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1 // Copyright 2015 The Chromium Authors. All rights reserved. | 1 // Copyright 2015 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #include "base/profiler/stack_sampling_profiler.h" | 5 #include "base/profiler/stack_sampling_profiler.h" |
6 | 6 |
7 #include <algorithm> | 7 #include <algorithm> |
8 #include <map> | |
8 #include <utility> | 9 #include <utility> |
9 | 10 |
11 #include "base/atomic_sequence_num.h" | |
12 #include "base/atomicops.h" | |
10 #include "base/bind.h" | 13 #include "base/bind.h" |
11 #include "base/bind_helpers.h" | 14 #include "base/bind_helpers.h" |
12 #include "base/callback.h" | 15 #include "base/callback.h" |
13 #include "base/lazy_instance.h" | 16 #include "base/lazy_instance.h" |
14 #include "base/location.h" | 17 #include "base/location.h" |
15 #include "base/macros.h" | 18 #include "base/macros.h" |
19 #include "base/memory/ptr_util.h" | |
20 #include "base/memory/singleton.h" | |
16 #include "base/profiler/native_stack_sampler.h" | 21 #include "base/profiler/native_stack_sampler.h" |
17 #include "base/synchronization/lock.h" | 22 #include "base/synchronization/lock.h" |
23 #include "base/threading/thread.h" | |
24 #include "base/threading/thread_restrictions.h" | |
18 #include "base/threading/thread_task_runner_handle.h" | 25 #include "base/threading/thread_task_runner_handle.h" |
19 #include "base/timer/elapsed_timer.h" | 26 #include "base/timer/elapsed_timer.h" |
20 | 27 |
21 namespace base { | 28 namespace base { |
22 | 29 |
23 namespace { | 30 namespace { |
24 | 31 |
25 // Used to ensure only one profiler is running at a time. | 32 // This value is used when there is no collection in progress and thus no ID |
26 LazyInstance<Lock>::Leaky concurrent_profiling_lock = LAZY_INSTANCE_INITIALIZER; | 33 // for referencing the active collection to the SamplingThread. |
27 | 34 const int NULL_COLLECTION_ID = -1; |
28 // AsyncRunner ---------------------------------------------------------------- | |
29 | |
30 // Helper class to allow a profiler to be run completely asynchronously from the | |
31 // initiator, without being concerned with the profiler's lifetime. | |
32 class AsyncRunner { | |
33 public: | |
34 // Sets up a profiler and arranges for it to be deleted on its completed | |
35 // callback. | |
36 static void Run(PlatformThreadId thread_id, | |
37 const StackSamplingProfiler::SamplingParams& params, | |
38 const StackSamplingProfiler::CompletedCallback& callback); | |
39 | |
40 private: | |
41 AsyncRunner(); | |
42 | |
43 // Runs the callback and deletes the AsyncRunner instance. |profiles| is not | |
44 // const& because it must be passed with std::move. | |
45 static void RunCallbackAndDeleteInstance( | |
46 std::unique_ptr<AsyncRunner> object_to_be_deleted, | |
47 const StackSamplingProfiler::CompletedCallback& callback, | |
48 scoped_refptr<SingleThreadTaskRunner> task_runner, | |
49 StackSamplingProfiler::CallStackProfiles profiles); | |
50 | |
51 std::unique_ptr<StackSamplingProfiler> profiler_; | |
52 | |
53 DISALLOW_COPY_AND_ASSIGN(AsyncRunner); | |
54 }; | |
55 | |
56 // static | |
57 void AsyncRunner::Run( | |
58 PlatformThreadId thread_id, | |
59 const StackSamplingProfiler::SamplingParams& params, | |
60 const StackSamplingProfiler::CompletedCallback &callback) { | |
61 std::unique_ptr<AsyncRunner> runner(new AsyncRunner); | |
62 AsyncRunner* temp_ptr = runner.get(); | |
63 temp_ptr->profiler_.reset( | |
64 new StackSamplingProfiler(thread_id, params, | |
65 Bind(&AsyncRunner::RunCallbackAndDeleteInstance, | |
66 Passed(&runner), callback, | |
67 ThreadTaskRunnerHandle::Get()))); | |
68 // The callback won't be called until after Start(), so temp_ptr will still | |
69 // be valid here. | |
70 temp_ptr->profiler_->Start(); | |
71 } | |
72 | |
73 AsyncRunner::AsyncRunner() {} | |
74 | |
75 void AsyncRunner::RunCallbackAndDeleteInstance( | |
76 std::unique_ptr<AsyncRunner> object_to_be_deleted, | |
77 const StackSamplingProfiler::CompletedCallback& callback, | |
78 scoped_refptr<SingleThreadTaskRunner> task_runner, | |
79 StackSamplingProfiler::CallStackProfiles profiles) { | |
80 callback.Run(std::move(profiles)); | |
81 // Delete the instance on the original calling thread. | |
82 task_runner->DeleteSoon(FROM_HERE, object_to_be_deleted.release()); | |
83 } | |
84 | 35 |
85 void ChangeAtomicFlags(subtle::Atomic32* flags, | 36 void ChangeAtomicFlags(subtle::Atomic32* flags, |
86 subtle::Atomic32 set, | 37 subtle::Atomic32 set, |
87 subtle::Atomic32 clear) { | 38 subtle::Atomic32 clear) { |
88 DCHECK(set != 0 || clear != 0); | 39 DCHECK(set != 0 || clear != 0); |
89 DCHECK_EQ(0, set & clear); | 40 DCHECK_EQ(0, set & clear); |
90 | 41 |
91 subtle::Atomic32 bits = subtle::NoBarrier_Load(flags); | 42 subtle::Atomic32 bits = subtle::NoBarrier_Load(flags); |
92 while (true) { | 43 while (true) { |
