71 lines
1.6 KiB
C++
71 lines
1.6 KiB
C++
// SPDX-License-Identifier: BSD-2-Clause
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// author: Max Kellermann <max.kellermann@gmail.com>
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#pragma once
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#include "util/BindMethod.hxx"
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#include "util/IntrusiveList.hxx"
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class EventLoop;
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/**
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* Defer execution until the next event loop iteration. Use this to
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* move calls out of the current stack frame, to avoid surprising side
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* effects for callers up in the call chain.
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*
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* This class is not thread-safe, all methods must be called from the
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* thread that runs the #EventLoop.
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*/
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class DeferEvent final : AutoUnlinkIntrusiveListHook
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{
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friend class EventLoop;
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friend struct IntrusiveListBaseHookTraits<DeferEvent>;
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EventLoop &loop;
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using Callback = BoundMethod<void() noexcept>;
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const Callback callback;
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public:
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DeferEvent(EventLoop &_loop, Callback _callback) noexcept
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:loop(_loop), callback(_callback) {}
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DeferEvent(const DeferEvent &) = delete;
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DeferEvent &operator=(const DeferEvent &) = delete;
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auto &GetEventLoop() const noexcept {
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return loop;
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}
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bool IsPending() const noexcept {
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return is_linked();
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}
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void Schedule() noexcept;
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/**
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* Schedule this event, but only after the #EventLoop is idle,
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* i.e. before going to sleep.
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*/
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void ScheduleIdle() noexcept;
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/**
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* Schedule this event, but only after the next #EventLoop
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* iteration (i.e. after the epoll_wait() call, after handling
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* all pending I/O events). This is useful for repeated I/O
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* operations that should not occupy the whole #EventLoop,
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* starving all other I/O events.
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*/
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void ScheduleNext() noexcept;
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void Cancel() noexcept {
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if (IsPending())
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unlink();
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}
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private:
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void Run() noexcept {
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callback();
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}
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};
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