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150 wiersze
4.1 KiB
150 wiersze
4.1 KiB
// 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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// 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 "leveldb/write_batch.h"
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#include "db/dbformat.h"
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#include "db/memtable.h"
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#include "db/write_batch_internal.h"
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#include "leveldb/db.h"
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#include "util/coding.h"
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namespace leveldb {
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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() { Clear(); }
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WriteBatch::~WriteBatch() = default;
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WriteBatch::Handler::~Handler() = default;
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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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size_t WriteBatch::ApproximateSize() const { return rep_.size(); }
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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;
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int found = 0;
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while (!input.empty()) {
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found++;
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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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} 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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} else {
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return Status::Corruption("bad WriteBatch Delete");
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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);//默认value的最大字节长度不会超过变长32位的表示。
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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::Append(const WriteBatch& source) {
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WriteBatchInternal::Append(this, &source);
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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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void Put(const Slice& key, const Slice& value) override {
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mem_->Add(sequence_, kTypeValue, key, value);
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sequence_++;
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}
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void Delete(const Slice& key) override {
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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* memtable) {
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MemTableInserter inserter;
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inserter.sequence_ = WriteBatchInternal::Sequence(b);
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inserter.mem_ = memtable;
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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 leveldb
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