93 subtle::Atomic32 existing = | 44 subtle::Atomic32 existing = |
(...skipping 59 matching lines...) Expand 10 before | Expand all | Expand 10 after Loading... | |
153 StackSamplingProfiler::CallStackProfile | 104 StackSamplingProfiler::CallStackProfile |
154 StackSamplingProfiler::CallStackProfile::CopyForTesting() const { | 105 StackSamplingProfiler::CallStackProfile::CopyForTesting() const { |
155 return CallStackProfile(*this); | 106 return CallStackProfile(*this); |
156 } | 107 } |
157 | 108 |
158 StackSamplingProfiler::CallStackProfile::CallStackProfile( | 109 StackSamplingProfiler::CallStackProfile::CallStackProfile( |
159 const CallStackProfile& other) = default; | 110 const CallStackProfile& other) = default; |
160 | 111 |
161 // StackSamplingProfiler::SamplingThread -------------------------------------- | 112 // StackSamplingProfiler::SamplingThread -------------------------------------- |
162 | 113 |
163 StackSamplingProfiler::SamplingThread::SamplingThread( | 114 class StackSamplingProfiler::SamplingThread : public Thread { |
164 std::unique_ptr<NativeStackSampler> native_sampler, | 115 public: |
165 const SamplingParams& params, | 116 class TestAPI { |
166 const CompletedCallback& completed_callback) | 117 public: |
167 : native_sampler_(std::move(native_sampler)), | 118 // Disables inherent idle-shutdown behavior. |
168 params_(params), | 119 static void DisableIdleShutdown(); |
169 stop_event_(WaitableEvent::ResetPolicy::AUTOMATIC, | 120 |
170 WaitableEvent::InitialState::NOT_SIGNALED), | 121 // Begins an idle shutdown as if the idle-timer had expired. |
171 completed_callback_(completed_callback) {} | 122 static void ShutdownIfIdle(); |
172 | 123 }; |
173 StackSamplingProfiler::SamplingThread::~SamplingThread() {} | 124 |
174 | 125 struct CollectionContext { |
175 void StackSamplingProfiler::SamplingThread::ThreadMain() { | 126 CollectionContext(PlatformThreadId target, |
176 PlatformThread::SetName("Chrome_SamplingProfilerThread"); | 127 const SamplingParams& params, |
177 | 128 const CompletedCallback& callback, |
178 // For now, just ignore any requests to profile while another profiler is | 129 WaitableEvent* finished, |
179 // working. | 130 std::unique_ptr<NativeStackSampler> sampler) |
180 if (!concurrent_profiling_lock.Get().Try()) | 131 : collection_id(next_collection_id_.GetNext()), |
132 target(target), | |
133 params(params), | |
134 callback(callback), | |
135 finished(finished), | |
136 native_sampler(std::move(sampler)) {} | |
137 ~CollectionContext() {} | |
138 | |
139 // An identifier for this collection, used to uniquely identify it to | |
140 // outside interests. | |
141 const int collection_id; | |
142 | |
143 const PlatformThreadId target; // ID of The thread being sampled. | |
144 const SamplingParams params; // Information about how to sample. | |
145 const CompletedCallback callback; // Callback made when sampling complete. | |
146 WaitableEvent* const finished; // Signaled when all sampling complete. | |
147 | |
148 // Platform-specific module that does the actual sampling. | |
149 std::unique_ptr<NativeStackSampler> native_sampler; | |
150 | |
151 // The absolute time for the next sample. | |
152 Time next_sample_time; | |
153 | |
154 // The time that a profile was started, for calculating the total duration. | |
155 Time profile_start_time; | |
156 | |
157 // Counters that indicate the current position along the acquisition. | |
158 int burst = 0; | |
159 int sample = 0; | |
160 | |
161 // The collected stack samples. The active profile is always at the back(). | |
162 CallStackProfiles profiles; | |
163 | |
164 private: | |
165 static StaticAtomicSequenceNumber next_collection_id_; | |
166 }; | |
167 | |
168 // Gets the single instance of this class. | |
169 static SamplingThread* GetInstance(); | |
170 | |
171 // Starts the thread. | |
172 void Start(); | |
173 | |
174 // Adds a new CollectionContext to the thread. This can be called externally | |
175 // from any thread. This returns an ID that can later be used to stop | |
176 // the sampling. | |
177 int Add(std::unique_ptr<CollectionContext> collection); | |
178 | |
179 // Removes an active collection based on its ID, forcing it to run its | |
180 // callback if any data has been collected. This can be called externally | |
181 // from any thread. | |
182 void Remove(int id); | |
183 | |
184 private: | |
185 friend class TestAPI; | |
186 friend struct DefaultSingletonTraits<SamplingThread>; | |
187 | |
188 // The different states in which the sampling-thread can be. | |
189 enum ThreadExecutionState { | |
190 // The thread is not running, either because it has never been started or | |
191 // because it has exited. It will be started (or restarted) when a sampling | |
Mike Wittman
2017/02/27 23:27:34
As the code is currently, the state is only set to
bcwhite
2017/03/13 18:50:17
Done.
