1 /*
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11  * copyright notice, this list of conditions and the following disclaimer
12  * in the documentation and/or other materials provided with the
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19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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29  */
30 
31 #ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_HEAP_IMPL_GC_TASK_RUNNER_H_
32 #define THIRD_PARTY_BLINK_RENDERER_PLATFORM_HEAP_IMPL_GC_TASK_RUNNER_H_
33 
34 #include <memory>
35 #include "base/location.h"
36 #include "third_party/blink/renderer/platform/heap/thread_state.h"
37 #include "third_party/blink/renderer/platform/scheduler/public/thread.h"
38 #include "third_party/blink/renderer/platform/wtf/cross_thread_functional.h"
39 
40 namespace blink {
41 
42 class GCTaskObserver final : public Thread::TaskObserver {
43   USING_FAST_MALLOC(GCTaskObserver);
44 
45  public:
GCTaskObserver()46   GCTaskObserver() : nesting_(0) {}
47 
~GCTaskObserver()48   ~GCTaskObserver() override {
49     // m_nesting can be 1 if this was unregistered in a task and
50     // didProcessTask was not called.
51     DCHECK(!nesting_ || nesting_ == 1);
52   }
53 
WillProcessTask(const base::PendingTask &,bool)54   void WillProcessTask(const base::PendingTask&, bool) override { nesting_++; }
55 
DidProcessTask(const base::PendingTask &)56   void DidProcessTask(const base::PendingTask&) override {
57     // In the production code WebKit::initialize is called from inside the
58     // message loop so we can get didProcessTask() without corresponding
59     // willProcessTask once. This is benign.
60     if (nesting_)
61       nesting_--;
62 
63     ThreadState::Current()->SafePoint(nesting_
64                                           ? BlinkGC::kHeapPointersOnStack
65                                           : BlinkGC::kNoHeapPointersOnStack);
66   }
67 
68  private:
69   int nesting_;
70 };
71 
72 class GCTaskRunner final {
73   USING_FAST_MALLOC(GCTaskRunner);
74 
75  public:
GCTaskRunner(Thread * thread)76   explicit GCTaskRunner(Thread* thread)
77       : gc_task_observer_(std::make_unique<GCTaskObserver>()), thread_(thread) {
78     thread_->AddTaskObserver(gc_task_observer_.get());
79   }
80 
~GCTaskRunner()81   ~GCTaskRunner() { thread_->RemoveTaskObserver(gc_task_observer_.get()); }
82 
83  private:
84   std::unique_ptr<GCTaskObserver> gc_task_observer_;
85   Thread* thread_;
86 };
87 
88 }  // namespace blink
89 
90 #endif  // THIRD_PARTY_BLINK_RENDERER_PLATFORM_HEAP_IMPL_GC_TASK_RUNNER_H_
91