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100 rivejä
2.6 KiB
100 rivejä
2.6 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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#include "db/builder.h"
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#include "db/dbformat.h"
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#include "db/filename.h"
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#include "db/table_cache.h"
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#include "db/version_edit.h"
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#include "leveldb/db.h"
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#include "leveldb/env.h"
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#include "leveldb/iterator.h"
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namespace leveldb {
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/**
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* description:目的，将内存中的数据写入一个新的 SSTable 文件
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* @param dbname
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* @param env
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* @param options
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* @param table_cache
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* @param iter
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* @param meta ：存储新sstable的相关元数据
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* @return
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*/
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Status BuildTable(const std::string& dbname, Env* env, const Options& options,
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TableCache* table_cache, Iterator* iter, FileMetaData* meta) {
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Status s;
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meta->file_size = 0;
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iter->SeekToFirst();
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std::string fname = TableFileName(dbname, meta->number);
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if (iter->Valid()) {
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WritableFile* file;
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s = env->NewWritableFile(fname, &file);
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if (!s.ok()) {
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return s;
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}
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TableBuilder* builder = new TableBuilder(options, file);
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meta->smallest.DecodeFrom(iter->key());//这里是internal_key
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auto tmp_ts = DecodeFixed64(iter->value().data() + iter->value().size() - kTSLength);
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meta->oldest_ts = tmp_ts;
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meta->newer_ts = tmp_ts;
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Slice key;
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for (; iter->Valid(); iter->Next()) {
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key = iter->key();
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builder->Add(key, iter->value());
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tmp_ts = DecodeFixed64(iter->value().data() + iter->value().size() - kTSLength);
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meta->oldest_ts = meta->oldest_ts > tmp_ts ? tmp_ts : meta->oldest_ts;
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meta->newer_ts = meta->newer_ts > tmp_ts ? meta->newer_ts : tmp_ts;
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}
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if (!key.empty()) {
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meta->largest.DecodeFrom(key);
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}
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// Finish and check for builder errors
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s = builder->Finish();
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if (s.ok()) {
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meta->file_size = builder->FileSize();
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assert(meta->file_size > 0);
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}
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delete builder;
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// Finish and check for file errors
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if (s.ok()) {
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s = file->Sync();
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}
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if (s.ok()) {
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s = file->Close();
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}
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delete file;
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file = nullptr;
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if (s.ok()) {
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// Verify that the table is usable
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Iterator* it = table_cache->NewIterator(ReadOptions(), meta->number,
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meta->file_size);
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s = it->status();
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delete it;
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}
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}
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// Check for input iterator errors
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if (!iter->status().ok()) {
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s = iter->status();
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}
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if (s.ok() && meta->file_size > 0) {
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// Keep it
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} else {
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env->RemoveFile(fname);
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}
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return s;
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}
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} // namespace leveldb
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