base/profiler/stack_sampling_profiler_unittest.cc - external/github.com/flutter/engine - Git at Google

 // Copyright 2015 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 "base/bind.h"
 #include "base/compiler_specific.h"
 #include "base/path_service.h"
 #include "base/profiler/stack_sampling_profiler.h"
 #include "base/strings/stringprintf.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/platform_thread.h"
 #include "base/time/time.h"
 #include "testing/gtest/include/gtest/gtest.h"

 namespace base {

 using SamplingParams = StackSamplingProfiler::SamplingParams;
 using Frame = StackSamplingProfiler::Frame;
 using Module = StackSamplingProfiler::Module;
 using Sample = StackSamplingProfiler::Sample;
 using CallStackProfile = StackSamplingProfiler::CallStackProfile;
 using CallStackProfiles = StackSamplingProfiler::CallStackProfiles;

 namespace {

 // A thread to target for profiling, whose stack is guaranteed to contain
 // SignalAndWaitUntilSignaled() when coordinated with the main thread.
 class TargetThread : public PlatformThread::Delegate {
  public:
   TargetThread();

   // PlatformThread::Delegate:
   void ThreadMain() override;

   // Waits for the thread to have started and be executing in
   // SignalAndWaitUntilSignaled().
   void WaitForThreadStart();

   // Allows the thread to return from SignalAndWaitUntilSignaled() and finish
   // execution.
   void SignalThreadToFinish();

   // This function is guaranteed to be executing between calls to
   // WaitForThreadStart() and SignalThreadToFinish(). This function is static so
   // that we can get a straightforward address for it in one of the tests below,
   // rather than dealing with the complexity of a member function pointer
   // representation.
   static void SignalAndWaitUntilSignaled(WaitableEvent* thread_started_event,
                                          WaitableEvent* finish_event);

   PlatformThreadId id() const { return id_; }

  private:
   WaitableEvent thread_started_event_;
   WaitableEvent finish_event_;
   PlatformThreadId id_;

   DISALLOW_COPY_AND_ASSIGN(TargetThread);
 };

 TargetThread::TargetThread()
     : thread_started_event_(false, false), finish_event_(false, false),
       id_(0) {}

 void TargetThread::ThreadMain() {
   id_ = PlatformThread::CurrentId();
   SignalAndWaitUntilSignaled(&thread_started_event_, &finish_event_);
 }

 void TargetThread::WaitForThreadStart() {
   thread_started_event_.Wait();
 }

 void TargetThread::SignalThreadToFinish() {
   finish_event_.Signal();
 }

 // static
 // Disable inlining for this function so that it gets its own stack frame.
 NOINLINE void TargetThread::SignalAndWaitUntilSignaled(
     WaitableEvent* thread_started_event,
     WaitableEvent* finish_event) {
   thread_started_event->Signal();
   volatile int x = 1;
   finish_event->Wait();
   x = 0;  // Prevent tail call to WaitableEvent::Wait().
   ALLOW_UNUSED_LOCAL(x);
 }

 // Called on the profiler thread when complete, to collect profiles.
 void SaveProfiles(CallStackProfiles* profiles,
                   const CallStackProfiles& pending_profiles) {
   *profiles = pending_profiles;
 }

 // Called on the profiler thread when complete. Collects profiles produced by
 // the profiler, and signals an event to allow the main thread to know that that
 // the profiler is done.
 void SaveProfilesAndSignalEvent(CallStackProfiles* profiles,
                                 WaitableEvent* event,
                                 const CallStackProfiles& pending_profiles) {
   *profiles = pending_profiles;
   event->Signal();
 }

 // Executes the function with the target thread running and executing within
 // SignalAndWaitUntilSignaled(). Performs all necessary target thread startup
 // and shutdown work before and afterward.
 template <class Function>
 void WithTargetThread(Function function) {
   TargetThread target_thread;
   PlatformThreadHandle target_thread_handle;
   EXPECT_TRUE(PlatformThread::Create(0, &target_thread, &target_thread_handle));

   target_thread.WaitForThreadStart();

   function(target_thread.id());

   target_thread.SignalThreadToFinish();

   PlatformThread::Join(target_thread_handle);
 }

 // Captures profiles as specified by |params| on the TargetThread, and returns
 // them in |profiles|. Waits up to |profiler_wait_time| for the profiler to
 // complete.
 void CaptureProfilesWithObjectCallback(const SamplingParams& params,
                                        CallStackProfiles* profiles,
                                        TimeDelta profiler_wait_time) {
   profiles->clear();

