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// 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.
///
/// <pre>
/// 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();
/// </pre>
///
#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 <utility>
#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 <typename CallbackType>
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 <typename... Args>
void MakeForwarder(RepeatingCallback<void(Args...)>* out) const {
using ForwarderType = void (CancelableCallbackImpl::*)(Args...);
ForwarderType forwarder = &CancelableCallbackImpl::ForwardRepeating;
*out = BindRepeating(forwarder, weak_ptr_factory_.GetWeakPtr());
}
template <typename... Args>
void MakeForwarder(OnceCallback<void(Args...)>* out) const {
using ForwarderType = void (CancelableCallbackImpl::*)(Args...);
ForwarderType forwarder = &CancelableCallbackImpl::ForwardOnce;
*out = BindOnce(forwarder, weak_ptr_factory_.GetWeakPtr());
}
template <typename... Args>
void ForwardRepeating(Args... args) {
callback_.Run(std::forward<Args>(args)...);
}
template <typename... Args>
void ForwardOnce(Args... args) {
weak_ptr_factory_.InvalidateWeakPtrs();
std::move(callback_).Run(std::forward<Args>(args)...);
}
// The stored closure that may be cancelled.
CallbackType callback_;
mutable base::WeakPtrFactory<CancelableCallbackImpl> weak_ptr_factory_{this};
};
} // namespace internal
///
/// Consider using base::WeakPtr directly instead of base::CancelableCallback
/// for the task cancellation.
///
template <typename Signature>
using CancelableOnceCallback =
internal::CancelableCallbackImpl<OnceCallback<Signature>>;
using CancelableOnceClosure = CancelableOnceCallback<void()>;
template <typename Signature>
using CancelableRepeatingCallback =
internal::CancelableCallbackImpl<RepeatingCallback<Signature>>;
using CancelableRepeatingClosure = CancelableRepeatingCallback<void()>;
} // namespace base
#endif // !USING_CHROMIUM_INCLUDES
#endif // CEF_INCLUDE_BASE_CEF_CANCELABLE_CALLBACK_H_
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