Mike Wittman
2017/03/14 18:57:33
I think it would be clearer to remove the "(or res
bcwhite
2017/03/16 15:56:25
Done.
| |
192 // request is received. | |
193 NOT_STARTED, | |
194 | |
195 // The thread is running and processing tasks. This is the state when any | |
196 // sampling requests are active and during the "idle" period afterward | |
197 // before the thread is stopped. | |
198 RUNNING, | |
199 | |
200 // Once all sampling requests have finished and the "idle" period has | |
201 // expired, the thread will be set to this state and its shutdown | |
202 // initiated. | |
Mike Wittman
2017/02/27 23:27:34
We should mention that new profiling requests (whi
bcwhite
2017/03/13 18:50:17
Done.
| |
203 EXITING, | |
204 }; | |
205 | |
206 SamplingThread(); | |
207 ~SamplingThread() override; | |
208 | |
209 // Get task runner that is usable from the outside. | |
210 scoped_refptr<SingleThreadTaskRunner> GetOrCreateTaskRunner(); | |
211 scoped_refptr<SingleThreadTaskRunner> GetTaskRunner( | |
212 ThreadExecutionState* out_state); | |
213 | |
214 // Get task runner that is usable from the sampling thread itself. | |
215 scoped_refptr<SingleThreadTaskRunner> GetTaskRunnerOnSamplingThread(); | |
216 | |
217 // Finishes a collection and reports collected data via callback. | |
218 void FinishCollection(CollectionContext* collection); | |
219 | |
220 // Records a single sample of a collection. | |
221 void RecordSample(CollectionContext* collection); | |
222 | |
223 // Check if the sampling thread is idle and begin a shutdown if so. | |
224 void ScheduleShutdownIfIdle(); | |
225 | |
226 // These methods are tasks that get posted to the internal message queue. | |
227 void AddCollectionTask(std::unique_ptr<CollectionContext> collection); | |
228 void RemoveCollectionTask(int id); | |
229 void PerformCollectionTask(int id); | |
230 void ShutdownTask(int add_events); | |
231 | |
232 // Updates the |next_sample_time| time based on configured parameters. | |
233 bool UpdateNextSampleTime(CollectionContext* collection); | |
234 | |
235 // Thread: | |
236 void CleanUp() override; | |
237 | |
238 // The task-runner for the sampling thread and some information about it. | |
239 // This must always be accessed while holding the lock. The saved task-runner | |
240 // can be freely used by any calling thread. | |
241 Lock task_runner_lock_; | |
242 scoped_refptr<SingleThreadTaskRunner> task_runner_; | |
243 ThreadExecutionState task_runner_thread_state_ = NOT_STARTED; | |
244 bool task_runner_disable_idle_shutdown_for_testing_ = false; | |
245 | |
246 // A counter that notes adds of new collection requests. It is incremented | |
247 // when changes occur so that delayed shutdown tasks are able to detect if | |
248 // samething new has happened while it was waiting. Like all |task_runner_*| | |
249 // vars, this must be accessed while holding |task_runner_lock_|. | |
250 int task_runner_add_events_ = 0; | |
251 | |
252 // A map of IDs to collection contexts. Because this class is a singleton | |
253 // that is never destroyed, context objects will never be destructed except | |
254 // by explicit action. Thus, it's acceptable to pass unretained pointers | |
255 // to these objects when posting tasks. | |
256 std::map<int, std::unique_ptr<CollectionContext>> active_collections_; | |
257 | |
258 DISALLOW_COPY_AND_ASSIGN(SamplingThread); | |
259 }; | |
260 | |
261 void StackSamplingProfiler::SamplingThread::TestAPI::DisableIdleShutdown() { | |
262 SamplingThread* sampler = SamplingThread::GetInstance(); | |
263 DCHECK(sampler); | |
264 | |
265 { | |
266 AutoLock lock(sampler->task_runner_lock_); | |
267 sampler->task_runner_disable_idle_shutdown_for_testing_ = true; | |
268 } | |
269 } | |
270 | |
271 void StackSamplingProfiler::SamplingThread::TestAPI::ShutdownIfIdle() { | |
272 SamplingThread* sampler = SamplingThread::GetInstance(); | |
273 DCHECK(sampler); | |
274 | |
275 ThreadExecutionState state; | |
276 scoped_refptr<SingleThreadTaskRunner> task_runner = | |
277 sampler->GetTaskRunner(&state); | |
278 DCHECK_EQ(RUNNING, state); | |
279 DCHECK(task_runner); | |
280 | |
281 int add_events; | |
282 { | |
283 AutoLock lock(sampler->task_runner_lock_); | |
284 add_events = sampler->task_runner_add_events_; | |
285 } | |
286 | |
287 // ShutdownTask will check if the thread is idle and skip the shutdown if not. | |
