rocksdb/db/blob/blob_log_writer.h
mrambacher 3dff28cf9b Use SystemClock* instead of std::shared_ptr<SystemClock> in lower level routines (#8033)
Summary:
For performance purposes, the lower level routines were changed to use a SystemClock* instead of a std::shared_ptr<SystemClock>.  The shared ptr has some performance degradation on certain hardware classes.

For most of the system, there is no risk of the pointer being deleted/invalid because the shared_ptr will be stored elsewhere.  For example, the ImmutableDBOptions stores the Env which has a std::shared_ptr<SystemClock> in it.  The SystemClock* within the ImmutableDBOptions is essentially a "short cut" to gain access to this constant resource.

There were a few classes (PeriodicWorkScheduler?) where the "short cut" property did not hold.  In those cases, the shared pointer was preserved.

Using db_bench readrandom perf_level=3 on my EC2 box, this change performed as well or better than 6.17:

6.17: readrandom   :      28.046 micros/op 854902 ops/sec;   61.3 MB/s (355999 of 355999 found)
6.18: readrandom   :      32.615 micros/op 735306 ops/sec;   52.7 MB/s (290999 of 290999 found)
PR: readrandom   :      27.500 micros/op 871909 ops/sec;   62.5 MB/s (367999 of 367999 found)

(Note that the times for 6.18 are prior to revert of the SystemClock).

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8033

Reviewed By: pdillinger

Differential Revision: D27014563

Pulled By: mrambacher

fbshipit-source-id: ad0459eba03182e454391b5926bf5cdd45657b67
2021-03-15 04:34:11 -07:00

84 lines
2.6 KiB
C++

// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#pragma once
#include <cstdint>
#include <memory>
#include <string>
#include "db/blob/blob_log_format.h"
#include "rocksdb/slice.h"
#include "rocksdb/statistics.h"
#include "rocksdb/status.h"
#include "rocksdb/types.h"
namespace ROCKSDB_NAMESPACE {
class WritableFileWriter;
class SystemClock;
/**
* BlobLogWriter is the blob log stream writer. It provides an append-only
* abstraction for writing blob data.
*
*
* Look at blob_db_format.h to see the details of the record formats.
*/
class BlobLogWriter {
public:
// Create a writer that will append data to "*dest".
// "*dest" must be initially empty.
// "*dest" must remain live while this BlobLogWriter is in use.
BlobLogWriter(std::unique_ptr<WritableFileWriter>&& dest, SystemClock* clock,
Statistics* statistics, uint64_t log_number, bool use_fsync,
bool do_flush, uint64_t boffset = 0);
// No copying allowed
BlobLogWriter(const BlobLogWriter&) = delete;
BlobLogWriter& operator=(const BlobLogWriter&) = delete;
~BlobLogWriter();
static void ConstructBlobHeader(std::string* buf, const Slice& key,
const Slice& val, uint64_t expiration);
Status AddRecord(const Slice& key, const Slice& val, uint64_t* key_offset,
uint64_t* blob_offset);
Status AddRecord(const Slice& key, const Slice& val, uint64_t expiration,
uint64_t* key_offset, uint64_t* blob_offset);
Status EmitPhysicalRecord(const std::string& headerbuf, const Slice& key,
const Slice& val, uint64_t* key_offset,
uint64_t* blob_offset);
Status AppendFooter(BlobLogFooter& footer, std::string* checksum_method,
std::string* checksum_value);
Status WriteHeader(BlobLogHeader& header);
WritableFileWriter* file() { return dest_.get(); }
const WritableFileWriter* file() const { return dest_.get(); }
uint64_t get_log_number() const { return log_number_; }
Status Sync();
private:
std::unique_ptr<WritableFileWriter> dest_;
SystemClock* clock_;
Statistics* statistics_;
uint64_t log_number_;
uint64_t block_offset_; // Current offset in block
bool use_fsync_;
bool do_flush_;
public:
enum ElemType { kEtNone, kEtFileHdr, kEtRecord, kEtFileFooter };
ElemType last_elem_type_;
};
} // namespace ROCKSDB_NAMESPACE