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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.
- //
- // CancelableCallback is a wrapper around butil::Callback that allows
- // cancellation of a callback. CancelableCallback takes a reference on the
- // wrapped callback until this object is destroyed or Reset()/Cancel() are
- // called.
- //
- // NOTE:
- //
- // Calling CancelableCallback::Cancel() brings the object back to its natural,
- // default-constructed state, i.e., CancelableCallback::callback() will return
- // a null callback.
- //
- // THREAD-SAFETY:
- //
- // CancelableCallback objects must be created on, posted to, cancelled on, and
- // destroyed on the same thread.
- //
- //
- // EXAMPLE USAGE:
- //
- // In the following example, the test is verifying that RunIntensiveTest()
- // Quit()s the message loop within 4 seconds. The cancelable callback is posted
- // to the message loop, the intensive test runs, the message loop is run,
- // then the callback is cancelled.
- //
- // void TimeoutCallback(const std::string& timeout_message) {
- // FAIL() << timeout_message;
- // MessageLoop::current()->QuitWhenIdle();
- // }
- //
- // CancelableClosure timeout(butil::Bind(&TimeoutCallback, "Test timed out."));
- // MessageLoop::current()->PostDelayedTask(FROM_HERE, timeout.callback(),
- // 4000) // 4 seconds to run.
- // RunIntensiveTest();
- // MessageLoop::current()->Run();
- // timeout.Cancel(); // Hopefully this is hit before the timeout callback runs.
- //
- #ifndef BUTIL_CANCELABLE_CALLBACK_H_
- #define BUTIL_CANCELABLE_CALLBACK_H_
- #include "butil/base_export.h"
- #include "butil/bind.h"
- #include "butil/callback.h"
- #include "butil/callback_internal.h"
- #include "butil/compiler_specific.h"
- #include "butil/logging.h"
- #include "butil/memory/weak_ptr.h"
- namespace butil {
- template <typename Sig>
- class CancelableCallback;
- template <>
- class CancelableCallback<void(void)> {
- public:
- CancelableCallback() : weak_factory_(this) {}
- // |callback| must not be null.
- explicit CancelableCallback(const butil::Callback<void(void)>& callback)
- : weak_factory_(this),
- callback_(callback) {
- DCHECK(!callback.is_null());
- InitializeForwarder();
- }
- ~CancelableCallback() {}
- // Cancels and drops the reference to the wrapped callback.
- void Cancel() {
- weak_factory_.InvalidateWeakPtrs();
- forwarder_.Reset();
- callback_.Reset();
- }
- // Returns true if the wrapped callback has been cancelled.
- bool IsCancelled() const {
- return callback_.is_null();
- }
- // Sets |callback| as the closure that may be cancelled. |callback| may not
- // be null. Outstanding and any previously wrapped callbacks are cancelled.
- void Reset(const butil::Callback<void(void)>& callback) {
- DCHECK(!callback.is_null());
- // Outstanding tasks (e.g., posted to a message loop) must not be called.
- Cancel();
- // |forwarder_| is no longer valid after Cancel(), so re-bind.
- InitializeForwarder();
- callback_ = callback;
- }
- // Returns a callback that can be disabled by calling Cancel().
- const butil::Callback<void(void)>& callback() const {
- return forwarder_;
- }
- private:
- void Forward() {
- callback_.Run();
- }
- // Helper method to bind |forwarder_| using a weak pointer from
- // |weak_factory_|.
- void InitializeForwarder() {
- forwarder_ = butil::Bind(&CancelableCallback<void(void)>::Forward,
- weak_factory_.GetWeakPtr());
- }
- // Used to ensure Forward() is not run when this object is destroyed.
- butil::WeakPtrFactory<CancelableCallback<void(void)> > weak_factory_;
- // The wrapper closure.
- butil::Callback<void(void)> forwarder_;
- // The stored closure that may be cancelled.
- butil::Callback<void(void)> callback_;
- DISALLOW_COPY_AND_ASSIGN(CancelableCallback);
- };
- template <typename A1>
- class CancelableCallback<void(A1)> {
- public:
- CancelableCallback() : weak_factory_(this) {}
- // |callback| must not be null.
