rocksdb/db/table_cache.cc

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// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
//
// 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/dbformat.h"
#include "db/filename.h"
#include "db/version_edit.h"
#include "rocksdb/statistics.h"
#include "table/iterator_wrapper.h"
#include "table/table_reader.h"
#include "table/get_context.h"
#include "util/coding.h"
#include "util/file_reader_writer.h"
#include "util/perf_context_imp.h"
#include "util/stop_watch.h"
namespace rocksdb {
namespace {
template <class T>
static void DeleteEntry(const Slice& key, void* value) {
T* typed_value = reinterpret_cast<T*>(value);
delete typed_value;
}
static void UnrefEntry(void* arg1, void* arg2) {
Cache* cache = reinterpret_cast<Cache*>(arg1);
Cache::Handle* h = reinterpret_cast<Cache::Handle*>(arg2);
cache->Release(h);
}
static Slice GetSliceForFileNumber(const uint64_t* file_number) {
return Slice(reinterpret_cast<const char*>(file_number),
sizeof(*file_number));
}
#ifndef ROCKSDB_LITE
void AppendVarint64(IterKey* key, uint64_t v) {
char buf[10];
auto ptr = EncodeVarint64(buf, v);
key->TrimAppend(key->Size(), buf, ptr - buf);
}
#endif // ROCKSDB_LITE
} // namespace
TableCache::TableCache(const ImmutableCFOptions& ioptions,
const EnvOptions& env_options, Cache* const cache)
: ioptions_(ioptions), env_options_(env_options), cache_(cache) {
if (ioptions_.row_cache) {
// If the same cache is shared by multiple instances, we need to
// disambiguate its entries.
PutVarint64(&row_cache_id_, ioptions_.row_cache->NewId());
}
}
TableCache::~TableCache() {
}
TableReader* TableCache::GetTableReaderFromHandle(Cache::Handle* handle) {
return reinterpret_cast<TableReader*>(cache_->Value(handle));
}
void TableCache::ReleaseHandle(Cache::Handle* handle) {
cache_->Release(handle);
}
Status TableCache::FindTable(const EnvOptions& env_options,
const InternalKeyComparator& internal_comparator,
const FileDescriptor& fd, Cache::Handle** handle,
const bool no_io) {
PERF_TIMER_GUARD(find_table_nanos);
Status s;
uint64_t number = fd.GetNumber();
Slice key = GetSliceForFileNumber(&number);
*handle = cache_->Lookup(key);
if (*handle == nullptr) {
if (no_io) { // Dont do IO and return a not-found status
return Status::Incomplete("Table not found in table_cache, no_io is set");
}
std::string fname =
TableFileName(ioptions_.db_paths, fd.GetNumber(), fd.GetPathId());
unique_ptr<RandomAccessFile> file;
unique_ptr<TableReader> table_reader;
s = ioptions_.env->NewRandomAccessFile(fname, &file, env_options);
RecordTick(ioptions_.statistics, NO_FILE_OPENS);
if (s.ok()) {
if (ioptions_.advise_random_on_open) {
file->Hint(RandomAccessFile::RANDOM);
}
StopWatch sw(ioptions_.env, ioptions_.statistics, TABLE_OPEN_IO_MICROS);
std::unique_ptr<RandomAccessFileReader> file_reader(
new RandomAccessFileReader(std::move(file)));
s = ioptions_.table_factory->NewTableReader(
ioptions_, env_options, internal_comparator, std::move(file_reader),
fd.GetFileSize(), &table_reader);
}
if (!s.ok()) {
assert(table_reader == nullptr);
RecordTick(ioptions_.statistics, NO_FILE_ERRORS);
// We do not cache error results so that if the error is transient,
// or somebody repairs the file, we recover automatically.
} else {
*handle = cache_->Insert(key, table_reader.release(), 1,
&DeleteEntry<TableReader>);
}
}
return s;
}
Iterator* TableCache::NewIterator(const ReadOptions& options,
const EnvOptions& env_options,
const InternalKeyComparator& icomparator,
const FileDescriptor& fd,
TableReader** table_reader_ptr,
bool for_compaction, Arena* arena) {
PERF_TIMER_GUARD(new_table_iterator_nanos);
if (table_reader_ptr != nullptr) {
*table_reader_ptr = nullptr;
}
TableReader* table_reader = fd.table_reader;
Cache::Handle* handle = nullptr;
Status s;
if (table_reader == nullptr) {
s = FindTable(env_options, icomparator, fd, &handle,
options.read_tier == kBlockCacheTier);
if (!s.ok()) {
return NewErrorIterator(s, arena);
}
table_reader = GetTableReaderFromHandle(handle);
}
Iterator* result = table_reader->NewIterator(options, arena);
if (handle != nullptr) {
result->RegisterCleanup(&UnrefEntry, cache_, handle);
}
if (table_reader_ptr != nullptr) {
*table_reader_ptr = table_reader;
}
if (for_compaction) {
table_reader->SetupForCompaction();
}
return result;
}
Status TableCache::Get(const ReadOptions& options,
const InternalKeyComparator& internal_comparator,
const FileDescriptor& fd, const Slice& k,
GetContext* get_context) {
TableReader* t = fd.table_reader;
Status s;
Cache::Handle* handle = nullptr;
std::string* row_cache_entry = nullptr;
#ifndef ROCKSDB_LITE
IterKey row_cache_key;
std::string row_cache_entry_buffer;
if (ioptions_.row_cache) {
uint64_t fd_number = fd.GetNumber();
auto user_key = ExtractUserKey(k);
// We use the user key as cache key instead of the internal key,
// otherwise the whole cache would be invalidated every time the
// sequence key increases. However, to support caching snapshot
// reads, we append the sequence number (incremented by 1 to
// distinguish from 0) only in this case.
