78 lines
1.9 KiB
C++
78 lines
1.9 KiB
C++
// 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() : is_valid_(true) {
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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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sequence_checker_.DetachFromSequence();
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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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DCHECK(sequence_checker_.CalledOnValidSequencedThread() || HasOneRef())
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<< "WeakPtrs must be invalidated on the same sequenced thread.";
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is_valid_ = false;
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}
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bool WeakReference::Flag::IsValid() const {
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DCHECK(sequence_checker_.CalledOnValidSequencedThread())
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<< "WeakPtrs must be checked on the same sequenced thread.";
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return is_valid_;
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}
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WeakReference::Flag::~Flag() {
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}
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WeakReference::WeakReference() {
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}
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WeakReference::WeakReference(const Flag* flag) : flag_(flag) {
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}
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WeakReference::~WeakReference() {
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}
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bool WeakReference::is_valid() const { return flag_.get() && flag_->IsValid(); }
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WeakReferenceOwner::WeakReferenceOwner() {
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}
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WeakReferenceOwner::~WeakReferenceOwner() {
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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 create a new one.
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if (!HasRefs())
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flag_ = new WeakReference::Flag();
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return WeakReference(flag_.get());
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}
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void WeakReferenceOwner::Invalidate() {
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if (flag_.get()) {
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flag_->Invalidate();
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flag_ = NULL;
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}
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}
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WeakPtrBase::WeakPtrBase() {
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}
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WeakPtrBase::~WeakPtrBase() {
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}
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WeakPtrBase::WeakPtrBase(const WeakReference& ref) : ref_(ref) {
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}
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} // namespace internal
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} // namespace base
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