   WithTargetThread([&params, profiles, profiler_wait_time](
       PlatformThreadId target_thread_id) {
     WaitableEvent sampling_thread_completed(true, false);
     const StackSamplingProfiler::CompletedCallback callback =
         Bind(&SaveProfilesAndSignalEvent, Unretained(profiles),
              Unretained(&sampling_thread_completed));
     StackSamplingProfiler profiler(target_thread_id, params, callback);
     profiler.Start();
     sampling_thread_completed.TimedWait(profiler_wait_time);
     profiler.Stop();
     sampling_thread_completed.Wait();
   });
 }

 // Captures profiles as specified by |params| on the TargetThread, and returns
 // them in |profiles|. Uses the default callback rather than a per-object
 // callback.
 void CaptureProfilesWithDefaultCallback(const SamplingParams& params,
                                         CallStackProfiles* profiles) {
   profiles->clear();

   WithTargetThread([&params, profiles](PlatformThreadId target_thread_id) {
     WaitableEvent sampling_thread_completed(false, false);
     StackSamplingProfiler::SetDefaultCompletedCallback(
         Bind(&SaveProfilesAndSignalEvent, Unretained(profiles),
              Unretained(&sampling_thread_completed)));

     StackSamplingProfiler profiler(target_thread_id, params);
     profiler.Start();
     sampling_thread_completed.Wait();

     StackSamplingProfiler::SetDefaultCompletedCallback(
         StackSamplingProfiler::CompletedCallback());
   });
 }

 // Runs the profiler with |params| on the TargetThread, with no default or
 // per-object callback.
 void RunProfilerWithNoCallback(const SamplingParams& params,
                                TimeDelta profiler_wait_time) {
   WithTargetThread([&params, profiler_wait_time](
       PlatformThreadId target_thread_id) {
     StackSamplingProfiler profiler(target_thread_id, params);
     profiler.Start();
     // Since we don't specify a callback, we don't have a synchronization
     // mechanism with the sampling thread. Just sleep instead.
     PlatformThread::Sleep(profiler_wait_time);
     profiler.Stop();
   });
 }

 // If this executable was linked with /INCREMENTAL (the default for non-official
 // debug and release builds on Windows), function addresses do not correspond to
 // function code itself, but instead to instructions in the Incremental Link
 // Table that jump to the functions. Checks for a jump instruction and if
 // present does a little decompilation to find the function's actual starting
 // address.
 const void* MaybeFixupFunctionAddressForILT(const void* function_address) {
 #if defined(_WIN64)
   const unsigned char* opcode =
       reinterpret_cast<const unsigned char*>(function_address);
   if (*opcode == 0xe9) {
     // This is a relative jump instruction. Assume we're in the ILT and compute
     // the function start address from the instruction offset.
     const int32* offset = reinterpret_cast<const int32*>(opcode + 1);
     const unsigned char* next_instruction =
         reinterpret_cast<const unsigned char*>(offset + 1);
     return next_instruction + *offset;
   }
 #endif
   return function_address;
 }

 // Searches through the frames in |sample|, returning an iterator to the first
 // frame that has an instruction pointer between |function_address| and
 // |function_address| + |size|. Returns sample.end() if no such frames are
 // found.
 Sample::const_iterator FindFirstFrameWithinFunction(
     const Sample& sample,
     const void* function_address,
     int function_size) {
   function_address = MaybeFixupFunctionAddressForILT(function_address);
   for (auto it = sample.begin(); it != sample.end(); ++it) {
     if ((it->instruction_pointer >= function_address) &&
         (it->instruction_pointer <
          (static_cast<const unsigned char*>(function_address) + function_size)))
       return it;
   }
   return sample.end();
 }

 // Formats a sample into a string that can be output for test diagnostics.
 std::string FormatSampleForDiagnosticOutput(
     const Sample& sample,
     const std::vector<Module>& modules) {
   std::string output;
   for (const Frame& frame: sample) {
     output += StringPrintf(
         "0x%p %s\n", frame.instruction_pointer,
         modules[frame.module_index].filename.AsUTF8Unsafe().c_str());
   }
   return output;
 }

 // Returns a duration that is longer than the test timeout. We would use
 // TimeDelta::Max() but https://crbug.com/465948.
 TimeDelta AVeryLongTimeDelta() { return TimeDelta::FromDays(1); }

 }  // namespace


 // The tests below are enabled for Win x64 only, pending implementation of the
 // tested functionality on other platforms/architectures.