288 task_runner->PostTask(FROM_HERE, Bind(&SamplingThread::ShutdownTask, | |
289 Unretained(sampler), add_events)); | |
290 } | |
291 | |
292 StaticAtomicSequenceNumber StackSamplingProfiler::SamplingThread:: | |
293 CollectionContext::next_collection_id_; | |
294 | |
295 StackSamplingProfiler::SamplingThread::SamplingThread() | |
296 : Thread("Chrome_SamplingProfilerThread") {} | |
297 | |
298 StackSamplingProfiler::SamplingThread::~SamplingThread() { | |
299 Stop(); | |
300 } | |
301 | |
302 StackSamplingProfiler::SamplingThread* | |
303 StackSamplingProfiler::SamplingThread::GetInstance() { | |
304 return Singleton<SamplingThread, LeakySingletonTraits<SamplingThread>>::get(); | |
305 } | |
306 | |
307 void StackSamplingProfiler::SamplingThread::Start() { | |
308 Thread::Options options; | |
309 // Use a higher priority for a more accurate sampling interval. | |
310 options.priority = ThreadPriority::DISPLAY; | |
311 Thread::StartWithOptions(options); | |
312 } | |
313 | |
314 int StackSamplingProfiler::SamplingThread::Add( | |
315 std::unique_ptr<CollectionContext> collection) { | |
316 int id = collection->collection_id; | |
317 scoped_refptr<SingleThreadTaskRunner> task_runner = GetOrCreateTaskRunner(); | |
318 | |
319 task_runner->PostTask(FROM_HERE, Bind(&SamplingThread::AddCollectionTask, | |
320 Unretained(this), Passed(&collection))); | |
321 | |
322 return id; | |
323 } | |
324 | |
325 void StackSamplingProfiler::SamplingThread::Remove(int id) { | |
326 ThreadExecutionState state; | |
327 scoped_refptr<SingleThreadTaskRunner> task_runner = GetTaskRunner(&state); | |
328 if (state != RUNNING) | |
181 return; | 329 return; |
182 | 330 DCHECK(task_runner); |
183 CallStackProfiles profiles; | 331 |
184 CollectProfiles(&profiles); | 332 // This can fail if the thread were to exit between acquisition of the task |
185 concurrent_profiling_lock.Get().Release(); | 333 // runner above and the call below. In that case, however, everything has |
186 completed_callback_.Run(std::move(profiles)); | 334 // stopped so there's no need to try to stop it. |
187 } | 335 task_runner->PostTask(FROM_HERE, Bind(&SamplingThread::RemoveCollectionTask, |
188 | 336 Unretained(this), id)); |
189 // Depending on how long the sampling takes and the length of the sampling | 337 } |
190 // interval, a burst of samples could take arbitrarily longer than | 338 |
191 // samples_per_burst * sampling_interval. In this case, we (somewhat | 339 scoped_refptr<SingleThreadTaskRunner> |
192 // arbitrarily) honor the number of samples requested rather than strictly | 340 StackSamplingProfiler::SamplingThread::GetOrCreateTaskRunner() { |
Mike Wittman
2017/02/27 23:27:34
We should rename this to something like GetOrCreat
bcwhite
2017/03/13 18:50:17
Done. This is exactly why I didn't want these hel
Mike Wittman
2017/03/14 18:57:33
The most important values for Chrome code are read
| |
193 // adhering to the sampling intervals. Once we have established users for the | 341 AutoLock lock(task_runner_lock_); |
194 // StackSamplingProfiler and the collected data to judge, we may go the other | 342 ++task_runner_add_events_; |
195 // way or make this behavior configurable. | 343 |
196 void StackSamplingProfiler::SamplingThread::CollectProfile( | 344 if (task_runner_thread_state_ == RUNNING) { |
197 CallStackProfile* profile, | 345 DCHECK(task_runner_); |
198 TimeDelta* elapsed_time, | 346 // This shouldn't be called from the sampling thread as it's inefficient. |
199 bool* was_stopped) { | 347 // Use GetTaskRunnerOnSamplingThread() instead. |
200 ElapsedTimer profile_timer; | 348 DCHECK_NE(GetThreadId(), PlatformThread::CurrentId()); |
201 native_sampler_->ProfileRecordingStarting(&profile->modules); | 349 return task_runner_; |
202 profile->sampling_period = params_.sampling_interval; | 350 } |
203 *was_stopped = false; | 351 |
204 TimeDelta previous_elapsed_sample_time; | 352 if (task_runner_thread_state_ == EXITING) { |
205 for (int i = 0; i < params_.samples_per_burst; ++i) { | 353 // The previous instance has only been partially cleaned up. It is necessary |
206 if (i != 0) { | 354 // to call Stop() before Start(). This is safe even the thread has never |
Mike Wittman
2017/02/27 23:27:34
The last sentence is no longer relevant and can be
bcwhite
2017/03/13 18:50:17
Done.
