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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 == nullptr) {
std::string fname = TableFileName(dbname_, file_number);
RandomAccessFile* file = nullptr;
Table* table = nullptr;
s = env_->NewRandomAccessFile(fname, &file);
if (!s.ok()) {
std::string old_fname = SSTTableFileName(dbname_, file_number);
if (env_->NewRandomAccessFile(old_fname, &file).ok()) {
s = Status::OK();
}
}
if (s.ok()) {
s = Table::Open(options_, file, file_size, &table);
}
if (!s.ok()) {
assert(table == nullptr);
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 != nullptr) {
*tableptr = nullptr;
}
Cache::Handle* handle = nullptr;
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 != nullptr) {
*tableptr = table;
}
return result;
}
Status TableCache::Get(const ReadOptions& options, uint64_t file_number,
uint64_t file_size, const Slice& k, void* arg,
void (*handle_result)(void*, const Slice&,
const Slice&)) {
Cache::Handle* handle = nullptr;
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, handle_result);
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
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