mirror of
https://github.com/facebook/rocksdb.git
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fb2346fc1f
Summary: I'm cleaning up some code preparing for the big diff review tomorrow. This is the first part of the cleanup. Changes are mostly cosmetic. The goal is to decrease amount of code difference between columnfamilies and master branch. This diff also fixes race condition when dropping column family. Test Plan: Ran db_stress with variety of parameters Reviewers: dhruba, haobo Differential Revision: https://reviews.facebook.net/D16833
525 lines
18 KiB
C++
525 lines
18 KiB
C++
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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//
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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#include "db/memtable.h"
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#include <memory>
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#include "db/dbformat.h"
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#include "db/merge_context.h"
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#include "rocksdb/comparator.h"
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#include "rocksdb/env.h"
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#include "rocksdb/iterator.h"
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#include "rocksdb/merge_operator.h"
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#include "rocksdb/slice_transform.h"
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#include "util/arena.h"
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#include "util/coding.h"
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#include "util/murmurhash.h"
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#include "util/mutexlock.h"
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#include "util/perf_context_imp.h"
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#include "util/statistics.h"
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#include "util/stop_watch.h"
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namespace rocksdb {
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MemTable::MemTable(const InternalKeyComparator& cmp,
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const Options& options)
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: comparator_(cmp),
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refs_(0),
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arena_(options.arena_block_size),
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table_(options.memtable_factory->CreateMemTableRep(
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comparator_, &arena_, options.prefix_extractor.get())),
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flush_in_progress_(false),
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flush_completed_(false),
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file_number_(0),
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first_seqno_(0),
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mem_next_logfile_number_(0),
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locks_(options.inplace_update_support ? options.inplace_update_num_locks
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: 0),
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prefix_extractor_(options.prefix_extractor.get()) {
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if (prefix_extractor_ && options.memtable_prefix_bloom_bits > 0) {
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prefix_bloom_.reset(new DynamicBloom(options.memtable_prefix_bloom_bits,
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options.memtable_prefix_bloom_probes));
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}
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}
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MemTable::~MemTable() {
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assert(refs_ == 0);
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}
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size_t MemTable::ApproximateMemoryUsage() {
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return arena_.ApproximateMemoryUsage() + table_->ApproximateMemoryUsage();
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}
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int MemTable::KeyComparator::operator()(const char* prefix_len_key1,
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const char* prefix_len_key2) const {
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// Internal keys are encoded as length-prefixed strings.
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Slice k1 = GetLengthPrefixedSlice(prefix_len_key1);
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Slice k2 = GetLengthPrefixedSlice(prefix_len_key2);
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return comparator.Compare(k1, k2);
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}
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int MemTable::KeyComparator::operator()(const char* prefix_len_key,
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const Slice& key)
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const {
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// Internal keys are encoded as length-prefixed strings.
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Slice a = GetLengthPrefixedSlice(prefix_len_key);
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return comparator.Compare(a, key);
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}
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Slice MemTableRep::UserKey(const char* key) const {
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Slice slice = GetLengthPrefixedSlice(key);
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return Slice(slice.data(), slice.size() - 8);
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}
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// Encode a suitable internal key target for "target" and return it.
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// Uses *scratch as scratch space, and the returned pointer will point
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// into this scratch space.
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const char* EncodeKey(std::string* scratch, const Slice& target) {
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scratch->clear();
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PutVarint32(scratch, target.size());
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scratch->append(target.data(), target.size());
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return scratch->data();
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}
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class MemTableIterator: public Iterator {
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public:
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MemTableIterator(const MemTable& mem, const ReadOptions& options)
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: mem_(mem), iter_(), dynamic_prefix_seek_(false), valid_(false) {
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if (options.prefix) {
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iter_.reset(mem_.table_->GetPrefixIterator(*options.prefix));
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} else if (options.prefix_seek) {
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dynamic_prefix_seek_ = true;
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iter_.reset(mem_.table_->GetDynamicPrefixIterator());
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} else {
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iter_.reset(mem_.table_->GetIterator());
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}
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}
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virtual bool Valid() const { return valid_; }
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virtual void Seek(const Slice& k) {
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if (dynamic_prefix_seek_ && mem_.prefix_bloom_ &&
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!mem_.prefix_bloom_->MayContain(
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mem_.prefix_extractor_->Transform(ExtractUserKey(k)))) {
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valid_ = false;
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return;
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}
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iter_->Seek(k, nullptr);
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valid_ = iter_->Valid();
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}
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virtual void SeekToFirst() {
