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// Copyright (c) 2009 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.
// Some basic utilities for aiding in the management of Tasks and Callbacks.
//
// AutoTaskRunner, and its brother AutoCallbackRunner are the scoped_ptr
// equivalents for callbacks. They are useful for ensuring a callback is
// executed and delete in the face of multiple return points in a function.
//
// TaskToCallbackAdapter converts a Task to a Callback0::Type since the two type
// heirarchies are strangely separate.
//
// CleanupCallback wraps another Callback and provides the ability to register
// objects for deletion as well as cleanup tasks that will be run on the
// callback's destruction. The deletion and cleanup tasks will be run on
// whatever thread the CleanupCallback is destroyed in.
#ifndef MEDIA_BASE_CALLBACK_
#define MEDIA_BASE_CALLBACK_
#include <vector>
#include "base/scoped_ptr.h"
#include "base/task.h"
namespace media {
class AutoTaskRunner {
public:
// Takes ownership of the task.
explicit AutoTaskRunner(Task* task)
: task_(task) {
}
~AutoTaskRunner() {
if (task_.get()) {
task_->Run();
}
}
Task* release() { return task_.release(); }
private:
scoped_ptr<Task> task_;
DISALLOW_COPY_AND_ASSIGN(AutoTaskRunner);
};
class AutoCallbackRunner {
public:
// Takes ownership of the callback.
explicit AutoCallbackRunner(Callback0::Type* callback)
: callback_(callback) {
}
~AutoCallbackRunner() {
if (callback_.get()) {
callback_->Run();
}
}
Callback0::Type* release() { return callback_.release(); }
private:
scoped_ptr<Callback0::Type> callback_;
DISALLOW_COPY_AND_ASSIGN(AutoCallbackRunner);
};
class TaskToCallbackAdapter : public Callback0::Type {
public:
static Callback0::Type* NewCallback(Task* task) {
return new TaskToCallbackAdapter(task);
}
virtual ~TaskToCallbackAdapter() {}
virtual void RunWithParams(const Tuple0& params) { task_->Run(); }
private:
TaskToCallbackAdapter(Task* task) : task_(task) {}
scoped_ptr<Task> task_;
DISALLOW_COPY_AND_ASSIGN(TaskToCallbackAdapter);
};
template <typename CallbackType>
class CleanupCallback : public CallbackType {
public:
explicit CleanupCallback(CallbackType* callback) : callback_(callback) {}
virtual ~CleanupCallback() {
for (size_t i = 0; i < run_when_done_.size(); i++) {
run_when_done_[i]->Run();
delete run_when_done_[i];
}
}
virtual void RunWithParams(const typename CallbackType::TupleType& params) {
callback_->RunWithParams(params);
}
template <typename T>
void DeleteWhenDone(T* ptr) {
class Deleter : public Task {
public:
Deleter(T* p) : ptr_(p) {}
virtual void Run() {
delete ptr_;
}
private:
T* ptr_;
};
RunWhenDone(new Deleter(ptr));
}
void RunWhenDone(Task* ptr) {
run_when_done_.push_back(ptr);
}
private:
scoped_ptr<CallbackType> callback_;
std::vector<Task*> run_when_done_;
DISALLOW_COPY_AND_ASSIGN(CleanupCallback);
};
} // namespace media
#endif // MEDIA_BASE_CALLBACK_
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