 // Checks that the basic expected information is present in a sampled call stack
 // profile.
 #if defined(_WIN64)
 #define MAYBE_Basic Basic
 #else
 #define MAYBE_Basic DISABLED_Basic
 #endif
 TEST(StackSamplingProfilerTest, MAYBE_Basic) {
   SamplingParams params;
   params.sampling_interval = TimeDelta::FromMilliseconds(0);
   params.samples_per_burst = 1;
   params.user_data = 100;
   params.preserve_sample_ordering = true;

   std::vector<CallStackProfile> profiles;
   CaptureProfilesWithObjectCallback(params, &profiles, AVeryLongTimeDelta());

   // Check that the profile and samples sizes are correct, and the module
   // indices are in range.
   ASSERT_EQ(1u, profiles.size());
   const CallStackProfile& profile = profiles[0];
   ASSERT_EQ(1u, profile.samples.size());
   EXPECT_EQ(params.sampling_interval, profile.sampling_period);
   const Sample& sample = profile.samples[0];
   for (const auto& frame : sample) {
     ASSERT_GE(frame.module_index, 0u);
     ASSERT_LT(frame.module_index, profile.modules.size());
   }
   EXPECT_EQ(100u, profile.user_data);
   EXPECT_EQ(true, profile.preserve_sample_ordering);

   // Check that the stack contains a frame for
   // TargetThread::SignalAndWaitUntilSignaled() and that the frame has this
   // executable's module.
   //
   // Since we don't have a good way to know the function size, use 100 bytes as
   // a reasonable window to locate the instruction pointer.
   Sample::const_iterator loc = FindFirstFrameWithinFunction(
       sample,
       reinterpret_cast<const void*>(&TargetThread::SignalAndWaitUntilSignaled),
       100);
   ASSERT_TRUE(loc != sample.end())
       << "Function at "
       << MaybeFixupFunctionAddressForILT(
           reinterpret_cast<const void*>(
               &TargetThread::SignalAndWaitUntilSignaled))
       << " was not found in stack:\n"
       << FormatSampleForDiagnosticOutput(sample, profile.modules);
   FilePath executable_path;
   EXPECT_TRUE(PathService::Get(FILE_EXE, &executable_path));
   EXPECT_EQ(executable_path, profile.modules[loc->module_index].filename);
 }

 // Checks that the expected number of profiles and samples are present in the
 // call stack profiles produced.
 #if defined(_WIN64)
 #define MAYBE_MultipleProfilesAndSamples MultipleProfilesAndSamples
 #else
 #define MAYBE_MultipleProfilesAndSamples DISABLED_MultipleProfilesAndSamples
 #endif
 TEST(StackSamplingProfilerTest, MAYBE_MultipleProfilesAndSamples) {
   SamplingParams params;
   params.burst_interval = params.sampling_interval =
       TimeDelta::FromMilliseconds(0);
   params.bursts = 2;
   params.samples_per_burst = 3;

   std::vector<CallStackProfile> profiles;
   CaptureProfilesWithObjectCallback(params, &profiles, AVeryLongTimeDelta());

   ASSERT_EQ(2u, profiles.size());
   EXPECT_EQ(3u, profiles[0].samples.size());
   EXPECT_EQ(3u, profiles[1].samples.size());
 }

 // Checks that no call stack profiles are captured if the profiling is stopped
 // during the initial delay.
 #if defined(_WIN64)
 #define MAYBE_StopDuringInitialDelay StopDuringInitialDelay
 #else
 #define MAYBE_StopDuringInitialDelay DISABLED_StopDuringInitialDelay
 #endif
 TEST(StackSamplingProfilerTest, MAYBE_StopDuringInitialDelay) {
   SamplingParams params;
   params.initial_delay = TimeDelta::FromSeconds(60);

   std::vector<CallStackProfile> profiles;
   CaptureProfilesWithObjectCallback(params, &profiles,
                                     TimeDelta::FromMilliseconds(0));

