<?php
namespace React\EventLoop;
interface LoopInterface
{
/**
* [Advanced] Register a listener to be notified when a stream is ready to read.
*
* Note that this low-level API is considered advanced usage.
* Most use cases should probably use the higher-level
* [readable Stream API](https://github.com/reactphp/stream#readablestreaminterface)
* instead.
*
* The first parameter MUST be a valid stream resource that supports
* checking whether it is ready to read by this loop implementation.
* A single stream resource MUST NOT be added more than once.
* Instead, either call [`removeReadStream()`](#removereadstream) first or
* react to this event with a single listener and then dispatch from this
* listener. This method MAY throw an `Exception` if the given resource type
* is not supported by this loop implementation.
*
* The listener callback function MUST be able to accept a single parameter,
* the stream resource added by this method or you MAY use a function which
* has no parameters at all.
*
* The listener callback function MUST NOT throw an `Exception`.
* The return value of the listener callback function will be ignored and has
* no effect, so for performance reasons you're recommended to not return
* any excessive data structures.
*
* If you want to access any variables within your callback function, you
* can bind arbitrary data to a callback closure like this:
*
* ```php
* $loop->addReadStream($stream, function ($stream) use ($name) {
* echo $name . ' said: ' . fread($stream);
* });
* ```
*
* See also [example #11](examples).
*
* You can invoke [`removeReadStream()`](#removereadstream) to remove the
* read event listener for this stream.
*
* The execution order of listeners when multiple streams become ready at
* the same time is not guaranteed.
*
* @param resource $stream The PHP stream resource to check.
* @param callable $listener Invoked when the stream is ready.
* @throws \Exception if the given resource type is not supported by this loop implementation
* @see self::removeReadStream()
*/
public function addReadStream($stream, $listener);
/**
* [Advanced] Register a listener to be notified when a stream is ready to write.
*
* Note that this low-level API is considered advanced usage.
* Most use cases should probably use the higher-level
* [writable Stream API](https://github.com/reactphp/stream#writablestreaminterface)
* instead.
*
* The first parameter MUST be a valid stream resource that supports
* checking whether it is ready to write by this loop implementation.
* A single stream resource MUST NOT be added more than once.
* Instead, either call [`removeWriteStream()`](#removewritestream) first or
* react to this event with a single listener and then dispatch from this
* listener. This method MAY throw an `Exception` if the given resource type
* is not supported by this loop implementation.
*
* The listener callback function MUST be able to accept a single parameter,
* the stream resource added by this method or you MAY use a function which
* has no parameters at all.
*
* The listener callback function MUST NOT throw an `Exception`.
* The return value of the listener callback function will be ignored and has
* no effect, so for performance reasons you're recommended to not return
* any excessive data structures.
*
* If you want to access any variables within your callback function, you
* can bind arbitrary data to a callback closure like this:
*
* ```php
* $loop->addWriteStream($stream, function ($stream) use ($name) {
* fwrite($stream, 'Hello ' . $name);
* });
* ```
*
* See also [example #12](examples).
*
* You can invoke [`removeWriteStream()`](#removewritestream) to remove the
* write event listener for this stream.
*
* The execution order of listeners when multiple streams become ready at
* the same time is not guaranteed.
*
* Some event loop implementations are known to only trigger the listener if
* the stream *becomes* readable (edge-triggered) and may not trigger if the
* stream has already been readable from the beginning.
* This also implies that a stream may not be recognized as readable when data
* is still left in PHP's internal stream buffers.
* As such, it's recommended to use `stream_set_read_buffer($stream, 0);`
* to disable PHP's internal read buffer in this case.
*
* @param resource $stream The PHP stream resource to check.
* @param callable $listener Invoked when the stream is ready.
* @throws \Exception if the given resource type is not supported by this loop implementation
* @see self::removeWriteStream()
*/
public function addWriteStream($stream, $listener);
/**
* Remove the read event listener for the given stream.
*
* Removing a stream from the loop that has already been removed or trying
* to remove a stream that was never added or is invalid has no effect.
*
* @param resource $stream The PHP stream resource.
*/
public function removeReadStream($stream);
/**
* Remove the write event listener for the given stream.
*
* Removing a stream from the loop that has already been removed or trying
* to remove a stream that was never added or is invalid has no effect.
*
* @param resource $stream The PHP stream resource.
*/
public function removeWriteStream($stream);
/**
* Enqueue a callback to be invoked once after the given interval.
*
* The timer callback function MUST be able to accept a single parameter,
* the timer instance as also returned by this method or you MAY use a
* function which has no parameters at all.
*
* The timer callback function MUST NOT throw an `Exception`.
* The return value of the timer callback function will be ignored and has
* no effect, so for performance reasons you're recommended to not return
* any excessive data structures.
