Add profiling infrastructure and widget

1 files changed, 134 insertions, 0 deletions

diff --git a/src/common/profiler.h b/src/common/profiler.h
new file mode 100644
index 00000000..53c4f6ea
--- /dev/null
+++ b/src/common/profiler.h
@@ -0,0 +1,134 @@
+// 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
+
+using Duration = std::chrono::nanoseconds;
+using Clock = std::chrono::high_resolution_clock;
+
+/**
+ * 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