scalable changelog redesign

This patch provides a rewritten changelog system that is designed to run
efficiently on both small and large wikis. The patch includes a plugin to
convert changelogs from the current format. The conversion is
non-destructive and happens automatically. For more information on the new
changelog format see "http://wiki.splitbrain.org/wiki:changelog".

Structure
In short the changelog is now stored in per-page changelog files, with a
recent changes cache. The recent changes cache is kept in
"/data/meta/_dokuwiki.changes" and trimmed daily. The per-page changelogs
are kept in "/data/meta/<ns>/<page_id>.changes" files. To preserve
revision information for revisions stored in the attic, the "*.changes"
files are not removed when their page is deleted. This allows the full
life-cycle of page creation, deletion, and reversion to be tracked.

Format
The changelog line format now uses a general "line type" field in place of
the special "minor" change syntax. There is also an extra field that can
be used to store arbitrary data associated with special line types. The
reverted line type (R) is a good example. There the extra field holds the
revision date used as the source for reverting the page. See the wiki for
the complete syntax description.

Code Notes
The changelog functions have been rewritten to load the whole file only if
it is small. For larger files, the function loads only the relevant
chunk(s). Parsed changelog lines are cached in memory to speed future
function calls.

getRevisionInfo
A binary search is used to locate the chunk expected to contain the
requested revision. The whole chunk is parsed, and adjacent lines are
optimistically cached to speed consecutive calls.

getRevisions
Reads the changelog file backwards (newest first) in chunks until the
requested number of lines have been read. Parsed changelog lines are
cached for subsequent calls to getRevisionInfo. Because revisions are read
from the changelog they are no longer guaranteed to exist in the attic.

(Note: Even with lines of arbitrary length getRevisionInfo and
getRevisions never split changelog lines while reading. This is done by
sliding the "file pointer" forward to the end of a line after each blind
seek.)

isMinor
Removed. To detect a minor edit check the type as follows:
$parsed_logline['type']

darcs-hash:20060830182753-05dcb-1c5ea17f581197a33732a8d11da223d809c03506.gz

1 files changed, 294 insertions, 272 deletions

diff --git a/inc/common.php b/inc/common.php
index 3064c4fda..a0e1e882b 100644
--- a/inc/common.php
+++ b/inc/common.php
@@ -94,16 +94,20 @@ function pageinfo(){
   $info['editable']  = ($info['writable'] && empty($info['lock']));
   $info['lastmod']   = @filemtime($info['filepath']);
 
+  //load page meta data
+  $info['meta'] = p_get_metadata($ID);
+
   //who's the editor
   if($REV){
-    $revinfo = getRevisionInfo($ID,$REV,false);
+    $revinfo = getRevisionInfo($ID, $REV, 1024);
   }else{
-    $revinfo = getRevisionInfo($ID,$info['lastmod'],false);
+    $revinfo = $info['meta']['last_change'];
   }
   $info['ip']     = $revinfo['ip'];
   $info['user']   = $revinfo['user'];
   $info['sum']    = $revinfo['sum'];
-  $info['minor']  = $revinfo['minor'];
+  // See also $INFO['meta']['last_change'] which is the most recent log line for page $ID.
+  // Use $INFO['meta']['last_change']['type']==='e' in place of $info['minor'].
 
   if($revinfo['user']){
     $info['editor'] = $revinfo['user'];
@@ -710,46 +714,53 @@ function dbglog($msg){
 }
 
 /**
- * Add's an entry to the changelog
+ * Add's an entry to the changelog and saves the metadata for the page
  *
  * @author Andreas Gohr <andi@splitbrain.org>
+ * @author Esther Brunner <wikidesign@gmail.com>
+ * @author Ben Coburn <btcoburn@silicodon.net>
  */
-function addLogEntry($date,$id,$summary='',$minor=false){
-  global $conf;
+function addLogEntry($date, $id, $type='E', $summary='', $extra=''){
+  global $conf, $INFO;
 
