Indexer improvement: Only write the words index when needed

This adds a simple boolean variable that tracks if new words have been
added. When editing a page in many cases all words have already been
used somewhere else or just one or two words are new. Until this change
all words indexes read were always written, now only the changed ones
are written. The overhead of the new boolean variable should be low.

1 files changed, 4 insertions, 1 deletions

diff --git a/inc/indexer.php b/inc/indexer.php
index a07c3b89a..8174f73d0 100644
--- a/inc/indexer.php
+++ b/inc/indexer.php
@@ -252,6 +252,8 @@ function idx_getPageWords($page){
 
     // arrive here with $words = array(wordlen => array(word => frequency))
 
+    $word_idx_modified = false;
+
     $index = array(); //resulting index
     foreach (array_keys($words) as $wlen){
         $word_idx = idx_getIndex('w',$wlen);
@@ -260,6 +262,7 @@ function idx_getPageWords($page){
             if(!is_int($wid)){
                 $wid = count($word_idx);
                 $word_idx[] = "$word\n";
+                $word_idx_modified = true;
             }
             if(!isset($index[$wlen]))
                 $index[$wlen] = array();
@@ -267,7 +270,7 @@ function idx_getPageWords($page){
         }
 
         // save back word index
-        if(!idx_saveIndex('w',$wlen,$word_idx)){
+        if($word_idx_modified && !idx_saveIndex('w',$wlen,$word_idx)){
             trigger_error("Failed to write word index", E_USER_ERROR);
             return false;
         }