   EXPECT_TRUE(profiles.empty());
 }

 // Checks that the single completed call stack profile is captured if the
 // profiling is stopped between bursts.
 #if defined(_WIN64)
 #define MAYBE_StopDuringInterBurstInterval StopDuringInterBurstInterval
 #else
 #define MAYBE_StopDuringInterBurstInterval DISABLED_StopDuringInterBurstInterval
 #endif
 TEST(StackSamplingProfilerTest, MAYBE_StopDuringInterBurstInterval) {
   SamplingParams params;
   params.sampling_interval = TimeDelta::FromMilliseconds(0);
   params.burst_interval = TimeDelta::FromSeconds(60);
   params.bursts = 2;
   params.samples_per_burst = 1;

   std::vector<CallStackProfile> profiles;
   CaptureProfilesWithObjectCallback(params, &profiles,
                                     TimeDelta::FromMilliseconds(50));

   ASSERT_EQ(1u, profiles.size());
   EXPECT_EQ(1u, profiles[0].samples.size());
 }

 // Checks that only completed call stack profiles are captured.
 #if defined(_WIN64)
 #define MAYBE_StopDuringInterSampleInterval StopDuringInterSampleInterval
 #else
 #define MAYBE_StopDuringInterSampleInterval \
   DISABLED_StopDuringInterSampleInterval
 #endif
 TEST(StackSamplingProfilerTest, MAYBE_StopDuringInterSampleInterval) {
   SamplingParams params;
   params.sampling_interval = TimeDelta::FromSeconds(60);
   params.samples_per_burst = 2;

   std::vector<CallStackProfile> profiles;
   CaptureProfilesWithObjectCallback(params, &profiles,
                                     TimeDelta::FromMilliseconds(50));

   EXPECT_TRUE(profiles.empty());
 }

 // Checks that profiles are captured via the default completed callback.
 #if defined(_WIN64)
 #define MAYBE_DefaultCallback DefaultCallback
 #else
 #define MAYBE_DefaultCallback DISABLED_DefaultCallback
 #endif
 TEST(StackSamplingProfilerTest, MAYBE_DefaultCallback) {
   SamplingParams params;
   params.samples_per_burst = 1;

   CallStackProfiles profiles;
   CaptureProfilesWithDefaultCallback(params, &profiles);

   EXPECT_EQ(1u, profiles.size());
   EXPECT_EQ(1u, profiles[0].samples.size());
 }

 // Checks that profiles are queued until a default callback is set, then
 // delivered.
 #if defined(_WIN64)
 #define MAYBE_ProfilesQueuedWithNoCallback ProfilesQueuedWithNoCallback
 #else
 #define MAYBE_ProfilesQueuedWithNoCallback DISABLED_ProfilesQueuedWithNoCallback
 #endif
 TEST(StackSamplingProfilerTest, MAYBE_ProfilesQueuedWithNoCallback) {
   SamplingParams params;
   params.samples_per_burst = 1;

   RunProfilerWithNoCallback(params, TimeDelta::FromMilliseconds(50));

   CallStackProfiles profiles;
   // This should immediately call SaveProfiles on this thread.
   StackSamplingProfiler::SetDefaultCompletedCallback(
       Bind(&SaveProfiles, Unretained(&profiles)));
   EXPECT_EQ(1u, profiles.size());
   EXPECT_EQ(1u, profiles[0].samples.size());
   StackSamplingProfiler::SetDefaultCompletedCallback(
       StackSamplingProfiler::CompletedCallback());
 }

 // Checks that we can destroy the profiler while profiling.
 #if defined(_WIN64)
 #define MAYBE_DestroyProfilerWhileProfiling DestroyProfilerWhileProfiling
 #else
 #define MAYBE_DestroyProfilerWhileProfiling \
   DISABLED_DestroyProfilerWhileProfiling
 #endif
 TEST(StackSamplingProfilerTest, MAYBE_DestroyProfilerWhileProfiling) {
   SamplingParams params;
   params.sampling_interval = TimeDelta::FromMilliseconds(10);

   CallStackProfiles profiles;
   WithTargetThread([&params, &profiles](PlatformThreadId target_thread_id) {
     scoped_ptr<StackSamplingProfiler> profiler;
     profiler.reset(new StackSamplingProfiler(
         target_thread_id, params, Bind(&SaveProfiles, Unretained(&profiles))));
     profiler->Start();
     profiler.reset();

     // Wait longer than a sample interval to catch any use-after-free actions by
     // the profiler thread.
     PlatformThread::Sleep(TimeDelta::FromMilliseconds(50));
   });
 }