-  if(!@is_writable($conf['changelog'])){
-    msg($conf['changelog'].' is not writable!',-1);
-    return;
-  }
+  $id = cleanid($id);
+  $file = wikiFN($id);
+  $created = @filectime($file);
+  $minor = ($type==='e');
+  $wasRemoved = ($type==='D');
 
   if(!$date) $date = time(); //use current time if none supplied
   $remote = $_SERVER['REMOTE_ADDR'];
   $user   = $_SERVER['REMOTE_USER'];
 
-  if($conf['useacl'] && $user && $minor){
-    $summary = '*'.$summary;
-  }else{
-    $summary = ' '.$summary;
+  $logline = array(
+    'date'  => $date,
+    'ip'    => $remote,
+    'type'  => $type,
+    'id'    => $id,
+    'user'  => $user,
+    'sum'   => $summary,
+    'extra' => $extra
+  );
+
+  // update metadata
+  if (!$wasRemoved) {
+    $meta = array();
+    if (!$INFO['exists']){ // newly created
+      $meta['date']['created'] = $created;
+      if ($user) $meta['creator'] = $INFO['userinfo']['name'];
+    } elseif (!$minor) {   // non-minor modification
+      $meta['date']['modified'] = $date;
+      if ($user) $meta['contributor'][$user] = $INFO['userinfo']['name'];
+    }
+    $meta['last_change'] = $logline;
+    p_set_metadata($id, $meta, true);
   }
 
-  $logline = join("\t",array($date,$remote,$id,$user,$summary))."\n";
-  io_saveFile($conf['changelog'],$logline,true);
-}
-
-/**
- * Checks an summary entry if it was a minor edit
- *
- * The summary is cleaned of the marker char
- *
- * @author Andreas Gohr <andi@splitbrain.org>
- */
-function isMinor(&$summary){
-  if(substr($summary,0,1) == '*'){
-    $summary = substr($summary,1);
-    return true;
-  }
-  $summary = trim($summary);
-  return false;
+  // add changelog lines
+  $logline = implode("\t", $logline)."\n";
+  io_saveFile(metaFN($id,'.changes'),$logline,true); //page changelog
+  io_saveFile($conf['changelog'],$logline,true); //global changelog cache
 }
 
 /**
@@ -759,58 +770,39 @@ function isMinor(&$summary){
  *
  * @see getRecents()
  * @author Andreas Gohr <andi@splitbrain.org>
+ * @author Ben Coburn <btcoburn@silicodon.net>
  */
 function _handleRecent($line,$ns,$flags){
   static $seen  = array();         //caches seen pages and skip them
   if(empty($line)) return false;   //skip empty lines
 
   // split the line into parts
-  list($dt,$ip,$id,$usr,$sum) = explode("\t",$line);
+  $recent = parseChangelogLine($line);
+  if ($recent===false) { return false; }
 
   // skip seen ones
-  if($seen[$id]) return false;
-  $recent = array();
+  if(isset($seen[$recent['id']])) return false;
 
-  // check minors
-  if(isMinor($sum)){
-    // skip minors
-    if($flags & RECENTS_SKIP_MINORS) return false;
-    $recent['minor'] = true;
-  }else{
-    $recent['minor'] = false;
-  }
+  // skip minors
+  if($recent['type']==='e' && ($flags & RECENTS_SKIP_MINORS)) return false;
 
   // remember in seen to skip additional sights
-  $seen[$id] = 1;
+  $seen[$recent['id']] = 1;
 
   // check if it's a hidden page
-  if(isHiddenPage($id)) return false;
+  if(isHiddenPage($recent['id'])) return false;
 
   // filter namespace
-  if (($ns) && (strpos($id,$ns.':') !== 0)) return false;
+  if (($ns) && (strpos($recent['id'],$ns.':') !== 0)) return false;
 
   // exclude subnamespaces
-  if (($flags & RECENTS_SKIP_SUBSPACES) && (getNS($id) != $ns)) return false;
+  if (($flags & RECENTS_SKIP_SUBSPACES) && (getNS($recent['id']) != $ns)) return false;
 
   // check ACL
-  if (auth_quickaclcheck($id) < AUTH_READ) return false;
+  if (auth_quickaclcheck($recent['id']) < AUTH_READ) return false;
 
