_blob,
bool allow_refresh) {
auto mem = arena_.AllocateAligned(sizeof(DBIter));
db_iter_ = new (mem) DBIter(env, read_options, cf_options, mutable_cf_options,
cf_options.user_comparator, nullptr, sequence,
true, max_sequential_skip_in_iteration,
read_callback, db_impl, cfd, allow_blob);
sv_number_ = version_number;
allow_refresh_ = allow_refresh;
}
Status ArenaWrappedDBIter::Refresh() {
if (cfd_ == nullptr || db_impl_ == nullptr || !allow_refresh_) {
return Status::NotSupported("Creating renew iterator is not allowed.");
}
assert(db_iter_ != nullptr);
// TODO(yiwu): For last_seq_same_as_publish_seq_==false, this is not the
// correct behavior. Will be corrected automatically when we take a snapshot
// here for the case of WritePreparedTxnDB.
SequenceNumber latest_seq = db_impl_->GetLatestSequenceNumber();
uint64_t cur_sv_number = cfd_->GetSuperVersionNumber();
if (sv_number_ != cur_sv_number) {
Env* env = db_iter_->env();
db_iter_->~DBIter();
arena_.~Arena();
new (&arena_) Arena();
SuperVersion* sv = cfd_->GetReferencedSuperVersion(db_impl_->mutex());
if (read_callback_) {
read_callback_->Refresh(latest_seq);
}
Init(env, read_options_, *(cfd_->ioptions()), sv->mutable_cf_options,
latest_seq, sv->mutable_cf_options.max_sequential_skip_in_iterations,
cur_sv_number, read_callback_, db_impl_, cfd_, allow_blob_,
allow_refresh_);
InternalIterator* internal_iter = db_impl_->NewInternalIterator(
read_options_, cfd_, sv, &arena_, db_iter_->GetRangeDelAggregator(),
latest_seq);
SetIterUnderDBIter(internal_iter);
} else {
db_iter_->set_sequence(latest_seq);
db_iter_->set_valid(false);
}
return Status::OK();
}
ArenaWrappedDBIter* NewArenaWrappedDbIterator(
Env* env, const ReadOptions& read_options,
const ImmutableCFOptions& cf_options,
const MutableCFOptions& mutable_cf_options, const SequenceNumber& sequence,
uint64_t max_sequential_skip_in_iterations, uint64_t version_number,
ReadCallback* read_callback, DBImpl* db_impl, ColumnFamilyData* cfd,
bool allow_blob, bool allow_refresh) {
ArenaWrappedDBIter* iter = new ArenaWrappedDBIter();
iter->Init(env, read_options, cf_options, mutable_cf_options, sequence,
max_sequential_skip_in_iterations, version_number, read_callback,
db_impl, cfd, allow_blob, allow_refresh);
if (db_impl != nullptr && cfd != nullptr && allow_refresh) {
iter->StoreRefreshInfo(read_options, db_impl, cfd, read_callback,
allow_blob);
}
return iter;
}
} // namespace rocksdb

