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/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ART_RUNTIME_GC_REFERENCE_PROCESSOR_H_
#define ART_RUNTIME_GC_REFERENCE_PROCESSOR_H_
#include "base/locks.h"
#include "jni.h"
#include "reference_queue.h"
#include "runtime_globals.h"
namespace art {
class IsMarkedVisitor;
class TimingLogger;
namespace mirror {
class Class;
class FinalizerReference;
class Object;
class Reference;
} // namespace mirror
namespace gc {
namespace collector {
class GarbageCollector;
} // namespace collector
class Heap;
// Used to process java.lang.ref.Reference instances concurrently or paused.
class ReferenceProcessor {
public:
ReferenceProcessor();
// Initialize for a reference processing pass. Called before suspending weak
// access.
void Setup(Thread* self,
collector::GarbageCollector* collector,
bool concurrent,
bool clear_soft_references)
REQUIRES(!Locks::reference_processor_lock_);
// Enqueue all types of java.lang.ref.References, and mark through finalizers.
// Assumes there is no concurrent mutator-driven marking, i.e. all potentially
// mutator-accessible objects should be marked before this.
void ProcessReferences(Thread* self, TimingLogger* timings)
REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES(!Locks::reference_processor_lock_);
// The slow path bool is contained in the reference class object, can only be set once
// Only allow setting this with mutators suspended so that we can avoid using a lock in the
// GetReferent fast path as an optimization.
void EnableSlowPath() REQUIRES_SHARED(Locks::mutator_lock_);
void BroadcastForSlowPath(Thread* self);
// Decode the referent, may block if references are being processed. In the normal
// no-read-barrier or Baker-read-barrier cases, we assume reference is not a PhantomReference.
ObjPtr<mirror::Object> GetReferent(Thread* self, ObjPtr<mirror::Reference> reference)
REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!Locks::reference_processor_lock_);
// Collects the cleared references and returns a task, to be executed after FinishGC, that will
// enqueue all of them.
SelfDeletingTask* CollectClearedReferences(Thread* self) REQUIRES(!Locks::mutator_lock_);
void DelayReferenceReferent(ObjPtr<mirror::Class> klass,
ObjPtr<mirror::Reference> ref,
collector::GarbageCollector* collector)
REQUIRES_SHARED(Locks::mutator_lock_);
void UpdateRoots(IsMarkedVisitor* visitor)
REQUIRES_SHARED(Locks::mutator_lock_, Locks::heap_bitmap_lock_);
// Make a circular list with reference if it is not enqueued. Uses the finalizer queue lock.
bool MakeCircularListIfUnenqueued(ObjPtr<mirror::FinalizerReference> reference)
REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(!Locks::reference_processor_lock_,
!Locks::reference_queue_finalizer_references_lock_);
void ClearReferent(ObjPtr<mirror::Reference> ref)
REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(!Locks::reference_processor_lock_);
uint32_t ForwardSoftReferences(TimingLogger* timings)
REQUIRES_SHARED(Locks::mutator_lock_);
private:
bool SlowPathEnabled() REQUIRES_SHARED(Locks::mutator_lock_);
// Called by ProcessReferences.
void DisableSlowPath(Thread* self) REQUIRES(Locks::reference_processor_lock_)
REQUIRES_SHARED(Locks::mutator_lock_);
// Wait until reference processing is done.
void WaitUntilDoneProcessingReferences(Thread* self)
REQUIRES_SHARED(Locks::mutator_lock_)
REQUIRES(Locks::reference_processor_lock_);
// Collector which is clearing references, used by the GetReferent to return referents which are
// already marked. Only updated by thread currently running GC.
// Guarded by reference_processor_lock_ when not read by collector. Only the collector changes
// it.
collector::GarbageCollector* collector_;
// Reference processor state. Only valid while weak reference processing is suspended.
// Used by GetReferent and friends to return early.
enum class RpState : uint8_t { kStarting, kInitMarkingDone, kInitClearingDone };
RpState rp_state_ GUARDED_BY(Locks::reference_processor_lock_);
bool concurrent_; // Running concurrently with mutator? Only used by GC thread.
bool clear_soft_references_; // Only used by GC thread.
// Condition that people wait on if they attempt to get the referent of a reference while
// processing is in progress. Broadcast when an empty checkpoint is requested, but not for other
// checkpoints or thread suspensions. See mutator_gc_coord.md.
ConditionVariable condition_ GUARDED_BY(Locks::reference_processor_lock_);
// Reference queues used by the GC.
ReferenceQueue soft_reference_queue_;
ReferenceQueue weak_reference_queue_;
ReferenceQueue finalizer_reference_queue_;
ReferenceQueue phantom_reference_queue_;
ReferenceQueue cleared_references_;
DISALLOW_COPY_AND_ASSIGN(ReferenceProcessor);
};
} // namespace gc
} // namespace art
#endif // ART_RUNTIME_GC_REFERENCE_PROCESSOR_H_
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