*
* Unlike [`addPeriodicTimer()`](#addperiodictimer), this method will ensure
* the callback will be invoked only once after the given interval.
* You can invoke [`cancelTimer`](#canceltimer) to cancel a pending timer.
*
* ```php
* $loop->addTimer(0.8, function () {
* echo 'world!' . PHP_EOL;
* });
*
* $loop->addTimer(0.3, function () {
* echo 'hello ';
* });
* ```
*
* See also [example #1](examples).
*
* If you want to access any variables within your callback function, you
* can bind arbitrary data to a callback closure like this:
*
* ```php
* function hello($name, LoopInterface $loop)
* {
* $loop->addTimer(1.0, function () use ($name) {
* echo "hello $name\n";
* });
* }
*
* hello('Tester', $loop);
* ```
*
* This interface does not enforce any particular timer resolution, so
* special care may have to be taken if you rely on very high precision with
* millisecond accuracy or below. Event loop implementations SHOULD work on
* a best effort basis and SHOULD provide at least millisecond accuracy
* unless otherwise noted. Many existing event loop implementations are
* known to provide microsecond accuracy, but it's generally not recommended
* to rely on this high precision.
*
* Similarly, the execution order of timers scheduled to execute at the
* same time (within its possible accuracy) is not guaranteed.
*
* This interface suggests that event loop implementations SHOULD use a
* monotonic time source if available. Given that a monotonic time source is
* only available as of PHP 7.3 by default, event loop implementations MAY
* fall back to using wall-clock time.
* While this does not affect many common use cases, this is an important
* distinction for programs that rely on a high time precision or on systems
* that are subject to discontinuous time adjustments (time jumps).
* This means that if you schedule a timer to trigger in 30s and then adjust
* your system time forward by 20s, the timer SHOULD still trigger in 30s.
* See also [event loop implementations](#loop-implementations) for more details.
*
* @param int|float $interval The number of seconds to wait before execution.
* @param callable $callback The callback to invoke.
*
* @return TimerInterface
*/
public function addTimer($interval, $callback);
/**
* Enqueue a callback to be invoked repeatedly after the given interval.
*
* The timer callback function MUST be able to accept a single parameter,
* the timer instance as also returned by this method or you MAY use a
* function which has no parameters at all.
*
* The timer callback function MUST NOT throw an `Exception`.
* The return value of the timer callback function will be ignored and has
* no effect, so for performance reasons you're recommended to not return
* any excessive data structures.
*
* Unlike [`addTimer()`](#addtimer), this method will ensure the the
* callback will be invoked infinitely after the given interval or until you
* invoke [`cancelTimer`](#canceltimer).
*
* ```php
* $timer = $loop->addPeriodicTimer(0.1, function () {
* echo 'tick!' . PHP_EOL;
* });
*
* $loop->addTimer(1.0, function () use ($loop, $timer) {
* $loop->cancelTimer($timer);
* echo 'Done' . PHP_EOL;
* });
* ```
*
* See also [example #2](examples).
*
* If you want to limit the number of executions, you can bind
* arbitrary data to a callback closure like this:
*
* ```php
* function hello($name, LoopInterface $loop)
* {
* $n = 3;
* $loop->addPeriodicTimer(1.0, function ($timer) use ($name, $loop, &$n) {
* if ($n > 0) {
* --$n;
* echo "hello $name\n";
* } else {
* $loop->cancelTimer($timer);
* }
* });
* }
*
* hello('Tester', $loop);
* ```
*
* This interface does not enforce any particular timer resolution, so
* special care may have to be taken if you rely on very high precision with
* millisecond accuracy or below. Event loop implementations SHOULD work on
* a best effort basis and SHOULD provide at least millisecond accuracy
* unless otherwise noted. Many existing event loop implementations are
* known to provide microsecond accuracy, but it's generally not recommended
* to rely on this high precision.
*
* Similarly, the execution order of timers scheduled to execute at the
* same time (within its possible accuracy) is not guaranteed.
*
* This interface suggests that event loop implementations SHOULD use a
* monotonic time source if available. Given that a monotonic time source is
* only available as of PHP 7.3 by default, event loop implementations MAY
* fall back to using wall-clock time.
* While this does not affect many common use cases, this is an important
* distinction for programs that rely on a high time precision or on systems
* that are subject to discontinuous time adjustments (time jumps).
* This means that if you schedule a timer to trigger in 30s and then adjust
* your system time forward by 20s, the timer SHOULD still trigger in 30s.
* See also [event loop implementations](#loop-implementations) for more details.
*
* Additionally, periodic timers may be subject to timer drift due to
* re-scheduling after each invocation. As such, it's generally not
* recommended to rely on this for high precision intervals with millisecond
* accuracy or below.
*
* @param int|float $interval The number of seconds to wait before execution.
