Martin Michelsen
43 lines
1.2 KiB
C++
43 lines
1.2 KiB
C++
#pragma once
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#include <event2/event.h>
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#include <condition_variable>
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#include <functional>
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#include <memory>
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#include <mutex>
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#include <optional>
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#include <stdexcept>
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// Calls a function on the given base's event thread. This function returns
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// when the call has been enqueued, not necessarily after it returns.
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void forward_to_event_thread(std::shared_ptr<struct event_base> base, std::function<void()>&& fn);
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// Calls a function on the given base's event thread and waits for it to
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// return. Returns the value returned on that thread.
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template <typename T>
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T call_on_event_thread(std::shared_ptr<struct event_base> base, std::function<T()>&& compute) {
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std::optional<T> ret;
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std::string exc_what;
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std::mutex ret_lock;
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std::condition_variable ret_cv;
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std::unique_lock<std::mutex> g(ret_lock);
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forward_to_event_thread(base, [&]() -> void {
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std::lock_guard<std::mutex> g(ret_lock);
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try {
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ret = compute();
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} catch (const std::exception& e) {
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exc_what = e.what();
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}
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ret_cv.notify_one();
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});
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ret_cv.wait(g);
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if (!ret.has_value()) {
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throw std::runtime_error(exc_what);
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}
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return ret.value();
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}
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template <>
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void call_on_event_thread<void>(std::shared_ptr<struct event_base> base, std::function<void()>&& compute);
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