API: Fix ApiQueryBacklinks logic and use *_from_namespace
authorBrad Jorsch <bjorsch@wikimedia.org>
Thu, 21 Aug 2014 17:39:27 +0000 (13:39 -0400)
committerAaron Schulz <aschulz@wikimedia.org>
Wed, 1 Oct 2014 20:23:31 +0000 (20:23 +0000)
The original intent of this patch was to have ApiQueryBacklinks use the
*_from_namespace fields added in Icca99b6a. It does that, but in the
process several other bugs were found in the module:

* Continuation could skip pages when blredirect was used.
* The result object would be populated incorrectly if
  $wgAPIMaxResultSize was hit and blredirect was used.
* Continuation could (probably) skip or (maybe) repeat pages when
  blredirect was used and $wgAPIMaxResultSize was hit.

In the process of analyzing and fixing these problems, the code was
heavily refactored.

Change-Id: I32381c0f082d2f8e063af99ee353ae003c163c23

includes/api/ApiQueryBacklinks.php

index c141246..e344236 100644 (file)
@@ -39,8 +39,8 @@ class ApiQueryBacklinks extends ApiQueryGeneratorBase {
         */
        private $rootTitle;
 
-       private $params, $contID, $redirID, $redirect;
-       private $bl_ns, $bl_from, $bl_table, $bl_code, $bl_title, $bl_fields, $hasNS;
+       private $params, $cont, $redirect;
+       private $bl_ns, $bl_from, $bl_from_ns, $bl_table, $bl_code, $bl_title, $bl_fields, $hasNS;
 
        /**
         * Maps ns and title to pageid
@@ -84,6 +84,7 @@ class ApiQueryBacklinks extends ApiQueryGeneratorBase {
                parent::__construct( $query, $moduleName, $code );
                $this->bl_ns = $prefix . '_namespace';
                $this->bl_from = $prefix . '_from';
+               $this->bl_from_ns = $prefix . '_from_namespace';
                $this->bl_table = $settings['linktbl'];
                $this->bl_code = $code;
                $this->helpUrl = $settings['helpurl'];
@@ -119,12 +120,7 @@ class ApiQueryBacklinks extends ApiQueryGeneratorBase {
         * @param ApiPageSet $resultPageSet
         * @return void
         */
-       private function prepareFirstQuery( $resultPageSet = null ) {
-               /* SELECT page_id, page_title, page_namespace, page_is_redirect
-                * FROM pagelinks, page WHERE pl_from=page_id
-                * AND pl_title='Foo' AND pl_namespace=0
-                * LIMIT 11 ORDER BY pl_from
-                */
+       private function runFirstQuery( $resultPageSet = null ) {
                $this->addTables( array( $this->bl_table, 'page' ) );
                $this->addWhere( "{$this->bl_from}=page_id" );
                if ( is_null( $resultPageSet ) ) {
@@ -132,18 +128,25 @@ class ApiQueryBacklinks extends ApiQueryGeneratorBase {
                } else {
                        $this->addFields( $resultPageSet->getPageTableFields() );
                }
+               $this->addFields( array( 'page_is_redirect', 'from_ns' => 'page_namespace' ) );
 
-               $this->addFields( 'page_is_redirect' );
                $this->addWhereFld( $this->bl_title, $this->rootTitle->getDBkey() );
-
                if ( $this->hasNS ) {
                        $this->addWhereFld( $this->bl_ns, $this->rootTitle->getNamespace() );
                }
-               $this->addWhereFld( 'page_namespace', $this->params['namespace'] );
+               $this->addWhereFld( $this->bl_from_ns, $this->params['namespace'] );
 
-               if ( !is_null( $this->contID ) ) {
+               if ( count( $this->cont ) >= 2 ) {
                        $op = $this->params['dir'] == 'descending' ? '<' : '>';
-                       $this->addWhere( "{$this->bl_from}$op={$this->contID}" );
+                       if ( count( $this->params['namespace'] ) > 1 ) {
+                               $this->addWhere(
+                                       "{$this->bl_from_ns} $op {$this->cont[0]} OR " .
+                                       "({$this->bl_from_ns} = {$this->cont[0]} AND " .
+                                       "{$this->bl_from} $op= {$this->cont[1]})"
+                               );
+                       } else {
+                               $this->addWhere( "{$this->bl_from} $op= {$this->cont[1]}" );
+                       }
                }
 
                if ( $this->params['filterredir'] == 'redirects' ) {
@@ -156,20 +159,56 @@ class ApiQueryBacklinks extends ApiQueryGeneratorBase {
 
