ladybird/Userland/Libraries/LibThreading/BackgroundAction.h
Lucas CHOLLET 2693745336 LibThreading+Everywhere: Support returning error from BackgroundAction
This patch allows returning an `Error` from the `on_complete` callback
in `BackgroundAction`.

It also adds a custom callback to manage errors returned during its
execution.
2022-12-15 17:36:57 +00:00

89 lines
2.3 KiB
C++

/*
* Copyright (c) 2019-2020, Sergey Bugaev <bugaevc@serenityos.org>
* Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2022, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Function.h>
#include <AK/NonnullRefPtr.h>
#include <AK/Optional.h>
#include <AK/Queue.h>
#include <LibCore/Event.h>
#include <LibCore/EventLoop.h>
#include <LibCore/Object.h>
#include <LibThreading/Thread.h>
namespace Threading {
template<typename Result>
class BackgroundAction;
class BackgroundActionBase {
template<typename Result>
friend class BackgroundAction;
private:
BackgroundActionBase() = default;
static void enqueue_work(Function<void()>);
static Thread& background_thread();
};
template<typename Result>
class BackgroundAction final : public Core::Object
, private BackgroundActionBase {
C_OBJECT(BackgroundAction);
public:
void cancel()
{
m_cancelled = true;
}
bool is_cancelled() const
{
return m_cancelled;
}
virtual ~BackgroundAction() = default;
private:
BackgroundAction(Function<Result(BackgroundAction&)> action, Function<ErrorOr<void>(Result)> on_complete, Optional<Function<void(Error)>> on_error = {})
: Core::Object(&background_thread())
, m_action(move(action))
, m_on_complete(move(on_complete))
{
if (on_error.has_value())
m_on_error = on_error.release_value();
enqueue_work([this, origin_event_loop = &Core::EventLoop::current()] {
m_result = m_action(*this);
if (m_on_complete) {
origin_event_loop->deferred_invoke([this] {
auto maybe_error = m_on_complete(m_result.release_value());
if (maybe_error.is_error())
m_on_error(maybe_error.release_error());
remove_from_parent();
});
origin_event_loop->wake();
} else {
this->remove_from_parent();
}
});
}
bool m_cancelled { false };
Function<Result(BackgroundAction&)> m_action;
Function<ErrorOr<void>(Result)> m_on_complete;
Function<void(Error)> m_on_error = [](Error error) {
dbgln("Error occurred while running a BackgroundAction: {}", error);
};
Optional<Result> m_result;
};
}