   // check existance
-  if(!@file_exists(wikiFN($id))){
-    if($flags & RECENTS_SKIP_DELETED){
-      return false;
-    }else{
-      $recent['del'] = true;
-    }
-  }else{
-    $recent['del'] = false;
-  }
-
-  $recent['id']   = $id;
-  $recent['date'] = $dt;
-  $recent['ip']   = $ip;
-  $recent['user'] = $usr;
-  $recent['sum']  = $sum;
+  if((!@file_exists(wikiFN($recent['id']))) && ($flags & RECENTS_SKIP_DELETED)) return false;
 
   return $recent;
 }
@@ -832,7 +824,7 @@ function _handleRecent($line,$ns,$flags){
  * @param string $ns      restrict to given namespace
  * @param bool   $flags   see above
  *
- * @author Andreas Gohr <andi@splitbrain.org>
+ * @author Ben Coburn <btcoburn@silicodon.net>
  */
 function getRecents($first,$num,$ns='',$flags=0){
   global $conf;
@@ -842,190 +834,245 @@ function getRecents($first,$num,$ns='',$flags=0){
   if(!$num)
     return $recent;
 
-  if(!@is_readable($conf['changelog'])){
-    msg($conf['changelog'].' is not readable',-1);
-    return $recent;
-  }
-
-  $fh  = fopen($conf['changelog'],'r');
-  $buf = '';
-  $csz = 4096;                              //chunksize
-  fseek($fh,0,SEEK_END);                    // jump to the end
-  $pos = ftell($fh);                        // position pointer
-
-  // now read backwards into buffer
-  while($pos > 0){
-    $pos -= $csz;                           // seek to previous chunk...
-    if($pos < 0) {                          // ...or rest of file
-      $csz += $pos;
-      $pos = 0;
+  // read all recent changes. (kept short)
+  $lines = file($conf['changelog']);
+
+  // handle lines
+  for($i = count($lines)-1; $i >= 0; $i--){
+    $rec = _handleRecent($lines[$i], $ns, $flags);
+    if($rec !== false) {
+      if(--$first >= 0) continue; // skip first entries
+      $recent[] = $rec;
+      $count++;
+      // break when we have enough entries
+      if($count >= $num){ break; }
     }
+  }
 
-    fseek($fh,$pos);
-
-    $buf = fread($fh,$csz).$buf;            // prepend to buffer
-
-    $lines = explode("\n",$buf);            // split buffer into lines
-
-    if($pos > 0){
-      $buf = array_shift($lines);           // first one may be still incomplete
-    }
-
-    $cnt = count($lines);
-    if(!$cnt) continue;                     // no lines yet
-
-    // handle lines
-    for($i = $cnt-1; $i >= 0; $i--){
-      $rec = _handleRecent($lines[$i],$ns,$flags);
-      if($rec !== false){
-        if(--$first >= 0) continue;         // skip first entries
-        $recent[] = $rec;
-        $count++;
-
-        // break while when we have enough entries
-        if($count >= $num){
-          $pos = 0; // will break the while loop
-          break;    // will break the for loop
-        }
-      }
-    }
-  }// end of while
-
-  fclose($fh);
   return $recent;
 }
 
 /**
- * Compare the logline $a to the timestamp $b
- * @author Yann Hamon <yann.hamon@mandragor.org>
- * @return integer 0 if the logline has timestamp $b, <0 if the timestam
- *         of $a is greater than $b, >0 else.
- */
-function hasTimestamp($a, $b)
-{
-  if (strpos($a, $b) === 0)
-    return 0;
-  else
-    return strcmp ($a, $b);
-}
-
-/**
- * performs a dichotomic search on an array using
- * a custom compare function
+ * parses a changelog line into it's components
  *
- * @author Yann Hamon <yann.hamon@mandragor.org>
+ * @author Ben Coburn <btcoburn@silicodon.net>
  */
-function array_dichotomic_search($ar, $value, $compareFunc) {
-  $value = trim($value);
-  if (!$ar || !$value || !$compareFunc) return (null);
-  $len = count($ar);
-
-  $l = 0;
-  $r = $len-1;
-
-  do {
-    $i = floor(($l+$r)/2);
-    if ($compareFunc($ar[$i], $value)<0)
-      $l = $i+1;
-    else
-     $r = $i-1;
-  } while ($compareFunc($ar[$i], $value)!=0 && $l<=$r);
-
-  if ($compareFunc($ar[$i], $value)==0)
-    return $i;
-  else
-    return -1;
+function parseChangelogLine($line) {
+  $tmp = explode("\t", $line);
+    if ($tmp!==false && count($tmp)>1) {
+      $info = array();
+      $info['date']  = $tmp[0]; // unix timestamp
+      $info['ip']    = $tmp[1]; // IPv4 address (127.0.0.1)
+      $info['type']  = $tmp[2]; // log line type
+      $info['id']    = $tmp[3]; // page id
+      $info['user']  = $tmp[4]; // user name
+      $info['sum']   = $tmp[5]; // edit summary (or action reason)
+      $info['extra'] = rtrim($tmp[6], "\n"); // extra data (varies by line type)
+      return $info;
+  } else { return false; }
 }
 
