distinguish failed text retrieval from empty text, consolidate text retrieval retry...

diff --git a/maintenance/dumpTextPass.php b/maintenance/dumpTextPass.php
index f83ab1a..75fd9ab 100644 (file)
--- a/maintenance/dumpTextPass.php
+++ b/maintenance/dumpTextPass.php
@@ -38,7 +38,9 @@ class TextPassDumper extends BackupDumper {
        var $prefetchCount = 0;
        
        var $failures = 0;
-       var $maxFailures = 200;
+       var $maxFailures = 5;
+    var $failedTextRetrievals = 0;
+       var $maxConsecutiveFailedTextRetrievals = 200;
        var $failureTimeout = 5; // Seconds to sleep after db failure
 
        var $php = "php";
@@ -203,11 +205,50 @@ class TextPassDumper extends BackupDumper {
        }
        
        private function doGetText( $id ) {
-               if ( $this->spawn ) {
-                       return $this->getTextSpawned( $id );
-               } else {
-                       return $this->getTextDbSafe( $id );
+
+               $this->failures = 0;
+               $ex = new MWException( "Graceful storage failure" );
+               while (true) {
+                       if ( $this->spawn ) {
+                               if ($this->failures) {
+                                       // we don't know why it failed, could be the child process 
+                                       // borked, could be db entry busted, could be db server out to lunch, 
+                                       // so cover all bases
+                                       $this->closeSpawn();
+                                       $this->openSpawn();
+                               }
+                               $text =  $this->getTextSpawned( $id );
+                       } else {
+                               $text =  $this->getTextDbSafe( $id );
+                       }
+                       if ( $text === false ) {
+                               $this->failures++;
+                               if ( $this->failures > $this->maxFailures) {
+                                       $this->progress( "Failed to retrieve revision text for text id ".
+                                                                        "$id after $this->maxFailures tries, giving up" );
+                                       // were there so many bad retrievals in a row we want to bail?
+                                   // at some point we have to declare the dump irretrievably broken
+                                       $this->failedTextRetrievals++;
+                                       if ($this->failedTextRetrievals > $this->maxConsecutiveFailedTextRetrievals) {
+                                               throw $ex;
+                                       }
+                                       else {
+                                               // would be nice to return something better to the caller someday,
+                                               // log what we know about the failure and about the revision
+                                               return("");
+                                       }
+                               } else {
+                                       $this->progress( "Error $this->failures " .
+                                                                "of allowed $this->maxFailures retrieving revision text for text id $id! " .
+                                                                "Pausing $this->failureTimeout seconds before retry..." );
+                                       sleep( $this->failureTimeout );
+                               }
+                       } else {
+                               $this->failedTextRetrievals= 0;
+                               return( $text );
+                       }
                }
+
        }
        
        /**
@@ -223,19 +264,7 @@ class TextPassDumper extends BackupDumper {
                        } catch ( DBQueryError $ex ) {
                                $text = false;
                        }
-                       if ( $text === false ) {
-                               $this->failures++;
-                               if ( $this->failures > $this->maxFailures ) {
-                                       throw $ex;
-                               } else {
-                                       $this->progress( "Database failure $this->failures " .
-                                               "of allowed $this->maxFailures for revision $id! " .
-                                               "Pausing $this->failureTimeout seconds..." );
-                                       sleep( $this->failureTimeout );
-                               }
-                       } else {
-                               return $text;
-                       }
+                       return $text;
                }
        }
        
@@ -264,21 +293,9 @@ class TextPassDumper extends BackupDumper {
                        // First time?
                        $this->openSpawn();
                }
-               while ( true ) {
-                       
-                       $text = $this->getTextSpawnedOnce( $id );
-                       if ( !is_string( $text ) ) {
-                               $this->progress( "Database subprocess failed. Respawning..." );
-                               
-                               $this->closeSpawn();
-                               sleep( $this->failureTimeout );
-                               $this->openSpawn();
-                               
-                               continue;
-                       }
-                       wfRestoreWarnings();
-                       return $text;
-               }
+               $text = $this->getTextSpawnedOnce( $id );
+               wfRestoreWarnings();
+               return $text;
        }
        
        function openSpawn() {
@@ -354,6 +371,9 @@ class TextPassDumper extends BackupDumper {
                if ( $len === false ) return false;
                
                $nbytes = intval( $len );
+               // actual error, not zero-length text
+               if ($nbytes < 0 ) return false;
+
                $text = "";
                
                // Subprocess may not send everything at once, we have to loop.

diff --git a/maintenance/fetchText.php b/maintenance/fetchText.php
index 55b64d2..b4db724 100644 (file)
--- a/maintenance/fetchText.php
+++ b/maintenance/fetchText.php
@@ -28,7 +28,17 @@ class FetchText extends Maintenance {
                $this->mDescription = "Fetch the revision text from an old_id";
        }
 
-       public function execute() {
+       /*
+     * returns a string containing the following in order:
+     *   textid
+        *   \n
+        *   length of text (-1 on error = failure to retrieve/unserialize/gunzip/etc)
+        *   \n
+        *   text  (may be empty)
+        *
+        * note that that the text string itself is *not* followed by newline
+        */
+        public function execute() {
                $db = wfGetDB( DB_SLAVE );
                $stdin = $this->getStdin();
                while ( !feof( $stdin ) ) {
@@ -39,7 +49,14 @@ class FetchText extends Maintenance {
                        }
                        $textId = intval( $line );
                        $text = $this->doGetText( $db, $textId );
-                       $this->output( $textId . "\n" . strlen( $text ) . "\n" . $text );
+                       if ($text === false) {
+                               # actual error, not zero-length text
+                               $textLen = "-1";
+                       }
+                       else {
+                               $textLen = strlen($text);
+                       }
+                       $this->output( $textId . "\n" . $textLen . "\n" . $text );
                }
        }