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228 lines
8.6 KiB
228 lines
8.6 KiB
/* Copyright (C) 2017 The Android Open Source Project
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This file implements interfaces from the file jvmti.h. This implementation
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* is licensed under the same terms as the file jvmti.h. The
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* copyright and license information for the file jvmti.h follows.
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*
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* Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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#ifndef ART_OPENJDKJVMTI_JVMTI_WEAK_TABLE_H_
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#define ART_OPENJDKJVMTI_JVMTI_WEAK_TABLE_H_
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#include <unordered_map>
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#include "base/globals.h"
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#include "base/macros.h"
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#include "base/mutex.h"
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#include "gc/system_weak.h"
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#include "gc_root-inl.h"
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#include "jvmti.h"
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#include "jvmti_allocator.h"
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#include "mirror/object.h"
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#include "thread-current-inl.h"
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namespace openjdkjvmti {
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class EventHandler;
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// A system-weak container mapping objects to elements of the template type. This corresponds
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// to a weak hash map. For historical reasons the stored value is called "tag."
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template <typename T>
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class JvmtiWeakTable : public art::gc::SystemWeakHolder {
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public:
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JvmtiWeakTable()
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: art::gc::SystemWeakHolder(art::kTaggingLockLevel),
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update_since_last_sweep_(false) {
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}
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// Remove the mapping for the given object, returning whether such a mapping existed (and the old
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// value).
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ALWAYS_INLINE bool Remove(art::ObjPtr<art::mirror::Object> obj, /* out */ T* tag)
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REQUIRES_SHARED(art::Locks::mutator_lock_)
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REQUIRES(!allow_disallow_lock_);
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ALWAYS_INLINE bool RemoveLocked(art::ObjPtr<art::mirror::Object> obj, /* out */ T* tag)
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REQUIRES_SHARED(art::Locks::mutator_lock_)
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REQUIRES(allow_disallow_lock_);
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// Set the mapping for the given object. Returns true if this overwrites an already existing
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// mapping.
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ALWAYS_INLINE virtual bool Set(art::ObjPtr<art::mirror::Object> obj, T tag)
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REQUIRES_SHARED(art::Locks::mutator_lock_)
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REQUIRES(!allow_disallow_lock_);
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ALWAYS_INLINE virtual bool SetLocked(art::ObjPtr<art::mirror::Object> obj, T tag)
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REQUIRES_SHARED(art::Locks::mutator_lock_)
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REQUIRES(allow_disallow_lock_);
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// Return the value associated with the given object. Returns true if the mapping exists, false
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// otherwise.
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bool GetTag(art::ObjPtr<art::mirror::Object> obj, /* out */ T* result)
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REQUIRES_SHARED(art::Locks::mutator_lock_)
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REQUIRES(!allow_disallow_lock_) {
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art::Thread* self = art::Thread::Current();
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art::MutexLock mu(self, allow_disallow_lock_);
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Wait(self);
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return GetTagLocked(self, obj, result);
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}
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bool GetTagLocked(art::ObjPtr<art::mirror::Object> obj, /* out */ T* result)
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REQUIRES_SHARED(art::Locks::mutator_lock_)
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REQUIRES(allow_disallow_lock_) {
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art::Thread* self = art::Thread::Current();
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allow_disallow_lock_.AssertHeld(self);
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Wait(self);
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return GetTagLocked(self, obj, result);
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}
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// Sweep the container. DO NOT CALL MANUALLY.
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ALWAYS_INLINE void Sweep(art::IsMarkedVisitor* visitor)
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REQUIRES_SHARED(art::Locks::mutator_lock_)
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REQUIRES(!allow_disallow_lock_);
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// Return all objects that have a value mapping in tags.
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ALWAYS_INLINE
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jvmtiError GetTaggedObjects(jvmtiEnv* jvmti_env,
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jint tag_count,
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const T* tags,
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/* out */ jint* count_ptr,
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/* out */ jobject** object_result_ptr,
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/* out */ T** tag_result_ptr)
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REQUIRES_SHARED(art::Locks::mutator_lock_)
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REQUIRES(!allow_disallow_lock_);
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// Locking functions, to allow coarse-grained locking and amortization.
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ALWAYS_INLINE void Lock() ACQUIRE(allow_disallow_lock_);
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ALWAYS_INLINE void Unlock() RELEASE(allow_disallow_lock_);
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ALWAYS_INLINE void AssertLocked() ASSERT_CAPABILITY(allow_disallow_lock_);
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ALWAYS_INLINE art::ObjPtr<art::mirror::Object> Find(T tag)
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REQUIRES_SHARED(art::Locks::mutator_lock_)
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REQUIRES(!allow_disallow_lock_);
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protected:
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// Should HandleNullSweep be called when Sweep detects the release of an object?
