mirror of
https://bitbucket.org/chromiumembedded/cef
synced 2024-12-12 09:37:37 +01:00
122397acfc
Changes to the CEF public API: - Add base::Bind, base::Callback, base::Lock, base::WeakPtr, scoped_refptr, scoped_ptr and supporting types. - Add include/wrapper/cef_closure_task.h helpers for converting a base::Closure to a CefTask. - Change CefRefPtr to extend scoped_refptr. -- Change CefBase method signatures to match RefCountedThreadSafeBase. - Change IMPLEMENT_REFCOUNTING to use base::AtomicRefCount*. -- Remove the CefAtomic* functions. -- IMPLEMENT_REFCOUNTING now enforces via a compile-time error that the correct class name was passed to the macro. - Change IMPLEMENT_LOCKING to use base::Lock. -- Remove the CefCriticalSection class. -- Deprecate the IMPLEMENT_LOCKING macro. -- base::Lock will DCHECK() in Debug builds if lock usage is reentrant. - Move include/internal/cef_tuple.h to include/base/cef_tuple.h. - Allow an empty |callback| parameter passed to CefBeginTracing. Changes to the CEF implementation: - Fix incorrect names passed to the IMPLEMENT_REFCOUNTING macro. - Fix instances of reentrant locking in the CefXmlObject and CefRequest implementations. - Remove use of the IMPLEMENT_LOCKING macro. Changes to cef_unittests: - Add tests/unittests/chromium_includes.h and always include it first from unit test .cc files to avoid name conflicts with Chromium types. - Fix wrong header include ordering. - Remove use of the IMPLEMENT_LOCKING macro. Changes to cefclient and cefsimple: - Use base::Bind and cef_closure_task.h instead of NewCefRunnable*. - Remove use of the IMPEMENT_LOCKING macro. - Fix incorrect/unnecessary locking. - Add additional runtime thread checks. - Windows: Perform actions on the UI thread instead of the main thread when running in multi-threaded-message-loop mode to avoid excessive locking. git-svn-id: https://chromiumembedded.googlecode.com/svn/trunk@1769 5089003a-bbd8-11dd-ad1f-f1f9622dbc98
383 lines
13 KiB
C++
383 lines
13 KiB
C++
// Copyright (c) 2014 Marshall A. Greenblatt. Portions copyright (c) 2012
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// Google Inc. All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Google Inc. nor the name Chromium Embedded
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// Framework nor the names of its contributors may be used to endorse
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// or promote products derived from this software without specific prior
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// written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// Weak pointers are pointers to an object that do not affect its lifetime,
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// and which may be invalidated (i.e. reset to NULL) by the object, or its
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// owner, at any time, most commonly when the object is about to be deleted.
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// Weak pointers are useful when an object needs to be accessed safely by one
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// or more objects other than its owner, and those callers can cope with the
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// object vanishing and e.g. tasks posted to it being silently dropped.
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// Reference-counting such an object would complicate the ownership graph and
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// make it harder to reason about the object's lifetime.
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// EXAMPLE:
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//
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// class Controller {
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// public:
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// void SpawnWorker() { Worker::StartNew(weak_factory_.GetWeakPtr()); }
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// void WorkComplete(const Result& result) { ... }
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// private:
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// // Member variables should appear before the WeakPtrFactory, to ensure
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// // that any WeakPtrs to Controller are invalidated before its members
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// // variable's destructors are executed, rendering them invalid.
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// WeakPtrFactory<Controller> weak_factory_;
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// };
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//
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// class Worker {
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// public:
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// static void StartNew(const WeakPtr<Controller>& controller) {
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// Worker* worker = new Worker(controller);
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// // Kick off asynchronous processing...
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// }
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// private:
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// Worker(const WeakPtr<Controller>& controller)
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// : controller_(controller) {}
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// void DidCompleteAsynchronousProcessing(const Result& result) {
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// if (controller_)
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// controller_->WorkComplete(result);
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// }
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// WeakPtr<Controller> controller_;
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// };
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//
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// With this implementation a caller may use SpawnWorker() to dispatch multiple
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// Workers and subsequently delete the Controller, without waiting for all
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// Workers to have completed.
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// ------------------------- IMPORTANT: Thread-safety -------------------------
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// Weak pointers may be passed safely between threads, but must always be
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// dereferenced and invalidated on the same thread otherwise checking the
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// pointer would be racey.
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//
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// To ensure correct use, the first time a WeakPtr issued by a WeakPtrFactory
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// is dereferenced, the factory and its WeakPtrs become bound to the calling
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// thread, and cannot be dereferenced or invalidated on any other thread. Bound
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// WeakPtrs can still be handed off to other threads, e.g. to use to post tasks
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// back to object on the bound thread.
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//
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// Invalidating the factory's WeakPtrs un-binds it from the thread, allowing it
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// to be passed for a different thread to use or delete it.