112
db/arena_wrapped_db_iter.h Normal file
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@ -0,0 +1,112 @@
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root 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.
#pragma once
#include <stdint.h>
#include <string>
#include "db/db_impl/db_impl.h"
#include "db/db_iter.h"
#include "db/dbformat.h"
#include "db/range_del_aggregator.h"
#include "memory/arena.h"
#include "options/cf_options.h"
#include "rocksdb/db.h"
#include "rocksdb/iterator.h"
#include "util/autovector.h"
namespace rocksdb {
class Arena;
// A wrapper iterator which wraps DB Iterator and the arena, with which the DB
// iterator is supposed to be allocated. This class is used as an entry point of
// a iterator hierarchy whose memory can be allocated inline. In that way,
// accessing the iterator tree can be more cache friendly. It is also faster
// to allocate.
// When using the class's Iterator interface, the behavior is exactly
// the same as the inner DBIter.
class ArenaWrappedDBIter : public Iterator {
public:
virtual ~ArenaWrappedDBIter() { db_iter_->~DBIter(); }
// Get the arena to be used to allocate memory for DBIter to be wrapped,
// as well as child iterators in it.
virtual Arena* GetArena() { return &arena_; }
virtual ReadRangeDelAggregator* GetRangeDelAggregator() {
return db_iter_->GetRangeDelAggregator();
}
// Set the internal iterator wrapped inside the DB Iterator. Usually it is
// a merging iterator.
virtual void SetIterUnderDBIter(InternalIterator* iter) {
static_cast<DBIter*>(db_iter_)->SetIter(iter);
}
virtual bool Valid() const override { return db_iter_->Valid(); }
virtual void SeekToFirst() override { db_iter_->SeekToFirst(); }
virtual void SeekToLast() override { db_iter_->SeekToLast(); }
virtual void Seek(const Slice& target) override { db_iter_->Seek(target); }
virtual void SeekForPrev(const Slice& target) override {
db_iter_->SeekForPrev(target);
}
virtual void Next() override { db_iter_->Next(); }
virtual void Prev() override { db_iter_->Prev(); }
virtual Slice key() const override { return db_iter_->key(); }
virtual Slice value() const override { return db_iter_->value(); }
virtual Status status() const override { return db_iter_->status(); }
bool IsBlob() const { return db_iter_->IsBlob(); }
virtual Status GetProperty(std::string prop_name, std::string* prop) override;
virtual Status Refresh() override;
void Init(Env* env, const ReadOptions& read_options,
const ImmutableCFOptions& cf_options,
const MutableCFOptions& mutable_cf_options,
const SequenceNumber& sequence,
uint64_t max_sequential_skip_in_iterations, uint64_t version_number,
ReadCallback* read_callback, DBImpl* db_impl, ColumnFamilyData* cfd,
bool allow_blob, bool allow_refresh);
// Store some parameters so we can refresh the iterator at a later point
// with these same params
void StoreRefreshInfo(const ReadOptions& read_options, DBImpl* db_impl,
ColumnFamilyData* cfd, ReadCallback* read_callback,
bool allow_blob) {
read_options_ = read_options;
db_impl_ = db_impl;
cfd_ = cfd;
read_callback_ = read_callback;
allow_blob_ = allow_blob;
}
private:
DBIter* db_iter_;
Arena arena_;
uint64_t sv_number_;
ColumnFamilyData* cfd_ = nullptr;
DBImpl* db_impl_ = nullptr;
ReadOptions read_options_;
ReadCallback* read_callback_;
bool allow_blob_ = false;
bool allow_refresh_ = true;
};
// Generate the arena wrapped iterator class.
// `db_impl` and `cfd` are used for reneweal. If left null, renewal will not
// be supported.
extern ArenaWrappedDBIter* NewArenaWrappedDbIterator(
Env* env, const ReadOptions& read_options,
const ImmutableCFOptions& cf_options,
const MutableCFOptions& mutable_cf_options, const SequenceNumber& sequence,
uint64_t max_sequential_skip_in_iterations, uint64_t version_number,
ReadCallback* read_callback, DBImpl* db_impl = nullptr,
ColumnFamilyData* cfd = nullptr, bool allow_blob = false,
bool allow_refresh = true);
} // namespace rocksdb

1
db/db_blob_index_test.cc
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@ -12,6 +12,7 @@
#include <utility>
#include <vector>
#include "db/arena_wrapped_db_iter.h"
#include "db/column_family.h"
#include "db/db_iter.h"
#include "db/db_test_util.h"

1
db/db_impl/db_impl.cc
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@ -25,6 +25,7 @@
#include <utility>
#include <vector>
#include "db/arena_wrapped_db_iter.h"
#include "db/builder.h"
#include "db/compaction/compaction_job.h"
#include "db/db_info_dumper.h"

1
db/db_impl/db_impl_readonly.cc
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@ -3,6 +3,7 @@
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#include "db/arena_wrapped_db_iter.h"
#include "db/db_impl/db_impl_readonly.h"
#include "db/compacted_db_impl.h"

2
db/db_impl/db_impl_secondary.cc
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@ -7,7 +7,7 @@
#include <cinttypes>
#include "db/db_iter.h"
#include "db/arena_wrapped_db_iter.h"
#include "db/merge_context.h"
#include "logging/auto_roll_logger.h"
#include "monitoring/perf_context_imp.h"

