/*
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* Copyright (C) 2016 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ART_RUNTIME_GC_SYSTEM_WEAK_H_
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#define ART_RUNTIME_GC_SYSTEM_WEAK_H_
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#include "base/mutex.h"
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#include "object_callbacks.h"
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#include "thread-inl.h"
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namespace art {
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namespace gc {
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class AbstractSystemWeakHolder {
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public:
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virtual ~AbstractSystemWeakHolder() {}
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virtual void Allow() REQUIRES_SHARED(Locks::mutator_lock_) = 0;
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virtual void Disallow() REQUIRES_SHARED(Locks::mutator_lock_) = 0;
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// See Runtime::BroadcastForNewSystemWeaks for the broadcast_for_checkpoint definition.
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virtual void Broadcast(bool broadcast_for_checkpoint) = 0;
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virtual void Sweep(IsMarkedVisitor* visitor) REQUIRES_SHARED(Locks::mutator_lock_) = 0;
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};
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class SystemWeakHolder : public AbstractSystemWeakHolder {
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public:
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explicit SystemWeakHolder(LockLevel level)
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: allow_disallow_lock_("SystemWeakHolder", level),
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new_weak_condition_("SystemWeakHolder new condition", allow_disallow_lock_),
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allow_new_system_weak_(true) {
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}
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virtual ~SystemWeakHolder() {}
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void Allow() override
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REQUIRES_SHARED(Locks::mutator_lock_)
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REQUIRES(!allow_disallow_lock_) {
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CHECK(!kUseReadBarrier);
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MutexLock mu(Thread::Current(), allow_disallow_lock_);
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allow_new_system_weak_ = true;
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new_weak_condition_.Broadcast(Thread::Current());
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}
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void Disallow() override
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REQUIRES_SHARED(Locks::mutator_lock_)
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REQUIRES(!allow_disallow_lock_) {
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CHECK(!kUseReadBarrier);
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MutexLock mu(Thread::Current(), allow_disallow_lock_);
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allow_new_system_weak_ = false;
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}
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void Broadcast(bool broadcast_for_checkpoint ATTRIBUTE_UNUSED) override
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REQUIRES(!allow_disallow_lock_) {
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MutexLock mu(Thread::Current(), allow_disallow_lock_);
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new_weak_condition_.Broadcast(Thread::Current());
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}
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// WARNING: For lock annotations only.
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Mutex* GetAllowDisallowLock() const RETURN_CAPABILITY(allow_disallow_lock_) {
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return nullptr;
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}
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protected:
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void Wait(Thread* self)
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REQUIRES_SHARED(Locks::mutator_lock_)
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REQUIRES(allow_disallow_lock_) {
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// Wait for GC's sweeping to complete and allow new records
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while (UNLIKELY((!kUseReadBarrier && !allow_new_system_weak_) ||
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(kUseReadBarrier && !self->GetWeakRefAccessEnabled()))) {
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// Check and run the empty checkpoint before blocking so the empty checkpoint will work in the
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// presence of threads blocking for weak ref access.
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self->CheckEmptyCheckpointFromWeakRefAccess(&allow_disallow_lock_);
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new_weak_condition_.WaitHoldingLocks(self);
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}
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}
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Mutex allow_disallow_lock_;
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ConditionVariable new_weak_condition_ GUARDED_BY(allow_disallow_lock_);
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bool allow_new_system_weak_ GUARDED_BY(allow_disallow_lock_);
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};
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} // namespace gc
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} // namespace art
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#endif // ART_RUNTIME_GC_SYSTEM_WEAK_H_
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