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iter_->SeekToFirst();
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valid_ = iter_->Valid();
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}
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virtual void SeekToLast() {
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iter_->SeekToLast();
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valid_ = iter_->Valid();
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}
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virtual void Next() {
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assert(Valid());
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iter_->Next();
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valid_ = iter_->Valid();
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}
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virtual void Prev() {
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assert(Valid());
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iter_->Prev();
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valid_ = iter_->Valid();
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}
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virtual Slice key() const {
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assert(Valid());
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return GetLengthPrefixedSlice(iter_->key());
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}
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virtual Slice value() const {
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assert(Valid());
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Slice key_slice = GetLengthPrefixedSlice(iter_->key());
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return GetLengthPrefixedSlice(key_slice.data() + key_slice.size());
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}
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virtual Status status() const { return Status::OK(); }
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private:
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const MemTable& mem_;
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std::shared_ptr<MemTableRep::Iterator> iter_;
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bool dynamic_prefix_seek_;
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bool valid_;
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// No copying allowed
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MemTableIterator(const MemTableIterator&);
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void operator=(const MemTableIterator&);
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};
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Iterator* MemTable::NewIterator(const ReadOptions& options) {
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return new MemTableIterator(*this, options);
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}
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port::RWMutex* MemTable::GetLock(const Slice& key) {
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static murmur_hash hash;
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return &locks_[hash(key) % locks_.size()];
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}
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void MemTable::Add(SequenceNumber s, ValueType type,
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const Slice& key, /* user key */
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const Slice& value) {
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// Format of an entry is concatenation of:
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// key_size : varint32 of internal_key.size()
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// key bytes : char[internal_key.size()]
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// value_size : varint32 of value.size()
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// value bytes : char[value.size()]
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size_t key_size = key.size();
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size_t val_size = value.size();
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size_t internal_key_size = key_size + 8;
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const size_t encoded_len =
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VarintLength(internal_key_size) + internal_key_size +
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VarintLength(val_size) + val_size;
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char* buf = arena_.Allocate(encoded_len);
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char* p = EncodeVarint32(buf, internal_key_size);
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memcpy(p, key.data(), key_size);
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p += key_size;
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EncodeFixed64(p, (s << 8) | type);
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p += 8;
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p = EncodeVarint32(p, val_size);
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memcpy(p, value.data(), val_size);
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assert((unsigned)(p + val_size - buf) == (unsigned)encoded_len);
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table_->Insert(buf);
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if (prefix_bloom_) {
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assert(prefix_extractor_);
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prefix_bloom_->Add(prefix_extractor_->Transform(key));
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}
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// The first sequence number inserted into the memtable
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assert(first_seqno_ == 0 || s > first_seqno_);
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if (first_seqno_ == 0) {
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first_seqno_ = s;
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}
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}
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// Callback from MemTable::Get()
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namespace {
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struct Saver {
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Status* status;
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const LookupKey* key;
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bool* found_final_value; // Is value set correctly? Used by KeyMayExist
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bool* merge_in_progress;
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std::string* value;
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const MergeOperator* merge_operator;
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// the merge operations encountered;
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MergeContext* merge_context;
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MemTable* mem;
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Logger* logger;
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Statistics* statistics;
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bool inplace_update_support;
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};
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} // namespace
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static bool SaveValue(void* arg, const char* entry) {
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Saver* s = reinterpret_cast<Saver*>(arg);
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MergeContext* merge_context = s->merge_context;
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const MergeOperator* merge_operator = s->merge_operator;
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assert(s != nullptr && merge_context != nullptr);
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// entry format is:
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// klength varint32
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// userkey char[klength-8]
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// tag uint64
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// vlength varint32
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// value char[vlength]
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// Check that it belongs to same user key. We do not check the
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// sequence number since the Seek() call above should have skipped
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// all entries with overly large sequence numbers.