                $this->addOption( 'LIMIT', $this->params['limit'] + 1 );
                $sort = ( $this->params['dir'] == 'descending' ? ' DESC' : '' );
-               $this->addOption( 'ORDER BY', $this->bl_from . $sort );
+               $orderBy = array();
+               if ( count( $this->params['namespace'] ) > 1 ) {
+                       $orderBy[] = $this->bl_from_ns . $sort;
+               }
+               $orderBy[] = $this->bl_from . $sort;
+               $this->addOption( 'ORDER BY', $orderBy );
                $this->addOption( 'STRAIGHT_JOIN' );
+
+               $res = $this->select( __METHOD__ );
+               $count = 0;
+               foreach ( $res as $row ) {
+                       if ( ++$count > $this->params['limit'] ) {
+                               // We've reached the one extra which shows that there are
+                               // additional pages to be had. Stop here...
+                               // Continue string may be overridden at a later step
+                               $this->continueStr = "{$row->from_ns}|{$row->page_id}";
+                               break;
+                       }
+
+                       // Fill in continuation fields for later steps
+                       if ( count( $this->cont ) < 2 ) {
+                               $this->cont[] = $row->from_ns;
+                               $this->cont[] = $row->page_id;
+                       }
+
+                       $this->pageMap[$row->page_namespace][$row->page_title] = $row->page_id;
+                       $t = Title::makeTitle( $row->page_namespace, $row->page_title );
+                       if ( $row->page_is_redirect ) {
+                               $this->redirTitles[] = $t;
+                       }
+
+                       if ( is_null( $resultPageSet ) ) {
+                               $a = array( 'pageid' => intval( $row->page_id ) );
+                               ApiQueryBase::addTitleInfo( $a, $t );
+                               if ( $row->page_is_redirect ) {
+                                       $a['redirect'] = '';
+                               }
+                               // Put all the results in an array first
+                               $this->resultArr[$a['pageid']] = $a;
+                       } else {
+                               $resultPageSet->processDbRow( $row );
+                       }
+               }
        }
 
        /**
         * @param ApiPageSet $resultPageSet
         * @return void
         */
-       private function prepareSecondQuery( $resultPageSet = null ) {
-               /* SELECT page_id, page_title, page_namespace, page_is_redirect, pl_title, pl_namespace
-                  FROM pagelinks, page WHERE pl_from=page_id
-                  AND (pl_title='Foo' AND pl_namespace=0) OR (pl_title='Bar' AND pl_namespace=1)
-                  ORDER BY pl_namespace, pl_title, pl_from LIMIT 11
-                */
+       private function runSecondQuery( $resultPageSet = null ) {
                $db = $this->getDB();
                $this->addTables( array( 'page', $this->bl_table ) );
                $this->addWhere( "{$this->bl_from}=page_id" );
@@ -180,7 +219,7 @@ class ApiQueryBacklinks extends ApiQueryGeneratorBase {
                        $this->addFields( $resultPageSet->getPageTableFields() );
                }
 
-               $this->addFields( $this->bl_title );
+               $this->addFields( array( $this->bl_title, 'from_ns' => 'page_namespace' ) );
                if ( $this->hasNS ) {
                        $this->addFields( $this->bl_ns );
                }
@@ -195,30 +234,33 @@ class ApiQueryBacklinks extends ApiQueryGeneratorBase {
                        $redirDBkey = $t->getDBkey();
                        $titleWhere[] = "{$this->bl_title} = " . $db->addQuotes( $redirDBkey ) .
                                ( $this->hasNS ? " AND {$this->bl_ns} = {$redirNs}" : '' );
-                       $allRedirNs[] = $redirNs;
-                       $allRedirDBkey[] = $redirDBkey;
+                       $allRedirNs[$redirNs] = true;
+                       $allRedirDBkey[$redirDBkey] = true;
                }
                $this->addWhere( $db->makeList( $titleWhere, LIST_OR ) );
                $this->addWhereFld( 'page_namespace', $this->params['namespace'] );
 