* @param callable $callback The callback to invoke.
*
* @return TimerInterface
*/
public function addPeriodicTimer($interval, $callback);
/**
* Cancel a pending timer.
*
* See also [`addPeriodicTimer()`](#addperiodictimer) and [example #2](examples).
*
* Calling this method on a timer instance that has not been added to this
* loop instance or on a timer that has already been cancelled has no effect.
*
* @param TimerInterface $timer The timer to cancel.
*
* @return void
*/
public function cancelTimer(TimerInterface $timer);
/**
* Schedule a callback to be invoked on a future tick of the event loop.
*
* This works very much similar to timers with an interval of zero seconds,
* but does not require the overhead of scheduling a timer queue.
*
* The tick callback function MUST be able to accept zero parameters.
*
* The tick callback function MUST NOT throw an `Exception`.
* The return value of the tick callback function will be ignored and has
* no effect, so for performance reasons you're recommended to not return
* any excessive data structures.
*
* If you want to access any variables within your callback function, you
* can bind arbitrary data to a callback closure like this:
*
* ```php
* function hello($name, LoopInterface $loop)
* {
* $loop->futureTick(function () use ($name) {
* echo "hello $name\n";
* });
* }
*
* hello('Tester', $loop);
* ```
*
* Unlike timers, tick callbacks are guaranteed to be executed in the order
* they are enqueued.
* Also, once a callback is enqueued, there's no way to cancel this operation.
*
* This is often used to break down bigger tasks into smaller steps (a form
* of cooperative multitasking).
*
* ```php
* $loop->futureTick(function () {
* echo 'b';
* });
* $loop->futureTick(function () {
* echo 'c';
* });
* echo 'a';
* ```
*
* See also [example #3](examples).
*
* @param callable $listener The callback to invoke.
*
* @return void
*/
public function futureTick($listener);
/**
* Register a listener to be notified when a signal has been caught by this process.
*
* This is useful to catch user interrupt signals or shutdown signals from
* tools like `supervisor` or `systemd`.
*
* The listener callback function MUST be able to accept a single parameter,
* the signal added by this method or you MAY use a function which
* has no parameters at all.
*
* The listener callback function MUST NOT throw an `Exception`.
* The return value of the listener callback function will be ignored and has
* no effect, so for performance reasons you're recommended to not return
* any excessive data structures.
*
* ```php
* $loop->addSignal(SIGINT, function (int $signal) {
* echo 'Caught user interrupt signal' . PHP_EOL;
* });
* ```
*
* See also [example #4](examples).
*
* Signaling is only available on Unix-like platform, Windows isn't
* supported due to operating system limitations.
* This method may throw a `BadMethodCallException` if signals aren't
* supported on this platform, for example when required extensions are
* missing.
*
* **Note: A listener can only be added once to the same signal, any
* attempts to add it more then once will be ignored.**
*
* @param int $signal
* @param callable $listener
*
* @throws \BadMethodCallException when signals aren't supported on this
* platform, for example when required extensions are missing.
*
* @return void
*/
public function addSignal($signal, $listener);
/**
* Removes a previously added signal listener.
*
* ```php
* $loop->removeSignal(SIGINT, $listener);
* ```
*
* Any attempts to remove listeners that aren't registered will be ignored.
*
* @param int $signal
* @param callable $listener
*
* @return void
*/
public function removeSignal($signal, $listener);
/**
* Run the event loop until there are no more tasks to perform.
*
* For many applications, this method is the only directly visible
* invocation on the event loop.
* As a rule of thumb, it is usally recommended to attach everything to the
* same loop instance and then run the loop once at the bottom end of the
* application.
*
* ```php
* $loop->run();
* ```
*
* This method will keep the loop running until there are no more tasks
* to perform. In other words: This method will block until the last
* timer, stream and/or signal has been removed.
*
* Likewise, it is imperative to ensure the application actually invokes
* this method once. Adding listeners to the loop and missing to actually
* run it will result in the application exiting without actually waiting
* for any of the attached listeners.
*
* This method MUST NOT be called while the loop is already running.
* This method MAY be called more than once after it has explicity been
* [`stop()`ped](#stop) or after it automatically stopped because it
* previously did no longer have anything to do.
*
* @return void
*/
public function run();
/**
* Instruct a running event loop to stop.
*
* This method is considered advanced usage and should be used with care.
* As a rule of thumb, it is usually recommended to let the loop stop
* only automatically when it no longer has anything to do.
*
* This method can be used to explicitly instruct the event loop to stop:
*
* ```php
* $loop->addTimer(3.0, function () use ($loop) {
* $loop->stop();
* });
* ```
*
* Calling this method on a loop instance that is not currently running or
* on a loop instance that has already been stopped has no effect.
*
* @return void
*/
public function stop();
}