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
103 lines
3.5 KiB
C++
103 lines
3.5 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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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#pragma once
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#include <rocksdb/rocksdb_namespace.h>
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#include <rocksdb/status.h>
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#include <stdint.h>
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#include <memory>
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#ifdef _WIN32
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// Windows API macro interference
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#undef GetCurrentTime
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#endif
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namespace ROCKSDB_NAMESPACE {
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struct ConfigOptions;
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// A SystemClock is an interface used by the rocksdb implementation to access
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// operating system time-related functionality.
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class SystemClock {
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public:
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virtual ~SystemClock() {}
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static const char* Type() { return "SystemClock"; }
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// The name of this system clock
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virtual const char* Name() const = 0;
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// Return a default SystemClock suitable for the current operating
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// system.
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static const std::shared_ptr<SystemClock>& Default();
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// Returns the number of micro-seconds since some fixed point in time.
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// It is often used as system time such as in GenericRateLimiter
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// and other places so a port needs to return system time in order to work.
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virtual uint64_t NowMicros() = 0;
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// Returns the number of nano-seconds since some fixed point in time. Only
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// useful for computing deltas of time in one run.
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// Default implementation simply relies on NowMicros.
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// In platform-specific implementations, NowNanos() should return time points
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// that are MONOTONIC.
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virtual uint64_t NowNanos() { return NowMicros() * 1000; }
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// Returns the number of micro-seconds of CPU time used by the current thread.
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// 0 indicates not supported.
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virtual uint64_t CPUMicros() { return 0; }
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// Returns the number of nano-seconds of CPU time used by the current thread.
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// Default implementation simply relies on CPUMicros.
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// 0 indicates not supported.
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virtual uint64_t CPUNanos() { return CPUMicros() * 1000; }
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// Sleep/delay the thread for the prescribed number of micro-seconds.
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virtual void SleepForMicroseconds(int micros) = 0;
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// Get the number of seconds since the Epoch, 1970-01-01 00:00:00 (UTC).
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// Only overwrites *unix_time on success.
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virtual Status GetCurrentTime(int64_t* unix_time) = 0;
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// Converts seconds-since-Jan-01-1970 to a printable string
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virtual std::string TimeToString(uint64_t time) = 0;
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};
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// Wrapper class for a SystemClock. Redirects all methods (except Name)
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// of the SystemClock interface to the target/wrapped class.
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class SystemClockWrapper : public SystemClock {
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public:
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explicit SystemClockWrapper(const std::shared_ptr<SystemClock>& t)
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: target_(t) {}
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uint64_t NowMicros() override { return target_->NowMicros(); }
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uint64_t NowNanos() override { return target_->NowNanos(); }
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uint64_t CPUMicros() override { return target_->CPUMicros(); }
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uint64_t CPUNanos() override { return target_->CPUNanos(); }
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virtual void SleepForMicroseconds(int micros) override {
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return target_->SleepForMicroseconds(micros);
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}
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Status GetCurrentTime(int64_t* unix_time) override {
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return target_->GetCurrentTime(unix_time);
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}
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std::string TimeToString(uint64_t time) override {
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return target_->TimeToString(time);
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}
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protected:
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std::shared_ptr<SystemClock> target_;
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};
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} // end namespace ROCKSDB_NAMESPACE
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