| |
207 // Always wait, even if for 0 seconds, so we can observe a signal on | 355 // been started. |
208 // stop_event_. | 356 Stop(); |
209 if (stop_event_.TimedWait( | 357 } |
210 std::max(params_.sampling_interval - previous_elapsed_sample_time, | 358 |
211 TimeDelta()))) { | 359 // The thread is not running. Start it and get associated runner. The task- |
212 *was_stopped = true; | 360 // runner has to be saved for future use because though it can be used from |
213 break; | 361 // any thread, it can be acquired via task_runner() only on the created |
214 } | 362 // thread and the thread that creates it (i.e. this thread). |
215 } | 363 Start(); |
216 ElapsedTimer sample_timer; | 364 task_runner_thread_state_ = RUNNING; |
217 profile->samples.push_back(Sample()); | 365 task_runner_ = Thread::task_runner(); |
218 native_sampler_->RecordStackSample(&profile->samples.back()); | 366 |
219 previous_elapsed_sample_time = sample_timer.Elapsed(); | 367 // Detach the sampling thread from the "sequence" (i.e. thread) that |
220 } | 368 // started it so that it can be self-managed or stopped by another thread. |
221 | 369 DetachFromSequence(); |
222 *elapsed_time = profile_timer.Elapsed(); | 370 |
223 profile->profile_duration = *elapsed_time; | 371 return task_runner_; |
224 native_sampler_->ProfileRecordingStopped(); | 372 } |
225 } | 373 |
226 | 374 scoped_refptr<SingleThreadTaskRunner> |
227 // In an analogous manner to CollectProfile() and samples exceeding the expected | 375 StackSamplingProfiler::SamplingThread::GetTaskRunner( |
228 // total sampling time, bursts may also exceed the burst_interval. We adopt the | 376 ThreadExecutionState* out_state) { |
229 // same wait-and-see approach here. | 377 AutoLock lock(task_runner_lock_); |
230 void StackSamplingProfiler::SamplingThread::CollectProfiles( | 378 if (out_state) |
231 CallStackProfiles* profiles) { | 379 *out_state = task_runner_thread_state_; |
232 if (stop_event_.TimedWait(params_.initial_delay)) | 380 if (task_runner_thread_state_ != RUNNING) { |
381 DCHECK(!task_runner_); | |
382 return nullptr; | |
383 } | |
384 | |
385 // This shouldn't be called from the sampling thread as it's inefficient. | |
386 // Use GetTaskRunnerOnSamplingThread() instead. | |
387 DCHECK_NE(GetThreadId(), PlatformThread::CurrentId()); | |
388 | |
389 return task_runner_; | |
390 } | |
391 | |
392 scoped_refptr<SingleThreadTaskRunner> | |
393 StackSamplingProfiler::SamplingThread::GetTaskRunnerOnSamplingThread() { | |
394 // This should be called only from the sampling thread as it has limited | |
395 // accessibility. | |
396 DCHECK_EQ(GetThreadId(), PlatformThread::CurrentId()); | |
397 | |
398 return Thread::task_runner(); | |
399 } | |
400 | |
401 void StackSamplingProfiler::SamplingThread::FinishCollection( | |
402 CollectionContext* collection) { | |
403 // If there is no duration for the final profile (because it was stopped), | |
404 // calculate it now. | |
405 if (!collection->profiles.empty() && | |
406 collection->profiles.back().profile_duration == TimeDelta()) { | |
407 collection->profiles.back().profile_duration = | |
408 Time::Now() - collection->profile_start_time; | |
409 } | |
410 | |
411 // Run the associated callback, passing the collected profiles. It's okay to | |
412 // move them because this collection is about to be deleted. | |
413 collection->callback.Run(std::move(collection->profiles)); | |
414 | |
415 // Signal that this collection is finished. | |
416 collection->finished->Signal(); | |
417 | |
418 // Remove this collection from the map of known ones. This must be done | |
419 // last as the |collection| parameter is invalid after this point. | |
420 size_t count = active_collections_.erase(collection->collection_id); | |
421 DCHECK_EQ(1U, count); | |
422 } | |
423 | |
424 void StackSamplingProfiler::SamplingThread::RecordSample( | |
425 CollectionContext* collection) { | |
426 DCHECK(collection->native_sampler); | |
427 | |
428 // If this is the first sample of a burst, a new Profile needs to be created | |
429 // and filled. | |
430 if (collection->sample == 0) { | |
431 collection->profiles.push_back(CallStackProfile()); | |
432 CallStackProfile& profile = collection->profiles.back(); | |
433 profile.sampling_period = collection->params.sampling_interval; | |
434 collection->profile_start_time = Time::Now(); | |
435 collection->native_sampler->ProfileRecordingStarting(&profile.modules); | |
436 } | |
437 | |
438 // The currently active profile being captured. | |
439 CallStackProfile& profile = collection->profiles.back(); | |
440 | |
441 // Record a single sample. | |
442 profile.samples.push_back(Sample()); | |
443 collection->native_sampler->RecordStackSample(&profile.samples.back()); | |
444 | |
