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-rw-r--r--db/table_cache.cc121
1 files changed, 121 insertions, 0 deletions
diff --git a/db/table_cache.cc b/db/table_cache.cc
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+++ b/db/table_cache.cc
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+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#include "db/table_cache.h"
+
+#include "db/filename.h"
+#include "leveldb/env.h"
+#include "leveldb/table.h"
+#include "util/coding.h"
+
+namespace leveldb {
+
+struct TableAndFile {
+ RandomAccessFile* file;
+ Table* table;
+};
+
+static void DeleteEntry(const Slice& key, void* value) {
+ TableAndFile* tf = reinterpret_cast<TableAndFile*>(value);
+ delete tf->table;
+ delete tf->file;
+ delete tf;
+}
+
+static void UnrefEntry(void* arg1, void* arg2) {
+ Cache* cache = reinterpret_cast<Cache*>(arg1);
+ Cache::Handle* h = reinterpret_cast<Cache::Handle*>(arg2);
+ cache->Release(h);
+}
+
+TableCache::TableCache(const std::string& dbname,
+ const Options* options,
+ int entries)
+ : env_(options->env),
+ dbname_(dbname),
+ options_(options),
+ cache_(NewLRUCache(entries)) {
+}
+
+TableCache::~TableCache() {
+ delete cache_;
+}
+
+Status TableCache::FindTable(uint64_t file_number, uint64_t file_size,
+ Cache::Handle** handle) {
+ Status s;
+ char buf[sizeof(file_number)];
+ EncodeFixed64(buf, file_number);
+ Slice key(buf, sizeof(buf));
+ *handle = cache_->Lookup(key);
+ if (*handle == NULL) {
+ std::string fname = TableFileName(dbname_, file_number);
+ RandomAccessFile* file = NULL;
+ Table* table = NULL;
+ s = env_->NewRandomAccessFile(fname, &file);
+ if (s.ok()) {
+ s = Table::Open(*options_, file, file_size, &table);
+ }
+
+ if (!s.ok()) {
+ assert(table == NULL);
+ delete file;
+ // We do not cache error results so that if the error is transient,
+ // or somebody repairs the file, we recover automatically.
+ } else {
+ TableAndFile* tf = new TableAndFile;
+ tf->file = file;
+ tf->table = table;
+ *handle = cache_->Insert(key, tf, 1, &DeleteEntry);
+ }
+ }
+ return s;
+}
+
+Iterator* TableCache::NewIterator(const ReadOptions& options,
+ uint64_t file_number,
+ uint64_t file_size,
+ Table** tableptr) {
+ if (tableptr != NULL) {
+ *tableptr = NULL;
+ }
+
+ Cache::Handle* handle = NULL;
+ Status s = FindTable(file_number, file_size, &handle);
+ if (!s.ok()) {
+ return NewErrorIterator(s);
+ }
+
+ Table* table = reinterpret_cast<TableAndFile*>(cache_->Value(handle))->table;
+ Iterator* result = table->NewIterator(options);
+ result->RegisterCleanup(&UnrefEntry, cache_, handle);
+ if (tableptr != NULL) {
+ *tableptr = table;
+ }
+ return result;
+}
+
+Status TableCache::Get(const ReadOptions& options,
+ uint64_t file_number,
+ uint64_t file_size,
+ const Slice& k,
+ void* arg,
+ void (*saver)(void*, const Slice&, const Slice&)) {
+ Cache::Handle* handle = NULL;
+ Status s = FindTable(file_number, file_size, &handle);
+ if (s.ok()) {
+ Table* t = reinterpret_cast<TableAndFile*>(cache_->Value(handle))->table;
+ s = t->InternalGet(options, k, arg, saver);
+ cache_->Release(handle);
+ }
+ return s;
+}
+
+void TableCache::Evict(uint64_t file_number) {
+ char buf[sizeof(file_number)];
+ EncodeFixed64(buf, file_number);
+ cache_->Erase(Slice(buf, sizeof(buf)));
+}
+
+} // namespace leveldb