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95 linhas
2.6 KiB
95 linhas
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/table_cache.h"
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#include "db/filename.h"
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#include "leveldb/env.h"
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#include "leveldb/table.h"
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#include "util/coding.h"
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namespace leveldb {
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struct TableAndFile {
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RandomAccessFile* file;
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Table* table;
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};
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static void DeleteEntry(const Slice& key, void* value) {
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TableAndFile* tf = reinterpret_cast<TableAndFile*>(value);
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delete tf->table;
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delete tf->file;
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delete tf;
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}
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static void UnrefEntry(void* arg1, void* arg2) {
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Cache* cache = reinterpret_cast<Cache*>(arg1);
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Cache::Handle* h = reinterpret_cast<Cache::Handle*>(arg2);
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cache->Release(h);
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}
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TableCache::TableCache(const std::string& dbname,
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const Options* options,
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int entries)
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: env_(options->env),
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dbname_(dbname),
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options_(options),
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cache_(NewLRUCache(entries)) {
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}
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TableCache::~TableCache() {
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delete cache_;
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}
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Iterator* TableCache::NewIterator(const ReadOptions& options,
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uint64_t file_number,
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uint64_t file_size,
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Table** tableptr) {
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if (tableptr != NULL) {
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*tableptr = NULL;
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}
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char buf[sizeof(file_number)];
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EncodeFixed64(buf, file_number);
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Slice key(buf, sizeof(buf));
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Cache::Handle* handle = cache_->Lookup(key);
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if (handle == NULL) {
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std::string fname = TableFileName(dbname_, file_number);
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RandomAccessFile* file = NULL;
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Table* table = NULL;
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Status s = env_->NewRandomAccessFile(fname, &file);
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if (s.ok()) {
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s = Table::Open(*options_, file, file_size, &table);
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}
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if (!s.ok()) {
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assert(table == NULL);
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delete file;
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// We do not cache error results so that if the error is transient,
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// or somebody repairs the file, we recover automatically.
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return NewErrorIterator(s);
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}
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TableAndFile* tf = new TableAndFile;
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tf->file = file;
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tf->table = table;
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handle = cache_->Insert(key, tf, 1, &DeleteEntry);
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}
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Table* table = reinterpret_cast<TableAndFile*>(cache_->Value(handle))->table;
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Iterator* result = table->NewIterator(options);
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result->RegisterCleanup(&UnrefEntry, cache_, handle);
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if (tableptr != NULL) {
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*tableptr = table;
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}
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return result;
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}
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void TableCache::Evict(uint64_t file_number) {
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char buf[sizeof(file_number)];
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EncodeFixed64(buf, file_number);
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cache_->Erase(Slice(buf, sizeof(buf)));
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}
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} // namespace leveldb
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