You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
rocksdb/utilities/persistent_cache/block_cache_tier.cc

359 lines
9.9 KiB

// 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.
#ifndef ROCKSDB_LITE
#include "utilities/persistent_cache/block_cache_tier.h"
#include <regex>
#include <utility>
#include <vector>
#include "util/stop_watch.h"
#include "utilities/persistent_cache/block_cache_tier_file.h"
namespace rocksdb {
//
// BlockCacheImpl
//
Status BlockCacheTier::Open() {
Status status;
WriteLock _(&lock_);
assert(!size_);
// Check the validity of the options
status = opt_.ValidateSettings();
assert(status.ok());
if (!status.ok()) {
Error(opt_.log, "Invalid block cache options");
return status;
}
// Create base directory or cleanup existing directory
status = opt_.env->CreateDirIfMissing(opt_.path);
if (!status.ok()) {
Error(opt_.log, "Error creating directory %s. %s", opt_.path.c_str(),
status.ToString().c_str());
return status;
}
// Create base/<cache dir> directory
status = opt_.env->CreateDir(GetCachePath());
if (!status.ok()) {
// directory already exisits, clean it up
status = CleanupCacheFolder(GetCachePath());
assert(status.ok());
if (!status.ok()) {
Error(opt_.log, "Error creating directory %s. %s", opt_.path.c_str(),
status.ToString().c_str());
return status;
}
}
assert(!cache_file_);
NewCacheFile();
assert(cache_file_);
if (opt_.pipeline_writes_) {
assert(!insert_th_.joinable());
insert_th_ = std::thread(&BlockCacheTier::InsertMain, this);
}
return Status::OK();
}
Status BlockCacheTier::CleanupCacheFolder(const std::string& folder) {
std::vector<std::string> files;
Status status = opt_.env->GetChildren(folder, &files);
if (!status.ok()) {
Error(opt_.log, "Error getting files for %s. %s", folder.c_str(),
status.ToString().c_str());
return status;
}
// cleanup files with the patter :digi:.rc
for (auto file : files) {
try {
const std::regex cache_file_regex("(0-9)+\\.rc$");
if (std::regex_match(file, cache_file_regex)) {
// cache file
Info(opt_.log, "Removing file %s.", file.c_str());
status = opt_.env->DeleteFile(folder + "/" + file);
if (!status.ok()) {
Error(opt_.log, "Error deleting file %s. %s", file.c_str(),
status.ToString().c_str());
return Status::IOError("Error deleting file " + file);
}
} else {
Info(opt_.log, "Skipping file %s.", file.c_str());
}
} catch (const std::regex_error& e) {
// Since std library is evolving, you can potentially get an exception for
// certain older compiler version. It is safer to exit cleanly.
return Status::IOError(e.what());
}
}
return Status::OK();
}
Status BlockCacheTier::Close() {
// stop the insert thread
if (opt_.pipeline_writes_ && insert_th_.joinable()) {
InsertOp op(/*quit=*/true);
insert_ops_.Push(std::move(op));
insert_th_.join();
}
// stop the writer before
writer_.Stop();
// clear all metadata
WriteLock _(&lock_);
metadata_.Clear();
return Status::OK();
}
std::string BlockCacheTier::PrintStats() {
std::ostringstream os;
os << "persistentcache.blockcachetier.bytes_piplined: "
<< stats_.bytes_pipelined_.ToString() << std::endl
<< "persistentcache.blockcachetier.bytes_written: "
<< stats_.bytes_written_.ToString() << std::endl
<< "persistentcache.blockcachetier.bytes_read: "
<< stats_.bytes_read_.ToString() << std::endl
<< "persistentcache.blockcachetier.insert_dropped"
<< stats_.insert_dropped_ << std::endl
<< "persistentcache.blockcachetier.cache_hits: " << stats_.cache_hits_
<< std::endl
<< "persistentcache.blockcachetier.cache_misses: " << stats_.cache_misses_
<< std::endl
<< "persistentcache.blockcachetier.cache_errors: " << stats_.cache_errors_
<< std::endl
<< "persistentcache.blockcachetier.cache_hits_pct: "
<< stats_.CacheHitPct() << std::endl
<< "persistentcache.blockcachetier.cache_misses_pct: "
<< stats_.CacheMissPct() << std::endl
<< "persistentcache.blockcachetier.read_hit_latency: "
<< stats_.read_hit_latency_.ToString() << std::endl
<< "persistentcache.blockcachetier.read_miss_latency: "
<< stats_.read_miss_latency_.ToString() << std::endl
<< "persistenetcache.blockcachetier.write_latency: "
<< stats_.write_latency_.ToString() << std::endl
<< PersistentCacheTier::PrintStats();
return os.str();
}
Status BlockCacheTier::Insert(const Slice& key, const char* data,
const size_t size) {
// update stats
stats_.bytes_pipelined_.Add(size);
if (opt_.pipeline_writes_) {
// off load the write to the write thread
insert_ops_.Push(
InsertOp(key.ToString(), std::move(std::string(data, size))));
return Status::OK();
}
