113 lines
3.8 KiB
C++
113 lines
3.8 KiB
C++
/*
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* Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef API_NETEQ_TICK_TIMER_H_
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#define API_NETEQ_TICK_TIMER_H_
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#include <stdint.h>
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#include <memory>
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#include "rtc_base/checks.h"
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namespace webrtc {
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// Implements a time counter. The counter is advanced with the Increment()
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// methods, and is queried with the ticks() accessor. It is assumed that one
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// "tick" of the counter corresponds to 10 ms.
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// A TickTimer object can provide two types of associated time-measuring
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// objects: Stopwatch and Countdown.
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class TickTimer {
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public:
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// Stopwatch measures time elapsed since it was started, by querying the
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// associated TickTimer for the current time. The intended use is to request a
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// new Stopwatch object from a TickTimer object with the GetNewStopwatch()
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// method. Note: since the Stopwatch object contains a reference to the
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// TickTimer it is associated with, it cannot outlive the TickTimer.
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class Stopwatch {
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public:
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explicit Stopwatch(const TickTimer& ticktimer);
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uint64_t ElapsedTicks() const { return ticktimer_.ticks() - starttick_; }
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uint64_t ElapsedMs() const {
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const uint64_t elapsed_ticks = ticktimer_.ticks() - starttick_;
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const int ms_per_tick = ticktimer_.ms_per_tick();
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return elapsed_ticks < UINT64_MAX / ms_per_tick
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? elapsed_ticks * ms_per_tick
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: UINT64_MAX;
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}
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private:
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const TickTimer& ticktimer_;
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const uint64_t starttick_;
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};
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// Countdown counts down from a given start value with each tick of the
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// associated TickTimer, until zero is reached. The Finished() method will
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// return true if zero has been reached, false otherwise. The intended use is
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// to request a new Countdown object from a TickTimer object with the
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// GetNewCountdown() method. Note: since the Countdown object contains a
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// reference to the TickTimer it is associated with, it cannot outlive the
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// TickTimer.
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class Countdown {
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public:
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Countdown(const TickTimer& ticktimer, uint64_t ticks_to_count);
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~Countdown();
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bool Finished() const {
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return stopwatch_->ElapsedTicks() >= ticks_to_count_;
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}
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private:
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const std::unique_ptr<Stopwatch> stopwatch_;
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const uint64_t ticks_to_count_;
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};
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TickTimer() : TickTimer(10) {}
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explicit TickTimer(int ms_per_tick) : ms_per_tick_(ms_per_tick) {
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RTC_DCHECK_GT(ms_per_tick_, 0);
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}
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TickTimer(const TickTimer&) = delete;
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TickTimer& operator=(const TickTimer&) = delete;
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void Increment() { ++ticks_; }
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// Mainly intended for testing.
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void Increment(uint64_t x) { ticks_ += x; }
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uint64_t ticks() const { return ticks_; }
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int ms_per_tick() const { return ms_per_tick_; }
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// Returns a new Stopwatch object, based on the current TickTimer. Note that
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// the new Stopwatch object contains a reference to the current TickTimer,
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// and must therefore not outlive the TickTimer.
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std::unique_ptr<Stopwatch> GetNewStopwatch() const {
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return std::unique_ptr<Stopwatch>(new Stopwatch(*this));
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}
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// Returns a new Countdown object, based on the current TickTimer. Note that
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// the new Countdown object contains a reference to the current TickTimer,
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// and must therefore not outlive the TickTimer.
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std::unique_ptr<Countdown> GetNewCountdown(uint64_t ticks_to_count) const {
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return std::unique_ptr<Countdown>(new Countdown(*this, ticks_to_count));
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}
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private:
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uint64_t ticks_ = 0;
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const int ms_per_tick_;
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};
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} // namespace webrtc
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#endif // API_NETEQ_TICK_TIMER_H_
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