mirror of
https://github.com/danog/parallel.git
synced 2024-12-02 17:52:14 +01:00
291 lines
8.5 KiB
PHP
291 lines
8.5 KiB
PHP
<?php
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namespace Amp\Parallel\Context;
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use Amp\Loop;
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use Amp\Parallel\Sync\ChannelException;
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use Amp\Parallel\Sync\ChannelledSocket;
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use Amp\Parallel\Sync\ExitResult;
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use Amp\Parallel\Sync\SynchronizationError;
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use Amp\Promise;
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use function Amp\call;
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/**
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* Implements an execution context using native multi-threading.
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*
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* The thread context is not itself threaded. A local instance of the context is
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* maintained both in the context that creates the thread and in the thread
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* itself.
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*/
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class Thread implements Context {
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const EXIT_CHECK_FREQUENCY = 250;
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/** @var Internal\Thread An internal thread instance. */
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private $thread;
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/** @var \Amp\Parallel\Sync\ChannelledSocket A channel for communicating with the thread. */
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private $channel;
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/** @var resource */
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private $socket;
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/** @var callable */
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private $function;
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/** @var mixed[] */
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private $args;
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/** @var int */
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private $oid = 0;
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/** @var string */
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private $watcher;
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/**
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* Checks if threading is enabled.
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*
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* @return bool True if threading is enabled, otherwise false.
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*/
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public static function supported(): bool {
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return \extension_loaded('pthreads');
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}
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/**
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* Creates and starts a new thread.
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*
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* @param callable $function The callable to invoke in the thread. First argument is an instance of
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* \Amp\Parallel\Sync\Channel.
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* @param mixed ...$args Additional arguments to pass to the given callable.
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*
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* @return Thread The thread object that was spawned.
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*/
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public static function run(callable $function, ...$args): self {
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$thread = new self($function, ...$args);
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$thread->start();
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return $thread;
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}
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/**
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* Creates a new thread.
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*
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* @param callable $function The callable to invoke in the thread. First argument is an instance of
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* \Amp\Parallel\Sync\Channel.
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* @param mixed ...$args Additional arguments to pass to the given callable.
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*
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* @throws \Error Thrown if the pthreads extension is not available.
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*/
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public function __construct(callable $function, ...$args) {
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if (!self::supported()) {
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throw new \Error("The pthreads extension is required to create threads.");
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}
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$this->function = $function;
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$this->args = $args;
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}
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/**
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* Returns the thread to the condition before starting. The new thread can be started and run independently of the
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* first thread.
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*/
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public function __clone() {
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$this->thread = null;
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$this->socket = null;
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$this->channel = null;
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$this->oid = 0;
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}
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/**
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* Kills the thread if it is still running.
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*
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* @throws \Amp\Parallel\Context\ContextException
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*/
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public function __destruct() {
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if (\getmypid() === $this->oid) {
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$this->kill();
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}
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}
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/**
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* Checks if the context is running.
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*
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* @return bool True if the context is running, otherwise false.
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*/
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public function isRunning(): bool {
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return $this->channel !== null;
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}
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/**
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* Spawns the thread and begins the thread's execution.
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*
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* @throws \Amp\Parallel\Context\StatusError If the thread has already been started.
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* @throws \Amp\Parallel\Context\ContextException If starting the thread was unsuccessful.
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*/
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public function start() {
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if ($this->oid !== 0) {
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throw new StatusError('The thread has already been started.');
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}
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$this->oid = \getmypid();
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$sockets = @\stream_socket_pair(
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\stripos(\PHP_OS, "win") === 0 ? STREAM_PF_INET : STREAM_PF_UNIX,
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STREAM_SOCK_STREAM,
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STREAM_IPPROTO_IP
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);
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if ($sockets === false) {
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$message = "Failed to create socket pair";
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if ($error = \error_get_last()) {
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$message .= \sprintf(" Errno: %d; %s", $error["type"], $error["message"]);
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}
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throw new ContextException($message);
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}
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list($channel, $this->socket) = $sockets;
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$thread = $this->thread = new Internal\Thread($this->socket, $this->function, $this->args);
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if (!$this->thread->start(\PTHREADS_INHERIT_INI)) {
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throw new ContextException('Failed to start the thread.');
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}
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$channel = $this->channel = new ChannelledSocket($channel, $channel);
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$this->watcher = Loop::repeat(self::EXIT_CHECK_FREQUENCY, static function ($watcher) use ($thread, $channel) {
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if (!$thread->isRunning()) {
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// Delay closing to avoid race condition between thread exiting and data becoming available.
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Loop::delay(self::EXIT_CHECK_FREQUENCY, [$channel, "close"]);
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Loop::cancel($watcher);
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}
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});
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Loop::disable($this->watcher);
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}
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/**
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* Immediately kills the context.
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*
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* @throws ContextException If killing the thread was unsuccessful.
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*/
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public function kill() {
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if ($this->thread !== null) {
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try {
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if ($this->thread->isRunning() && !$this->thread->kill()) {
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throw new ContextException('Could not kill thread.');
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}
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} finally {
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$this->close();
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}
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}
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}
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/**
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* Closes channel and socket if still open.
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*/
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private function close() {
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if ($this->channel !== null) {
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$this->channel->close();
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}
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$this->channel = null;
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Loop::cancel($this->watcher);
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}
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/**
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* Gets a promise that resolves when the context ends and joins with the
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* parent context.
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*
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* @return \Amp\Promise<mixed>
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*
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* @throws StatusError Thrown if the context has not been started.
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* @throws SynchronizationError Thrown if an exit status object is not received.
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* @throws ContextException If the context stops responding.
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*/
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public function join(): Promise {
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if ($this->channel == null || $this->thread === null) {
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throw new StatusError('The thread has not been started or has already finished.');
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}
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return call(function () {
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Loop::enable($this->watcher);
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try {
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$response = yield $this->channel->receive();
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if (!$response instanceof ExitResult) {
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throw new SynchronizationError('Did not receive an exit result from thread.');
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}
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} catch (ChannelException $exception) {
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$this->kill();
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throw new ContextException(
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"The context stopped responding, potentially due to a fatal error or calling exit",
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0,
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$exception
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);
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} catch (\Throwable $exception) {
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$this->kill();
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throw $exception;
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} finally {
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Loop::disable($this->watcher);
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$this->close();
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}
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return $response->getResult();
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});
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}
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/**
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* {@inheritdoc}
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*/
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public function receive(): Promise {
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if ($this->channel === null) {
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throw new StatusError('The process has not been started.');
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}
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return call(function () {
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Loop::enable($this->watcher);
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try {
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$data = yield $this->channel->receive();
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} finally {
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Loop::disable($this->watcher);
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}
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if ($data instanceof ExitResult) {
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$data = $data->getResult();
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throw new SynchronizationError(\sprintf(
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'Thread process unexpectedly exited with result of type: %s',
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\is_object($data) ? \get_class($data) : \gettype($data)
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));
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}
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return $data;
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});
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}
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/**
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* {@inheritdoc}
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*/
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public function send($data): Promise {
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if ($this->channel === null) {
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throw new StatusError('The thread has not been started or has already finished.');
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}
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if ($data instanceof ExitResult) {
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throw new \Error('Cannot send exit result objects.');
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}
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return call(function () use ($data) {
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Loop::enable($this->watcher);
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try {
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$result = yield $this->channel->send($data);
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} finally {
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Loop::disable($this->watcher);
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}
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return $result;
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});
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}
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}
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