- explicit CancelableCallback(const butil::Callback<void(A1)>& callback)
- : weak_factory_(this),
- callback_(callback) {
- DCHECK(!callback.is_null());
- InitializeForwarder();
- }
- ~CancelableCallback() {}
- // Cancels and drops the reference to the wrapped callback.
- void Cancel() {
- weak_factory_.InvalidateWeakPtrs();
- forwarder_.Reset();
- callback_.Reset();
- }
- // Returns true if the wrapped callback has been cancelled.
- bool IsCancelled() const {
- return callback_.is_null();
- }
- // Sets |callback| as the closure that may be cancelled. |callback| may not
- // be null. Outstanding and any previously wrapped callbacks are cancelled.
- void Reset(const butil::Callback<void(A1)>& callback) {
- DCHECK(!callback.is_null());
- // Outstanding tasks (e.g., posted to a message loop) must not be called.
- Cancel();
- // |forwarder_| is no longer valid after Cancel(), so re-bind.
- InitializeForwarder();
- callback_ = callback;
- }
- // Returns a callback that can be disabled by calling Cancel().
- const butil::Callback<void(A1)>& callback() const {
- return forwarder_;
- }
- private:
- void Forward(A1 a1) const {
- callback_.Run(a1);
- }
- // Helper method to bind |forwarder_| using a weak pointer from
- // |weak_factory_|.
- void InitializeForwarder() {
- forwarder_ = butil::Bind(&CancelableCallback<void(A1)>::Forward,
- weak_factory_.GetWeakPtr());
- }
- // Used to ensure Forward() is not run when this object is destroyed.
- butil::WeakPtrFactory<CancelableCallback<void(A1)> > weak_factory_;
- // The wrapper closure.
- butil::Callback<void(A1)> forwarder_;
- // The stored closure that may be cancelled.
- butil::Callback<void(A1)> callback_;
- DISALLOW_COPY_AND_ASSIGN(CancelableCallback);
- };
- template <typename A1, typename A2>
- class CancelableCallback<void(A1, A2)> {
- public:
- CancelableCallback() : weak_factory_(this) {}
- // |callback| must not be null.
- explicit CancelableCallback(const butil::Callback<void(A1, A2)>& callback)
- : weak_factory_(this),
- callback_(callback) {
- DCHECK(!callback.is_null());
- InitializeForwarder();
- }
- ~CancelableCallback() {}
- // Cancels and drops the reference to the wrapped callback.
- void Cancel() {
- weak_factory_.InvalidateWeakPtrs();
- forwarder_.Reset();
- callback_.Reset();
- }
- // Returns true if the wrapped callback has been cancelled.
- bool IsCancelled() const {
- return callback_.is_null();
- }
- // Sets |callback| as the closure that may be cancelled. |callback| may not
- // be null. Outstanding and any previously wrapped callbacks are cancelled.
- void Reset(const butil::Callback<void(A1, A2)>& callback) {
- DCHECK(!callback.is_null());
- // Outstanding tasks (e.g., posted to a message loop) must not be called.
- Cancel();
- // |forwarder_| is no longer valid after Cancel(), so re-bind.
- InitializeForwarder();
- callback_ = callback;
- }
- // Returns a callback that can be disabled by calling Cancel().
- const butil::Callback<void(A1, A2)>& callback() const {
- return forwarder_;
- }
- private:
- void Forward(A1 a1, A2 a2) const {
- callback_.Run(a1, a2);
- }
- // Helper method to bind |forwarder_| using a weak pointer from
- // |weak_factory_|.
- void InitializeForwarder() {
- forwarder_ = butil::Bind(&CancelableCallback<void(A1, A2)>::Forward,
- weak_factory_.GetWeakPtr());
- }
- // Used to ensure Forward() is not run when this object is destroyed.
- butil::WeakPtrFactory<CancelableCallback<void(A1, A2)> > weak_factory_;
- // The wrapper closure.
- butil::Callback<void(A1, A2)> forwarder_;
- // The stored closure that may be cancelled.
- butil::Callback<void(A1, A2)> callback_;
- DISALLOW_COPY_AND_ASSIGN(CancelableCallback);
- };
- typedef CancelableCallback<void(void)> CancelableClosure;
- } // namespace butil
- #endif // BUTIL_CANCELABLE_CALLBACK_H_
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