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1 // Copyright 2017 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #include "base/task_scheduler/scheduler_single_thread_task_runner_manager.h" | |
6 | |
7 #include <algorithm> | |
8 #include <memory> | |
9 #include <string> | |
10 | |
11 #include "base/bind.h" | |
12 #include "base/callback.h" | |
13 #include "base/memory/ptr_util.h" | |
14 #include "base/single_thread_task_runner.h" | |
15 #include "base/strings/stringprintf.h" | |
16 #include "base/synchronization/atomic_flag.h" | |
17 #include "base/task_scheduler/delayed_task_manager.h" | |
18 #include "base/task_scheduler/scheduler_worker.h" | |
19 #include "base/task_scheduler/sequence.h" | |
20 #include "base/task_scheduler/task.h" | |
21 #include "base/task_scheduler/task_tracker.h" | |
22 #include "base/task_scheduler/task_traits.h" | |
23 #include "base/threading/platform_thread.h" | |
24 #include "base/time/time.h" | |
25 | |
26 namespace base { | |
27 namespace internal { | |
28 | |
29 namespace { | |
30 | |
31 // Allows for checking the PlatformThread::CurrentRef() against a set | |
32 // PlatformThreadRef atomically without using locks. | |
33 class AtomicThreadRefChecker { | |
34 public: | |
35 AtomicThreadRefChecker() = default; | |
36 ~AtomicThreadRefChecker() = default; | |
37 | |
38 void Set() { | |
39 thread_ref_ = PlatformThread::CurrentRef(); | |
40 is_set_.Set(); | |
41 } | |
42 | |
43 bool IsCurrentThreadSameAsSetThread() { | |
44 return is_set_.IsSet() && thread_ref_ == PlatformThread::CurrentRef(); | |
45 } | |
46 | |
47 private: | |
48 AtomicFlag is_set_; | |
49 PlatformThreadRef thread_ref_; | |
50 | |
51 DISALLOW_COPY_AND_ASSIGN(AtomicThreadRefChecker); | |
52 }; | |
53 | |
54 class SchedulerWorkerDelegate : public SchedulerWorker::Delegate { | |
55 public: | |
56 SchedulerWorkerDelegate(const std::string& thread_name) | |
57 : thread_name_(thread_name) {} | |
58 | |
59 // SchedulerWorker::Delegate: | |
60 void OnMainEntry(SchedulerWorker* worker) override { | |
61 thread_ref_checker_.Set(); | |
62 PlatformThread::SetName(thread_name_); | |
63 } | |
64 | |
65 scoped_refptr<Sequence> GetWork(SchedulerWorker* worker) override { | |
66 AutoSchedulerLock auto_lock(sequence_lock_); | |
67 return std::move(sequence_); | |
68 } | |
69 | |
70 void DidRunTask() override {} | |
71 | |
72 void ReEnqueueSequence(scoped_refptr<Sequence> sequence) override { | |
73 AutoSchedulerLock auto_lock(sequence_lock_); | |
74 DCHECK(!sequence_); | |
75 sequence_ = std::move(sequence); | |
76 } | |
77 | |
78 TimeDelta GetSleepTimeout() override { return TimeDelta::Max(); } | |
79 | |
80 bool CanDetach(SchedulerWorker* worker) override { return false; } | |
81 | |
82 void OnDetach() override { NOTREACHED(); } | |
83 | |
84 bool RunsTasksOnCurrentThread() { | |
85 // We check the thread ref instead of the sequence for the benefit of COM | |
86 // callbacks which may execute without a sequence context. | |
87 return thread_ref_checker_.IsCurrentThreadSameAsSetThread(); | |
88 } | |
89 | |
90 private: | |
91 const std::string thread_name_; | |
92 | |
93 // Synchronizes access to |sequence_| and handles the fact that | |
94 // ReEnqueueSequence() is called on both the worker thread for reenqueuing | |
95 // the sequence and off of the worker thread to seed the sequence for | |
96 // GetWork(). | |
97 SchedulerLock sequence_lock_; | |
98 scoped_refptr<Sequence> sequence_; | |
99 | |