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uint32_t key_length;
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const char* key_ptr = GetVarint32Ptr(entry, entry + 5, &key_length);
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if (s->mem->GetInternalKeyComparator().user_comparator()->Compare(
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Slice(key_ptr, key_length - 8), s->key->user_key()) == 0) {
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// Correct user key
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const uint64_t tag = DecodeFixed64(key_ptr + key_length - 8);
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switch (static_cast<ValueType>(tag & 0xff)) {
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case kTypeValue: {
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if (s->inplace_update_support) {
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s->mem->GetLock(s->key->user_key())->ReadLock();
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}
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Slice v = GetLengthPrefixedSlice(key_ptr + key_length);
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*(s->status) = Status::OK();
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if (*(s->merge_in_progress)) {
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assert(merge_operator);
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if (!merge_operator->FullMerge(s->key->user_key(), &v,
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merge_context->GetOperands(), s->value,
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s->logger)) {
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RecordTick(s->statistics, NUMBER_MERGE_FAILURES);
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*(s->status) =
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Status::Corruption("Error: Could not perform merge.");
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}
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} else {
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s->value->assign(v.data(), v.size());
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}
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if (s->inplace_update_support) {
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s->mem->GetLock(s->key->user_key())->Unlock();
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}
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*(s->found_final_value) = true;
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return false;
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}
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case kTypeDeletion: {
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if (*(s->merge_in_progress)) {
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assert(merge_operator);
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*(s->status) = Status::OK();
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if (!merge_operator->FullMerge(s->key->user_key(), nullptr,
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merge_context->GetOperands(), s->value,
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s->logger)) {
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RecordTick(s->statistics, NUMBER_MERGE_FAILURES);
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*(s->status) =
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Status::Corruption("Error: Could not perform merge.");
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}
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} else {
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*(s->status) = Status::NotFound();
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}
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*(s->found_final_value) = true;
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return false;
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}
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case kTypeMerge: {
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std::string merge_result; // temporary area for merge results later
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Slice v = GetLengthPrefixedSlice(key_ptr + key_length);
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*(s->merge_in_progress) = true;
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merge_context->PushOperand(v);
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while (merge_context->GetNumOperands() >= 2) {
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// Attempt to associative merge. (Returns true if successful)
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if (merge_operator->PartialMerge(
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s->key->user_key(), merge_context->GetOperand(0),
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merge_context->GetOperand(1), &merge_result, s->logger)) {
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merge_context->PushPartialMergeResult(merge_result);
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} else {
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// Stack them because user can't associative merge
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break;
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}
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}
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return true;
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}
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default:
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assert(false);
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return true;
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}
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}
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// s->state could be Corrupt, merge or notfound
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return false;
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}
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bool MemTable::Get(const LookupKey& key, std::string* value, Status* s,
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MergeContext& merge_context, const Options& options) {
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StopWatchNano memtable_get_timer(options.env, false);
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StartPerfTimer(&memtable_get_timer);
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Slice user_key = key.user_key();
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bool found_final_value = false;
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bool merge_in_progress = s->IsMergeInProgress();
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if (prefix_bloom_ &&
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!prefix_bloom_->MayContain(prefix_extractor_->Transform(user_key))) {
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// iter is null if prefix bloom says the key does not exist
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} else {
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Saver saver;
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saver.status = s;
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saver.found_final_value = &found_final_value;
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saver.merge_in_progress = &merge_in_progress;
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saver.key = &key;
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saver.value = value;
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saver.status = s;
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saver.mem = this;
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saver.merge_context = &merge_context;
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saver.merge_operator = options.merge_operator.get();
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saver.logger = options.info_log.get();
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saver.inplace_update_support = options.inplace_update_support;
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saver.statistics = options.statistics.get();
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table_->Get(key, &saver, SaveValue);
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}
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// No change to value, since we have not yet found a Put/Delete
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if (!found_final_value && merge_in_progress) {
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*s = Status::MergeInProgress("");
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}
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BumpPerfTime(&perf_context.get_from_memtable_time, &memtable_get_timer);
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BumpPerfCount(&perf_context.get_from_memtable_count);
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return found_final_value;
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}
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void MemTable::Update(SequenceNumber seq,
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const Slice& key,
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const Slice& value) {
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LookupKey lkey(key, seq);
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Slice mem_key = lkey.memtable_key();
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std::unique_ptr<MemTableRep::Iterator> iter(
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table_->GetIterator(lkey.user_key()));
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iter->Seek(lkey.internal_key(), mem_key.data());
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if (iter->Valid()) {
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// entry format is:
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// key_length varint32
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// userkey char[klength-8]
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// tag uint64
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// vlength varint32
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// value char[vlength]
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// Check that it belongs to same user key. We do not check the
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// sequence number since the Seek() call above should have skipped
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// all entries with overly large sequence numbers.
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const char* entry = iter->key();
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uint32_t key_length = 0;
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const char* key_ptr = GetVarint32Ptr(entry, entry + 5, &key_length);
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if (comparator_.comparator.user_comparator()->Compare(
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Slice(key_ptr, key_length - 8), lkey.user_key()) == 0) {
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// Correct user key
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const uint64_t tag = DecodeFixed64(key_ptr + key_length - 8);
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switch (static_cast<ValueType>(tag & 0xff)) {
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case kTypeValue: {
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Slice prev_value = GetLengthPrefixedSlice(key_ptr + key_length);
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uint32_t prev_size = prev_value.size();
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uint32_t new_size = value.size();
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// Update value, if new value size <= previous value size
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if (new_size <= prev_size ) {
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char* p = EncodeVarint32(const_cast<char*>(key_ptr) + key_length,
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new_size);
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WriteLock wl(GetLock(lkey.user_key()));
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memcpy(p, value.data(), value.size());
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assert((unsigned)((p + value.size()) - entry) ==
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(unsigned)(VarintLength(key_length) + key_length +
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VarintLength(value.size()) + value.size()));
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return;
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}
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}
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default:
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// If the latest value is kTypeDeletion, kTypeMerge or kTypeLogData
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// we don't have enough space for update inplace
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Add(seq, kTypeValue, key, value);
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return;
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}
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}
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}
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// key doesn't exist
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Add(seq, kTypeValue, key, value);
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}
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bool MemTable::UpdateCallback(SequenceNumber seq,
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const Slice& key,
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const Slice& delta,
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const Options& options) {
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LookupKey lkey(key, seq);
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Slice memkey = lkey.memtable_key();
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std::shared_ptr<MemTableRep::Iterator> iter(
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table_->GetIterator(lkey.user_key()));
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iter->Seek(lkey.internal_key(), memkey.data());
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if (iter->Valid()) {
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// entry format is:
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// key_length varint32
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// userkey char[klength-8]
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// tag uint64
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// vlength varint32
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// value char[vlength]
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// Check that it belongs to same user key. We do not check the
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// sequence number since the Seek() call above should have skipped
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// all entries with overly large sequence numbers.