 }  // namespace base
	// Copyright 2015 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 "base/bind.h"
	#include "base/compiler_specific.h"
	#include "base/path_service.h"
	#include "base/profiler/stack_sampling_profiler.h"
	#include "base/strings/stringprintf.h"
	#include "base/synchronization/waitable_event.h"
	#include "base/threading/platform_thread.h"
	#include "base/time/time.h"
	#include "testing/gtest/include/gtest/gtest.h"

	namespace base {

	using SamplingParams = StackSamplingProfiler::SamplingParams;
	using Frame = StackSamplingProfiler::Frame;
	using Module = StackSamplingProfiler::Module;
	using Sample = StackSamplingProfiler::Sample;
	using CallStackProfile = StackSamplingProfiler::CallStackProfile;
	using CallStackProfiles = StackSamplingProfiler::CallStackProfiles;

	namespace {

	// A thread to target for profiling, whose stack is guaranteed to contain
	// SignalAndWaitUntilSignaled() when coordinated with the main thread.
	class TargetThread : public PlatformThread::Delegate {
	public:
	TargetThread();

	// PlatformThread::Delegate:
	void ThreadMain() override;

	// Waits for the thread to have started and be executing in
	// SignalAndWaitUntilSignaled().
	void WaitForThreadStart();

	// Allows the thread to return from SignalAndWaitUntilSignaled() and finish
	// execution.
	void SignalThreadToFinish();

	// This function is guaranteed to be executing between calls to
	// WaitForThreadStart() and SignalThreadToFinish(). This function is static so
	// that we can get a straightforward address for it in one of the tests below,
	// rather than dealing with the complexity of a member function pointer
	// representation.
	static void SignalAndWaitUntilSignaled(WaitableEvent* thread_started_event,
	WaitableEvent* finish_event);

	PlatformThreadId id() const { return id_; }

	private:
	WaitableEvent thread_started_event_;
	WaitableEvent finish_event_;
	PlatformThreadId id_;

	DISALLOW_COPY_AND_ASSIGN(TargetThread);
	};

	TargetThread::TargetThread()
	: thread_started_event_(false, false), finish_event_(false, false),
	id_(0) {}

	void TargetThread::ThreadMain() {
	id_ = PlatformThread::CurrentId();
	SignalAndWaitUntilSignaled(&thread_started_event_, &finish_event_);
	}

	void TargetThread::WaitForThreadStart() {
	thread_started_event_.Wait();
	}

	void TargetThread::SignalThreadToFinish() {
	finish_event_.Signal();
	}

	// static
	// Disable inlining for this function so that it gets its own stack frame.
	NOINLINE void TargetThread::SignalAndWaitUntilSignaled(
	WaitableEvent* thread_started_event,
	WaitableEvent* finish_event) {
	thread_started_event->Signal();
	volatile int x = 1;
	finish_event->Wait();
	x = 0; // Prevent tail call to WaitableEvent::Wait().
	ALLOW_UNUSED_LOCAL(x);
	}

	// Called on the profiler thread when complete, to collect profiles.
	void SaveProfiles(CallStackProfiles* profiles,
	const CallStackProfiles& pending_profiles) {
	*profiles = pending_profiles;
	}

	// Called on the profiler thread when complete. Collects profiles produced by
	// the profiler, and signals an event to allow the main thread to know that that
	// the profiler is done.
	void SaveProfilesAndSignalEvent(CallStackProfiles* profiles,
	WaitableEvent* event,
	const CallStackProfiles& pending_profiles) {
	*profiles = pending_profiles;
	event->Signal();
	}

	// Executes the function with the target thread running and executing within
	// SignalAndWaitUntilSignaled(). Performs all necessary target thread startup
	// and shutdown work before and afterward.
	template <class Function>
	void WithTargetThread(Function function) {
	TargetThread target_thread;
	PlatformThreadHandle target_thread_handle;
	EXPECT_TRUE(PlatformThread::Create(0, &target_thread, &target_thread_handle));

	target_thread.WaitForThreadStart();

	function(target_thread.id());

	target_thread.SignalThreadToFinish();

	PlatformThread::Join(target_thread_handle);
	}

	// Captures profiles as specified by \|params\| on the TargetThread, and returns
	// them in \|profiles\|. Waits up to \|profiler_wait_time\| for the profiler to
	// complete.
	void CaptureProfilesWithObjectCallback(const SamplingParams& params,
	CallStackProfiles* profiles,
	TimeDelta profiler_wait_time) {
	profiles->clear();