445 // If this is the last sample of a burst, record the total time. | |
446 if (collection->sample == collection->params.samples_per_burst - 1) { | |
447 profile.profile_duration = Time::Now() - collection->profile_start_time; | |
448 collection->native_sampler->ProfileRecordingStopped(); | |
449 } | |
450 } | |
451 | |
452 void StackSamplingProfiler::SamplingThread::ScheduleShutdownIfIdle() { | |
453 if (!active_collections_.empty()) | |
233 return; | 454 return; |
234 | 455 |
235 TimeDelta previous_elapsed_profile_time; | 456 int add_events; |
236 for (int i = 0; i < params_.bursts; ++i) { | 457 { |
237 if (i != 0) { | 458 AutoLock lock(task_runner_lock_); |
238 // Always wait, even if for 0 seconds, so we can observe a signal on | 459 if (task_runner_disable_idle_shutdown_for_testing_) |
239 // stop_event_. | |
240 if (stop_event_.TimedWait( | |
241 std::max(params_.burst_interval - previous_elapsed_profile_time, | |
242 TimeDelta()))) | |
243 return; | |
244 } | |
245 | |
246 CallStackProfile profile; | |
247 bool was_stopped = false; | |
248 CollectProfile(&profile, &previous_elapsed_profile_time, &was_stopped); | |
249 if (!profile.samples.empty()) | |
250 profiles->push_back(std::move(profile)); | |
251 | |
252 if (was_stopped) | |
253 return; | 460 return; |
254 } | 461 add_events = task_runner_add_events_; |
255 } | 462 } |
256 | 463 |
257 void StackSamplingProfiler::SamplingThread::Stop() { | 464 GetTaskRunnerOnSamplingThread()->PostDelayedTask( |
258 stop_event_.Signal(); | 465 FROM_HERE, |
466 Bind(&SamplingThread::ShutdownTask, Unretained(this), add_events), | |
467 TimeDelta::FromSeconds(60)); | |
468 } | |
469 | |
470 void StackSamplingProfiler::SamplingThread::AddCollectionTask( | |
471 std::unique_ptr<CollectionContext> collection) { | |
472 const int collection_id = collection->collection_id; | |
473 const TimeDelta initial_delay = collection->params.initial_delay; | |
474 | |
475 active_collections_.insert( | |
476 std::make_pair(collection_id, std::move(collection))); | |
477 | |
478 GetTaskRunnerOnSamplingThread()->PostDelayedTask( | |
479 FROM_HERE, Bind(&SamplingThread::PerformCollectionTask, Unretained(this), | |
480 collection_id), | |
481 initial_delay); | |
482 | |
483 // Another increment of "create requests" serves to invalidate any pending | |
484 // shutdown tasks that may have been initiated between the Add() and this | |
485 // task running. | |
486 { | |
487 AutoLock lock(task_runner_lock_); | |
488 ++task_runner_add_events_; | |
489 } | |
490 } | |
491 | |
492 void StackSamplingProfiler::SamplingThread::RemoveCollectionTask(int id) { | |
493 auto found = active_collections_.find(id); | |
494 if (found == active_collections_.end()) | |
495 return; | |
496 | |
497 FinishCollection(found->second.get()); | |
498 ScheduleShutdownIfIdle(); | |
499 } | |
500 | |
501 void StackSamplingProfiler::SamplingThread::PerformCollectionTask(int id) { | |
502 auto found = active_collections_.find(id); | |
503 | |
504 // The task won't be found if it has been stopped. | |
505 if (found == active_collections_.end()) | |
506 return; | |
507 | |
508 CollectionContext* collection = found->second.get(); | |
509 | |
510 // Handle first-run with no "next time". | |
511 if (collection->next_sample_time == Time()) | |
512 collection->next_sample_time = Time::Now(); | |
513 | |
514 // Do the collection of a single sample. | |
515 RecordSample(collection); | |
516 | |
517 // Update the time of the next sample recording. | |
518 if (UpdateNextSampleTime(collection)) { | |
519 bool success = GetTaskRunnerOnSamplingThread()->PostDelayedTask( | |
520 FROM_HERE, | |
521 Bind(&SamplingThread::PerformCollectionTask, Unretained(this), id), | |
522 std::max(collection->next_sample_time - Time::Now(), TimeDelta())); | |
523 DCHECK(success); | |
524 } else { | |
525 // All capturing has completed so finish the collection. Let object expire. | |
526 // The |collection| variable will be invalid after this call. | |
527 FinishCollection(collection); | |
528 ScheduleShutdownIfIdle(); | |
529 } | |
530 } | |
531 | |
532 void StackSamplingProfiler::SamplingThread::ShutdownTask(int add_events) { | |
533 // Holding this lock ensures that any attempt to start another job will | |
534 // get postponed until task_runner_ is cleared, thus eliminating the race. | |
535 AutoLock lock(task_runner_lock_); | |
536 | |
537 // If the current count of creation requests doesn't match the passed count | |
538 // then other tasks have been created since this was posted. Abort shutdown. | |
539 if (task_runner_add_events_ != add_events) | |
540 return; | |
541 | |
542 // There can be no new AddCollectionTasks at this point because creating | |
543 // those always increments "create requests". There may be other requests, | |