375
db/db_iter.cc
View File

@ -46,73 +46,7 @@ static void DumpInternalIter(Iterator* iter) {
}
#endif
// Memtables and sstables that make the DB representation contain
// (userkey,seq,type) => uservalue entries. DBIter
// combines multiple entries for the same userkey found in the DB
// representation into a single entry while accounting for sequence
// numbers, deletion markers, overwrites, etc.
class DBIter final: public Iterator {
public:
// The following is grossly complicated. TODO: clean it up
// Which direction is the iterator currently moving?
// (1) When moving forward:
// (1a) if current_entry_is_merged_ = false, the internal iterator is
// positioned at the exact entry that yields this->key(), this->value()
// (1b) if current_entry_is_merged_ = true, the internal iterator is
// positioned immediately after the last entry that contributed to the
// current this->value(). That entry may or may not have key equal to
// this->key().
// (2) When moving backwards, the internal iterator is positioned
// just before all entries whose user key == this->key().
enum Direction {
kForward,
kReverse
};
// LocalStatistics contain Statistics counters that will be aggregated per
// each iterator instance and then will be sent to the global statistics when
// the iterator is destroyed.
//
// The purpose of this approach is to avoid perf regression happening
// when multiple threads bump the atomic counters from a DBIter::Next().
struct LocalStatistics {
explicit LocalStatistics() { ResetCounters(); }
void ResetCounters() {
next_count_ = 0;
next_found_count_ = 0;
prev_count_ = 0;
prev_found_count_ = 0;
bytes_read_ = 0;
skip_count_ = 0;
}
void BumpGlobalStatistics(Statistics* global_statistics) {
RecordTick(global_statistics, NUMBER_DB_NEXT, next_count_);
RecordTick(global_statistics, NUMBER_DB_NEXT_FOUND, next_found_count_);
RecordTick(global_statistics, NUMBER_DB_PREV, prev_count_);
RecordTick(global_statistics, NUMBER_DB_PREV_FOUND, prev_found_count_);
RecordTick(global_statistics, ITER_BYTES_READ, bytes_read_);
RecordTick(global_statistics, NUMBER_ITER_SKIP, skip_count_);
PERF_COUNTER_ADD(iter_read_bytes, bytes_read_);
ResetCounters();
}
// Map to Tickers::NUMBER_DB_NEXT
uint64_t next_count_;
// Map to Tickers::NUMBER_DB_NEXT_FOUND
uint64_t next_found_count_;
// Map to Tickers::NUMBER_DB_PREV
uint64_t prev_count_;
// Map to Tickers::NUMBER_DB_PREV_FOUND
uint64_t prev_found_count_;
// Map to Tickers::ITER_BYTES_READ
uint64_t bytes_read_;
// Map to Tickers::NUMBER_ITER_SKIP
uint64_t skip_count_;
};
DBIter(Env* _env, const ReadOptions& read_options,
DBIter::DBIter(Env* _env, const ReadOptions& read_options,
const ImmutableCFOptions& cf_options,
const MutableCFOptions& mutable_cf_options, const Comparator* cmp,
InternalIterator* iter, SequenceNumber s, bool arena_mode,
@ -154,65 +88,9 @@ class DBIter final: public Iterator {
if (iter_.iter()) {
iter_.iter()->SetPinnedItersMgr(&pinned_iters_mgr_);
}
}
// No copying allowed
DBIter(const DBIter&) = delete;
void operator=(const DBIter&) = delete;
}
~DBIter() override {
// Release pinned data if any
if (pinned_iters_mgr_.PinningEnabled()) {
pinned_iters_mgr_.ReleasePinnedData();
}
RecordTick(statistics_, NO_ITERATOR_DELETED);
ResetInternalKeysSkippedCounter();
local_stats_.BumpGlobalStatistics(statistics_);
iter_.DeleteIter(arena_mode_);
}
virtual void SetIter(InternalIterator* iter) {
assert(iter_.iter() == nullptr);
iter_.Set(iter);
iter_.iter()->SetPinnedItersMgr(&pinned_iters_mgr_);
}
virtual ReadRangeDelAggregator* GetRangeDelAggregator() {
return &range_del_agg_;
}
bool Valid() const override { return valid_; }
Slice key() const override {
assert(valid_);
if(start_seqnum_ > 0) {
return saved_key_.GetInternalKey();
} else {
return saved_key_.GetUserKey();
}
}
Slice value() const override {
assert(valid_);
if (current_entry_is_merged_) {
// If pinned_value_ is set then the result of merge operator is one of
// the merge operands and we should return it.
return pinned_value_.data() ? pinned_value_ : saved_value_;
} else if (direction_ == kReverse) {
return pinned_value_;
} else {
return iter_.value();
}
}
Status status() const override {
if (status_.ok()) {
return iter_.status();
} else {
assert(!valid_);
return status_;
}
}
bool IsBlob() const {
assert(valid_ && (allow_blob_ || !is_blob_));
return is_blob_;
}
Status GetProperty(std::string prop_name, std::string* prop) override {
Status DBIter::GetProperty(std::string prop_name, std::string* prop) {
if (prop == nullptr) {
return Status::InvalidArgument("prop is nullptr");
}
@ -231,138 +109,9 @@ class DBIter final: public Iterator {
return Status::OK();