	WithTargetThread([&params, profiles, profiler_wait_time](
	PlatformThreadId target_thread_id) {
	WaitableEvent sampling_thread_completed(true, false);
	const StackSamplingProfiler::CompletedCallback callback =
	Bind(&SaveProfilesAndSignalEvent, Unretained(profiles),
	Unretained(&sampling_thread_completed));
	StackSamplingProfiler profiler(target_thread_id, params, callback);
	profiler.Start();
	sampling_thread_completed.TimedWait(profiler_wait_time);
	profiler.Stop();
	sampling_thread_completed.Wait();
	});
	}

	// Captures profiles as specified by \|params\| on the TargetThread, and returns
	// them in \|profiles\|. Uses the default callback rather than a per-object
	// callback.
	void CaptureProfilesWithDefaultCallback(const SamplingParams& params,
	CallStackProfiles* profiles) {
	profiles->clear();

	WithTargetThread([&params, profiles](PlatformThreadId target_thread_id) {
	WaitableEvent sampling_thread_completed(false, false);
	StackSamplingProfiler::SetDefaultCompletedCallback(
	Bind(&SaveProfilesAndSignalEvent, Unretained(profiles),
	Unretained(&sampling_thread_completed)));

	StackSamplingProfiler profiler(target_thread_id, params);
	profiler.Start();
	sampling_thread_completed.Wait();

	StackSamplingProfiler::SetDefaultCompletedCallback(
	StackSamplingProfiler::CompletedCallback());
	});
	}

	// Runs the profiler with \|params\| on the TargetThread, with no default or
	// per-object callback.
	void RunProfilerWithNoCallback(const SamplingParams& params,
	TimeDelta profiler_wait_time) {
	WithTargetThread([&params, profiler_wait_time](
	PlatformThreadId target_thread_id) {
	StackSamplingProfiler profiler(target_thread_id, params);
	profiler.Start();
	// Since we don't specify a callback, we don't have a synchronization
	// mechanism with the sampling thread. Just sleep instead.
	PlatformThread::Sleep(profiler_wait_time);
	profiler.Stop();
	});
	}

	// If this executable was linked with /INCREMENTAL (the default for non-official
	// debug and release builds on Windows), function addresses do not correspond to
	// function code itself, but instead to instructions in the Incremental Link
	// Table that jump to the functions. Checks for a jump instruction and if
	// present does a little decompilation to find the function's actual starting
	// address.
	const void* MaybeFixupFunctionAddressForILT(const void* function_address) {
	#if defined(_WIN64)
	const unsigned char* opcode =
	reinterpret_cast<const unsigned char*>(function_address);
	if (*opcode == 0xe9) {
	// This is a relative jump instruction. Assume we're in the ILT and compute
	// the function start address from the instruction offset.
	const int32* offset = reinterpret_cast<const int32*>(opcode + 1);
	const unsigned char* next_instruction =
	reinterpret_cast<const unsigned char*>(offset + 1);
	return next_instruction + *offset;
	}
	#endif
	return function_address;
	}

	// Searches through the frames in \|sample\|, returning an iterator to the first
	// frame that has an instruction pointer between \|function_address\| and
	// \|function_address\| + \|size\|. Returns sample.end() if no such frames are
	// found.
	Sample::const_iterator FindFirstFrameWithinFunction(
	const Sample& sample,
	const void* function_address,
	int function_size) {
	function_address = MaybeFixupFunctionAddressForILT(function_address);
	for (auto it = sample.begin(); it != sample.end(); ++it) {
	if ((it->instruction_pointer >= function_address) &&
	(it->instruction_pointer <
	(static_cast<const unsigned char*>(function_address) + function_size)))
	return it;
	}
	return sample.end();
	}

	// Formats a sample into a string that can be output for test diagnostics.
	std::string FormatSampleForDiagnosticOutput(
	const Sample& sample,
	const std::vector<Module>& modules) {
	std::string output;
	for (const Frame& frame: sample) {
	output += StringPrintf(
	"0x%p %s\n", frame.instruction_pointer,
	modules[frame.module_index].filename.AsUTF8Unsafe().c_str());
	}
	return output;
	}

	// Returns a duration that is longer than the test timeout. We would use
	// TimeDelta::Max() but https://crbug.com/465948.
	TimeDelta AVeryLongTimeDelta() { return TimeDelta::FromDays(1); }

	} // namespace


	// The tests below are enabled for Win x64 only, pending implementation of the
	// tested functionality on other platforms/architectures.

