Removed complex replag handling, now just query master when record isn't present...

followup to r92009

diff --git a/includes/upload/UploadStash.php b/includes/upload/UploadStash.php
index 1156f47..6727fb0 100644 (file)
--- a/includes/upload/UploadStash.php
+++ b/includes/upload/UploadStash.php
@@ -22,10 +22,6 @@ class UploadStash {
        // Format of the key for files -- has to be suitable as a filename itself (e.g. ab12cd34ef.jpg)
        const KEY_FORMAT_REGEX = '/^[\w-\.]+\.\w*$/';
 
-       // When a given stashed file can't be loaded, wait for the slaves to catch up.  If they're more than MAX_LAG
-       // behind, throw an exception instead. (at what point is broken better than slow?)
-       const MAX_LAG = 30;
-
        /**
         * repository that this uses to store temp files
         * public because we sometimes need to get a LocalFile within the same repo.
@@ -98,23 +94,9 @@ class UploadStash {
                $dbr = $this->repo->getSlaveDb();
 
                if ( !isset( $this->fileMetadata[$key] ) ) {
-                       // try this first.  if it fails to find the row, check for lag, wait, try again. if its still missing, throw an exception.
-                       // this more complex solution keeps things moving for page loads with many requests
-                       // (ie. validating image ownership) when replag is high
                        if ( !$this->fetchFileMetadata( $key ) ) {
-                               $lag = $dbr->getLag();
-                               if ( $lag > 0 && $lag <= self::MAX_LAG ) {
-                                       // if there's not too much replication lag, just wait for the slave to catch up to our last insert.
-                                       sleep( ceil( $lag ) );
-                               } elseif ( $lag > self::MAX_LAG ) {
-                                       // that's a lot of lag to introduce into the middle of the UI.
-                                       throw new UploadStashMaxLagExceededException(
-                                               'Couldn\'t load stashed file metadata, and replication lag is above threshold: (MAX_LAG=' . self::MAX_LAG . ')'
-                                       );
-                               }
-
-                               // now that the waiting has happened, try again
-                               $this->fetchFileMetadata( $key );
+                               // If nothing was received, it's likely due to replication lag.  Check the master to see if the record is there.
+                               $this->fetchFileMetadata( $key, true );
                        }
 
                        if ( !isset( $this->fileMetadata[$key] ) ) {
@@ -470,9 +452,16 @@ class UploadStash {
         * @param $key String: key
         * @return boolean
         */
-       protected function fetchFileMetadata( $key ) {
+       protected function fetchFileMetadata( $key, $readFromMaster = false ) {
                // populate $fileMetadata[$key]
-               $dbr = $this->repo->getSlaveDb();
+               $dbr = null;
+               if( $readFromMaster ) {
+                       // sometimes reading from the master is necessary, if there's replication lag.
+                       $dbr = $this->repo->getMasterDb();
+               } else {
+                       $dbr = $this->repo->getSlaveDb();
+               }
+
                $row = $dbr->selectRow(
                        'uploadstash',
                        '*',
@@ -685,5 +674,4 @@ class UploadStashFileException extends MWException {};
 class UploadStashZeroLengthFileException extends MWException {};
 class UploadStashNotLoggedInException extends MWException {};
 class UploadStashWrongOwnerException extends MWException {};
-class UploadStashMaxLagExceededException extends MWException {};
 class UploadStashNoSuchKeyException extends MWException {};