100 lines
2.6 KiB
C++
100 lines
2.6 KiB
C++
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// Copyright (c) 2011 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "base/memory/weak_ptr.h"
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namespace base {
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namespace internal {
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WeakReference::Flag::Flag() {
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// Flags only become bound when checked for validity, or invalidated,
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// so that we can check that later validity/invalidation operations on
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// the same Flag take place on the same sequenced thread.
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DETACH_FROM_SEQUENCE(sequence_checker_);
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}
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void WeakReference::Flag::Invalidate() {
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// The flag being invalidated with a single ref implies that there are no
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// weak pointers in existence. Allow deletion on other thread in this case.
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#if DCHECK_IS_ON()
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DCHECK(sequence_checker_.CalledOnValidSequence() || HasOneRef())
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<< "WeakPtrs must be invalidated on the same sequenced thread.";
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#endif
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invalidated_.Set();
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}
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bool WeakReference::Flag::IsValid() const {
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// WeakPtrs must be checked on the same sequenced thread.
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DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
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return !invalidated_.IsSet();
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}
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bool WeakReference::Flag::MaybeValid() const {
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return !invalidated_.IsSet();
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}
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void WeakReference::Flag::DetachFromSequence() {
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DETACH_FROM_SEQUENCE(sequence_checker_);
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}
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WeakReference::Flag::~Flag() = default;
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WeakReference::WeakReference() = default;
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WeakReference::WeakReference(const scoped_refptr<Flag>& flag) : flag_(flag) {}
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WeakReference::~WeakReference() = default;
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WeakReference::WeakReference(WeakReference&& other) noexcept = default;
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WeakReference::WeakReference(const WeakReference& other) = default;
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bool WeakReference::IsValid() const {
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return flag_ && flag_->IsValid();
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}
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bool WeakReference::MaybeValid() const {
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return flag_ && flag_->MaybeValid();
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}
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WeakReferenceOwner::WeakReferenceOwner()
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: flag_(MakeRefCounted<WeakReference::Flag>()) {}
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WeakReferenceOwner::~WeakReferenceOwner() {
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flag_->Invalidate();
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}
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WeakReference WeakReferenceOwner::GetRef() const {
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// If we hold the last reference to the Flag then detach the SequenceChecker.
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if (!HasRefs())
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flag_->DetachFromSequence();
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return WeakReference(flag_);
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}
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void WeakReferenceOwner::Invalidate() {
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flag_->Invalidate();
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flag_ = MakeRefCounted<WeakReference::Flag>();
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}
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WeakPtrBase::WeakPtrBase() : ptr_(0) {}
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WeakPtrBase::~WeakPtrBase() = default;
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WeakPtrBase::WeakPtrBase(const WeakReference& ref, uintptr_t ptr)
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: ref_(ref), ptr_(ptr) {
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DCHECK(ptr_);
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}
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WeakPtrFactoryBase::WeakPtrFactoryBase(uintptr_t ptr) : ptr_(ptr) {
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DCHECK(ptr_);
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}
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WeakPtrFactoryBase::~WeakPtrFactoryBase() {
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ptr_ = 0;
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}
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} // namespace internal
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} // namespace base
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