-               if ( !is_null( $this->redirID ) ) {
+               if ( count( $this->cont ) >= 6 ) {
                        $op = $this->params['dir'] == 'descending' ? '<' : '>';
-                       /** @var $first Title */
-                       $first = $this->redirTitles[0];
-                       $title = $db->addQuotes( $first->getDBkey() );
-                       $ns = $first->getNamespace();
-                       $from = $this->redirID;
-                       if ( $this->hasNS ) {
-                               $this->addWhere( "{$this->bl_ns} $op $ns OR " .
-                                       "({$this->bl_ns} = $ns AND " .
-                                       "({$this->bl_title} $op $title OR " .
-                                       "({$this->bl_title} = $title AND " .
-                                       "{$this->bl_from} $op= $from)))" );
-                       } else {
-                               $this->addWhere( "{$this->bl_title} $op $title OR " .
-                                       "({$this->bl_title} = $title AND " .
-                                       "{$this->bl_from} $op= $from)" );
+
+                       $where = "{$this->bl_from} $op= {$this->cont[5]}";
+                       // Don't bother with namespace, title, or from_namespace if it's
+                       // otherwise constant in the where clause.
+                       if ( count( $this->params['namespace'] ) > 1 ) {
+                               $where = "{$this->bl_from_ns} $op {$this->cont[4]} OR " .
+                                       "({$this->bl_from_ns} = {$this->cont[4]} AND ($where))";
+                       }
+                       if ( count( $allRedirDBkey ) > 1 ) {
+                               $title = $db->addQuotes( $this->cont[3] );
+                               $where = "{$this->bl_title} $op $title OR " .
+                                       "({$this->bl_title} = $title AND ($where))";
                        }
+                       if ( $this->hasNS && count( $allRedirNs ) > 1 ) {
+                               $where = "{$this->bl_ns} $op {$this->cont[2]} OR " .
+                                       "({$this->bl_ns} = {$this->cont[2]} AND ($where))";
+                       }
+
+                       $this->addWhere( $where );
                }
                if ( $this->params['filterredir'] == 'redirects' ) {
                        $this->addWhereFld( 'page_is_redirect', 1 );
@@ -229,16 +271,57 @@ class ApiQueryBacklinks extends ApiQueryGeneratorBase {
                $this->addOption( 'LIMIT', $this->params['limit'] + 1 );
                $orderBy = array();
                $sort = ( $this->params['dir'] == 'descending' ? ' DESC' : '' );
-               // Don't order by namespace/title if it's constant in the WHERE clause
-               if ( $this->hasNS && count( array_unique( $allRedirNs ) ) != 1 ) {
+               // Don't order by namespace/title/from_namespace if it's constant in the WHERE clause
+               if ( $this->hasNS && count( $allRedirNs ) > 1 ) {
                        $orderBy[] = $this->bl_ns . $sort;
                }
-               if ( count( array_unique( $allRedirDBkey ) ) != 1 ) {
+               if ( count( $allRedirDBkey ) > 1 ) {
                        $orderBy[] = $this->bl_title . $sort;
                }
+               if ( count( $this->params['namespace'] ) > 1 ) {
+                       $orderBy[] = $this->bl_from_ns . $sort;
+               }
                $orderBy[] = $this->bl_from . $sort;
                $this->addOption( 'ORDER BY', $orderBy );
                $this->addOption( 'USE INDEX', array( 'page' => 'PRIMARY' ) );
+
+               $res = $this->select( __METHOD__ );
+               $count = 0;
+               foreach ( $res as $row ) {
+                       $ns = $this->hasNS ? $row->{$this->bl_ns} : NS_FILE;
+
+                       if ( ++$count > $this->params['limit'] ) {
+                               // We've reached the one extra which shows that there are
+                               // additional pages to be had. Stop here...
+                               // Note we must keep the parameters for the first query constant
+                               // This may be overridden at a later step
+                               $title = $row->{$this->bl_title};
+                               $this->continueStr = join( '|', array_slice( $this->cont, 0, 2 ) ) .
+                                       "|$ns|$title|{$row->from_ns}|{$row->page_id}";
+                               break;
+                       }
+
+                       // Fill in continuation fields for later steps
+                       if ( count( $this->cont ) < 6 ) {
+                               $this->cont[] = $ns;
+                               $this->cont[] = $row->{$this->bl_title};
+                               $this->cont[] = $row->from_ns;
+                               $this->cont[] = $row->page_id;
+                       }
+
+                       if ( is_null( $resultPageSet ) ) {
+                               $a['pageid'] = intval( $row->page_id );
+                               ApiQueryBase::addTitleInfo( $a, Title::makeTitle( $row->page_namespace, $row->page_title ) );
+                               if ( $row->page_is_redirect ) {
+                                       $a['redirect'] = '';
+                               }
+                               $parentID = $this->pageMap[$ns][$row->{$this->bl_title}];
+                               // Put all the results in an array first
+                               $this->resultArr[$parentID]['redirlinks'][$row->page_id] = $a;
+                       } else {
+                               $resultPageSet->processDbRow( $row );
+                       }
+               }
        }
 
