Chris@0: <?php
Chris@0: 
Chris@0: /*
Chris@0:  * This file is part of Psy Shell.
Chris@0:  *
Chris@0:  * (c) 2012-2017 Justin Hileman
Chris@0:  *
Chris@0:  * For the full copyright and license information, please view the LICENSE
Chris@0:  * file that was distributed with this source code.
Chris@0:  */
Chris@0: 
Chris@0: namespace Psy\ExecutionLoop;
Chris@0: 
Chris@0: use Psy\Context;
Chris@0: use Psy\Shell;
Chris@0: 
Chris@0: /**
Chris@0:  * A forking version of the Psy Shell execution loop.
Chris@0:  *
Chris@0:  * This version is preferred, as it won't die prematurely if user input includes
Chris@0:  * a fatal error, such as redeclaring a class or function.
Chris@0:  */
Chris@0: class ForkingLoop extends Loop
Chris@0: {
Chris@0:     private $savegame;
Chris@0: 
Chris@0:     /**
Chris@0:      * Run the execution loop.
Chris@0:      *
Chris@0:      * Forks into a master and a loop process. The loop process will handle the
Chris@0:      * evaluation of all instructions, then return its state via a socket upon
Chris@0:      * completion.
Chris@0:      *
Chris@0:      * @param Shell $shell
Chris@0:      */
Chris@0:     public function run(Shell $shell)
Chris@0:     {
Chris@0:         list($up, $down) = stream_socket_pair(STREAM_PF_UNIX, STREAM_SOCK_STREAM, STREAM_IPPROTO_IP);
Chris@0: 
Chris@0:         if (!$up) {
Chris@0:             throw new \RuntimeException('Unable to create socket pair.');
Chris@0:         }
Chris@0: 
Chris@0:         $pid = pcntl_fork();
Chris@0:         if ($pid < 0) {
Chris@0:             throw new \RuntimeException('Unable to start execution loop.');
Chris@0:         } elseif ($pid > 0) {
Chris@0:             // This is the main thread. We'll just wait for a while.
Chris@0: 
Chris@0:             // We won't be needing this one.
Chris@0:             fclose($up);
Chris@0: 
Chris@0:             // Wait for a return value from the loop process.
Chris@0:             $read   = array($down);
Chris@0:             $write  = null;
Chris@0:             $except = null;
Chris@0:             if (stream_select($read, $write, $except, null) === false) {
Chris@0:                 throw new \RuntimeException('Error waiting for execution loop.');
Chris@0:             }
Chris@0: 
Chris@0:             $content = stream_get_contents($down);
Chris@0:             fclose($down);
Chris@0: 
Chris@0:             if ($content) {
Chris@0:                 $shell->setScopeVariables(@unserialize($content));
Chris@0:             }
Chris@0: 
Chris@0:             return;
Chris@0:         }
Chris@0: 
Chris@0:         // This is the child process. It's going to do all the work.
Chris@0:         if (function_exists('setproctitle')) {
Chris@0:             setproctitle('psysh (loop)');
Chris@0:         }
Chris@0: 
Chris@0:         // We won't be needing this one.
Chris@0:         fclose($down);
Chris@0: 
Chris@0:         // Let's do some processing.
Chris@0:         parent::run($shell);
Chris@0: 
Chris@0:         // Send the scope variables back up to the main thread
Chris@0:         fwrite($up, $this->serializeReturn($shell->getScopeVariables(false)));
Chris@0:         fclose($up);
Chris@0: 
Chris@0:         posix_kill(posix_getpid(), SIGKILL);
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Create a savegame at the start of each loop iteration.
Chris@0:      */
Chris@0:     public function beforeLoop()
Chris@0:     {
Chris@0:         $this->createSavegame();
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Clean up old savegames at the end of each loop iteration.
Chris@0:      */
Chris@0:     public function afterLoop()
Chris@0:     {
Chris@0:         // if there's an old savegame hanging around, let's kill it.
Chris@0:         if (isset($this->savegame)) {
Chris@0:             posix_kill($this->savegame, SIGKILL);
Chris@0:             pcntl_signal_dispatch();
Chris@0:         }
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Create a savegame fork.
Chris@0:      *
Chris@0:      * The savegame contains the current execution state, and can be resumed in
Chris@0:      * the event that the worker dies unexpectedly (for example, by encountering
Chris@0:      * a PHP fatal error).
Chris@0:      */
Chris@0:     private function createSavegame()
Chris@0:     {
Chris@0:         // the current process will become the savegame
Chris@0:         $this->savegame = posix_getpid();
Chris@0: 
Chris@0:         $pid = pcntl_fork();
Chris@0:         if ($pid < 0) {
Chris@0:             throw new \RuntimeException('Unable to create savegame fork.');
Chris@0:         } elseif ($pid > 0) {
Chris@0:             // we're the savegame now... let's wait and see what happens
Chris@0:             pcntl_waitpid($pid, $status);
Chris@0: 
Chris@0:             // worker exited cleanly, let's bail
Chris@0:             if (!pcntl_wexitstatus($status)) {
Chris@0:                 posix_kill(posix_getpid(), SIGKILL);
Chris@0:             }
Chris@0: 
Chris@0:             // worker didn't exit cleanly, we'll need to have another go
Chris@0:             $this->createSavegame();
Chris@0:         }
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Serialize all serializable return values.
Chris@0:      *
Chris@0:      * A naïve serialization will run into issues if there is a Closure or
Chris@0:      * SimpleXMLElement (among other things) in scope when exiting the execution
Chris@0:      * loop. We'll just ignore these unserializable classes, and serialize what
Chris@0:      * we can.
Chris@0:      *
Chris@0:      * @param array $return
Chris@0:      *
Chris@0:      * @return string
Chris@0:      */
Chris@0:     private function serializeReturn(array $return)
Chris@0:     {
Chris@0:         $serializable = array();
Chris@0: 
Chris@0:         foreach ($return as $key => $value) {
Chris@0:             // No need to return magic variables
Chris@0:             if (Context::isSpecialVariableName($key)) {
Chris@0:                 continue;
Chris@0:             }
Chris@0: 
Chris@0:             // Resources and Closures don't error, but they don't serialize well either.
Chris@0:             if (is_resource($value) || $value instanceof \Closure) {
Chris@0:                 continue;
Chris@0:             }
Chris@0: 
Chris@0:             try {
Chris@0:                 @serialize($value);
Chris@0:                 $serializable[$key] = $value;
Chris@0:             } catch (\Exception $e) {
Chris@0:                 // we'll just ignore this one...
Chris@0:             } catch (\Throwable $e) {
Chris@0:                 // and this one too...
Chris@0:             }
Chris@0:         }
Chris@0: 
Chris@0:         return @serialize($serializable);
Chris@0:     }
Chris@0: }