1 files changed, 98 insertions, 0 deletions
diff --git a/chromium/chrome/common/thread_profiler_unittest.cc b/chromium/chrome/common/thread_profiler_unittest.cc
new file mode 100644
index 00000000000..cf8018139a6
--- /dev/null
+++ b/chromium/chrome/common/thread_profiler_unittest.cc
@@ -0,0 +1,98 @@
+// Copyright 2018 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.
+
+#include "chrome/common/thread_profiler.h"
+
+#include "base/macros.h"
+#include "base/test/bind_test_util.h"
+#include "base/test/simple_test_tick_clock.h"
+#include "base/time/time.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+
+class TestScheduler : public PeriodicSamplingScheduler {
+ public:
+  TestScheduler(base::TimeDelta sampling_duration,
+                double fraction_of_execution_time_to_sample)
+      : PeriodicSamplingScheduler(sampling_duration,
+                                  fraction_of_execution_time_to_sample,
+                                  kStartTime),
+        rand_double_value_(0.0) {
+    tick_clock_.SetNowTicks(kStartTime);
+  }
+
+  double RandDouble() const override { return rand_double_value_; }
+  base::TimeTicks Now() const override { return tick_clock_.NowTicks(); }
+
+  void SetRandDouble(double value) { rand_double_value_ = value; }
+  base::SimpleTestTickClock& tick_clock() { return tick_clock_; }
+
+ private:
+  static constexpr base::TimeTicks kStartTime = base::TimeTicks();
+  base::SimpleTestTickClock tick_clock_;
+  double rand_double_value_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestScheduler);
+};
+
+constexpr base::TimeTicks TestScheduler::kStartTime;
+
+}  // namespace
+
+TEST(ThreadProfilerTest, PeriodicSamplingScheduler) {
+  const base::TimeDelta sampling_duration = base::TimeDelta::FromSeconds(30);
+  const double fraction_of_execution_time_to_sample = 0.01;
+
+  const base::TimeDelta expected_period =
+      sampling_duration / fraction_of_execution_time_to_sample;
+
+  TestScheduler scheduler(sampling_duration,
+                          fraction_of_execution_time_to_sample);
+
+  // The first collection should be exactly at the start time, since the random
+  // value is 0.0.
+  scheduler.SetRandDouble(0.0);
+  EXPECT_EQ(base::TimeDelta::FromSeconds(0),
+            scheduler.GetTimeToNextCollection());
+
+  // With a random value of 1.0 the second collection should be at the end of
+  // the second period.
+  scheduler.SetRandDouble(1.0);
+  EXPECT_EQ(2 * expected_period - sampling_duration,
+            scheduler.GetTimeToNextCollection());
+
+  // With a random value of 0.25 the second collection should be a quarter into
+  // the third period exclusive of the sampling duration.
+  scheduler.SetRandDouble(0.25);
+  EXPECT_EQ(2 * expected_period + 0.25 * (expected_period - sampling_duration),
+            scheduler.GetTimeToNextCollection());
+}
+
+TEST(ThreadProfilerTest, PeriodicSamplingSchedulerWithJumpInTimeTicks) {
+  const base::TimeDelta sampling_duration = base::TimeDelta::FromSeconds(30);
+  const double fraction_of_execution_time_to_sample = 0.01;
+
+  const base::TimeDelta expected_period =
+      sampling_duration / fraction_of_execution_time_to_sample;
+
+  TestScheduler scheduler(sampling_duration,
+                          fraction_of_execution_time_to_sample);
+
+  // The first collection should be exactly at the start time, since the random
+  // value is 0.0.
+  scheduler.SetRandDouble(0.0);
+  EXPECT_EQ(base::TimeDelta::FromSeconds(0),
+            scheduler.GetTimeToNextCollection());
+
+  // Simulate a non-continuous jump in the current TimeTicks such that the next
+  // period would start before the current time. In this case the
+  // period start should be reset to the current time, and the next collection
+  // chosen within that period.
+  scheduler.tick_clock().Advance(expected_period +
+                                 base::TimeDelta::FromSeconds(1));
+  scheduler.SetRandDouble(0.5);
+  EXPECT_EQ(0.5 * (expected_period - sampling_duration),
+            scheduler.GetTimeToNextCollection());
+}