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#ifndef CEF_INCLUDE_BASE_CEF_WEAK_PTR_H_
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#define CEF_INCLUDE_BASE_CEF_WEAK_PTR_H_
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#pragma once
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#if defined(BASE_MEMORY_WEAK_PTR_H_)
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// Do nothing if the Chromium header has already been included.
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// This can happen in cases where Chromium code is used directly by the
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// client application. When using Chromium code directly always include
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// the Chromium header first to avoid type conflicts.
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#elif defined(BUILDING_CEF_SHARED)
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// When building CEF include the Chromium header directly.
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#include "base/memory/weak_ptr.h"
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#else // !BUILDING_CEF_SHARED
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// The following is substantially similar to the Chromium implementation.
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// If the Chromium implementation diverges the below implementation should be
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// updated to match.
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#include "include/base/cef_basictypes.h"
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#include "include/base/cef_logging.h"
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#include "include/base/cef_ref_counted.h"
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#include "include/base/cef_template_util.h"
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#include "include/base/cef_thread_checker.h"
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namespace base {
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template <typename T> class SupportsWeakPtr;
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template <typename T> class WeakPtr;
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namespace internal {
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// These classes are part of the WeakPtr implementation.
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// DO NOT USE THESE CLASSES DIRECTLY YOURSELF.
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class WeakReference {
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public:
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// Although Flag is bound to a specific thread, it may be deleted from another
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// via base::WeakPtr::~WeakPtr().
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class Flag : public RefCountedThreadSafe<Flag> {
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public:
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Flag();
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void Invalidate();
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bool IsValid() const;
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private:
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friend class base::RefCountedThreadSafe<Flag>;
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~Flag();
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// The current Chromium implementation uses SequenceChecker instead of
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// ThreadChecker to support SequencedWorkerPools. CEF does not yet expose
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// the concept of SequencedWorkerPools.
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ThreadChecker thread_checker_;
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bool is_valid_;
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};
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WeakReference();
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explicit WeakReference(const Flag* flag);
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~WeakReference();
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bool is_valid() const;
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private:
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scoped_refptr<const Flag> flag_;
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};
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class WeakReferenceOwner {
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public:
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WeakReferenceOwner();
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~WeakReferenceOwner();
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WeakReference GetRef() const;
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bool HasRefs() const {
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return flag_.get() && !flag_->HasOneRef();
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}
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void Invalidate();
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private:
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mutable scoped_refptr<WeakReference::Flag> flag_;
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};
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// This class simplifies the implementation of WeakPtr's type conversion
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// constructor by avoiding the need for a public accessor for ref_. A
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// WeakPtr<T> cannot access the private members of WeakPtr<U>, so this
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// base class gives us a way to access ref_ in a protected fashion.
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class WeakPtrBase {
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public:
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WeakPtrBase();
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~WeakPtrBase();
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protected:
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explicit WeakPtrBase(const WeakReference& ref);
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WeakReference ref_;
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};
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// This class provides a common implementation of common functions that would
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// otherwise get instantiated separately for each distinct instantiation of
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// SupportsWeakPtr<>.
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class SupportsWeakPtrBase {
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public:
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// A safe static downcast of a WeakPtr<Base> to WeakPtr<Derived>. This
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// conversion will only compile if there is exists a Base which inherits
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// from SupportsWeakPtr<Base>. See base::AsWeakPtr() below for a helper
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// function that makes calling this easier.
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template<typename Derived>
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static WeakPtr<Derived> StaticAsWeakPtr(Derived* t) {
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typedef
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is_convertible<Derived, internal::SupportsWeakPtrBase&> convertible;
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COMPILE_ASSERT(convertible::value,
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AsWeakPtr_argument_inherits_from_SupportsWeakPtr);
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return AsWeakPtrImpl<Derived>(t, *t);
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}
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private:
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// This template function uses type inference to find a Base of Derived
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// which is an instance of SupportsWeakPtr<Base>. We can then safely
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// static_cast the Base* to a Derived*.
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template <typename Derived, typename Base>
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static WeakPtr<Derived> AsWeakPtrImpl(
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Derived* t, const SupportsWeakPtr<Base>&) {
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WeakPtr<Base> ptr = t->Base::AsWeakPtr();
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return WeakPtr<Derived>(ptr.ref_, static_cast<Derived*>(ptr.ptr_));
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}
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};
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} // namespace internal
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template <typename T> class WeakPtrFactory;
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// The WeakPtr class holds a weak reference to |T*|.
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//
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// This class is designed to be used like a normal pointer. You should always
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// null-test an object of this class before using it or invoking a method that
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// may result in the underlying object being destroyed.
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//
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// EXAMPLE:
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//
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// class Foo { ... };
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// WeakPtr<Foo> foo;
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// if (foo)
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// foo->method();
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//
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template <typename T>
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class WeakPtr : public internal::WeakPtrBase {
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public:
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WeakPtr() : ptr_(NULL) {
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}
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// Allow conversion from U to T provided U "is a" T. Note that this
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// is separate from the (implicit) copy constructor.
