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rust-rocksdb/librocksdb-sys/rocksdb/env/emulated_clock.h

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// 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).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#pragma once
#include <atomic>
#include <string>
#include "rocksdb/status.h"
#include "rocksdb/system_clock.h"
namespace ROCKSDB_NAMESPACE {
// A SystemClock that can "mock" sleep and counts its operations.
class EmulatedSystemClock : public SystemClockWrapper {
private:
// Something to return when mocking current time
const int64_t maybe_starting_time_;
std::atomic<int> sleep_counter_{0};
std::atomic<int> cpu_counter_{0};
std::atomic<int64_t> addon_microseconds_{0};
// Do not modify in the env of a running DB (could cause deadlock)
std::atomic<bool> time_elapse_only_sleep_;
bool no_slowdown_;
public:
explicit EmulatedSystemClock(const std::shared_ptr<SystemClock>& base,
bool time_elapse_only_sleep = false);
static const char* kClassName() { return "TimeEmulatedSystemClock"; }
const char* Name() const override { return kClassName(); }
virtual void SleepForMicroseconds(int micros) override {
sleep_counter_++;
if (no_slowdown_ || time_elapse_only_sleep_) {
addon_microseconds_.fetch_add(micros);
}
if (!no_slowdown_) {
SystemClockWrapper::SleepForMicroseconds(micros);
}
}
void MockSleepForMicroseconds(int64_t micros) {
sleep_counter_++;
assert(no_slowdown_);
addon_microseconds_.fetch_add(micros);
}
void MockSleepForSeconds(int64_t seconds) {
sleep_counter_++;
assert(no_slowdown_);
addon_microseconds_.fetch_add(seconds * 1000000);
}
void SetTimeElapseOnlySleep(bool enabled) {
// We cannot set these before destroying the last DB because they might
// cause a deadlock or similar without the appropriate options set in
// the DB.
time_elapse_only_sleep_ = enabled;
no_slowdown_ = enabled;
}
bool IsTimeElapseOnlySleep() const { return time_elapse_only_sleep_.load(); }
void SetMockSleep(bool enabled = true) { no_slowdown_ = enabled; }
bool IsMockSleepEnabled() const { return no_slowdown_; }
int GetSleepCounter() const { return sleep_counter_.load(); }
virtual Status GetCurrentTime(int64_t* unix_time) override {
Status s;
if (time_elapse_only_sleep_) {
*unix_time = maybe_starting_time_;
} else {
s = SystemClockWrapper::GetCurrentTime(unix_time);
}
if (s.ok()) {
// mock microseconds elapsed to seconds of time
*unix_time += addon_microseconds_.load() / 1000000;
}
return s;
}
virtual uint64_t CPUNanos() override {
cpu_counter_++;
return SystemClockWrapper::CPUNanos();
}
virtual uint64_t CPUMicros() override {
cpu_counter_++;
return SystemClockWrapper::CPUMicros();
}
virtual uint64_t NowNanos() override {
return (time_elapse_only_sleep_ ? 0 : SystemClockWrapper::NowNanos()) +
addon_microseconds_.load() * 1000;
}
virtual uint64_t NowMicros() override {
return (time_elapse_only_sleep_ ? 0 : SystemClockWrapper::NowMicros()) +
addon_microseconds_.load();
}
int GetCpuCounter() const { return cpu_counter_.load(); }
void ResetCounters() {
cpu_counter_.store(0);
sleep_counter_.store(0);
}
};
} // namespace ROCKSDB_NAMESPACE