uint64_t seq_no =
options.snapshot == nullptr ? 0 : 1 + GetInternalKeySeqno(k);
// Compute row cache key.
row_cache_key.TrimAppend(row_cache_key.Size(), row_cache_id_.data(),
row_cache_id_.size());
AppendVarint64(&row_cache_key, fd_number);
AppendVarint64(&row_cache_key, seq_no);
row_cache_key.TrimAppend(row_cache_key.Size(), user_key.data(),
user_key.size());
if (auto row_handle = ioptions_.row_cache->Lookup(row_cache_key.GetKey())) {
auto found_row_cache_entry = static_cast<const std::string*>(
ioptions_.row_cache->Value(row_handle));
replayGetContextLog(*found_row_cache_entry, user_key, get_context);
ioptions_.row_cache->Release(row_handle);
RecordTick(ioptions_.statistics, ROW_CACHE_HIT);
return Status::OK();
}
// Not found, setting up the replay log.
RecordTick(ioptions_.statistics, ROW_CACHE_MISS);
row_cache_entry = &row_cache_entry_buffer;
}
#endif // ROCKSDB_LITE
if (!t) {
s = FindTable(env_options_, internal_comparator, fd, &handle,
options.read_tier == kBlockCacheTier);
if (s.ok()) {
t = GetTableReaderFromHandle(handle);
}
}
if (s.ok()) {
get_context->SetReplayLog(row_cache_entry); // nullptr if no cache.
s = t->Get(options, k, get_context);
get_context->SetReplayLog(nullptr);
if (handle != nullptr) {
ReleaseHandle(handle);
}
} else if (options.read_tier && s.IsIncomplete()) {
// Couldn't find Table in cache but treat as kFound if no_io set
get_context->MarkKeyMayExist();
return Status::OK();
}
#ifndef ROCKSDB_LITE
// Put the replay log in row cache only if something was found.
if (s.ok() && row_cache_entry && !row_cache_entry->empty()) {
size_t charge =
row_cache_key.Size() + row_cache_entry->size() + sizeof(std::string);
void* row_ptr = new std::string(std::move(*row_cache_entry));
auto row_handle = ioptions_.row_cache->Insert(
row_cache_key.GetKey(), row_ptr, charge, &DeleteEntry<std::string>);
ioptions_.row_cache->Release(row_handle);
}
#endif // ROCKSDB_LITE
return s;
}
Status TableCache::GetTableProperties(
const EnvOptions& env_options,
const InternalKeyComparator& internal_comparator, const FileDescriptor& fd,
std::shared_ptr<const TableProperties>* properties, bool no_io) {
Status s;
auto table_reader = fd.table_reader;
// table already been pre-loaded?
if (table_reader) {
*properties = table_reader->GetTableProperties();
return s;
}
Cache::Handle* table_handle = nullptr;
s = FindTable(env_options, internal_comparator, fd, &table_handle, no_io);
if (!s.ok()) {
return s;
}
assert(table_handle);
auto table = GetTableReaderFromHandle(table_handle);
*properties = table->GetTableProperties();
ReleaseHandle(table_handle);
return s;
}
size_t TableCache::GetMemoryUsageByTableReader(
const EnvOptions& env_options,
const InternalKeyComparator& internal_comparator,
const FileDescriptor& fd) {
Status s;
auto table_reader = fd.table_reader;
// table already been pre-loaded?
if (table_reader) {
return table_reader->ApproximateMemoryUsage();
}
Cache::Handle* table_handle = nullptr;
s = FindTable(env_options, internal_comparator, fd, &table_handle, true);
if (!s.ok()) {
return 0;
}
assert(table_handle);
auto table = GetTableReaderFromHandle(table_handle);
auto ret = table->ApproximateMemoryUsage();
ReleaseHandle(table_handle);
return ret;
}
void TableCache::Evict(Cache* cache, uint64_t file_number) {
cache->Erase(GetSliceForFileNumber(&file_number));
}
} // namespace rocksdb