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12f1137355
Summary: Introduces and uses a SystemClock class to RocksDB. This class contains the time-related functions of an Env and these functions can be redirected from the Env to the SystemClock. Many of the places that used an Env (Timer, PerfStepTimer, RepeatableThread, RateLimiter, WriteController) for time-related functions have been changed to use SystemClock instead. There are likely more places that can be changed, but this is a start to show what can/should be done. Over time it would be nice to migrate most (if not all) of the uses of the time functions from the Env to the SystemClock. There are several Env classes that implement these functions. Most of these have not been converted yet to SystemClock implementations; that will come in a subsequent PR. It would be good to unify many of the Mock Timer implementations, so that they behave similarly and be tested similarly (some override Sleep, some use a MockSleep, etc). Additionally, this change will allow new methods to be introduced to the SystemClock (like https://github.com/facebook/rocksdb/issues/7101 WaitFor) in a consistent manner across a smaller number of classes. Pull Request resolved: https://github.com/facebook/rocksdb/pull/7858 Reviewed By: pdillinger Differential Revision: D26006406 Pulled By: mrambacher fbshipit-source-id: ed10a8abbdab7ff2e23d69d85bd25b3e7e899e90
80 lines
2.3 KiB
C++
80 lines
2.3 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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const std::shared_ptr<SystemClock>& clock,
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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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std::shared_ptr<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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