/usr/include/kj/async-unix.h is in libcapnp-dev 0.4.0-1ubuntu2.
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// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this
// list of conditions and the following disclaimer.
// 2. 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.
//
// 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.
#ifndef KJ_ASYNC_UNIX_H_
#define KJ_ASYNC_UNIX_H_
#include "async.h"
#include "vector.h"
#include <signal.h>
#include <poll.h>
#include <pthread.h>
namespace kj {
class UnixEventPort: public EventPort {
// THIS INTERFACE IS LIKELY TO CHANGE; consider using only what is defined in async-io.h instead.
//
// An EventPort implementation which can wait for events on file descriptors as well as signals.
// This API only makes sense on Unix.
//
// The implementation uses `poll()` or possibly a platform-specific API (e.g. epoll, kqueue).
// To also wait on signals without race conditions, the implementation may block signals until
// just before `poll()` while using a signal handler which `siglongjmp()`s back to just before
// the signal was unblocked, or it may use a nicer platform-specific API like signalfd.
//
// The implementation reserves a signal for internal use. By default, it uses SIGUSR1. If you
// need to use SIGUSR1 for something else, you must offer a different signal by calling
// setReservedSignal() at startup.
public:
UnixEventPort();
~UnixEventPort();
Promise<short> onFdEvent(int fd, short eventMask);
// `eventMask` is a bitwise-OR of poll events (e.g. `POLLIN`, `POLLOUT`, etc.). The next time
// one or more of the given events occurs on `fd`, the set of events that occurred are returned.
Promise<siginfo_t> onSignal(int signum);
// When the given signal is delivered to this thread, return the corresponding siginfo_t.
// The signal must have been captured using `captureSignal()`.
//
// If `onSignal()` has not been called, the signal will remain blocked in this thread.
// Therefore, a signal which arrives before `onSignal()` was called will not be "missed" -- the
// next call to 'onSignal()' will receive it. Also, you can control which thread receives a
// process-wide signal by only calling `onSignal()` on that thread's event loop.
//
// The result of waiting on the same signal twice at once is undefined.
static void captureSignal(int signum);
// Arranges for the given signal to be captured and handled via UnixEventPort, so that you may
// then pass it to `onSignal()`. This method is static because it registers a signal handler
// which applies process-wide. If any other threads exist in the process when `captureSignal()`
// is called, you *must* set the signal mask in those threads to block this signal, otherwise
// terrible things will happen if the signal happens to be delivered to those threads. If at
// all possible, call `captureSignal()` *before* creating threads, so that threads you create in
// the future will inherit the proper signal mask.
//
// To un-capture a signal, simply install a different signal handler and then un-block it from
// the signal mask.
static void setReservedSignal(int signum);
// Sets the signal number which `UnixEventPort` reserves for internal use. If your application
// needs to use SIGUSR1, call this at startup (before any calls to `captureSignal()` and before
// constructing an `UnixEventPort`) to offer a different signal.
// implements EventPort ------------------------------------------------------
void wait() override;
void poll() override;
private:
class PollPromiseAdapter;
class SignalPromiseAdapter;
class PollContext;
PollPromiseAdapter* pollHead = nullptr;
PollPromiseAdapter** pollTail = &pollHead;
SignalPromiseAdapter* signalHead = nullptr;
SignalPromiseAdapter** signalTail = &signalHead;
void gotSignal(const siginfo_t& siginfo);
};
} // namespace kj
#endif // KJ_ASYNC_UNIX_H_
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