        /**
@@ -261,96 +344,145 @@ class ApiQueryBacklinks extends ApiQueryGeneratorBase {
                        $this->validateLimit( 'limit', $this->params['limit'], 1, $userMax, $botMax );
                }
 
-               $this->processContinue();
-               $this->prepareFirstQuery( $resultPageSet );
+               $this->rootTitle = $this->getTitleOrPageId( $this->params )->getTitle();
 
-               $res = $this->select( __METHOD__ . '::firstQuery' );
+               // only image titles are allowed for the root in imageinfo mode
+               if ( !$this->hasNS && $this->rootTitle->getNamespace() !== NS_FILE ) {
+                       $this->dieUsage(
+                               "The title for {$this->getModuleName()} query must be a file",
+                               'bad_image_title'
+                       );
+               }
 
-               $count = 0;
+               // Parse and validate continuation parameter
+               $this->cont = array();
+               if ( $this->params['continue'] !== null ) {
+                       $db = $this->getDB();
+                       $cont = explode( '|', $this->params['continue'] );
 
-               foreach ( $res as $row ) {
-                       if ( ++$count > $this->params['limit'] ) {
-                               // We've reached the one extra which shows that there are
-                               // additional pages to be had. Stop here...
-                               // Continue string preserved in case the redirect query doesn't pass the limit
-                               $this->continueStr = $this->getContinueStr( $row->page_id );
-                               break;
-                       }
+                       switch ( count( $cont ) ) {
+                               case 8:
+                                       // redirect page ID for result adding
+                                       $this->cont[7] = (int)$cont[7];
+                                       $this->dieContinueUsageIf( $cont[7] !== (string)$this->cont[7] );
 
-                       if ( is_null( $resultPageSet ) ) {
-                               $this->extractRowInfo( $row );
-                       } else {
-                               $this->pageMap[$row->page_namespace][$row->page_title] = $row->page_id;
-                               if ( $row->page_is_redirect ) {
-                                       $this->redirTitles[] = Title::makeTitle( $row->page_namespace, $row->page_title );
-                               }
+                                       /* Fall through */
 
-                               $resultPageSet->processDbRow( $row );
+                               case 7:
+                                       // top-level page ID for result adding
+                                       $this->cont[6] = (int)$cont[6];
+                                       $this->dieContinueUsageIf( $cont[6] !== (string)$this->cont[6] );
+
+                                       /* Fall through */
+
+                               case 6:
+                                       // ns for 2nd query (even for imageusage)
+                                       $this->cont[2] = (int)$cont[2];
+                                       $this->dieContinueUsageIf( $cont[2] !== (string)$this->cont[2] );
+
+                                       // title for 2nd query
+                                       $this->cont[3] = $cont[3];
+
+                                       // from_ns for 2nd query
+                                       $this->cont[4] = (int)$cont[4];
+                                       $this->dieContinueUsageIf( $cont[4] !== (string)$this->cont[4] );
+
+                                       // from_id for 1st query
+                                       $this->cont[5] = (int)$cont[5];
+                                       $this->dieContinueUsageIf( $cont[5] !== (string)$this->cont[5] );
+
+                                       /* Fall through */
+
+                               case 2:
+                                       // from_ns for 1st query
+                                       $this->cont[0] = (int)$cont[0];
+                                       $this->dieContinueUsageIf( $cont[0] !== (string)$this->cont[0] );
+
+                                       // from_id for 1st query
+                                       $this->cont[1] = (int)$cont[1];
+                                       $this->dieContinueUsageIf( $cont[1] !== (string)$this->cont[1] );
+
+                                       break;
+
+                               default:
+                                       $this->dieContinueUsageIf( true );
                        }
+
+                       ksort( $this->cont );
                }
 