}
return Status::InvalidArgument("Unidentified property.");
}
}
inline void Next() final override;
inline void Prev() final override;
inline void Seek(const Slice& target) final override;
inline void SeekForPrev(const Slice& target) final override;
inline void SeekToFirst() final override;
inline void SeekToLast() final override;
Env* env() { return env_; }
void set_sequence(uint64_t s) {
sequence_ = s;
if (read_callback_) {
read_callback_->Refresh(s);
}
}
void set_valid(bool v) { valid_ = v; }
private:
// For all methods in this block:
// PRE: iter_->Valid() && status_.ok()
// Return false if there was an error, and status() is non-ok, valid_ = false;
// in this case callers would usually stop what they were doing and return.
bool ReverseToForward();
bool ReverseToBackward();
bool FindValueForCurrentKey();
bool FindValueForCurrentKeyUsingSeek();
bool FindUserKeyBeforeSavedKey();
inline bool FindNextUserEntry(bool skipping, bool prefix_check);
inline bool FindNextUserEntryInternal(bool skipping, bool prefix_check);
bool ParseKey(ParsedInternalKey* key);
bool MergeValuesNewToOld();
void PrevInternal();
bool TooManyInternalKeysSkipped(bool increment = true);
inline bool IsVisible(SequenceNumber sequence);
// Temporarily pin the blocks that we encounter until ReleaseTempPinnedData()
// is called
void TempPinData() {
if (!pin_thru_lifetime_) {
pinned_iters_mgr_.StartPinning();
}
}
// Release blocks pinned by TempPinData()
void ReleaseTempPinnedData() {
if (!pin_thru_lifetime_ && pinned_iters_mgr_.PinningEnabled()) {
pinned_iters_mgr_.ReleasePinnedData();
}
}
inline void ClearSavedValue() {
if (saved_value_.capacity() > 1048576) {
std::string empty;
swap(empty, saved_value_);
} else {
saved_value_.clear();
}
}
inline void ResetInternalKeysSkippedCounter() {
local_stats_.skip_count_ += num_internal_keys_skipped_;
if (valid_) {
local_stats_.skip_count_--;
}
num_internal_keys_skipped_ = 0;
}
const SliceTransform* prefix_extractor_;
Env* const env_;
Logger* logger_;
UserComparatorWrapper user_comparator_;
const MergeOperator* const merge_operator_;
IteratorWrapper iter_;
ReadCallback* read_callback_;
// Max visible sequence number. It is normally the snapshot seq unless we have
// uncommitted data in db as in WriteUnCommitted.
SequenceNumber sequence_;
IterKey saved_key_;
// Reusable internal key data structure. This is only used inside one function
// and should not be used across functions. Reusing this object can reduce
// overhead of calling construction of the function if creating it each time.
ParsedInternalKey ikey_;
std::string saved_value_;
Slice pinned_value_;
// for prefix seek mode to support prev()
Statistics* statistics_;
uint64_t max_skip_;
uint64_t max_skippable_internal_keys_;
uint64_t num_internal_keys_skipped_;
const Slice* iterate_lower_bound_;
const Slice* iterate_upper_bound_;
IterKey prefix_start_buf_;
Status status_;
Slice prefix_start_key_;
Direction direction_;
bool valid_;
bool current_entry_is_merged_;
// True if we know that the current entry's seqnum is 0.
// This information is used as that the next entry will be for another
// user key.
bool is_key_seqnum_zero_;
const bool prefix_same_as_start_;
// Means that we will pin all data blocks we read as long the Iterator
// is not deleted, will be true if ReadOptions::pin_data is true
const bool pin_thru_lifetime_;
const bool total_order_seek_;
bool allow_blob_;
bool is_blob_;
bool arena_mode_;
// List of operands for merge operator.
MergeContext merge_context_;
ReadRangeDelAggregator range_del_agg_;
LocalStatistics local_stats_;
PinnedIteratorsManager pinned_iters_mgr_;
#ifdef ROCKSDB_LITE
ROCKSDB_FIELD_UNUSED
#endif
DBImpl* db_impl_;
#ifdef ROCKSDB_LITE
ROCKSDB_FIELD_UNUSED
#endif
ColumnFamilyData* cfd_;
// for diff snapshots we want the lower bound on the seqnum;
// if this value > 0 iterator will return internal keys
SequenceNumber start_seqnum_;
};
inline bool DBIter::ParseKey(ParsedInternalKey* ikey) {
bool DBIter::ParseKey(ParsedInternalKey* ikey) {
if (!ParseInternalKey(iter_.key(), ikey)) {
status_ = Status::Corruption("corrupted internal key in DBIter");
valid_ = false;
@ -429,13 +178,13 @@ void DBIter::Next() {
// keys against the prefix of the seeked key. Set to false when
// performing a seek without a key (e.g. SeekToFirst). Set to
// prefix_same_as_start_ for other iterations.
inline bool DBIter::FindNextUserEntry(bool skipping, bool prefix_check) {
bool DBIter::FindNextUserEntry(bool skipping, bool prefix_check) {
PERF_TIMER_GUARD(find_next_user_entry_time);
return FindNextUserEntryInternal(skipping, prefix_check);
}
// Actual implementation of DBIter::FindNextUserEntry()
