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<?php
namespace Amp;
use Amp\Loop\Driver;
use Amp\Loop\DriverFactory;
use Amp\Loop\InvalidWatcherError;
use Amp\Loop\UnsupportedFeatureException;
use Amp\Loop\Watcher;
/**
* Accessor to allow global access to the event loop.
*
* @see \Amp\Loop\Driver
*/
final class Loop
{
/**
* @var Driver
*/
private static $driver;
/**
* Disable construction as this is a static class.
*/
private function __construct()
{
// intentionally left blank
}
/**
* Sets the driver to be used for `Loop::run()`.
*
* @param Driver $driver
*/
public static function set(Driver $driver)
{
try {
self::$driver = new class extends Driver {
protected function activate(array $watchers)
{
throw new \Error("Can't activate watcher during garbage collection.");
}
protected function dispatch(bool $blocking)
{
throw new \Error("Can't dispatch during garbage collection.");
}
protected function deactivate(Watcher $watcher)
{
// do nothing
}
public function getHandle()
{
return null;
}
};
\gc_collect_cycles();
} finally {
self::$driver = $driver;
}
}
/**
* Run the event loop and optionally execute a callback within the scope of it.
*
* The loop MUST continue to run until it is either stopped explicitly, no referenced watchers exist anymore, or an
* exception is thrown that cannot be handled. Exceptions that cannot be handled are exceptions thrown from an
* error handler or exceptions that would be passed to an error handler but none exists to handle them.
*
* @param callable|null $callback The callback to execute.
*
* @return void
*/
public static function run(callable $callback = null)
{
if ($callback) {
self::$driver->defer($callback);
}
self::$driver->run();
}
/**
* Stop the event loop.
*
* When an event loop is stopped, it continues with its current tick and exits the loop afterwards. Multiple calls
* to stop MUST be ignored and MUST NOT raise an exception.
*
* @return void
*/
public static function stop()
{
self::$driver->stop();
}
/**
* Defer the execution of a callback.
*
* The deferred callable MUST be executed before any other type of watcher in a tick. Order of enabling MUST be
* preserved when executing the callbacks.
*
* The created watcher MUST immediately be marked as enabled, but only be activated (i.e. callback can be called)
* right before the next tick. Callbacks of watchers MUST NOT be called in the tick they were enabled.
*
* @param callable(string $watcherId, mixed $data) $callback The callback to defer. The `$watcherId` will be
* invalidated before the callback call.
* @param mixed $data Arbitrary data given to the callback function as the `$data` parameter.
*
* @return string An unique identifier that can be used to cancel, enable or disable the watcher.
*/
public static function defer(callable $callback, $data = null): string
{
return self::$driver->defer($callback, $data);
}
/**
* Delay the execution of a callback.
*
* The delay is a minimum and approximate, accuracy is not guaranteed. Order of calls MUST be determined by which
* timers expire first, but timers with the same expiration time MAY be executed in any order.
*
* The created watcher MUST immediately be marked as enabled, but only be activated (i.e. callback can be called)
* right before the next tick. Callbacks of watchers MUST NOT be called in the tick they were enabled.
*
* @param int $delay The amount of time, in milliseconds, to delay the execution for.
* @param callable(string $watcherId, mixed $data) $callback The callback to delay. The `$watcherId` will be
* invalidated before the callback call.
* @param mixed $data Arbitrary data given to the callback function as the `$data` parameter.
*
* @return string An unique identifier that can be used to cancel, enable or disable the watcher.
*/
public static function delay(int $delay, callable $callback, $data = null): string
{
return self::$driver->delay($delay, $callback, $data);
}
/**
* Repeatedly execute a callback.
*
* The interval between executions is a minimum and approximate, accuracy is not guaranteed. Order of calls MUST be
* determined by which timers expire first, but timers with the same expiration time MAY be executed in any order.
* The first execution is scheduled after the first interval period.
*
* The created watcher MUST immediately be marked as enabled, but only be activated (i.e. callback can be called)
* right before the next tick. Callbacks of watchers MUST NOT be called in the tick they were enabled.
*
* @param int $interval The time interval, in milliseconds, to wait between executions.
* @param callable(string $watcherId, mixed $data) $callback The callback to repeat.
* @param mixed $data Arbitrary data given to the callback function as the `$data` parameter.
*
* @return string An unique identifier that can be used to cancel, enable or disable the watcher.
*/
public static function repeat(int $interval, callable $callback, $data = null): string
{
return self::$driver->repeat($interval, $callback, $data);
}
/**
* Execute a callback when a stream resource becomes readable or is closed for reading.