	// Checks that the basic expected information is present in a sampled call stack
	// profile.
	#if defined(_WIN64)
	#define MAYBE_Basic Basic
	#else
	#define MAYBE_Basic DISABLED_Basic
	#endif
	TEST(StackSamplingProfilerTest, MAYBE_Basic) {
	SamplingParams params;
	params.sampling_interval = TimeDelta::FromMilliseconds(0);
	params.samples_per_burst = 1;
	params.user_data = 100;
	params.preserve_sample_ordering = true;

	std::vector<CallStackProfile> profiles;
	CaptureProfilesWithObjectCallback(params, &profiles, AVeryLongTimeDelta());

	// Check that the profile and samples sizes are correct, and the module
	// indices are in range.
	ASSERT_EQ(1u, profiles.size());
	const CallStackProfile& profile = profiles[0];
	ASSERT_EQ(1u, profile.samples.size());
	EXPECT_EQ(params.sampling_interval, profile.sampling_period);
	const Sample& sample = profile.samples[0];
	for (const auto& frame : sample) {
	ASSERT_GE(frame.module_index, 0u);
	ASSERT_LT(frame.module_index, profile.modules.size());
	}
	EXPECT_EQ(100u, profile.user_data);
	EXPECT_EQ(true, profile.preserve_sample_ordering);

	// Check that the stack contains a frame for
	// TargetThread::SignalAndWaitUntilSignaled() and that the frame has this
	// executable's module.
	//
	// Since we don't have a good way to know the function size, use 100 bytes as
	// a reasonable window to locate the instruction pointer.
	Sample::const_iterator loc = FindFirstFrameWithinFunction(
	sample,
	reinterpret_cast<const void*>(&TargetThread::SignalAndWaitUntilSignaled),
	100);
	ASSERT_TRUE(loc != sample.end())
	<< "Function at "
	<< MaybeFixupFunctionAddressForILT(
	reinterpret_cast<const void*>(
	&TargetThread::SignalAndWaitUntilSignaled))
	<< " was not found in stack:\n"
	<< FormatSampleForDiagnosticOutput(sample, profile.modules);
	FilePath executable_path;
	EXPECT_TRUE(PathService::Get(FILE_EXE, &executable_path));
	EXPECT_EQ(executable_path, profile.modules[loc->module_index].filename);
	}

	// Checks that the expected number of profiles and samples are present in the
	// call stack profiles produced.
	#if defined(_WIN64)
	#define MAYBE_MultipleProfilesAndSamples MultipleProfilesAndSamples
	#else
	#define MAYBE_MultipleProfilesAndSamples DISABLED_MultipleProfilesAndSamples
	#endif
	TEST(StackSamplingProfilerTest, MAYBE_MultipleProfilesAndSamples) {
	SamplingParams params;
	params.burst_interval = params.sampling_interval =
	TimeDelta::FromMilliseconds(0);
	params.bursts = 2;
	params.samples_per_burst = 3;

	std::vector<CallStackProfile> profiles;
	CaptureProfilesWithObjectCallback(params, &profiles, AVeryLongTimeDelta());

	ASSERT_EQ(2u, profiles.size());
	EXPECT_EQ(3u, profiles[0].samples.size());
	EXPECT_EQ(3u, profiles[1].samples.size());
	}

	// Checks that no call stack profiles are captured if the profiling is stopped
	// during the initial delay.
	#if defined(_WIN64)
	#define MAYBE_StopDuringInitialDelay StopDuringInitialDelay
	#else
	#define MAYBE_StopDuringInitialDelay DISABLED_StopDuringInitialDelay
	#endif
	TEST(StackSamplingProfilerTest, MAYBE_StopDuringInitialDelay) {
	SamplingParams params;
	params.initial_delay = TimeDelta::FromSeconds(60);

	std::vector<CallStackProfile> profiles;
	CaptureProfilesWithObjectCallback(params, &profiles,
	TimeDelta::FromMilliseconds(0));