inline bool DBIter::FindNextUserEntryInternal(bool skipping, bool prefix_check) {
bool DBIter::FindNextUserEntryInternal(bool skipping, bool prefix_check) {
// Loop until we hit an acceptable entry to yield
assert(iter_.Valid());
assert(status_.ok());
@ -1523,114 +1272,4 @@ Iterator* NewDBIterator(Env* env, const ReadOptions& read_options,
return db_iter;
}
ArenaWrappedDBIter::~ArenaWrappedDBIter() { db_iter_->~DBIter(); }
ReadRangeDelAggregator* ArenaWrappedDBIter::GetRangeDelAggregator() {
return db_iter_->GetRangeDelAggregator();
}
void ArenaWrappedDBIter::SetIterUnderDBIter(InternalIterator* iter) {
static_cast<DBIter*>(db_iter_)->SetIter(iter);
}
inline bool ArenaWrappedDBIter::Valid() const { return db_iter_->Valid(); }
inline void ArenaWrappedDBIter::SeekToFirst() { db_iter_->SeekToFirst(); }
inline void ArenaWrappedDBIter::SeekToLast() { db_iter_->SeekToLast(); }
inline void ArenaWrappedDBIter::Seek(const Slice& target) {
db_iter_->Seek(target);
}
inline void ArenaWrappedDBIter::SeekForPrev(const Slice& target) {
db_iter_->SeekForPrev(target);
}
inline void ArenaWrappedDBIter::Next() { db_iter_->Next(); }
inline void ArenaWrappedDBIter::Prev() { db_iter_->Prev(); }
inline Slice ArenaWrappedDBIter::key() const { return db_iter_->key(); }
inline Slice ArenaWrappedDBIter::value() const { return db_iter_->value(); }
inline Status ArenaWrappedDBIter::status() const { return db_iter_->status(); }
bool ArenaWrappedDBIter::IsBlob() const { return db_iter_->IsBlob(); }
inline Status ArenaWrappedDBIter::GetProperty(std::string prop_name,
std::string* prop) {
if (prop_name == "rocksdb.iterator.super-version-number") {
// First try to pass the value returned from inner iterator.
if (!db_iter_->GetProperty(prop_name, prop).ok()) {
*prop = ToString(sv_number_);
}
return Status::OK();
}
return db_iter_->GetProperty(prop_name, prop);
}
void ArenaWrappedDBIter::Init(Env* env, const ReadOptions& read_options,
const ImmutableCFOptions& cf_options,
const MutableCFOptions& mutable_cf_options,
const SequenceNumber& sequence,
uint64_t max_sequential_skip_in_iteration,
uint64_t version_number,
ReadCallback* read_callback, DBImpl* db_impl,
ColumnFamilyData* cfd, bool allow_blob,
bool allow_refresh) {
auto mem = arena_.AllocateAligned(sizeof(DBIter));
db_iter_ = new (mem) DBIter(env, read_options, cf_options, mutable_cf_options,
cf_options.user_comparator, nullptr, sequence,
true, max_sequential_skip_in_iteration,
read_callback, db_impl, cfd, allow_blob);
sv_number_ = version_number;
allow_refresh_ = allow_refresh;
}
Status ArenaWrappedDBIter::Refresh() {
if (cfd_ == nullptr || db_impl_ == nullptr || !allow_refresh_) {
return Status::NotSupported("Creating renew iterator is not allowed.");
}
assert(db_iter_ != nullptr);
// TODO(yiwu): For last_seq_same_as_publish_seq_==false, this is not the
// correct behavior. Will be corrected automatically when we take a snapshot
// here for the case of WritePreparedTxnDB.
SequenceNumber latest_seq = db_impl_->GetLatestSequenceNumber();
uint64_t cur_sv_number = cfd_->GetSuperVersionNumber();
if (sv_number_ != cur_sv_number) {
Env* env = db_iter_->env();
db_iter_->~DBIter();
arena_.~Arena();
new (&arena_) Arena();
SuperVersion* sv = cfd_->GetReferencedSuperVersion(db_impl_->mutex());
if (read_callback_) {
read_callback_->Refresh(latest_seq);
}
Init(env, read_options_, *(cfd_->ioptions()), sv->mutable_cf_options,
latest_seq, sv->mutable_cf_options.max_sequential_skip_in_iterations,
cur_sv_number, read_callback_, db_impl_, cfd_, allow_blob_,
allow_refresh_);
InternalIterator* internal_iter = db_impl_->NewInternalIterator(
read_options_, cfd_, sv, &arena_, db_iter_->GetRangeDelAggregator(),
latest_seq);
SetIterUnderDBIter(internal_iter);
} else {
db_iter_->set_sequence(latest_seq);
db_iter_->set_valid(false);
}
return Status::OK();
}
ArenaWrappedDBIter* NewArenaWrappedDbIterator(
Env* env, const ReadOptions& read_options,
const ImmutableCFOptions& cf_options,
const MutableCFOptions& mutable_cf_options, const SequenceNumber& sequence,
uint64_t max_sequential_skip_in_iterations, uint64_t version_number,
ReadCallback* read_callback, DBImpl* db_impl, ColumnFamilyData* cfd,
bool allow_blob, bool allow_refresh) {
ArenaWrappedDBIter* iter = new ArenaWrappedDBIter();
iter->Init(env, read_options, cf_options, mutable_cf_options, sequence,
max_sequential_skip_in_iterations, version_number, read_callback,
db_impl, cfd, allow_blob, allow_refresh);
if (db_impl != nullptr && cfd != nullptr && allow_refresh) {
iter->StoreRefreshInfo(read_options, db_impl, cfd, read_callback,
allow_blob);
}
return iter;
}
} // namespace rocksdb

