fork of https://github.com/oxigraph/rocksdb and https://github.com/facebook/rocksdb for nextgraph and oxigraph
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302 lines
8.9 KiB
302 lines
8.9 KiB
// 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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//
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// WriteBatch::rep_ :=
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// sequence: fixed64
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// count: fixed32
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// data: record[count]
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// record :=
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// kTypeValue varstring varstring
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// kTypeMerge varstring varstring
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// kTypeDeletion varstring
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// varstring :=
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// len: varint32
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// data: uint8[len]
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#include "rocksdb/write_batch.h"
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#include "rocksdb/options.h"
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#include "rocksdb/merge_operator.h"
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#include "db/dbformat.h"
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#include "db/db_impl.h"
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#include "db/memtable.h"
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#include "db/snapshot.h"
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#include "db/write_batch_internal.h"
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#include "util/coding.h"
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#include "util/statistics_imp.h"
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#include <stdexcept>
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namespace rocksdb {
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// WriteBatch header has an 8-byte sequence number followed by a 4-byte count.
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static const size_t kHeader = 12;
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WriteBatch::WriteBatch() {
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Clear();
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}
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WriteBatch::~WriteBatch() { }
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WriteBatch::Handler::~Handler() { }
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void WriteBatch::Handler::Merge(const Slice& key, const Slice& value) {
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throw std::runtime_error("Handler::Merge not implemented!");
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}
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void WriteBatch::Handler::LogData(const Slice& blob) {
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// If the user has not specified something to do with blobs, then we ignore
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// them.
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}
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bool WriteBatch::Handler::Continue() {
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return true;
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}
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void WriteBatch::Clear() {
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rep_.clear();
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rep_.resize(kHeader);
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}
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int WriteBatch::Count() const {
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return WriteBatchInternal::Count(this);
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}
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Status WriteBatch::Iterate(Handler* handler) const {
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Slice input(rep_);
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if (input.size() < kHeader) {
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return Status::Corruption("malformed WriteBatch (too small)");
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}
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input.remove_prefix(kHeader);
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Slice key, value, blob;
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int found = 0;
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while (!input.empty() && handler->Continue()) {
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char tag = input[0];
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input.remove_prefix(1);
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switch (tag) {
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case kTypeValue:
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if (GetLengthPrefixedSlice(&input, &key) &&
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GetLengthPrefixedSlice(&input, &value)) {
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handler->Put(key, value);
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found++;
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} else {
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return Status::Corruption("bad WriteBatch Put");
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}
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break;
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case kTypeDeletion:
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if (GetLengthPrefixedSlice(&input, &key)) {
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handler->Delete(key);
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found++;
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} else {
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return Status::Corruption("bad WriteBatch Delete");
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}
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break;
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case kTypeMerge:
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if (GetLengthPrefixedSlice(&input, &key) &&
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GetLengthPrefixedSlice(&input, &value)) {
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handler->Merge(key, value);
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found++;
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} else {
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return Status::Corruption("bad WriteBatch Merge");
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}
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break;
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case kTypeLogData:
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if (GetLengthPrefixedSlice(&input, &blob)) {
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handler->LogData(blob);
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} else {
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return Status::Corruption("bad WriteBatch Blob");
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}
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break;
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default:
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return Status::Corruption("unknown WriteBatch tag");
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}
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}
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if (found != WriteBatchInternal::Count(this)) {
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return Status::Corruption("WriteBatch has wrong count");
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} else {
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return Status::OK();
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}
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}
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int WriteBatchInternal::Count(const WriteBatch* b) {
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return DecodeFixed32(b->rep_.data() + 8);
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}
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void WriteBatchInternal::SetCount(WriteBatch* b, int n) {
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EncodeFixed32(&b->rep_[8], n);
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}
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SequenceNumber WriteBatchInternal::Sequence(const WriteBatch* b) {
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return SequenceNumber(DecodeFixed64(b->rep_.data()));
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}
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void WriteBatchInternal::SetSequence(WriteBatch* b, SequenceNumber seq) {
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EncodeFixed64(&b->rep_[0], seq);
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}
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void WriteBatch::Put(const Slice& key, const Slice& value) {
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WriteBatchInternal::SetCount(this, WriteBatchInternal::Count(this) + 1);
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rep_.push_back(static_cast<char>(kTypeValue));
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PutLengthPrefixedSlice(&rep_, key);
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PutLengthPrefixedSlice(&rep_, value);
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}
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void WriteBatch::Put(const SliceParts& key, const SliceParts& value) {
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WriteBatchInternal::SetCount(this, WriteBatchInternal::Count(this) + 1);
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rep_.push_back(static_cast<char>(kTypeValue));
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PutLengthPrefixedSliceParts(&rep_, key);
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PutLengthPrefixedSliceParts(&rep_, value);
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}
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void WriteBatch::Delete(const Slice& key) {