100 AtomicThreadRefChecker thread_ref_checker_; | |
101 | |
102 DISALLOW_COPY_AND_ASSIGN(SchedulerWorkerDelegate); | |
103 }; | |
104 | |
105 } // namespace | |
106 | |
107 class SchedulerSingleThreadTaskRunnerManager::SchedulerSingleThreadTaskRunner | |
108 : public SingleThreadTaskRunner { | |
109 public: | |
110 // Constructs a SchedulerSingleThreadTaskRunner that indirectly controls the | |
111 // lifetime of a dedicated |worker| for |traits|. | |
112 SchedulerSingleThreadTaskRunner( | |
113 SchedulerSingleThreadTaskRunnerManager* const outer, | |
114 const TaskTraits& traits, | |
115 SchedulerWorker* worker) | |
116 : outer_(outer), traits_(traits), worker_(worker) { | |
117 DCHECK(outer_); | |
118 DCHECK(worker_); | |
119 } | |
120 | |
121 // SingleThreadTaskRunner: | |
122 bool PostDelayedTask(const tracked_objects::Location& from_here, | |
123 const Closure& closure, | |
124 TimeDelta delay) override; | |
125 | |
126 bool PostNonNestableDelayedTask(const tracked_objects::Location& from_here, | |
127 const Closure& closure, | |
128 base::TimeDelta delay) override { | |
129 // Tasks are never nested within the task scheduler. | |
130 return PostDelayedTask(from_here, closure, delay); | |
131 } | |
132 | |
133 bool RunsTasksOnCurrentThread() const override { | |
134 auto* delegate = static_cast<SchedulerWorkerDelegate*>(worker_->delegate()); | |
135 return delegate->RunsTasksOnCurrentThread(); | |
136 } | |
137 | |
138 private: | |
139 ~SchedulerSingleThreadTaskRunner() override { | |
140 outer_->UnregisterSchedulerWorker(worker_); | |
141 } | |
142 | |
143 void PostTaskNow(std::unique_ptr<Task> task); | |
144 | |
145 // Sequence for all Tasks posted through this TaskRunner. | |
146 const scoped_refptr<Sequence> sequence_ = new Sequence; | |
147 | |
148 SchedulerSingleThreadTaskRunnerManager* const outer_; | |
149 const TaskTraits traits_; | |
150 SchedulerWorker* const worker_; | |
151 | |
152 DISALLOW_COPY_AND_ASSIGN(SchedulerSingleThreadTaskRunner); | |
153 }; | |
154 | |
155 bool SchedulerSingleThreadTaskRunnerManager::SchedulerSingleThreadTaskRunner:: | |
156 PostDelayedTask(const tracked_objects::Location& from_here, | |
157 const Closure& closure, | |
158 TimeDelta delay) { | |
159 auto task = MakeUnique<Task>(from_here, closure, traits_, delay); | |
160 task->single_thread_task_runner_ref = this; | |
161 | |
162 if (!outer_->task_tracker_->WillPostTask(task.get())) | |
163 return false; | |
164 | |
165 if (task->delayed_run_time.is_null()) { | |
166 PostTaskNow(std::move(task)); | |
167 } else { | |
168 outer_->delayed_task_manager_->AddDelayedTask( | |
169 std::move(task), | |
170 Bind(&SchedulerSingleThreadTaskRunner::PostTaskNow, Unretained(this))); | |
171 } | |
172 return true; | |
173 } | |
174 | |
175 void SchedulerSingleThreadTaskRunnerManager::SchedulerSingleThreadTaskRunner:: | |
176 PostTaskNow(std::unique_ptr<Task> task) { | |
177 const bool sequence_was_empty = sequence_->PushTask(std::move(task)); | |
178 if (sequence_was_empty) { | |
179 auto* delegate = static_cast<SchedulerWorkerDelegate*>(worker_->delegate()); | |
180 delegate->ReEnqueueSequence(sequence_); | |
181 worker_->WakeUp(); | |
182 } | |
183 } | |
184 | |
185 SchedulerSingleThreadTaskRunnerManager::SchedulerSingleThreadTaskRunnerManager( | |
186 const std::vector<SchedulerWorkerPoolParams>& worker_pool_params_vector, | |
187 const TaskScheduler::WorkerPoolIndexForTraitsCallback& | |
188 worker_pool_index_for_traits_callback, | |