339
db/db_iter.h
View File

@ -17,6 +17,7 @@
#include "options/cf_options.h"
#include "rocksdb/db.h"
#include "rocksdb/iterator.h"
#include "table/iterator_wrapper.h"
#include "util/autovector.h"
namespace rocksdb {
@ -46,9 +47,268 @@ namespace rocksdb {
// key: BBB value: v1
// key: BBC value: v1
//
class Arena;
class DBIter;
// Memtables and sstables that make the DB representation contain
// (userkey,seq,type) => uservalue entries. DBIter
// combines multiple entries for the same userkey found in the DB
// representation into a single entry while accounting for sequence
// numbers, deletion markers, overwrites, etc.
class DBIter final: public Iterator {
public:
// The following is grossly complicated. TODO: clean it up
// Which direction is the iterator currently moving?
// (1) When moving forward:
// (1a) if current_entry_is_merged_ = false, the internal iterator is
// positioned at the exact entry that yields this->key(), this->value()
// (1b) if current_entry_is_merged_ = true, the internal iterator is
// positioned immediately after the last entry that contributed to the
// current this->value(). That entry may or may not have key equal to
// this->key().
// (2) When moving backwards, the internal iterator is positioned
// just before all entries whose user key == this->key().
enum Direction {
kForward,
kReverse
};
// LocalStatistics contain Statistics counters that will be aggregated per
// each iterator instance and then will be sent to the global statistics when
// the iterator is destroyed.
//
// The purpose of this approach is to avoid perf regression happening
// when multiple threads bump the atomic counters from a DBIter::Next().
struct LocalStatistics {
explicit LocalStatistics() { ResetCounters(); }
void ResetCounters() {
next_count_ = 0;
next_found_count_ = 0;
prev_count_ = 0;
prev_found_count_ = 0;
bytes_read_ = 0;
skip_count_ = 0;
}
void BumpGlobalStatistics(Statistics* global_statistics) {
RecordTick(global_statistics, NUMBER_DB_NEXT, next_count_);
RecordTick(global_statistics, NUMBER_DB_NEXT_FOUND, next_found_count_);
RecordTick(global_statistics, NUMBER_DB_PREV, prev_count_);
RecordTick(global_statistics, NUMBER_DB_PREV_FOUND, prev_found_count_);
RecordTick(global_statistics, ITER_BYTES_READ, bytes_read_);
RecordTick(global_statistics, NUMBER_ITER_SKIP, skip_count_);
PERF_COUNTER_ADD(iter_read_bytes, bytes_read_);
ResetCounters();
}
// Map to Tickers::NUMBER_DB_NEXT
uint64_t next_count_;
// Map to Tickers::NUMBER_DB_NEXT_FOUND
uint64_t next_found_count_;
// Map to Tickers::NUMBER_DB_PREV
uint64_t prev_count_;
// Map to Tickers::NUMBER_DB_PREV_FOUND
uint64_t prev_found_count_;
// Map to Tickers::ITER_BYTES_READ
uint64_t bytes_read_;
// Map to Tickers::NUMBER_ITER_SKIP
uint64_t skip_count_;
};
DBIter(Env* _env, const ReadOptions& read_options,
const ImmutableCFOptions& cf_options,
const MutableCFOptions& mutable_cf_options, const Comparator* cmp,
InternalIterator* iter, SequenceNumber s, bool arena_mode,
uint64_t max_sequential_skip_in_iterations,
ReadCallback* read_callback, DBImpl* db_impl, ColumnFamilyData* cfd,
bool allow_blob);
// No copying allowed
DBIter(const DBIter&) = delete;
void operator=(const DBIter&) = delete;
~DBIter() override {
// Release pinned data if any
if (pinned_iters_mgr_.PinningEnabled()) {
pinned_iters_mgr_.ReleasePinnedData();
}
RecordTick(statistics_, NO_ITERATOR_DELETED);
ResetInternalKeysSkippedCounter();
local_stats_.BumpGlobalStatistics(statistics_);
iter_.DeleteIter(arena_mode_);
}
virtual void SetIter(InternalIterator* iter) {
assert(iter_.iter() == nullptr);
iter_.Set(iter);
iter_.iter()->SetPinnedItersMgr(&pinned_iters_mgr_);
}
virtual ReadRangeDelAggregator* GetRangeDelAggregator() {
return &range_del_agg_;
}
bool Valid() const override { return valid_; }
Slice key() const override {
assert(valid_);
if(start_seqnum_ > 0) {
return saved_key_.GetInternalKey();
} else {
return saved_key_.GetUserKey();
}
}
Slice value() const override {
assert(valid_);
if (current_entry_is_merged_) {
// If pinned_value_ is set then the result of merge operator is one of
// the merge operands and we should return it.
return pinned_value_.data() ? pinned_value_ : saved_value_;
} else if (direction_ == kReverse) {
return pinned_value_;
} else {
return iter_.value();
}
}
Status status() const override {
if (status_.ok()) {
return iter_.status();
} else {
assert(!valid_);
return status_;
}
}
bool IsBlob() const {
assert(valid_ && (allow_blob_ || !is_blob_));
return is_blob_;
}
Status GetProperty(std::string prop_name, std::string* prop) override;
void Next() final override;
void Prev() final override;
void Seek(const Slice& target) final override;
void SeekForPrev(const Slice& target) final override;
void SeekToFirst() final override;
void SeekToLast() final override;
Env* env() { return env_; }
void set_sequence(uint64_t s) {
sequence_ = s;
if (read_callback_) {
read_callback_->Refresh(s);
}
}
void set_valid(bool v) { valid_ = v; }
private:
// For all methods in this block:
// PRE: iter_->Valid() && status_.ok()
// Return false if there was an error, and status() is non-ok, valid_ = false;
// in this case callers would usually stop what they were doing and return.
bool ReverseToForward();
bool ReverseToBackward();
bool FindValueForCurrentKey();
bool FindValueForCurrentKeyUsingSeek();
bool FindUserKeyBeforeSavedKey();
bool FindNextUserEntry(bool skipping, bool prefix_check);
bool FindNextUserEntryInternal(bool skipping, bool prefix_check);
bool ParseKey(ParsedInternalKey* key);
bool MergeValuesNewToOld();
void PrevInternal();
bool TooManyInternalKeysSkipped(bool increment = true);
bool IsVisible(SequenceNumber sequence);
// Temporarily pin the blocks that we encounter until ReleaseTempPinnedData()
// is called