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WriteBatchInternal::SetCount(this, WriteBatchInternal::Count(this) + 1);
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rep_.push_back(static_cast<char>(kTypeDeletion));
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PutLengthPrefixedSlice(&rep_, key);
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}
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void WriteBatch::Merge(const Slice& key, const Slice& value) {
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WriteBatchInternal::SetCount(this, WriteBatchInternal::Count(this) + 1);
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rep_.push_back(static_cast<char>(kTypeMerge));
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PutLengthPrefixedSlice(&rep_, key);
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PutLengthPrefixedSlice(&rep_, value);
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}
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void WriteBatch::PutLogData(const Slice& blob) {
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rep_.push_back(static_cast<char>(kTypeLogData));
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PutLengthPrefixedSlice(&rep_, blob);
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}
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namespace {
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class MemTableInserter : public WriteBatch::Handler {
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public:
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SequenceNumber sequence_;
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MemTable* mem_;
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const Options* options_;
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DBImpl* db_;
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const bool filter_deletes_;
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MemTableInserter(SequenceNumber sequence, MemTable* mem, const Options* opts,
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DB* db, const bool filter_deletes)
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: sequence_(sequence),
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mem_(mem),
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options_(opts),
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db_(reinterpret_cast<DBImpl*>(db)),
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filter_deletes_(filter_deletes) {
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assert(mem_);
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if (filter_deletes_) {
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assert(options_);
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assert(db_);
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}
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}
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virtual void Put(const Slice& key, const Slice& value) {
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if (options_->inplace_update_support
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&& mem_->Update(sequence_, kTypeValue, key, value)) {
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RecordTick(options_->statistics.get(), NUMBER_KEYS_UPDATED);
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} else {
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mem_->Add(sequence_, kTypeValue, key, value);
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}
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sequence_++;
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}
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virtual void Merge(const Slice& key, const Slice& value) {
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bool perform_merge = false;
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if (options_->max_successive_merges > 0 && db_ != nullptr) {
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LookupKey lkey(key, sequence_);
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// Count the number of successive merges at the head
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// of the key in the memtable
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size_t num_merges = mem_->CountSuccessiveMergeEntries(lkey);
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if (num_merges >= options_->max_successive_merges) {
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perform_merge = true;
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}
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}
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if (perform_merge) {
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// 1) Get the existing value
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std::string get_value;
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// Pass in the sequence number so that we also include previous merge
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// operations in the same batch.
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SnapshotImpl read_from_snapshot;
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read_from_snapshot.number_ = sequence_;
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ReadOptions read_options;
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read_options.snapshot = &read_from_snapshot;
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db_->Get(read_options, key, &get_value);
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Slice get_value_slice = Slice(get_value);
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// 2) Apply this merge
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auto merge_operator = options_->merge_operator.get();
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assert(merge_operator);
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std::deque<std::string> operands;
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operands.push_front(value.ToString());
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std::string new_value;
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if (!merge_operator->FullMerge(key,
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&get_value_slice,
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operands,
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&new_value,
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options_->info_log.get())) {
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// Failed to merge!
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RecordTick(options_->statistics.get(), NUMBER_MERGE_FAILURES);
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// Store the delta in memtable
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perform_merge = false;
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} else {
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// 3) Add value to memtable
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mem_->Add(sequence_, kTypeValue, key, new_value);
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}
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}
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if (!perform_merge) {
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// Add merge operator to memtable
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mem_->Add(sequence_, kTypeMerge, key, value);
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}
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sequence_++;
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}
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virtual void Delete(const Slice& key) {
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if (filter_deletes_) {
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SnapshotImpl read_from_snapshot;
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read_from_snapshot.number_ = sequence_;
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ReadOptions ropts;
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ropts.snapshot = &read_from_snapshot;
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std::string value;
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if (!db_->KeyMayExist(ropts, key, &value)) {
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RecordTick(options_->statistics.get(), NUMBER_FILTERED_DELETES);
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return;
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}
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}
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mem_->Add(sequence_, kTypeDeletion, key, Slice());
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sequence_++;
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}
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};
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} // namespace
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Status WriteBatchInternal::InsertInto(const WriteBatch* b, MemTable* mem,
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const Options* opts, DB* db,
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const bool filter_deletes) {
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MemTableInserter inserter(WriteBatchInternal::Sequence(b), mem, opts, db,
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filter_deletes);
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return b->Iterate(&inserter);
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}
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void WriteBatchInternal::SetContents(WriteBatch* b, const Slice& contents) {
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assert(contents.size() >= kHeader);
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b->rep_.assign(contents.data(), contents.size());
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}
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void WriteBatchInternal::Append(WriteBatch* dst, const WriteBatch* src) {
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SetCount(dst, Count(dst) + Count(src));
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assert(src->rep_.size() >= kHeader);
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dst->rep_.append(src->rep_.data() + kHeader, src->rep_.size() - kHeader);
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}
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} // namespace rocksdb
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