assert(!opt_.pipeline_writes_);
return InsertImpl(key, Slice(data, size));
}
void BlockCacheTier::InsertMain() {
while (true) {
InsertOp op(insert_ops_.Pop());
if (op.signal_) {
// that is a secret signal to exit
break;
}
size_t retry = 0;
Status s;
while ((s = InsertImpl(Slice(op.key_), Slice(op.data_))).IsTryAgain()) {
if (retry > kMaxRetry) {
break;
}
// this can happen when the buffers are full, we wait till some buffers
// are free. Why don't we wait inside the code. This is because we want
// to support both pipelined and non-pipelined mode
buffer_allocator_.WaitUntilUsable();
retry++;
}
if (!s.ok()) {
stats_.insert_dropped_++;
}
}
}
Status BlockCacheTier::InsertImpl(const Slice& key, const Slice& data) {
// pre-condition
assert(key.size());
assert(data.size());
assert(cache_file_);
StopWatchNano timer(opt_.env);
WriteLock _(&lock_);
LBA lba;
if (metadata_.Lookup(key, &lba)) {
// the key already exisits, this is duplicate insert
return Status::OK();
}
while (!cache_file_->Append(key, data, &lba)) {
if (!cache_file_->Eof()) {
Debug(opt_.log, "Error inserting to cache file %d",
cache_file_->cacheid());
stats_.write_latency_.Add(timer.ElapsedNanos() / 1000);
return Status::TryAgain();
}
assert(cache_file_->Eof());
NewCacheFile();
}
// Insert into lookup index
BlockInfo* info = metadata_.Insert(key, lba);
assert(info);
if (!info) {
return Status::IOError("Unexpected error inserting to index");
}
// insert to cache file reverse mapping
cache_file_->Add(info);
// update stats
stats_.bytes_written_.Add(data.size());
stats_.write_latency_.Add(timer.ElapsedNanos() / 1000);
return Status::OK();
}
Status BlockCacheTier::Lookup(const Slice& key, unique_ptr<char[]>* val,
size_t* size) {
StopWatchNano timer(opt_.env);
LBA lba;
bool status;
status = metadata_.Lookup(key, &lba);
if (!status) {
stats_.cache_misses_++;
stats_.read_miss_latency_.Add(timer.ElapsedNanos() / 1000);
return Status::NotFound("blockcache: key not found");
}
BlockCacheFile* const file = metadata_.Lookup(lba.cache_id_);
if (!file) {
// this can happen because the block index and cache file index are
// different, and the cache file might be removed between the two lookups
stats_.cache_misses_++;
stats_.read_miss_latency_.Add(timer.ElapsedNanos() / 1000);
return Status::NotFound("blockcache: cache file not found");
}
assert(file->refs_);
unique_ptr<char[]> scratch(new char[lba.size_]);
Slice blk_key;
Slice blk_val;
status = file->Read(lba, &blk_key, &blk_val, scratch.get());
--file->refs_;
assert(status);
if (!status) {
stats_.cache_misses_++;
stats_.cache_errors_++;
stats_.read_miss_latency_.Add(timer.ElapsedNanos() / 1000);
return Status::NotFound("blockcache: error reading data");
}
assert(blk_key == key);
val->reset(new char[blk_val.size()]);
memcpy(val->get(), blk_val.data(), blk_val.size());
*size = blk_val.size();
stats_.bytes_read_.Add(*size);
stats_.cache_hits_++;
stats_.read_hit_latency_.Add(timer.ElapsedNanos() / 1000);
return Status::OK();
}
bool BlockCacheTier::Erase(const Slice& key) {
WriteLock _(&lock_);
BlockInfo* info = metadata_.Remove(key);
assert(info);
delete info;
return true;
}
void BlockCacheTier::NewCacheFile() {
lock_.AssertHeld();
Info(opt_.log, "Creating cache file %d", writer_cache_id_);
writer_cache_id_++;
cache_file_ = new WriteableCacheFile(opt_.env, &buffer_allocator_, &writer_,
GetCachePath(), writer_cache_id_,
opt_.cache_file_size, opt_.log);
bool status;
status =
cache_file_->Create(opt_.enable_direct_writes, opt_.enable_direct_reads);
assert(status);
// insert to cache files tree
status = metadata_.Insert(cache_file_);
(void)status;
assert(status);
}
bool BlockCacheTier::Reserve(const size_t size) {
WriteLock _(&lock_);
assert(size_ <= opt_.cache_size);
if (size + size_ <= opt_.cache_size) {
// there is enough space to write
size_ += size;
return true;
}
assert(size + size_ >= opt_.cache_size);
// there is not enough space to fit the requested data
// we can clear some space by evicting cold data
const double retain_fac = (100 - kEvictPct) / static_cast<double>(100);
while (size + size_ > opt_.cache_size * retain_fac) {
unique_ptr<BlockCacheFile> f(metadata_.Evict());
if (!f) {
// nothing is evictable
return false;
}
assert(!f->refs_);
uint64_t file_size;
if (!f->Delete(&file_size).ok()) {
// unable to delete file
return false;
}
assert(file_size <= size_);
size_ -= file_size;
}
size_ += size;
assert(size_ <= opt_.cache_size * 0.9);
return true;
}
} // namespace rocksdb
#endif // ifndef ROCKSDB_LITE