void TempPinData() {
if (!pin_thru_lifetime_) {
pinned_iters_mgr_.StartPinning();
}
}
// Release blocks pinned by TempPinData()
void ReleaseTempPinnedData() {
if (!pin_thru_lifetime_ && pinned_iters_mgr_.PinningEnabled()) {
pinned_iters_mgr_.ReleasePinnedData();
}
}
inline void ClearSavedValue() {
if (saved_value_.capacity() > 1048576) {
std::string empty;
swap(empty, saved_value_);
} else {
saved_value_.clear();
}
}
inline void ResetInternalKeysSkippedCounter() {
local_stats_.skip_count_ += num_internal_keys_skipped_;
if (valid_) {
local_stats_.skip_count_--;
}
num_internal_keys_skipped_ = 0;
}
const SliceTransform* prefix_extractor_;
Env* const env_;
Logger* logger_;
UserComparatorWrapper user_comparator_;
const MergeOperator* const merge_operator_;
IteratorWrapper iter_;
ReadCallback* read_callback_;
// Max visible sequence number. It is normally the snapshot seq unless we have
// uncommitted data in db as in WriteUnCommitted.
SequenceNumber sequence_;
IterKey saved_key_;
// Reusable internal key data structure. This is only used inside one function
// and should not be used across functions. Reusing this object can reduce
// overhead of calling construction of the function if creating it each time.
ParsedInternalKey ikey_;
std::string saved_value_;
Slice pinned_value_;
// for prefix seek mode to support prev()
Statistics* statistics_;
uint64_t max_skip_;
uint64_t max_skippable_internal_keys_;
uint64_t num_internal_keys_skipped_;
const Slice* iterate_lower_bound_;
const Slice* iterate_upper_bound_;
IterKey prefix_start_buf_;
Status status_;
Slice prefix_start_key_;
Direction direction_;
bool valid_;
bool current_entry_is_merged_;
// True if we know that the current entry's seqnum is 0.
// This information is used as that the next entry will be for another
// user key.
bool is_key_seqnum_zero_;
const bool prefix_same_as_start_;
// Means that we will pin all data blocks we read as long the Iterator
// is not deleted, will be true if ReadOptions::pin_data is true
const bool pin_thru_lifetime_;
const bool total_order_seek_;
bool allow_blob_;
bool is_blob_;
bool arena_mode_;
// List of operands for merge operator.
MergeContext merge_context_;
ReadRangeDelAggregator range_del_agg_;
LocalStatistics local_stats_;
PinnedIteratorsManager pinned_iters_mgr_;
#ifdef ROCKSDB_LITE
ROCKSDB_FIELD_UNUSED
#endif
DBImpl* db_impl_;
#ifdef ROCKSDB_LITE
ROCKSDB_FIELD_UNUSED
#endif
ColumnFamilyData* cfd_;
// for diff snapshots we want the lower bound on the seqnum;
// if this value > 0 iterator will return internal keys
SequenceNumber start_seqnum_;
};
// Return a new iterator that converts internal keys (yielded by
// "*internal_iter") that were live at the specified `sequence` number
// into appropriate user keys.
@ -61,79 +321,4 @@ extern Iterator* NewDBIterator(
ReadCallback* read_callback, DBImpl* db_impl = nullptr,
ColumnFamilyData* cfd = nullptr, bool allow_blob = false);
// A wrapper iterator which wraps DB Iterator and the arena, with which the DB
// iterator is supposed be allocated. This class is used as an entry point of
// a iterator hierarchy whose memory can be allocated inline. In that way,
// accessing the iterator tree can be more cache friendly. It is also faster
// to allocate.
// When using the class's Iterator interface, the behavior is exactly
// the same as the inner DBIter.
class ArenaWrappedDBIter : public Iterator {
public:
virtual ~ArenaWrappedDBIter();
// Get the arena to be used to allocate memory for DBIter to be wrapped,
// as well as child iterators in it.
virtual Arena* GetArena() { return &arena_; }
virtual ReadRangeDelAggregator* GetRangeDelAggregator();
// Set the internal iterator wrapped inside the DB Iterator. Usually it is
// a merging iterator.
virtual void SetIterUnderDBIter(InternalIterator* iter);
virtual bool Valid() const override;
virtual void SeekToFirst() override;
virtual void SeekToLast() override;
virtual void Seek(const Slice& target) override;
virtual void SeekForPrev(const Slice& target) override;
virtual void Next() override;
virtual void Prev() override;
virtual Slice key() const override;
virtual Slice value() const override;
virtual Status status() const override;
virtual Status Refresh() override;
bool IsBlob() const;
virtual Status GetProperty(std::string prop_name, std::string* prop) override;
void Init(Env* env, const ReadOptions& read_options,
const ImmutableCFOptions& cf_options,
const MutableCFOptions& mutable_cf_options,
const SequenceNumber& sequence,
uint64_t max_sequential_skip_in_iterations, uint64_t version_number,
ReadCallback* read_callback, DBImpl* db_impl, ColumnFamilyData* cfd,
bool allow_blob, bool allow_refresh);
void StoreRefreshInfo(const ReadOptions& read_options, DBImpl* db_impl,
ColumnFamilyData* cfd, ReadCallback* read_callback,
bool allow_blob) {
read_options_ = read_options;
db_impl_ = db_impl;
cfd_ = cfd;
read_callback_ = read_callback;
allow_blob_ = allow_blob;
}
private:
DBIter* db_iter_;
Arena arena_;
uint64_t sv_number_;
ColumnFamilyData* cfd_ = nullptr;
DBImpl* db_impl_ = nullptr;
ReadOptions read_options_;
ReadCallback* read_callback_;
bool allow_blob_ = false;
bool allow_refresh_ = true;
};
// Generate the arena wrapped iterator class.
// `db_impl` and `cfd` are used for reneweal. If left null, renewal will not
// be supported.
extern ArenaWrappedDBIter* NewArenaWrappedDbIterator(
Env* env, const ReadOptions& read_options,
const ImmutableCFOptions& cf_options,
const MutableCFOptions& mutable_cf_options, const SequenceNumber& sequence,
uint64_t max_sequential_skip_in_iterations, uint64_t version_number,
ReadCallback* read_callback, DBImpl* db_impl = nullptr,
ColumnFamilyData* cfd = nullptr, bool allow_blob = false,
bool allow_refresh = true);
} // namespace rocksdb

