Repo created

TMessagesProj/jni/voip/webrtc/base/memory/weak_ptr.cc

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