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authorPierre Schmitz <pierre@archlinux.de>2009-06-10 13:00:47 +0200
committerPierre Schmitz <pierre@archlinux.de>2009-06-10 13:00:47 +0200
commit72e90545454c0e014318fa3c81658e035aac58c1 (patch)
tree9212e3f46868989c4d57ae9a5c8a1a80e4dc0702 /includes/ForkController.php
parent565a0ccc371ec1a2a0e9b39487cbac18e6f60e25 (diff)
applying patch to version 1.15.0
Diffstat (limited to 'includes/ForkController.php')
-rw-r--r--includes/ForkController.php160
1 files changed, 160 insertions, 0 deletions
diff --git a/includes/ForkController.php b/includes/ForkController.php
new file mode 100644
index 00000000..09e1788b
--- /dev/null
+++ b/includes/ForkController.php
@@ -0,0 +1,160 @@
+<?php
+
+/**
+ * Class for managing forking command line scripts.
+ * Currently just does forking and process control, but it could easily be extended
+ * to provide IPC and job dispatch.
+ *
+ * This class requires the posix and pcntl extensions.
+ */
+class ForkController {
+ var $children = array();
+ var $termReceived = false;
+ var $flags = 0, $procsToStart = 0;
+
+ static $restartableSignals = array(
+ SIGFPE,
+ SIGILL,
+ SIGSEGV,
+ SIGBUS,
+ SIGABRT,
+ SIGSYS,
+ SIGPIPE,
+ SIGXCPU,
+ SIGXFSZ,
+ );
+
+ /**
+ * Pass this flag to __construct() to cause the class to automatically restart
+ * workers that exit with non-zero exit status or a signal such as SIGSEGV.
+ */
+ const RESTART_ON_ERROR = 1;
+
+ public function __construct( $numProcs, $flags = 0 ) {
+ if ( php_sapi_name() != 'cli' ) {
+ throw new MWException( "MultiProcess cannot be used from the web." );
+ }
+ $this->procsToStart = $numProcs;
+ $this->flags = $flags;
+ }
+
+ /**
+ * Start the child processes.
+ *
+ * This should only be called from the command line. It should be called
+ * as early as possible during execution.
+ *
+ * This will return 'child' in the child processes. In the parent process,
+ * it will run until all the child processes exit or a TERM signal is
+ * received. It will then return 'done'.
+ */
+ public function start() {
+ // Trap SIGTERM
+ pcntl_signal( SIGTERM, array( $this, 'handleTermSignal' ), false );
+
+ do {
+ // Start child processes
+ if ( $this->procsToStart ) {
+ if ( $this->forkWorkers( $this->procsToStart ) == 'child' ) {
+ return 'child';
+ }
+ $this->procsToStart = 0;
+ }
+
+ // Check child status
+ $status = false;
+ $deadPid = pcntl_wait( $status );
+
+ if ( $deadPid > 0 ) {
+ // Respond to child process termination
+ unset( $this->children[$deadPid] );
+ if ( $this->flags & self::RESTART_ON_ERROR ) {
+ if ( pcntl_wifsignaled( $status ) ) {
+ // Restart if the signal was abnormal termination
+ // Don't restart if it was deliberately killed
+ $signal = pcntl_wtermsig( $status );
+ if ( in_array( $signal, self::$restartableSignals ) ) {
+ echo "Worker exited with signal $signal, restarting\n";
+ $this->procsToStart++;
+ }
+ } elseif ( pcntl_wifexited( $status ) ) {
+ // Restart on non-zero exit status
+ $exitStatus = pcntl_wexitstatus( $status );
+ if ( $exitStatus > 0 ) {
+ echo "Worker exited with status $exitStatus, restarting\n";
+ $this->procsToStart++;
+ }
+ }
+ }
+ // Throttle restarts
+ if ( $this->procsToStart ) {
+ usleep( 500000 );
+ }
+ }
+
+ // Run signal handlers
+ if ( function_exists( 'pcntl_signal_dispatch' ) ) {
+ pcntl_signal_dispatch();
+ } else {
+ declare (ticks=1) { $status = $status; }
+ }
+ // Respond to TERM signal
+ if ( $this->termReceived ) {
+ foreach ( $this->children as $childPid => $unused ) {
+ posix_kill( $childPid, SIGTERM );
+ }
+ $this->termReceived = false;
+ }
+ } while ( count( $this->children ) );
+ pcntl_signal( SIGTERM, SIG_DFL );
+ return 'done';
+ }
+
+ protected function prepareEnvironment() {
+ global $wgCaches, $wgMemc;
+ // Don't share DB or memcached connections
+ wfGetLBFactory()->destroyInstance();
+ $wgCaches = array();
+ unset( $wgMemc );
+ }
+
+ /**
+ * Fork a number of worker processes.
+ */
+ protected function forkWorkers( $numProcs ) {
+ global $wgMemc, $wgCaches, $wgMainCacheType;
+
+ $this->prepareEnvironment();
+
+ // Create the child processes
+ for ( $i = 0; $i < $numProcs; $i++ ) {
+ // Do the fork
+ $pid = pcntl_fork();
+ if ( $pid === -1 || $pid === false ) {
+ echo "Error creating child processes\n";
+ exit( 1 );
+ }
+
+ if ( !$pid ) {
+ $this->initChild();
+ return 'child';
+ } else {
+ // This is the parent process
+ $this->children[$pid] = true;
+ }
+ }
+
+ return 'parent';
+ }
+
+ protected function initChild() {
+ global $wgMemc, $wgMainCacheType;
+ $wgMemc = wfGetCache( $wgMainCacheType );
+ $this->children = null;
+ pcntl_signal( SIGTERM, SIG_DFL );
+ }
+
+ protected function handleTermSignal( $signal ) {
+ $this->termReceived = true;
+ }
+}