1
db/db_iterator_test.cc
View File

@ -9,6 +9,7 @@
#include <functional>
#include "db/arena_wrapped_db_iter.h"
#include "db/db_iter.h"
#include "db/db_test_util.h"
#include "port/port.h"

1
src.mk
View File

@ -3,6 +3,7 @@ LIB_SOURCES = \
cache/clock_cache.cc \
cache/lru_cache.cc \
cache/sharded_cache.cc \
db/arena_wrapped_db_iter.cc \
db/builder.cc \
db/c.cc \
db/column_family.cc \

1
utilities/blob_db/blob_db_iterator.h
View File

@ -6,6 +6,7 @@
#pragma once
#ifndef ROCKSDB_LITE
#include "db/arena_wrapped_db_iter.h"
#include "monitoring/statistics.h"
#include "rocksdb/iterator.h"
#include "util/stop_watch.h"

1
utilities/transactions/write_prepared_txn_db.cc
View File

@ -13,6 +13,7 @@
#include <unordered_set>
#include <vector>
#include "db/arena_wrapped_db_iter.h"
#include "db/db_impl/db_impl.h"
#include "rocksdb/db.h"
#include "rocksdb/options.h"

1
utilities/transactions/write_unprepared_txn_db.cc
View File

@ -5,6 +5,7 @@
#ifndef ROCKSDB_LITE
#include "db/arena_wrapped_db_iter.h"
#include "utilities/transactions/write_unprepared_txn_db.h"
#include "rocksdb/utilities/transaction_db.h"
#include "util/cast_util.h"