*
* Warning: Closing resources locally, e.g. with `fclose`, might not invoke the callback. Be sure to `cancel` the
* watcher when closing the resource locally. Drivers MAY choose to notify the user if there are watchers on invalid
* resources, but are not required to, due to the high performance impact. Watchers on closed resources are
* therefore undefined behavior.
*
* Multiple watchers on the same stream MAY be executed in any order.
*
* The created watcher MUST immediately be marked as enabled, but only be activated (i.e. callback can be called)
* right before the next tick. Callbacks of watchers MUST NOT be called in the tick they were enabled.
*
* @param resource $stream The stream to monitor.
* @param callable(string $watcherId, resource $stream, mixed $data) $callback The callback to execute.
* @param mixed $data Arbitrary data given to the callback function as the `$data` parameter.
*
* @return string An unique identifier that can be used to cancel, enable or disable the watcher.
*/
public static function onReadable($stream, callable $callback, $data = null): string
{
return self::$driver->onReadable($stream, $callback, $data);
}
/**
* Execute a callback when a stream resource becomes writable or is closed for writing.
*
* Warning: Closing resources locally, e.g. with `fclose`, might not invoke the callback. Be sure to `cancel` the
* watcher when closing the resource locally. Drivers MAY choose to notify the user if there are watchers on invalid
* resources, but are not required to, due to the high performance impact. Watchers on closed resources are
* therefore undefined behavior.
*
* Multiple watchers on the same stream MAY be executed in any order.
*
* The created watcher MUST immediately be marked as enabled, but only be activated (i.e. callback can be called)
* right before the next tick. Callbacks of watchers MUST NOT be called in the tick they were enabled.
*
* @param resource $stream The stream to monitor.
* @param callable(string $watcherId, resource $stream, mixed $data) $callback The callback to execute.
* @param mixed $data Arbitrary data given to the callback function as the `$data` parameter.
*
* @return string An unique identifier that can be used to cancel, enable or disable the watcher.
*/
public static function onWritable($stream, callable $callback, $data = null): string
{
return self::$driver->onWritable($stream, $callback, $data);
}
/**
* Execute a callback when a signal is received.
*
* Warning: Installing the same signal on different instances of this interface is deemed undefined behavior.
* Implementations MAY try to detect this, if possible, but are not required to. This is due to technical
* limitations of the signals being registered globally per process.
*
* Multiple watchers on the same signal MAY be executed in any order.
*
* The created watcher MUST immediately be marked as enabled, but only be activated (i.e. callback can be called)
* right before the next tick. Callbacks of watchers MUST NOT be called in the tick they were enabled.
*
* @param int $signo The signal number to monitor.
* @param callable(string $watcherId, int $signo, mixed $data) $callback The callback to execute.
* @param mixed $data Arbitrary data given to the callback function as the $data parameter.
*
* @return string An unique identifier that can be used to cancel, enable or disable the watcher.
*
* @throws UnsupportedFeatureException If signal handling is not supported.
*/
public static function onSignal(int $signo, callable $callback, $data = null): string
{
return self::$driver->onSignal($signo, $callback, $data);
}
/**
* Enable a watcher to be active starting in the next tick.
*
* Watchers MUST immediately be marked as enabled, but only be activated (i.e. callbacks can be called) right before
* the next tick. Callbacks of watchers MUST NOT be called in the tick they were enabled.
*
* @param string $watcherId The watcher identifier.
*
* @return void
*
* @throws InvalidWatcherError If the watcher identifier is invalid.
*/
public static function enable(string $watcherId)
{
self::$driver->enable($watcherId);
}
/**
* Disable a watcher immediately.
*
* A watcher MUST be disabled immediately, e.g. if a defer watcher disables a later defer watcher, the second defer
* watcher isn't executed in this tick.
*
* Disabling a watcher MUST NOT invalidate the watcher. Calling this function MUST NOT fail, even if passed an
* invalid watcher.
*
* @param string $watcherId The watcher identifier.
*
* @return void
*/
public static function disable(string $watcherId)
{
if (\PHP_VERSION_ID < 70200 && !isset(self::$driver)) {
// Prior to PHP 7.2, self::$driver may be unset during destruct.
// See https://github.com/amphp/amp/issues/212.
return;
}
self::$driver->disable($watcherId);
}
/**
* Cancel a watcher.
*
* This will detatch the event loop from all resources that are associated to the watcher. After this operation the
* watcher is permanently invalid. Calling this function MUST NOT fail, even if passed an invalid watcher.
*
* @param string $watcherId The watcher identifier.
