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<?php |
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/** |
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* Class for managing forking command line scripts. |
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* |
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* This program is free software; you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License as published by |
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* the Free Software Foundation; either version 2 of the License, or |
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* (at your option) any later version. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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* |
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* You should have received a copy of the GNU General Public License along |
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* with this program; if not, write to the Free Software Foundation, Inc., |
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
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* http://www.gnu.org/copyleft/gpl.html |
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* |
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* @file |
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*/ |
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use MediaWiki\MediaWikiServices; |
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/** |
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* Class for managing forking command line scripts. |
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* Currently just does forking and process control, but it could easily be extended |
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* to provide IPC and job dispatch. |
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* |
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* This class requires the posix and pcntl extensions. |
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* |
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* @ingroup Maintenance |
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*/ |
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class ForkController { |
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protected $children = [], $childNumber = 0; |
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protected $termReceived = false; |
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protected $flags = 0, $procsToStart = 0; |
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protected static $restartableSignals = [ |
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SIGFPE, |
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SIGILL, |
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SIGSEGV, |
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SIGBUS, |
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SIGABRT, |
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SIGSYS, |
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SIGPIPE, |
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SIGXCPU, |
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SIGXFSZ, |
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]; |
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/** |
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* Pass this flag to __construct() to cause the class to automatically restart |
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* workers that exit with non-zero exit status or a signal such as SIGSEGV. |
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*/ |
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const RESTART_ON_ERROR = 1; |
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public function __construct( $numProcs, $flags = 0 ) { |
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if ( PHP_SAPI != 'cli' ) { |
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throw new MWException( "ForkController cannot be used from the web." ); |
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} |
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$this->procsToStart = $numProcs; |
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$this->flags = $flags; |
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} |
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/** |
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* Start the child processes. |
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* |
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* This should only be called from the command line. It should be called |
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* as early as possible during execution. |
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* |
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* This will return 'child' in the child processes. In the parent process, |
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* it will run until all the child processes exit or a TERM signal is |
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* received. It will then return 'done'. |
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* @return string |
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*/ |
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public function start() { |
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// Trap SIGTERM |
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pcntl_signal( SIGTERM, [ $this, 'handleTermSignal' ], false ); |
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do { |
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// Start child processes |
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if ( $this->procsToStart ) { |
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if ( $this->forkWorkers( $this->procsToStart ) == 'child' ) { |
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return 'child'; |
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} |
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$this->procsToStart = 0; |
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} |
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// Check child status |
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$status = false; |
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$deadPid = pcntl_wait( $status ); |
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if ( $deadPid > 0 ) { |
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// Respond to child process termination |
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unset( $this->children[$deadPid] ); |
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if ( $this->flags & self::RESTART_ON_ERROR ) { |
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if ( pcntl_wifsignaled( $status ) ) { |
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// Restart if the signal was abnormal termination |
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// Don't restart if it was deliberately killed |
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$signal = pcntl_wtermsig( $status ); |
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if ( in_array( $signal, self::$restartableSignals ) ) { |
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echo "Worker exited with signal $signal, restarting\n"; |
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$this->procsToStart++; |
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} |
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} elseif ( pcntl_wifexited( $status ) ) { |
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// Restart on non-zero exit status |
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$exitStatus = pcntl_wexitstatus( $status ); |
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if ( $exitStatus != 0 ) { |
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echo "Worker exited with status $exitStatus, restarting\n"; |
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$this->procsToStart++; |
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} else { |
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echo "Worker exited normally\n"; |
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} |
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} |
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} |
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// Throttle restarts |
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if ( $this->procsToStart ) { |
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usleep( 500000 ); |
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} |
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} |
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// Run signal handlers |
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if ( function_exists( 'pcntl_signal_dispatch' ) ) { |
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pcntl_signal_dispatch(); |
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} else { |
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declare( ticks = 1 ) { |
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$status = $status; |
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} |
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} |
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// Respond to TERM signal |
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if ( $this->termReceived ) { |
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foreach ( $this->children as $childPid => $unused ) { |
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posix_kill( $childPid, SIGTERM ); |
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} |
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$this->termReceived = false; |
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} |
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} while ( count( $this->children ) ); |
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pcntl_signal( SIGTERM, SIG_DFL ); |
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return 'done'; |
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} |
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/** |
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* Get the number of the child currently running. Note, this |
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* is not the pid, but rather which of the total number of children |
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* we are |
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* @return int |
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*/ |
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public function getChildNumber() { |
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return $this->childNumber; |
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} |
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protected function prepareEnvironment() { |
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global $wgMemc; |
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// Don't share DB, storage, or memcached connections |
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MediaWikiServices::resetChildProcessServices(); |
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FileBackendGroup::destroySingleton(); |
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LockManagerGroup::destroySingletons(); |
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JobQueueGroup::destroySingletons(); |
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ObjectCache::clear(); |
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RedisConnectionPool::destroySingletons(); |
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$wgMemc = null; |
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} |
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/** |
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* Fork a number of worker processes. |
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* |
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* @param int $numProcs |
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* @return string |
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*/ |
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protected function forkWorkers( $numProcs ) { |
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$this->prepareEnvironment(); |
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// Create the child processes |
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for ( $i = 0; $i < $numProcs; $i++ ) { |
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// Do the fork |
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$pid = pcntl_fork(); |
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if ( $pid === -1 || $pid === false ) { |
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echo "Error creating child processes\n"; |
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exit( 1 ); |
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} |
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if ( !$pid ) { |
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$this->initChild(); |
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$this->childNumber = $i; |
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return 'child'; |
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} else { |
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// This is the parent process |
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$this->children[$pid] = true; |
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} |
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} |
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return 'parent'; |
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} |
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protected function initChild() { |
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global $wgMemc, $wgMainCacheType; |
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$wgMemc = wfGetCache( $wgMainCacheType ); |
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$this->children = null; |
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pcntl_signal( SIGTERM, SIG_DFL ); |
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} |
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protected function handleTermSignal( $signal ) { |
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$this->termReceived = true; |
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} |
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} |
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wikimedia /
mediawiki
Loading history...
Only declaring a single property per statement allows you to later on add doc comments more easily.
It is also recommended by PSR2, so it is a common style that many people expect.