From ccabd0efb05ef07cbca76da18390f68c6c4fc00d Mon Sep 17 00:00:00 2001
From: Aaron Schulz <aschulz@wikimedia.org>
Date: Wed, 17 Apr 2013 22:05:47 -0700
Subject: [PATCH] Changed on-request job running to shell out instead of doing
 a loop.

* Also factored out a new wfShellExecDisabled() function.
* This will keep the process in the background if possible to avoid
  killing site performance, especially with slow jobs.
* This also keep fatals and uncatcheable exceptions from
  hitting the user.
* If $wgPhpCli is not set to an actual path or safe mode
  is on, then the old code will be used.

Change-Id: I6a28152251659ee53eee2604f16d5bf02c85a44f
---
 includes/GlobalFunctions.php | 40 +++++++++++++++++-----------
 includes/Wiki.php            | 51 ++++++++++++++++++++++--------------
 2 files changed, 56 insertions(+), 35 deletions(-)

diff --git a/includes/GlobalFunctions.php b/includes/GlobalFunctions.php
index 458ab548df..a81a33837e 100644
--- a/includes/GlobalFunctions.php
+++ b/includes/GlobalFunctions.php
@@ -2736,22 +2736,12 @@ function wfEscapeShellArg() {
 }
 
 /**
- * Execute a shell command, with time and memory limits mirrored from the PHP
- * configuration if supported.
- * @param string $cmd Command line, properly escaped for shell.
- * @param &$retval null|Mixed optional, will receive the program's exit code.
- *                 (non-zero is usually failure)
- * @param array $environ optional environment variables which should be
- *                 added to the executed command environment.
- * @param array $limits optional array with limits(filesize, memory, time, walltime)
- *                 this overwrites the global wgShellMax* limits.
- * @return string collected stdout as a string (trailing newlines stripped)
+ * Check if wfShellExec() is effectively disabled via php.ini config
+ * @return bool|string False or one of (safemode,disabled)
+ * @since 1.22
  */
-function wfShellExec( $cmd, &$retval = null, $environ = array(), $limits = array() ) {
-	global $IP, $wgMaxShellMemory, $wgMaxShellFileSize, $wgMaxShellTime,
-		$wgMaxShellWallClockTime, $wgShellCgroup;
-
-	static $disabled;
+function wfShellExecDisabled() {
+	static $disabled = null;
 	if ( is_null( $disabled ) ) {
 		$disabled = false;
 		if ( wfIniGetBool( 'safe_mode' ) ) {
@@ -2767,6 +2757,26 @@ function wfShellExec( $cmd, &$retval = null, $environ = array(), $limits = array
 			}
 		}
 	}
+	return $disabled;
+}
+
+/**
+ * Execute a shell command, with time and memory limits mirrored from the PHP
+ * configuration if supported.
+ * @param string $cmd Command line, properly escaped for shell.
+ * @param &$retval null|Mixed optional, will receive the program's exit code.
+ *                 (non-zero is usually failure)
+ * @param array $environ optional environment variables which should be
+ *                 added to the executed command environment.
+ * @param array $limits optional array with limits(filesize, memory, time, walltime)
+ *                 this overwrites the global wgShellMax* limits.
+ * @return string collected stdout as a string (trailing newlines stripped)
+ */
+function wfShellExec( $cmd, &$retval = null, $environ = array(), $limits = array() ) {
+	global $IP, $wgMaxShellMemory, $wgMaxShellFileSize, $wgMaxShellTime,
+		$wgMaxShellWallClockTime, $wgShellCgroup;
+
+	$disabled = wfShellExecDisabled();
 	if ( $disabled ) {
 		$retval = 1;
 		return $disabled == 'safemode' ?
diff --git a/includes/Wiki.php b/includes/Wiki.php
index 7d0d5af374..2fd12d5e84 100644
--- a/includes/Wiki.php
+++ b/includes/Wiki.php
@@ -599,7 +599,7 @@ class MediaWiki {
 	 * Do a job from the job queue
 	 */
 	private function doJobs() {
-		global $wgJobRunRate;
+		global $wgJobRunRate, $wgPhpCli, $IP;
 
 		if ( $wgJobRunRate <= 0 || wfReadOnly() ) {
 			return;
@@ -615,25 +615,36 @@ class MediaWiki {
 			$n = intval( $wgJobRunRate );
 		}
 
-		$group = JobQueueGroup::singleton();
-		do {
-			$job = $group->pop( JobQueueGroup::USE_CACHE ); // job from any queue
-			if ( $job ) {
-				$output = $job->toString() . "\n";
-				$t = - microtime( true );
-				wfProfileIn( __METHOD__ . '-' . get_class( $job ) );
-				$success = $job->run();
-				wfProfileOut( __METHOD__ . '-' . get_class( $job ) );
-				$group->ack( $job ); // done
-				$t += microtime( true );
-				$t = round( $t * 1000 );
-				if ( $success === false ) {
-					$output .= "Error: " . $job->getLastError() . ", Time: $t ms\n";
-				} else {
-					$output .= "Success, Time: $t ms\n";
+		if ( !wfShellExecDisabled() && is_executable( $wgPhpCli ) ) {
+			// Start a background process to run some of the jobs.
+			// This will be asynchronous on *nix though not on Windows.
+			wfProfileIn( __METHOD__ . '-exec' );
+			$retVal = 1;
+			$cmd = wfShellWikiCmd( "$IP/maintenance/runJobs.php", array( '--maxjobs', $n ) );
+			wfShellExec( "$cmd &", $retVal );
+			wfProfileOut( __METHOD__ . '-exec' );
+		} else {
+			// Fallback to running the jobs here while the user waits
+			$group = JobQueueGroup::singleton();
+			do {
+				$job = $group->pop( JobQueueGroup::USE_CACHE ); // job from any queue
+				if ( $job ) {
+					$output = $job->toString() . "\n";
+					$t = - microtime( true );
+					wfProfileIn( __METHOD__ . '-' . get_class( $job ) );
+					$success = $job->run();
+					wfProfileOut( __METHOD__ . '-' . get_class( $job ) );
+					$group->ack( $job ); // done
+					$t += microtime( true );
+					$t = round( $t * 1000 );
+					if ( $success === false ) {
+						$output .= "Error: " . $job->getLastError() . ", Time: $t ms\n";
+					} else {
+						$output .= "Success, Time: $t ms\n";
+					}
+					wfDebugLog( 'jobqueue', $output );
 				}
-				wfDebugLog( 'jobqueue', $output );
-			}
-		} while ( --$n && $job );
+			} while ( --$n && $job );
+		}
 	}
 }
-- 
2.20.1