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citra-canary/src/common/profiler.h

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// Copyright 2015 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#pragma once
#include <atomic>
#include <chrono>
#include "common/assert.h"
#include "common/thread.h"
namespace Common {
namespace Profiling {
// If this is defined to 0, it turns all Timers into no-ops.
#ifndef ENABLE_PROFILING
#define ENABLE_PROFILING 1
#endif
#if defined(_MSC_VER) && _MSC_VER <= 1800 // MSVC 2013
// MSVC up to 2013 doesn't use QueryPerformanceCounter for high_resolution_clock, so it has bad
// precision. We manually implement a clock based on QPC to get good results.
struct QPCClock {
using duration = std::chrono::microseconds;
using time_point = std::chrono::time_point<QPCClock>;
using rep = duration::rep;
using period = duration::period;
static const bool is_steady = false;
static time_point now();
};
using Clock = QPCClock;
#else
using Clock = std::chrono::high_resolution_clock;
#endif
using Duration = Clock::duration;
/**
* Represents a timing category that measured time can be accounted towards. Should be declared as a
* global variable and passed to Timers.
*/
class TimingCategory final {
public:
TimingCategory(const char* name, TimingCategory* parent = nullptr);
unsigned int GetCategoryId() const {
return category_id;
}
/// Adds some time to this category. Can safely be called from multiple threads at the same time.
void AddTime(Duration amount) {
std::atomic_fetch_add_explicit(
&accumulated_duration, amount.count(),
std::memory_order_relaxed);
}
/**
* Atomically retrieves the accumulated measured time for this category and resets the counter
* to zero. Can be safely called concurrently with AddTime.
*/
Duration GetAccumulatedTime() {
return Duration(std::atomic_exchange_explicit(
&accumulated_duration, (Duration::rep)0,
std::memory_order_relaxed));
}
private:
unsigned int category_id;
std::atomic<Duration::rep> accumulated_duration;
};
/**
* Measures time elapsed between a call to Start and a call to Stop and attributes it to the given
* TimingCategory. Start/Stop can be called multiple times on the same timer, but each call must be
* appropriately paired.
*
* When a Timer is started, it automatically pauses a previously running timer on the same thread,
* which is resumed when it is stopped. As such, no special action needs to be taken to avoid
* double-accounting of time on two categories.
*/
class Timer {
public:
Timer(TimingCategory& category) : category(category) {
}
void Start() {
#if ENABLE_PROFILING
ASSERT(!running);
previous_timer = current_timer;
current_timer = this;
if (previous_timer != nullptr)
previous_timer->StopTiming();
StartTiming();
#endif
}
void Stop() {
#if ENABLE_PROFILING
ASSERT(running);
StopTiming();
if (previous_timer != nullptr)
previous_timer->StartTiming();
current_timer = previous_timer;
#endif
}
private:
#if ENABLE_PROFILING
void StartTiming() {
start = Clock::now();
running = true;
}
void StopTiming() {
auto duration = Clock::now() - start;
running = false;
category.AddTime(std::chrono::duration_cast<Duration>(duration));
}
Clock::time_point start;
bool running = false;
Timer* previous_timer;
static thread_local Timer* current_timer;
#endif
TimingCategory& category;
};
/**
* A Timer that automatically starts timing when created and stops at the end of the scope. Should
* be used in the majority of cases.
*/
class ScopeTimer : public Timer {
public:
ScopeTimer(TimingCategory& category) : Timer(category) {
Start();
}
~ScopeTimer() {
Stop();
}
};
} // namespace Profiling
} // namespace Common