// Copyright (c) 2014 Marshall A. Greenblatt. Portions copyright (c) 2011 // Google Inc. All rights reserved. // // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions are // met: // // * Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // * Redistributions in binary form must reproduce the above // copyright notice, this list of conditions and the following disclaimer // in the documentation and/or other materials provided with the // distribution. // * Neither the name of Google Inc. nor the name Chromium Embedded // Framework nor the names of its contributors may be used to endorse // or promote products derived from this software without specific prior // written permission. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. /// /// \file /// CancelableCallback is a wrapper around base::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. /// ///
///   RunLoop run_loop;
///
///   void TimeoutCallback(const std::string& timeout_message) {
///     FAIL() << timeout_message;
///     run_loop.QuitWhenIdle();
///   }
///
///   CancelableOnceClosure timeout(
///       base::BindOnce(&TimeoutCallback, "Test timed out."));
///   ThreadTaskRunnerHandle::Get()->PostDelayedTask(FROM_HERE,
///                                                  timeout.callback(),
///                                                  TimeDelta::FromSeconds(4));
///   RunIntensiveTest();
///   run_loop.Run();
///   // Hopefully this is hit before the timeout callback runs.
///   timeout.Cancel();
/// 
/// #ifndef CEF_INCLUDE_BASE_CEF_CANCELABLE_CALLBACK_H_ #define CEF_INCLUDE_BASE_CEF_CANCELABLE_CALLBACK_H_ #pragma once #if defined(USING_CHROMIUM_INCLUDES) // When building CEF include the Chromium header directly. #include "base/cancelable_callback.h" #else // !USING_CHROMIUM_INCLUDES // The following is substantially similar to the Chromium implementation. // If the Chromium implementation diverges the below implementation should be // updated to match. #include #include "include/base/cef_bind.h" #include "include/base/cef_callback.h" #include "include/base/cef_compiler_specific.h" #include "include/base/cef_logging.h" #include "include/base/cef_weak_ptr.h" #include "include/base/internal/cef_callback_internal.h" namespace base { namespace internal { template class CancelableCallbackImpl { public: CancelableCallbackImpl() = default; CancelableCallbackImpl(const CancelableCallbackImpl&) = delete; CancelableCallbackImpl& operator=(const CancelableCallbackImpl&) = delete; // |callback| must not be null. explicit CancelableCallbackImpl(CallbackType callback) : callback_(std::move(callback)) { DCHECK(callback_); } ~CancelableCallbackImpl() = default; // Cancels and drops the reference to the wrapped callback. void Cancel() { weak_ptr_factory_.InvalidateWeakPtrs(); 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(CallbackType callback) { DCHECK(callback); // Outstanding tasks (e.g., posted to a message loop) must not be called. Cancel(); callback_ = std::move(callback); } // Returns a callback that can be disabled by calling Cancel(). CallbackType callback() const { if (!callback_) { return CallbackType(); } CallbackType forwarder; MakeForwarder(&forwarder); return forwarder; } private: template void MakeForwarder(RepeatingCallback* out) const { using ForwarderType = void (CancelableCallbackImpl::*)(Args...); ForwarderType forwarder = &CancelableCallbackImpl::ForwardRepeating; *out = BindRepeating(forwarder, weak_ptr_factory_.GetWeakPtr()); } template void MakeForwarder(OnceCallback* out) const { using ForwarderType = void (CancelableCallbackImpl::*)(Args...); ForwarderType forwarder = &CancelableCallbackImpl::ForwardOnce; *out = BindOnce(forwarder, weak_ptr_factory_.GetWeakPtr()); } template void ForwardRepeating(Args... args) { callback_.Run(std::forward(args)...); } template void ForwardOnce(Args... args) { weak_ptr_factory_.InvalidateWeakPtrs(); std::move(callback_).Run(std::forward(args)...); } // The stored closure that may be cancelled. CallbackType callback_; mutable base::WeakPtrFactory weak_ptr_factory_{this}; }; } // namespace internal /// /// Consider using base::WeakPtr directly instead of base::CancelableCallback /// for the task cancellation. /// template using CancelableOnceCallback = internal::CancelableCallbackImpl>; using CancelableOnceClosure = CancelableOnceCallback; template using CancelableRepeatingCallback = internal::CancelableCallbackImpl>; using CancelableRepeatingClosure = CancelableRepeatingCallback; } // namespace base #endif // !USING_CHROMIUM_INCLUDES #endif // CEF_INCLUDE_BASE_CEF_CANCELABLE_CALLBACK_H_