Merge "Configurable log sampling via $wgDebugLogGroups"

diff --git a/includes/DefaultSettings.php b/includes/DefaultSettings.php
index ebae110..6d0e36c 100644 (file)
--- a/includes/DefaultSettings.php
+++ b/includes/DefaultSettings.php
@@ -4895,10 +4895,29 @@ $wgDebugDBTransactions = false;
 $wgDebugDumpSql = false;
 
 /**
- * Set to an array of log group keys to filenames.
+ * Map of string log group names to log destinations.
+ *
  * If set, wfDebugLog() output for that group will go to that file instead
  * of the regular $wgDebugLogFile. Useful for enabling selective logging
  * in production.
+ *
+ * Log destinations may be string values specifying a filename or URI, or they
+ * may be filename or an associative array mapping 'target' to the desired
+ * filename. The associative array may also contain a 'sample' key with an
+ * integer value, specifying a sampling factor.
+ *
+ * @par Example:
+ * @code
+ * $wgDebugLogGroups['redis'] = '/var/log/mediawiki/redis.log';
+ * @endcode
+ *
+ * @par Advanced example:
+ * @code
+ * $wgDebugLogGroups['memcached'] = (
+ *     'target' => '/var/log/mediawiki/memcached.log',
+ *     'sample' => 1000,  // log 1 message out of every 1,000.
+ * );
+ * @endcode
  */
 $wgDebugLogGroups = array();
 

diff --git a/includes/GlobalFunctions.php b/includes/GlobalFunctions.php
index ff91ba0..d8fe38e 100644 (file)
--- a/includes/GlobalFunctions.php
+++ b/includes/GlobalFunctions.php
@@ -1008,7 +1008,12 @@ function wfDebugMem( $exact = false ) {
 
 /**
  * Send a line to a supplementary debug log file, if configured, or main debug log if not.
- * $wgDebugLogGroups[$logGroup] should be set to a filename to send to a separate log.
+ * To configure a supplementary log file, set $wgDebugLogGroups[$logGroup] to a string
+ * filename or an associative array mapping 'target' to the desired filename. The
+ * associative array may also contain a 'sample' key with an integer value, specifying
+ * a sampling factor.
+ *
+ * @since 1.23 support for sampling log messages via $wgDebugLogGroups.
  *
  * @param $logGroup String
  * @param $text String
@@ -1018,14 +1023,28 @@ function wfDebugMem( $exact = false ) {
 function wfDebugLog( $logGroup, $text, $public = true ) {
        global $wgDebugLogGroups;
        $text = trim( $text ) . "\n";
-       if ( isset( $wgDebugLogGroups[$logGroup] ) ) {
-               $time = wfTimestamp( TS_DB );
-               $wiki = wfWikiID();
-               $host = wfHostname();
-               wfErrorLog( "$time $host $wiki: $text", $wgDebugLogGroups[$logGroup] );
-       } elseif ( $public === true ) {
-               wfDebug( "[$logGroup] $text", false );
+
+       if ( !isset( $wgDebugLogGroups[$logGroup] ) ) {
+               if ( $public === true ) {
+                       wfDebug( "[$logGroup] $text", false );
+               }
+               return;
        }
+
+       $logConfig = $wgDebugLogGroups[$logGroup];
+       if ( is_array( $logConfig ) ) {
+               if ( isset( $logConfig['sample'] ) && mt_rand( 1, $logConfig['sample'] ) !== 1 ) {
+                       return;
+               }
+               $destination = $logConfig['destination'];
+       } else {
+               $destination = strval( $logConfig );
+       }
+
+       $time = wfTimestamp( TS_DB );
+       $wiki = wfWikiID();
+       $host = wfHostname();
+       wfErrorLog( "$time $host $wiki: $text", $destination );
 }
 
 /**