189 TaskTracker* task_tracker, | |
190 DelayedTaskManager* delayed_task_manager) | |
191 : worker_pool_params_vector_(worker_pool_params_vector), | |
192 worker_pool_index_for_traits_callback_( | |
193 worker_pool_index_for_traits_callback), | |
194 task_tracker_(task_tracker), | |
195 delayed_task_manager_(delayed_task_manager) { | |
196 DCHECK_GT(worker_pool_params_vector_.size(), 0U); | |
197 DCHECK(worker_pool_index_for_traits_callback_); | |
198 DCHECK(task_tracker_); | |
199 DCHECK(delayed_task_manager_); | |
200 } | |
201 | |
202 SchedulerSingleThreadTaskRunnerManager:: | |
203 ~SchedulerSingleThreadTaskRunnerManager() { | |
204 DCHECK(workers_.empty()) << "SchedulerSingleThreadTaskRunners must outlive " | |
205 "SchedulerSingleThreadTaskRunnerManager"; | |
206 } | |
207 | |
208 scoped_refptr<SingleThreadTaskRunner> | |
209 SchedulerSingleThreadTaskRunnerManager::CreateSingleThreadTaskRunnerWithTraits( | |
210 const TaskTraits& traits) { | |
211 size_t index = worker_pool_index_for_traits_callback_.Run(traits); | |
212 DCHECK_LT(index, worker_pool_params_vector_.size()); | |
213 return new SchedulerSingleThreadTaskRunner( | |
214 this, traits, | |
215 CreateAndRegisterSchedulerWorker(worker_pool_params_vector_[index])); | |
216 } | |
217 | |
218 void SchedulerSingleThreadTaskRunnerManager::JoinForTesting() { | |
219 decltype(workers_) local_workers; | |
220 { | |
221 AutoSchedulerLock auto_lock(workers_lock_); | |
222 local_workers = std::move(workers_); | |
223 } | |
224 | |
225 for (const auto& worker : local_workers) | |
226 worker->JoinForTesting(); | |
227 | |
228 { | |
229 AutoSchedulerLock auto_lock(workers_lock_); | |
230 DCHECK(workers_.empty()) | |
231 << "New worker(s) unexpectedly registered during join."; | |
232 workers_ = std::move(local_workers); | |
233 } | |
234 } | |
235 | |
236 SchedulerWorker* | |
237 SchedulerSingleThreadTaskRunnerManager::CreateAndRegisterSchedulerWorker( | |
238 const SchedulerWorkerPoolParams& params) { | |
239 AutoSchedulerLock auto_lock(workers_lock_); | |
240 int id = next_worker_id_++; | |
241 auto delegate = MakeUnique<SchedulerWorkerDelegate>(base::StringPrintf( | |
242 "TaskSchedulerSingleThreadWorker%d%s", id, params.name().c_str())); | |
243 workers_.emplace_back(SchedulerWorker::Create( | |
244 params.priority_hint(), std::move(delegate), task_tracker_, | |
245 SchedulerWorker::InitialState::DETACHED)); | |
246 return workers_.back().get(); | |
247 } | |
248 | |
249 void SchedulerSingleThreadTaskRunnerManager::UnregisterSchedulerWorker( | |
250 SchedulerWorker* worker) { | |
251 // Cleanup uses a SchedulerLock, so call Cleanup() after releasing | |
252 // |workers_lock_|. | |
253 scoped_refptr<SchedulerWorker> worker_to_destroy; | |
254 { | |
255 AutoSchedulerLock auto_lock(workers_lock_); | |
256 | |
257 // We might be joining, so no-op this if |workers_| is empty. | |
258 if (workers_.empty()) | |
259 return; | |
260 | |
261 auto worker_iter = | |
262 std::find_if(workers_.begin(), workers_.end(), | |
263 [worker](const scoped_refptr<SchedulerWorker>& candidate) { | |
264 return candidate.get() == worker; | |
265 }); | |
266 DCHECK(worker_iter != workers_.end()); | |
267 worker_to_destroy = std::move(*worker_iter); | |
268 workers_.erase(worker_iter); | |
269 } | |
270 worker_to_destroy->Cleanup(); | |
271 } | |
272 | |
273 } // namespace internal | |
274 } // namespace base | |
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