+               $this->runFirstQuery( $resultPageSet );
                if ( $this->redirect && count( $this->redirTitles ) ) {
                        $this->resetQueryParams();
-                       $this->prepareSecondQuery( $resultPageSet );
-                       $res = $this->select( __METHOD__ . '::secondQuery' );
-                       $count = 0;
-                       foreach ( $res as $row ) {
-                               if ( ++$count > $this->params['limit'] ) {
-                                       // We've reached the one extra which shows that there are
-                                       // additional pages to be had. Stop here...
-                                       // We need to keep the parent page of this redir in
-                                       if ( $this->hasNS ) {
-                                               $parentID = $this->pageMap[$row->{$this->bl_ns}][$row->{$this->bl_title}];
-                                       } else {
-                                               $parentID = $this->pageMap[NS_FILE][$row->{$this->bl_title}];
-                                       }
-                                       $this->continueStr = $this->getContinueRedirStr( $parentID, $row->page_id );
-                                       break;
-                               }
-
-                               if ( is_null( $resultPageSet ) ) {
-                                       $this->extractRedirRowInfo( $row );
-                               } else {
-                                       $resultPageSet->processDbRow( $row );
-                               }
-                       }
+                       $this->runSecondQuery( $resultPageSet );
                }
+
+               // Fill in any missing fields in case it's needed below
+               $this->cont += array( 0, 0, 0, '', 0, 0, 0 );
+
                if ( is_null( $resultPageSet ) ) {
                        // Try to add the result data in one go and pray that it fits
                        $fit = $result->addValue( 'query', $this->getModuleName(), array_values( $this->resultArr ) );
                        if ( !$fit ) {
                                // It didn't fit. Add elements one by one until the
                                // result is full.
+                               ksort( $this->resultArr );
+                               if ( count( $this->cont ) >= 7 ) {
+                                       $startAt = $this->cont[6];
+                               } else {
+                                       reset( $this->resultArr );
+                                       $startAt = key( $this->resultArr );
+                               }
+                               $idx = 0;
                                foreach ( $this->resultArr as $pageID => $arr ) {
+                                       if ( $pageID < $startAt ) {
+                                               continue;
+                                       }
+
                                        // Add the basic entry without redirlinks first
                                        $fit = $result->addValue(
                                                array( 'query', $this->getModuleName() ),
-                                               null, array_diff_key( $arr, array( 'redirlinks' => '' ) ) );
+                                               $idx, array_diff_key( $arr, array( 'redirlinks' => '' ) ) );
                                        if ( !$fit ) {
-                                               $this->continueStr = $this->getContinueStr( $pageID );
+                                               $this->continueStr = join( '|', array_slice( $this->cont, 0, 6 ) ) .
+                                                       "|$pageID";
                                                break;
                                        }
 
                                        $hasRedirs = false;
-                                       $redirLinks = isset( $arr['redirlinks'] ) ? $arr['redirlinks'] : array();
-                                       foreach ( (array)$redirLinks as $key => $redir ) {
+                                       $redirLinks = isset( $arr['redirlinks'] ) ? (array)$arr['redirlinks'] : array();
+                                       ksort( $redirLinks );
+                                       if ( count( $this->cont ) >= 8 && $pageID == $startAt ) {
+                                               $redirStartAt = $this->cont[7];
+                                       } else {
+                                               reset( $redirLinks );
+                                               $redirStartAt = key( $redirLinks );
+                                       }
+                                       foreach ( $redirLinks as $key => $redir ) {
+                                               if ( $key < $redirStartAt ) {
+                                                       continue;
+                                               }
+
                                                $fit = $result->addValue(
-                                                       array( 'query', $this->getModuleName(), $pageID, 'redirlinks' ),
-                                                       $key, $redir );
+                                                       array( 'query', $this->getModuleName(), $idx, 'redirlinks' ),
+                                                       null, $redir );
                                                if ( !$fit ) {
-                                                       $this->continueStr = $this->getContinueRedirStr( $pageID, $redir['pageid'] );
+                                                       $this->continueStr = join( '|', array_slice( $this->cont, 0, 6 ) ) .
+                                                               "|$pageID|$key";
                                                        break;
                                                }
                                                $hasRedirs = true;
                                        }
                                        if ( $hasRedirs ) {
                                                $result->setIndexedTagName_internal(
-                                                       array( 'query', $this->getModuleName(), $pageID, 'redirlinks' ),
+                                                       array( 'query', $this->getModuleName(), $idx, 'redirlinks' ),
                                                        $this->bl_code );
                                        }
                                        if ( !$fit ) {
                                                break;
                                        }
+
+                                       $idx++;
                                }
                        }
 
