Repo created

TMessagesProj/jni/voip/webrtc/base/timer/elapsed_timer.h

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+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_TIMER_ELAPSED_TIMER_H_
+#define BASE_TIMER_ELAPSED_TIMER_H_
+
+#include "base/base_export.h"
+#include "base/macros.h"
+#include "base/time/time.h"
+
+namespace base {
+
+// A simple wrapper around TimeTicks::Now().
+class BASE_EXPORT ElapsedTimer {
+ public:
+  ElapsedTimer();
+  ElapsedTimer(ElapsedTimer&& other);
+
+  void operator=(ElapsedTimer&& other);
+
+  // Returns the time elapsed since object construction.
+  TimeDelta Elapsed() const;
+
+  // Returns the timestamp of the creation of this timer.
+  TimeTicks Begin() const { return begin_; }
+
+ private:
+  TimeTicks begin_;
+
+  DISALLOW_COPY_AND_ASSIGN(ElapsedTimer);
+};
+
+// A simple wrapper around ThreadTicks::Now().
+class BASE_EXPORT ElapsedThreadTimer {
+ public:
+  ElapsedThreadTimer();
+
+  // Returns the ThreadTicks time elapsed since object construction.
+  // Only valid if |is_supported()| returns true, otherwise returns TimeDelta().
+  TimeDelta Elapsed() const;
+
+  bool is_supported() const { return is_supported_; }
+
+ private:
+  const bool is_supported_;
+  const ThreadTicks begin_;
+
+  DISALLOW_COPY_AND_ASSIGN(ElapsedThreadTimer);
+};
+
+// Whenever there's a ScopedMockElapsedTimersForTest in scope,
+// Elapsed(Thread)Timers will always return kMockElapsedTime from Elapsed().
+// This is useful, for example, in unit tests that verify that their impl
+// records timing histograms. It enables such tests to observe reliable timings.
+class BASE_EXPORT ScopedMockElapsedTimersForTest {
+ public:
+  static constexpr TimeDelta kMockElapsedTime =
+      TimeDelta::FromMilliseconds(1337);
+
+  // ScopedMockElapsedTimersForTest is not thread-safe (it must be instantiated
+  // in a test before other threads begin using ElapsedTimers; and it must
+  // conversely outlive any usage of ElapsedTimer in that test).
+  ScopedMockElapsedTimersForTest();
+  ~ScopedMockElapsedTimersForTest();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ScopedMockElapsedTimersForTest);
+};
+
+}  // namespace base
+
+#endif  // BASE_TIMER_ELAPSED_TIMER_H_