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virtual bool DoesHandleNullOnSweep() {
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return false;
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}
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// If DoesHandleNullOnSweep returns true, this function will be called.
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virtual void HandleNullSweep(T tag ATTRIBUTE_UNUSED) {}
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private:
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ALWAYS_INLINE
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bool SetLocked(art::Thread* self, art::ObjPtr<art::mirror::Object> obj, T tag)
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REQUIRES_SHARED(art::Locks::mutator_lock_)
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REQUIRES(allow_disallow_lock_);
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ALWAYS_INLINE
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bool RemoveLocked(art::Thread* self, art::ObjPtr<art::mirror::Object> obj, /* out */ T* tag)
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REQUIRES_SHARED(art::Locks::mutator_lock_)
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REQUIRES(allow_disallow_lock_);
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bool GetTagLocked(art::Thread* self, art::ObjPtr<art::mirror::Object> obj, /* out */ T* result)
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REQUIRES_SHARED(art::Locks::mutator_lock_)
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REQUIRES(allow_disallow_lock_) {
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auto it = tagged_objects_.find(art::GcRoot<art::mirror::Object>(obj));
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if (it != tagged_objects_.end()) {
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*result = it->second;
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return true;
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}
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// Performance optimization: To avoid multiple table updates, ensure that during GC we
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// only update once. See the comment on the implementation of GetTagSlowPath.
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if (art::kUseReadBarrier &&
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self != nullptr &&
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self->GetIsGcMarking() &&
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!update_since_last_sweep_) {
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return GetTagSlowPath(self, obj, result);
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}
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return false;
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}
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// Slow-path for GetTag. We didn't find the object, but we might be storing from-pointers and
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// are asked to retrieve with a to-pointer.
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ALWAYS_INLINE
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bool GetTagSlowPath(art::Thread* self, art::ObjPtr<art::mirror::Object> obj, /* out */ T* result)
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REQUIRES_SHARED(art::Locks::mutator_lock_)
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REQUIRES(allow_disallow_lock_);
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// Update the table by doing read barriers on each element, ensuring that to-space pointers
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// are stored.
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ALWAYS_INLINE
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void UpdateTableWithReadBarrier()
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REQUIRES_SHARED(art::Locks::mutator_lock_)
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REQUIRES(allow_disallow_lock_);
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template <bool kHandleNull>
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void SweepImpl(art::IsMarkedVisitor* visitor)
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REQUIRES_SHARED(art::Locks::mutator_lock_)
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REQUIRES(!allow_disallow_lock_);
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enum TableUpdateNullTarget {
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kIgnoreNull,
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kRemoveNull,
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kCallHandleNull
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};
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template <typename Updater, TableUpdateNullTarget kTargetNull>
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void UpdateTableWith(Updater& updater)
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REQUIRES_SHARED(art::Locks::mutator_lock_)
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REQUIRES(allow_disallow_lock_);
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template <typename Storage, class Allocator = JvmtiAllocator<T>>
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struct ReleasableContainer;
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struct HashGcRoot {
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size_t operator()(const art::GcRoot<art::mirror::Object>& r) const
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REQUIRES_SHARED(art::Locks::mutator_lock_) {
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return reinterpret_cast<uintptr_t>(r.Read<art::kWithoutReadBarrier>());
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}
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};
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struct EqGcRoot {
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bool operator()(const art::GcRoot<art::mirror::Object>& r1,
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const art::GcRoot<art::mirror::Object>& r2) const
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REQUIRES_SHARED(art::Locks::mutator_lock_) {
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return r1.Read<art::kWithoutReadBarrier>() == r2.Read<art::kWithoutReadBarrier>();
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}
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};
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using TagAllocator = JvmtiAllocator<std::pair<const art::GcRoot<art::mirror::Object>, T>>;
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std::unordered_map<art::GcRoot<art::mirror::Object>,
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T,
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HashGcRoot,
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EqGcRoot,
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TagAllocator> tagged_objects_
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GUARDED_BY(allow_disallow_lock_)
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GUARDED_BY(art::Locks::mutator_lock_);
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// To avoid repeatedly scanning the whole table, remember if we did that since the last sweep.
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bool update_since_last_sweep_;
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};
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} // namespace openjdkjvmti
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#endif // ART_OPENJDKJVMTI_JVMTI_WEAK_TABLE_H_
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