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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 "platform/heap/SafePoint.h" | 5 #include "platform/heap/SafePoint.h" |
| 6 | 6 |
| 7 #include "platform/heap/Heap.h" | |
| 8 #include "wtf/Atomics.h" | 7 #include "wtf/Atomics.h" |
| 9 #include "wtf/CurrentTime.h" | 8 #include "wtf/CurrentTime.h" |
| 10 | 9 |
| 11 namespace blink { | 10 namespace blink { |
| 12 | 11 |
| 13 using PushAllRegistersCallback = void (*)(SafePointBarrier*, ThreadState*, intpt
r_t*); | 12 using PushAllRegistersCallback = void (*)(SafePointBarrier*, ThreadState*, intpt
r_t*); |
| 14 extern "C" void pushAllRegisters(SafePointBarrier*, ThreadState*, PushAllRegiste
rsCallback); | 13 extern "C" void pushAllRegisters(SafePointBarrier*, ThreadState*, PushAllRegiste
rsCallback); |
| 15 | 14 |
| 16 static double lockingTimeout() | 15 static double lockingTimeout() |
| 17 { | 16 { |
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| 28 SafePointBarrier::~SafePointBarrier() | 27 SafePointBarrier::~SafePointBarrier() |
| 29 { | 28 { |
| 30 } | 29 } |
| 31 | 30 |
| 32 bool SafePointBarrier::parkOthers() | 31 bool SafePointBarrier::parkOthers() |
| 33 { | 32 { |
| 34 ASSERT(ThreadState::current()->isAtSafePoint()); | 33 ASSERT(ThreadState::current()->isAtSafePoint()); |
| 35 | 34 |
| 36 ThreadState* current = ThreadState::current(); | 35 ThreadState* current = ThreadState::current(); |
| 37 // Lock threadAttachMutex() to prevent threads from attaching. | 36 // Lock threadAttachMutex() to prevent threads from attaching. |
| 38 current->lockThreadAttachMutex(); | 37 ThreadState::lockThreadAttachMutex(); |
| 39 const ThreadStateSet& threads = current->heap().threads(); | 38 ThreadState::AttachedThreadStateSet& threads = ThreadState::attachedThreads(
); |
| 40 | 39 |
| 41 MutexLocker locker(m_mutex); | 40 MutexLocker locker(m_mutex); |
| 42 atomicAdd(&m_unparkedThreadCount, threads.size()); | 41 atomicAdd(&m_unparkedThreadCount, threads.size()); |
| 43 releaseStore(&m_canResume, 0); | 42 releaseStore(&m_canResume, 0); |
| 44 | 43 |
| 45 for (ThreadState* state : threads) { | 44 for (ThreadState* state : threads) { |
| 46 if (state == current) | 45 if (state == current) |
| 47 continue; | 46 continue; |
| 48 | 47 |
| 49 for (auto& interruptor : state->interruptors()) | 48 for (auto& interruptor : state->interruptors()) |
| 50 interruptor->requestInterrupt(); | 49 interruptor->requestInterrupt(); |
| 51 } | 50 } |
| 52 | 51 |
| 53 while (acquireLoad(&m_unparkedThreadCount) > 0) { | 52 while (acquireLoad(&m_unparkedThreadCount) > 0) { |
| 54 double expirationTime = currentTime() + lockingTimeout(); | 53 double expirationTime = currentTime() + lockingTimeout(); |
| 55 if (!m_parked.timedWait(m_mutex, expirationTime)) { | 54 if (!m_parked.timedWait(m_mutex, expirationTime)) { |
| 56 // One of the other threads did not return to a safepoint within the
maximum | 55 // One of the other threads did not return to a safepoint within the
maximum |
| 57 // time we allow for threads to be parked. Abandon the GC and resume
the | 56 // time we allow for threads to be parked. Abandon the GC and resume
the |
| 58 // currently parked threads. | 57 // currently parked threads. |
| 59 resumeOthers(true); | 58 resumeOthers(true); |
| 60 return false; | 59 return false; |
| 61 } | 60 } |
| 62 } | 61 } |
| 63 return true; | 62 return true; |
| 64 } | 63 } |
| 65 | 64 |
| 66 void SafePointBarrier::resumeOthers(bool barrierLocked) | 65 void SafePointBarrier::resumeOthers(bool barrierLocked) |
| 67 { | 66 { |
| 68 ThreadState* current = ThreadState::current(); | 67 ThreadState::AttachedThreadStateSet& threads = ThreadState::attachedThreads(
); |
| 69 const ThreadStateSet& threads = current->heap().threads(); | |
| 70 atomicSubtract(&m_unparkedThreadCount, threads.size()); | 68 atomicSubtract(&m_unparkedThreadCount, threads.size()); |
| 71 releaseStore(&m_canResume, 1); | 69 releaseStore(&m_canResume, 1); |
| 72 | 70 |
| 73 if (UNLIKELY(barrierLocked)) { | 71 if (UNLIKELY(barrierLocked)) { |
| 74 m_resume.broadcast(); | 72 m_resume.broadcast(); |
| 75 } else { | 73 } else { |
| 76 // FIXME: Resumed threads will all contend for m_mutex just | 74 // FIXME: Resumed threads will all contend for m_mutex just |
| 77 // to unlock it later which is a waste of resources. | 75 // to unlock it later which is a waste of resources. |
| 78 MutexLocker locker(m_mutex); | 76 MutexLocker locker(m_mutex); |
| 79 m_resume.broadcast(); | 77 m_resume.broadcast(); |
| 80 } | 78 } |
| 81 | 79 |
| 82 current->unlockThreadAttachMutex(); | 80 ThreadState::unlockThreadAttachMutex(); |
| 83 ASSERT(ThreadState::current()->isAtSafePoint()); | 81 ASSERT(ThreadState::current()->isAtSafePoint()); |
| 84 } | 82 } |
| 85 | 83 |
| 86 void SafePointBarrier::checkAndPark(ThreadState* state, SafePointAwareMutexLocke
r* locker) | 84 void SafePointBarrier::checkAndPark(ThreadState* state, SafePointAwareMutexLocke
r* locker) |
| 87 { | 85 { |
| 88 ASSERT(!state->sweepForbidden()); | 86 ASSERT(!state->sweepForbidden()); |
| 89 if (!acquireLoad(&m_canResume)) { | 87 if (!acquireLoad(&m_canResume)) { |
| 90 // If we are leaving the safepoint from a SafePointAwareMutexLocker | 88 // If we are leaving the safepoint from a SafePointAwareMutexLocker |
| 91 // call out to release the lock before going to sleep. This enables the | 89 // call out to release the lock before going to sleep. This enables the |
| 92 // lock to be acquired in the sweep phase, e.g. during weak processing | 90 // lock to be acquired in the sweep phase, e.g. during weak processing |
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| 133 // If no other thread is waiting for other threads to park then | 131 // If no other thread is waiting for other threads to park then |
| 134 // this counter can be negative: if N threads are at safe-points | 132 // this counter can be negative: if N threads are at safe-points |
| 135 // the counter will be -N. | 133 // the counter will be -N. |
| 136 if (!atomicDecrement(&m_unparkedThreadCount)) { | 134 if (!atomicDecrement(&m_unparkedThreadCount)) { |
| 137 MutexLocker locker(m_mutex); | 135 MutexLocker locker(m_mutex); |
| 138 m_parked.signal(); // Safe point reached. | 136 m_parked.signal(); // Safe point reached. |
| 139 } | 137 } |
| 140 } | 138 } |
| 141 | 139 |
| 142 } // namespace blink | 140 } // namespace blink |
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