	EXPECT_TRUE(profiles.empty());
	}

	// Checks that the single completed call stack profile is captured if the
	// profiling is stopped between bursts.
	#if defined(_WIN64)
	#define MAYBE_StopDuringInterBurstInterval StopDuringInterBurstInterval
	#else
	#define MAYBE_StopDuringInterBurstInterval DISABLED_StopDuringInterBurstInterval
	#endif
	TEST(StackSamplingProfilerTest, MAYBE_StopDuringInterBurstInterval) {
	SamplingParams params;
	params.sampling_interval = TimeDelta::FromMilliseconds(0);
	params.burst_interval = TimeDelta::FromSeconds(60);
	params.bursts = 2;
	params.samples_per_burst = 1;

	std::vector<CallStackProfile> profiles;
	CaptureProfilesWithObjectCallback(params, &profiles,
	TimeDelta::FromMilliseconds(50));

	ASSERT_EQ(1u, profiles.size());
	EXPECT_EQ(1u, profiles[0].samples.size());
	}

	// Checks that only completed call stack profiles are captured.
	#if defined(_WIN64)
	#define MAYBE_StopDuringInterSampleInterval StopDuringInterSampleInterval
	#else
	#define MAYBE_StopDuringInterSampleInterval \
	DISABLED_StopDuringInterSampleInterval
	#endif
	TEST(StackSamplingProfilerTest, MAYBE_StopDuringInterSampleInterval) {
	SamplingParams params;
	params.sampling_interval = TimeDelta::FromSeconds(60);
	params.samples_per_burst = 2;

	std::vector<CallStackProfile> profiles;
	CaptureProfilesWithObjectCallback(params, &profiles,
	TimeDelta::FromMilliseconds(50));

	EXPECT_TRUE(profiles.empty());
	}

	// Checks that profiles are captured via the default completed callback.
	#if defined(_WIN64)
	#define MAYBE_DefaultCallback DefaultCallback
	#else
	#define MAYBE_DefaultCallback DISABLED_DefaultCallback
	#endif
	TEST(StackSamplingProfilerTest, MAYBE_DefaultCallback) {
	SamplingParams params;
	params.samples_per_burst = 1;

	CallStackProfiles profiles;
	CaptureProfilesWithDefaultCallback(params, &profiles);

	EXPECT_EQ(1u, profiles.size());
	EXPECT_EQ(1u, profiles[0].samples.size());
	}

	// Checks that profiles are queued until a default callback is set, then
	// delivered.
	#if defined(_WIN64)
	#define MAYBE_ProfilesQueuedWithNoCallback ProfilesQueuedWithNoCallback
	#else
	#define MAYBE_ProfilesQueuedWithNoCallback DISABLED_ProfilesQueuedWithNoCallback
	#endif
	TEST(StackSamplingProfilerTest, MAYBE_ProfilesQueuedWithNoCallback) {
	SamplingParams params;
	params.samples_per_burst = 1;

	RunProfilerWithNoCallback(params, TimeDelta::FromMilliseconds(50));

	CallStackProfiles profiles;
	// This should immediately call SaveProfiles on this thread.
	StackSamplingProfiler::SetDefaultCompletedCallback(
	Bind(&SaveProfiles, Unretained(&profiles)));
	EXPECT_EQ(1u, profiles.size());
	EXPECT_EQ(1u, profiles[0].samples.size());
	StackSamplingProfiler::SetDefaultCompletedCallback(
	StackSamplingProfiler::CompletedCallback());
	}

	// Checks that we can destroy the profiler while profiling.
	#if defined(_WIN64)
	#define MAYBE_DestroyProfilerWhileProfiling DestroyProfilerWhileProfiling
	#else
	#define MAYBE_DestroyProfilerWhileProfiling \
	DISABLED_DestroyProfilerWhileProfiling
	#endif
	TEST(StackSamplingProfilerTest, MAYBE_DestroyProfilerWhileProfiling) {
	SamplingParams params;
	params.sampling_interval = TimeDelta::FromMilliseconds(10);

	CallStackProfiles profiles;
	WithTargetThread([&params, &profiles](PlatformThreadId target_thread_id) {
	scoped_ptr<StackSamplingProfiler> profiler;
	profiler.reset(new StackSamplingProfiler(
	target_thread_id, params, Bind(&SaveProfiles, Unretained(&profiles))));
	profiler->Start();
	profiler.reset();

	// Wait longer than a sample interval to catch any use-after-free actions by
	// the profiler thread.
	PlatformThread::Sleep(TimeDelta::FromMilliseconds(50));
	});
	}

	} // namespace base