544 // like Remove, but it's okay to schedule the thread to stop once they've | |
545 // been executed (i.e. "soon"). | |
546 StopSoon(); | |
547 | |
548 // StopSoon will have set the owning sequence (again) so it must be detached | |
549 // (again) in order for Stop/Start to be called (again) should more work | |
550 // come in. Holding the |task_runner_lock_| ensures the necessary happens- | |
551 // after with regard to this detach and future Thread API calls. | |
552 DetachFromSequence(); | |
553 | |
554 // Set the thread_state variable so the thread will be restarted when new | |
555 // work comes in. | |
556 task_runner_thread_state_ = EXITING; | |
557 } | |
558 | |
559 bool StackSamplingProfiler::SamplingThread::UpdateNextSampleTime( | |
560 CollectionContext* collection) { | |
561 // This will keep a consistent average interval between samples but will | |
562 // result in constant series of acquisitions, thus nearly locking out the | |
563 // target thread, if the interval is smaller than the time it takes to | |
564 // actually acquire the sample. Anything sampling that quickly is going | |
565 // to be a problem anyway so don't worry about it. | |
566 if (++collection->sample < collection->params.samples_per_burst) { | |
567 collection->next_sample_time += collection->params.sampling_interval; | |
568 return true; | |
569 } | |
570 | |
571 if (++collection->burst < collection->params.bursts) { | |
572 collection->sample = 0; | |
573 collection->next_sample_time += collection->params.burst_interval; | |
574 return true; | |
575 } | |
576 | |
577 return false; | |
578 } | |
579 | |
580 void StackSamplingProfiler::SamplingThread::CleanUp() { | |
581 // There should be no collections remaining when the thread stops. | |
582 DCHECK(active_collections_.empty()); | |
583 | |
584 // Let the parent clean up. | |
585 Thread::CleanUp(); | |
259 } | 586 } |
260 | 587 |
261 // StackSamplingProfiler ------------------------------------------------------ | 588 // StackSamplingProfiler ------------------------------------------------------ |
262 | 589 |
590 // static | |
591 bool StackSamplingProfiler::TestAPI::IsSamplingThreadRunning() { | |
592 return SamplingThread::GetInstance()->IsRunning(); | |
593 } | |
594 | |
595 // static | |
596 void StackSamplingProfiler::TestAPI::DisableIdleShutdown() { | |
597 SamplingThread::TestAPI::DisableIdleShutdown(); | |
598 } | |
599 | |
600 // static | |
601 void StackSamplingProfiler::TestAPI::InitiateSamplingThreadIdleShutdown() { | |
602 SamplingThread::TestAPI::ShutdownIfIdle(); | |
603 } | |
604 | |
263 subtle::Atomic32 StackSamplingProfiler::process_milestones_ = 0; | 605 subtle::Atomic32 StackSamplingProfiler::process_milestones_ = 0; |
264 | 606 |
265 StackSamplingProfiler::SamplingParams::SamplingParams() | 607 StackSamplingProfiler::SamplingParams::SamplingParams() |
266 : initial_delay(TimeDelta::FromMilliseconds(0)), | 608 : initial_delay(TimeDelta::FromMilliseconds(0)), |
267 bursts(1), | 609 bursts(1), |
268 burst_interval(TimeDelta::FromMilliseconds(10000)), | 610 burst_interval(TimeDelta::FromMilliseconds(10000)), |
269 samples_per_burst(300), | 611 samples_per_burst(300), |
270 sampling_interval(TimeDelta::FromMilliseconds(100)) { | 612 sampling_interval(TimeDelta::FromMilliseconds(100)) { |
271 } | 613 } |
272 | 614 |
273 StackSamplingProfiler::StackSamplingProfiler( | 615 StackSamplingProfiler::StackSamplingProfiler( |
274 PlatformThreadId thread_id, | |
275 const SamplingParams& params, | 616 const SamplingParams& params, |
276 const CompletedCallback& callback) | 617 const CompletedCallback& callback, |
277 : StackSamplingProfiler(thread_id, params, callback, nullptr) {} | 618 NativeStackSamplerTestDelegate* test_delegate) |
619 : StackSamplingProfiler(base::PlatformThread::CurrentId(), | |
620 params, | |
621 callback, | |
622 test_delegate) {} | |
278 | 623 |
279 StackSamplingProfiler::StackSamplingProfiler( | 624 StackSamplingProfiler::StackSamplingProfiler( |
280 PlatformThreadId thread_id, | 625 PlatformThreadId thread_id, |
281 const SamplingParams& params, | 626 const SamplingParams& params, |
282 const CompletedCallback& callback, | 627 const CompletedCallback& callback, |
283 NativeStackSamplerTestDelegate* test_delegate) | 628 NativeStackSamplerTestDelegate* test_delegate) |
284 : thread_id_(thread_id), params_(params), completed_callback_(callback), | 629 : thread_id_(thread_id), |
285 test_delegate_(test_delegate) { | 630 params_(params), |
286 } | 631 completed_callback_(callback), |
632 // The event starts "signaled" so code knows it's safe to start thread. | |
633 profiling_inactive_(WaitableEvent::ResetPolicy::MANUAL, | |
634 WaitableEvent::InitialState::SIGNALED), | |
635 collection_id_(NULL_COLLECTION_ID), | |
