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3dff28cf9b
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
79 lines
2.2 KiB
C++
79 lines
2.2 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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//
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#pragma once
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#include <memory>
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#include "db/blob/blob_log_format.h"
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#include "rocksdb/slice.h"
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namespace ROCKSDB_NAMESPACE {
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class RandomAccessFileReader;
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class Env;
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class Statistics;
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class Status;
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class SystemClock;
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/**
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* BlobLogSequentialReader is a general purpose log stream reader
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* implementation. The actual job of reading from the device is implemented by
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* the RandomAccessFileReader interface.
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*
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* Please see BlobLogWriter for details on the file and record layout.
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*/
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class BlobLogSequentialReader {
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public:
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enum ReadLevel {
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kReadHeader,
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kReadHeaderKey,
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kReadHeaderKeyBlob,
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};
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// Create a reader that will return log records from "*file_reader".
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BlobLogSequentialReader(std::unique_ptr<RandomAccessFileReader>&& file_reader,
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SystemClock* clock, Statistics* statistics);
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// No copying allowed
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BlobLogSequentialReader(const BlobLogSequentialReader&) = delete;
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BlobLogSequentialReader& operator=(const BlobLogSequentialReader&) = delete;
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~BlobLogSequentialReader();
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Status ReadHeader(BlobLogHeader* header);
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// Read the next record into *record. Returns true if read
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// successfully, false if we hit end of the input. The contents filled in
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// *record will only be valid until the next mutating operation on this
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// reader.
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// If blob_offset is non-null, return offset of the blob through it.
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Status ReadRecord(BlobLogRecord* record, ReadLevel level = kReadHeader,
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uint64_t* blob_offset = nullptr);
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Status ReadFooter(BlobLogFooter* footer);
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void ResetNextByte() { next_byte_ = 0; }
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uint64_t GetNextByte() const { return next_byte_; }
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private:
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Status ReadSlice(uint64_t size, Slice* slice, char* buf);
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const std::unique_ptr<RandomAccessFileReader> file_;
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SystemClock* clock_;
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Statistics* statistics_;
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Slice buffer_;
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char header_buf_[BlobLogRecord::kHeaderSize];
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// which byte to read next
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uint64_t next_byte_;
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};
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} // namespace ROCKSDB_NAMESPACE
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