Support custom offsets from SearchResultSet

Work to support interleaved AB testing of search will display
interleaved results of two search configurations on the first page of
results, but standard results on all pages other than the first page.
This means that while 20 results may be requested, the next 'new' result
of the primary query may be at position 10. Allow the SearchResultSet
to declare what the new offset is.

Bug: T150032
Change-Id: I14c0c33249fcdb66f72f5966e2aa72781a34daee

diff --git a/includes/search/SearchResultSet.php b/includes/search/SearchResultSet.php
index 978db27..89d2299 100644 (file)
--- a/includes/search/SearchResultSet.php
+++ b/includes/search/SearchResultSet.php
@@ -264,4 +264,14 @@ class SearchResultSet {
                $result->setExtensionData( $this->extraData[$id] );
                return $this->extraData[$id];
        }
+
+       /**
+        * @return int|null The offset the current page starts at. Typically
+        *  this should be null to allow the UI to decide on its own, but in
+        *  special cases like interleaved AB tests specifying explicitly is
+        *  necessary.
+        */
+       public function getOffset() {
+               return null;
+       }
 }

diff --git a/includes/specials/SpecialSearch.php b/includes/specials/SpecialSearch.php
index e89dbc9..b739c34 100644 (file)
--- a/includes/specials/SpecialSearch.php
+++ b/includes/specials/SpecialSearch.php
@@ -436,9 +436,17 @@ class SpecialSearch extends SpecialPage {
 
                // prev/next links
                if ( $totalRes > $this->limit || $this->offset ) {
+                       // Allow matches to define the correct offset, as interleaved
+                       // AB testing may require a different next page offset.
+                       if ( $textMatches && $textMatches->getOffset() !== null ) {
+                               $offset = $textMatches->getOffset();
+                       } else {
+                               $offset = $this->offset;
+                       }
+
                        $prevnext = $this->getLanguage()->viewPrevNext(
                                $this->getPageTitle(),
-                               $this->offset,
+                               $offset,
                                $this->limit,
                                $this->powerSearchOptions() + [ 'search' => $term ],
                                $this->limit + $this->offset >= $totalRes