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template <typename U>
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WeakPtr(const WeakPtr<U>& other) : WeakPtrBase(other), ptr_(other.ptr_) {
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}
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T* get() const { return ref_.is_valid() ? ptr_ : NULL; }
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T& operator*() const {
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DCHECK(get() != NULL);
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return *get();
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}
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T* operator->() const {
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DCHECK(get() != NULL);
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return get();
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}
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// Allow WeakPtr<element_type> to be used in boolean expressions, but not
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// implicitly convertible to a real bool (which is dangerous).
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//
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// Note that this trick is only safe when the == and != operators
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// are declared explicitly, as otherwise "weak_ptr1 == weak_ptr2"
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// will compile but do the wrong thing (i.e., convert to Testable
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// and then do the comparison).
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private:
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typedef T* WeakPtr::*Testable;
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public:
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operator Testable() const { return get() ? &WeakPtr::ptr_ : NULL; }
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void reset() {
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ref_ = internal::WeakReference();
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ptr_ = NULL;
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}
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private:
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// Explicitly declare comparison operators as required by the bool
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// trick, but keep them private.
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template <class U> bool operator==(WeakPtr<U> const&) const;
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template <class U> bool operator!=(WeakPtr<U> const&) const;
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friend class internal::SupportsWeakPtrBase;
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template <typename U> friend class WeakPtr;
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friend class SupportsWeakPtr<T>;
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friend class WeakPtrFactory<T>;
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WeakPtr(const internal::WeakReference& ref, T* ptr)
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: WeakPtrBase(ref),
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ptr_(ptr) {
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}
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// This pointer is only valid when ref_.is_valid() is true. Otherwise, its
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// value is undefined (as opposed to NULL).
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T* ptr_;
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};
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// A class may be composed of a WeakPtrFactory and thereby
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// control how it exposes weak pointers to itself. This is helpful if you only
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// need weak pointers within the implementation of a class. This class is also
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// useful when working with primitive types. For example, you could have a
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// WeakPtrFactory<bool> that is used to pass around a weak reference to a bool.
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template <class T>
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class WeakPtrFactory {
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public:
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explicit WeakPtrFactory(T* ptr) : ptr_(ptr) {
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}
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~WeakPtrFactory() {
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ptr_ = NULL;
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}
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WeakPtr<T> GetWeakPtr() {
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DCHECK(ptr_);
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return WeakPtr<T>(weak_reference_owner_.GetRef(), ptr_);
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}
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// Call this method to invalidate all existing weak pointers.
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void InvalidateWeakPtrs() {
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DCHECK(ptr_);
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weak_reference_owner_.Invalidate();
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}
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// Call this method to determine if any weak pointers exist.
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bool HasWeakPtrs() const {
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DCHECK(ptr_);
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return weak_reference_owner_.HasRefs();
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}
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private:
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internal::WeakReferenceOwner weak_reference_owner_;
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T* ptr_;
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DISALLOW_IMPLICIT_CONSTRUCTORS(WeakPtrFactory);
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};
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// A class may extend from SupportsWeakPtr to let others take weak pointers to
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// it. This avoids the class itself implementing boilerplate to dispense weak
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// pointers. However, since SupportsWeakPtr's destructor won't invalidate
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// weak pointers to the class until after the derived class' members have been
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// destroyed, its use can lead to subtle use-after-destroy issues.
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template <class T>
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class SupportsWeakPtr : public internal::SupportsWeakPtrBase {
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public:
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SupportsWeakPtr() {}
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WeakPtr<T> AsWeakPtr() {
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return WeakPtr<T>(weak_reference_owner_.GetRef(), static_cast<T*>(this));
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}
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protected:
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~SupportsWeakPtr() {}
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private:
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internal::WeakReferenceOwner weak_reference_owner_;
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DISALLOW_COPY_AND_ASSIGN(SupportsWeakPtr);
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};
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// Helper function that uses type deduction to safely return a WeakPtr<Derived>
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// when Derived doesn't directly extend SupportsWeakPtr<Derived>, instead it
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// extends a Base that extends SupportsWeakPtr<Base>.
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//
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// EXAMPLE:
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// class Base : public base::SupportsWeakPtr<Producer> {};
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// class Derived : public Base {};
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//
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// Derived derived;
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// base::WeakPtr<Derived> ptr = base::AsWeakPtr(&derived);
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//
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// Note that the following doesn't work (invalid type conversion) since
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// Derived::AsWeakPtr() is WeakPtr<Base> SupportsWeakPtr<Base>::AsWeakPtr(),
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// and there's no way to safely cast WeakPtr<Base> to WeakPtr<Derived> at
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// the caller.
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//
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// base::WeakPtr<Derived> ptr = derived.AsWeakPtr(); // Fails.
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template <typename Derived>
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WeakPtr<Derived> AsWeakPtr(Derived* t) {
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return internal::SupportsWeakPtrBase::StaticAsWeakPtr<Derived>(t);
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}
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} // namespace base
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#endif // !BUILDING_CEF_SHARED
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#endif // CEF_INCLUDE_BASE_CEF_WEAK_PTR_H_
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