Future.php
4f9915ecac81production

Future.php
View Options

			<?php

			/**
			* A 'future' or 'promise' is an object which represents the result of some
			* pending computation. For a more complete overview of futures, see
			* @{article:Using Futures}.
			*
			* @group futures
			* @stable
			*/
			abstract class Future {

			protected static $handlerInstalled = null;

			protected $result;
			protected $exception;

			/**
			* Is this future's process complete? Specifically, can this future be
			* resolved without blocking?
			*
			* @return bool If true, the external process is complete and resolving this
			* future will not block.
			*/
			abstract public function isReady();

			/**
			* Resolve a future and return its result, blocking until the result is ready
			* if necessary.
			*
			* @param float Optional timeout after which resolution will pause and
			* execution will return to the caller.
			* @return mixed Future result, or null if the timeout is hit.
			*/
			public function resolve($timeout = null) {
			$start = microtime(true);
			$wait = $this->getDefaultWait();
			do {
			$this->checkException();
			if ($this->isReady()) {
			break;
			}

			$read = $this->getReadSockets();
			$write = $this->getWriteSockets();

			if ($timeout !== null) {
			$elapsed = microtime(true) - $start;

			if ($elapsed > $timeout) {
			$this->checkException();
			return null;
			} else {
			$wait = $timeout - $elapsed;
			}
			}

			if ($read \|\| $write) {
			self::waitForSockets($read, $write, $wait);
			}
			} while (true);

			$this->checkException();
			return $this->getResult();
			}

			public function setException(Exception $ex) {
			$this->exception = $ex;
			return $this;
			}

			public function getException() {
			return $this->exception;
			}


			/**
			* If an exception was set by setException(), throw it.
			*/
			private function checkException() {
			if ($this->exception) {
			throw $this->exception;
			}
			}


			/**
			* Retrieve a list of sockets which we can wait to become readable while
			* a future is resolving. If your future has sockets which can be select()ed,
			* return them here (or in getWriteSockets()) to make the resolve loop do a
			* select(). If you do not return sockets in either case, you'll get a busy
			* wait.
			*
			* @return list A list of sockets which we expect to become readable.
			*/
			public function getReadSockets() {
			return array();
			}


			/**
			* Retrieve a list of sockets which we can wait to become writable while a
			* future is resolving. See getReadSockets().
			*
			* @return list A list of sockets which we expect to become writable.
			*/
			public function getWriteSockets() {
			return array();
			}


			/**
			* Wait for activity on one of several sockets.
			*
			* @param list List of sockets expected to become readable.
			* @param list List of sockets expected to become writable.
			* @param float Timeout, in seconds.
			* @return void
			*/
			public static function waitForSockets(
			array $read_list,
			array $write_list,
			$timeout = 1) {
			if (!self::$handlerInstalled) {
			// If we're spawning child processes, we need to install a signal handler
			// here to catch cases like execing '(sleep 60 &) &' where the child
			// exits but a socket is kept open. But we don't actually need to do
			// anything because the SIGCHLD will interrupt the stream_select(), as
			// long as we have a handler registered.
			if (function_exists('pcntl_signal')) {
			if (!pcntl_signal(SIGCHLD, array('Future', 'handleSIGCHLD'))) {
			throw new Exception('Failed to install signal handler!');
			}
			}
			self::$handlerInstalled = true;
			}

			$timeout_sec = (int)$timeout;
			$timeout_usec = (int)(1000000 * ($timeout - $timeout_sec));

			$exceptfds = array();
			$ok = @stream_select(
			$read_list,
			$write_list,
			$exceptfds,
			$timeout,
			$timeout_usec);

			if ($ok === false) {
			// Hopefully, means we received a SIGCHLD. In the worst case, we degrade
			// to a busy wait.
			}
			}

			public static function handleSIGCHLD($signo) {
			// This function is a dummy, we just need to have some handler registered
			// so that PHP will get interrupted during stream_select(). If we don't
			// register a handler, stream_select() won't fail.
			}


			/**
			* Retrieve the final result of the future. This method will be called after
			* the future is ready (as per isReady()) but before results are passed back
			* to the caller. The major use of this function is that you can override it
			* in subclasses to do postprocessing or error checking, which is
			* particularly useful if building application-specific futures on top of
			* primitive transport futures (like CurlFuture and ExecFuture) which can
			* make it tricky to hook this logic into the main pipeline.
			*
			* @return mixed Final resolution of this future.
			*/
			protected function getResult() {
			return $this->result;
			}

			/**
			* Default amount of time to wait on stream select for this future. Normally
			* 1 second is fine, but if the future has a timeout sooner than that it
			* should return the amount of time left before the timeout.
			*/
			public function getDefaultWait() {
			return 1;
			}

			public function start() {
			$this->isReady();
			return $this;
			}

			}

libphutil/src/future/Future.php4f9915ecac81production

Future.phpView Options

libphutil/src/future/Future.php
4f9915ecac81production

Future.php
View Options