@@ -364,91 +496,6 @@ class ApiQueryBacklinks extends ApiQueryGeneratorBase {
                }
        }
 
-       private function extractRowInfo( $row ) {
-               $this->pageMap[$row->page_namespace][$row->page_title] = $row->page_id;
-               $t = Title::makeTitle( $row->page_namespace, $row->page_title );
-               $a = array( 'pageid' => intval( $row->page_id ) );
-               ApiQueryBase::addTitleInfo( $a, $t );
-               if ( $row->page_is_redirect ) {
-                       $a['redirect'] = '';
-                       $this->redirTitles[] = $t;
-               }
-               // Put all the results in an array first
-               $this->resultArr[$a['pageid']] = $a;
-       }
-
-       private function extractRedirRowInfo( $row ) {
-               $a['pageid'] = intval( $row->page_id );
-               ApiQueryBase::addTitleInfo( $a, Title::makeTitle( $row->page_namespace, $row->page_title ) );
-               if ( $row->page_is_redirect ) {
-                       $a['redirect'] = '';
-               }
-               $ns = $this->hasNS ? $row->{$this->bl_ns} : NS_FILE;
-               $parentID = $this->pageMap[$ns][$row->{$this->bl_title}];
-               // Put all the results in an array first
-               $this->resultArr[$parentID]['redirlinks'][] = $a;
-               $this->getResult()->setIndexedTagName(
-                       $this->resultArr[$parentID]['redirlinks'],
-                       $this->bl_code
-               );
-       }
-
-       protected function processContinue() {
-               if ( !is_null( $this->params['continue'] ) ) {
-                       $this->parseContinueParam();
-               } else {
-                       $this->rootTitle = $this->getTitleOrPageId( $this->params )->getTitle();
-               }
-
-               // only image titles are allowed for the root in imageinfo mode
-               if ( !$this->hasNS && $this->rootTitle->getNamespace() !== NS_FILE ) {
-                       $this->dieUsage(
-                               "The title for {$this->getModuleName()} query must be an image",
-                               'bad_image_title'
-                       );
-               }
-       }
-
-       protected function parseContinueParam() {
-               $continueList = explode( '|', $this->params['continue'] );
-               // expected format:
-               // ns | key | id1 [| id2]
-               // ns+key: root title
-               // id1: first-level page ID to continue from
-               // id2: second-level page ID to continue from
-
-               // null stuff out now so we know what's set and what isn't
-               $this->rootTitle = $this->contID = $this->redirID = null;
-               $rootNs = intval( $continueList[0] );
-               $this->dieContinueUsageIf( $rootNs === 0 && $continueList[0] !== '0' );
-
-               $this->rootTitle = Title::makeTitleSafe( $rootNs, $continueList[1] );
-               $this->dieContinueUsageIf( !$this->rootTitle );
-
-               $contID = intval( $continueList[2] );
-               $this->dieContinueUsageIf( $contID === 0 && $continueList[2] !== '0' );
-
-               $this->contID = $contID;
-               $id2 = isset( $continueList[3] ) ? $continueList[3] : null;
-               $redirID = intval( $id2 );
-
-               if ( $redirID === 0 && $id2 !== '0' ) {
-                       // This one isn't required
-                       return;
-               }
-               $this->redirID = $redirID;
-       }
-
-       protected function getContinueStr( $lastPageID ) {
-               return $this->rootTitle->getNamespace() .
-               '|' . $this->rootTitle->getDBkey() .
-               '|' . $lastPageID;
-       }
-
-       protected function getContinueRedirStr( $lastPageID, $lastRedirID ) {
-               return $this->getContinueStr( $lastPageID ) . '|' . $lastRedirID;
-       }
-
        public function getAllowedParams() {
                $retval = array(
                        'title' => array(