636 test_delegate_(test_delegate) {} | |
287 | 637 |
288 StackSamplingProfiler::~StackSamplingProfiler() { | 638 StackSamplingProfiler::~StackSamplingProfiler() { |
639 // Stop is immediate but asynchronous. There is a non-zero probability that | |
640 // one more sample will be taken after this call returns. | |
289 Stop(); | 641 Stop(); |
290 if (!sampling_thread_handle_.is_null()) | |
291 PlatformThread::Join(sampling_thread_handle_); | |
292 } | |
293 | 642 |
294 // static | 643 // The behavior of sampling a thread that has exited is undefined and could |
295 void StackSamplingProfiler::StartAndRunAsync( | 644 // cause Bad Things(tm) to occur. The safety model provided by this class is |
296 PlatformThreadId thread_id, | 645 // that an instance of this object is expected to live at least as long as |
297 const SamplingParams& params, | 646 // the thread it is sampling. However, because the sampling is performed |
298 const CompletedCallback& callback) { | 647 // asynchronously by the SamplingThread, there is no way to guarantee this |
299 CHECK(ThreadTaskRunnerHandle::Get()); | 648 // is true without waiting for it to signal that it has finished. |
300 AsyncRunner::Run(thread_id, params, callback); | 649 // |
650 // The wait time should, at most, be only as long as it takes to collect one | |
651 // sample (~200us) or none at all if sampling has already completed. | |
652 ThreadRestrictions::ScopedAllowWait allow_wait; | |
653 profiling_inactive_.Wait(); | |
301 } | 654 } |
302 | 655 |
303 void StackSamplingProfiler::Start() { | 656 void StackSamplingProfiler::Start() { |
304 if (completed_callback_.is_null()) | 657 if (completed_callback_.is_null()) |
305 return; | 658 return; |
306 | 659 |
307 std::unique_ptr<NativeStackSampler> native_sampler = | 660 std::unique_ptr<NativeStackSampler> native_sampler = |
308 NativeStackSampler::Create(thread_id_, &RecordAnnotations, | 661 NativeStackSampler::Create(thread_id_, &RecordAnnotations, |
309 test_delegate_); | 662 test_delegate_); |
663 | |
310 if (!native_sampler) | 664 if (!native_sampler) |
311 return; | 665 return; |
312 | 666 |
313 sampling_thread_.reset(new SamplingThread(std::move(native_sampler), params_, | 667 // Wait for profiling to be "inactive", then reset it for the upcoming run. |
314 completed_callback_)); | 668 profiling_inactive_.Wait(); |
315 if (!PlatformThread::Create(0, sampling_thread_.get(), | 669 profiling_inactive_.Reset(); |
Mike Wittman
2017/02/27 23:27:34
We can avoid the manual reset by setting the reset
bcwhite
2017/03/13 18:50:17
True but only because there is currently nothing e
Mike Wittman
2017/03/14 18:57:33
Acknowledged.
| |
316 &sampling_thread_handle_)) | 670 |
317 sampling_thread_.reset(); | 671 DCHECK_EQ(NULL_COLLECTION_ID, collection_id_); |
672 collection_id_ = SamplingThread::GetInstance()->Add( | |
673 MakeUnique<SamplingThread::CollectionContext>( | |
674 thread_id_, params_, completed_callback_, &profiling_inactive_, | |
675 std::move(native_sampler))); | |
676 DCHECK_NE(NULL_COLLECTION_ID, collection_id_); | |
318 } | 677 } |
319 | 678 |
320 void StackSamplingProfiler::Stop() { | 679 void StackSamplingProfiler::Stop() { |
321 if (sampling_thread_) | 680 SamplingThread::GetInstance()->Remove(collection_id_); |
322 sampling_thread_->Stop(); | 681 collection_id_ = NULL_COLLECTION_ID; |
323 } | 682 } |
324 | 683 |
325 // static | 684 // static |
326 void StackSamplingProfiler::SetProcessMilestone(int milestone) { | 685 void StackSamplingProfiler::SetProcessMilestone(int milestone) { |
327 DCHECK_LE(0, milestone); | 686 DCHECK_LE(0, milestone); |
328 DCHECK_GT(static_cast<int>(sizeof(process_milestones_) * 8), milestone); | 687 DCHECK_GT(static_cast<int>(sizeof(process_milestones_) * 8), milestone); |
329 DCHECK_EQ(0, subtle::NoBarrier_Load(&process_milestones_) & (1 << milestone)); | 688 DCHECK_EQ(0, subtle::NoBarrier_Load(&process_milestones_) & (1 << milestone)); |
330 ChangeAtomicFlags(&process_milestones_, 1 << milestone, 0); | 689 ChangeAtomicFlags(&process_milestones_, 1 << milestone, 0); |
331 } | 690 } |
332 | 691 |
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378 } | 737 } |
379 | 738 |
380 bool operator<(const StackSamplingProfiler::Frame &a, | 739 bool operator<(const StackSamplingProfiler::Frame &a, |
381 const StackSamplingProfiler::Frame &b) { | 740 const StackSamplingProfiler::Frame &b) { |
382 return (a.module_index < b.module_index) || | 741 return (a.module_index < b.module_index) || |
383 (a.module_index == b.module_index && | 742 (a.module_index == b.module_index && |
384 a.instruction_pointer < b.instruction_pointer); | 743 a.instruction_pointer < b.instruction_pointer); |
385 } | 744 } |
386 | 745 |
387 } // namespace base | 746 } // namespace base |
OLD | NEW |