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const char* entry = iter->key();
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uint32_t key_length = 0;
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const char* key_ptr = GetVarint32Ptr(entry, entry + 5, &key_length);
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if (comparator_.comparator.user_comparator()->Compare(
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Slice(key_ptr, key_length - 8), lkey.user_key()) == 0) {
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// Correct user key
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const uint64_t tag = DecodeFixed64(key_ptr + key_length - 8);
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switch (static_cast<ValueType>(tag & 0xff)) {
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case kTypeValue: {
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Slice prev_value = GetLengthPrefixedSlice(key_ptr + key_length);
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uint32_t prev_size = prev_value.size();
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char* prev_buffer = const_cast<char*>(prev_value.data());
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uint32_t new_prev_size = prev_size;
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std::string str_value;
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WriteLock wl(GetLock(lkey.user_key()));
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auto status = options.inplace_callback(prev_buffer, &new_prev_size,
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delta, &str_value);
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if (status == UpdateStatus::UPDATED_INPLACE) {
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// Value already updated by callback.
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assert(new_prev_size <= prev_size);
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if (new_prev_size < prev_size) {
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// overwrite the new prev_size
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char* p = EncodeVarint32(const_cast<char*>(key_ptr) + key_length,
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new_prev_size);
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if (VarintLength(new_prev_size) < VarintLength(prev_size)) {
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// shift the value buffer as well.
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memcpy(p, prev_buffer, new_prev_size);
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}
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}
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RecordTick(options.statistics.get(), NUMBER_KEYS_UPDATED);
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return true;
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} else if (status == UpdateStatus::UPDATED) {
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Add(seq, kTypeValue, key, Slice(str_value));
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RecordTick(options.statistics.get(), NUMBER_KEYS_WRITTEN);
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return true;
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} else if (status == UpdateStatus::UPDATE_FAILED) {
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// No action required. Return.
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return true;
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}
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}
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default:
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break;
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}
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}
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}
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// If the latest value is not kTypeValue
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// or key doesn't exist
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return false;
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}
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|
|
|
size_t MemTable::CountSuccessiveMergeEntries(const LookupKey& key) {
|
|
Slice memkey = key.memtable_key();
|
|
|
|
// A total ordered iterator is costly for some memtablerep (prefix aware
|
|
// reps). By passing in the user key, we allow efficient iterator creation.
|
|
// The iterator only needs to be ordered within the same user key.
|
|
std::unique_ptr<MemTableRep::Iterator> iter(
|
|
table_->GetIterator(key.user_key()));
|
|
iter->Seek(key.internal_key(), memkey.data());
|
|
|
|
size_t num_successive_merges = 0;
|
|
|
|
for (; iter->Valid(); iter->Next()) {
|
|
const char* entry = iter->key();
|
|
uint32_t key_length = 0;
|
|
const char* iter_key_ptr = GetVarint32Ptr(entry, entry + 5, &key_length);
|
|
if (!comparator_.comparator.user_comparator()->Compare(
|
|
Slice(iter_key_ptr, key_length - 8), key.user_key()) == 0) {
|
|
break;
|
|
}
|
|
|
|
const uint64_t tag = DecodeFixed64(iter_key_ptr + key_length - 8);
|
|
if (static_cast<ValueType>(tag & 0xff) != kTypeMerge) {
|
|
break;
|
|
}
|
|
|
|
++num_successive_merges;
|
|
}
|
|
|
|
return num_successive_merges;
|
|
}
|
|
|
|
void MemTableRep::Get(const LookupKey& k, void* callback_args,
|
|
bool (*callback_func)(void* arg, const char* entry)) {
|
|
auto iter = GetIterator(k.user_key());
|
|
for (iter->Seek(k.internal_key(), k.memtable_key().data());
|
|
iter->Valid() && callback_func(callback_args, iter->key());
|
|
iter->Next()) {
|
|
}
|
|
}
|
|
|
|
} // namespace rocksdb
|