*
* @return void
*/
public static function cancel(string $watcherId)
{
if (\PHP_VERSION_ID < 70200 && !isset(self::$driver)) {
// Prior to PHP 7.2, self::$driver may be unset during destruct.
// See https://github.com/amphp/amp/issues/212.
return;
}
self::$driver->cancel($watcherId);
}
/**
* Reference a watcher.
*
* This will keep the event loop alive whilst the watcher is still being monitored. Watchers have this state by
* default.
*
* @param string $watcherId The watcher identifier.
*
* @return void
*
* @throws InvalidWatcherError If the watcher identifier is invalid.
*/
public static function reference(string $watcherId)
{
self::$driver->reference($watcherId);
}
/**
* Unreference a watcher.
*
* The event loop should exit the run method when only unreferenced watchers are still being monitored. Watchers
* are all referenced by default.
*
* @param string $watcherId The watcher identifier.
*
* @return void
*/
public static function unreference(string $watcherId)
{
if (\PHP_VERSION_ID < 70200 && !isset(self::$driver)) {
// Prior to PHP 7.2, self::$driver may be unset during destruct.
// See https://github.com/amphp/amp/issues/212.
return;
}
self::$driver->unreference($watcherId);
}
/**
* Returns the current loop time in millisecond increments. Note this value does not necessarily correlate to
* wall-clock time, rather the value returned is meant to be used in relative comparisons to prior values returned
* by this method (intervals, expiration calculations, etc.) and is only updated once per loop tick.
*
* @return int
*/
public static function now(): int
{
return self::$driver->now();
}
/**
* Stores information in the loop bound registry.
*
* Stored information is package private. Packages MUST NOT retrieve the stored state of other packages. Packages
* MUST use their namespace as prefix for keys. They may do so by using `SomeClass::class` as key.
*
* If packages want to expose loop bound state to consumers other than the package, they SHOULD provide a dedicated
* interface for that purpose instead of sharing the storage key.
*
* @param string $key The namespaced storage key.
* @param mixed $value The value to be stored.
*
* @return void
*/
public static function setState(string $key, $value)
{
self::$driver->setState($key, $value);
}
/**
* Gets information stored bound to the loop.
*
* Stored information is package private. Packages MUST NOT retrieve the stored state of other packages. Packages
* MUST use their namespace as prefix for keys. They may do so by using `SomeClass::class` as key.
*
* If packages want to expose loop bound state to consumers other than the package, they SHOULD provide a dedicated
* interface for that purpose instead of sharing the storage key.
*
* @param string $key The namespaced storage key.
*
* @return mixed The previously stored value or `null` if it doesn't exist.
*/
public static function getState(string $key)
{
return self::$driver->getState($key);
}
/**
* Set a callback to be executed when an error occurs.
*
* The callback receives the error as the first and only parameter. The return value of the callback gets ignored.
* If it can't handle the error, it MUST throw the error. Errors thrown by the callback or during its invocation
* MUST be thrown into the `run` loop and stop the driver.
*
* Subsequent calls to this method will overwrite the previous handler.
*
* @param callable(\Throwable $error)|null $callback The callback to execute. `null` will clear the
* current handler.
*
* @return callable(\Throwable $error)|null The previous handler, `null` if there was none.
*/
public static function setErrorHandler(callable $callback = null)
{
return self::$driver->setErrorHandler($callback);
}
/**
* Retrieve an associative array of information about the event loop driver.
*
* The returned array MUST contain the following data describing the driver's currently registered watchers:
*
* [
* "defer" => ["enabled" => int, "disabled" => int],
* "delay" => ["enabled" => int, "disabled" => int],
* "repeat" => ["enabled" => int, "disabled" => int],
* "on_readable" => ["enabled" => int, "disabled" => int],
* "on_writable" => ["enabled" => int, "disabled" => int],
* "on_signal" => ["enabled" => int, "disabled" => int],
* "enabled_watchers" => ["referenced" => int, "unreferenced" => int],
* "running" => bool
* ];
*
* Implementations MAY optionally add more information in the array but at minimum the above `key => value` format
* MUST always be provided.
*
* @return array Statistics about the loop in the described format.
*/
public static function getInfo(): array
{
return self::$driver->getInfo();
}
/**
* Retrieve the event loop driver that is in scope.
*
* @return Driver
*/
public static function get(): Driver
{
return self::$driver;
}
}
// Default factory, don't move this to a file loaded by the composer "files" autoload mechanism, otherwise custom
// implementations might have issues setting a default loop, because it's overridden by us then.
// @codeCoverageIgnoreStart
Loop::set((new DriverFactory)->create());
// @codeCoverageIgnoreEnd