 /**
- * gets additonal informations for a certain pagerevison
- * from the changelog
+ * Get the changelog information for a specific page id
+ * and revision (timestamp). Adjacent changelog lines
+ * are optimistically parsed and cached to speed up
+ * consecutive calls to getRevisionInfo. For large
+ * changelog files, only the chunk containing the
+ * requested changelog line is read.
  *
- * @author Andreas Gohr <andi@splitbrain.org>
- * @author Yann Hamon <yann.hamon@mandragor.org>
  * @author Ben Coburn <btcoburn@silicodon.net>
  */
-function getRevisionInfo($id,$rev,$mem_cache=true){
-  global $conf;
-  global $doku_temporary_revinfo_cache;
-  $cache =& $doku_temporary_revinfo_cache;
-  if(!$rev) return(null);
+function getRevisionInfo($id, $rev, $chunk_size=8192) {
+  global $cache_revinfo;
+  $cache =& $cache_revinfo;
+  if (!isset($cache[$id])) { $cache[$id] = array(); }
+  $rev = max($rev, 0);
 
   // check if it's already in the memory cache
-  if (is_array($cache) && isset($cache[$id]) && isset($cache[$id][$rev])) {
+  if (isset($cache[$id]) && isset($cache[$id][$rev])) {
     return $cache[$id][$rev];
   }
 
-  $info = array();
-  if(!@is_readable($conf['changelog'])){
-    msg($conf['changelog'].' is not readable',-1);
-    return $recent;
-  }
-  $loglines = file($conf['changelog']);
-
-  if (!$mem_cache) {
-    // Search for a line with a matching timestamp
-    $index = array_dichotomic_search($loglines, $rev, 'hasTimestamp');
-    if ($index == -1)
-      return;
-
-    // The following code is necessary when there is more than
-    // one line with one same timestamp
-    $loglines_matching = array();
-    for ($i=$index-1;$i>=0 && hasTimestamp($loglines[$i], $rev) == 0; $i--)
-      $loglines_matching[] = $loglines[$i];
-    $loglines_matching = array_reverse($loglines_matching);
-    $loglines_matching[] =  $loglines[$index];
-    $logsize = count($loglines);
-    for ($i=$index+1;$i<$logsize && hasTimestamp($loglines[$i], $rev) == 0; $i++)
-      $loglines_matching[] = $loglines[$i];
-
-    // pull off the line most recent line with the right id
-    $loglines_matching = array_reverse($loglines_matching); //newest first
-    foreach ($loglines_matching as $logline) {
-      $line = explode("\t", $logline);
-      if ($line[2]==$id) {
-        $info['date']  = $line[0];
-        $info['ip']    = $line[1];
-        $info['user']  = $line[3];
-        $info['sum']   = $line[4];
-        $info['minor'] = isMinor($info['sum']);
-        break;
+  $file = metaFN($id, '.changes');
+  if (!file_exists($file)) { return false; }
+  if (filesize($file)<$chunk_size || $chunk_size==0) {
+    // read whole file
+    $lines = file($file);
+    if ($lines===false) { return false; }
+  } else {
+    // read by chunk
+    $fp = fopen($file, 'rb'); // "file pointer"
+    if ($fp===false) { return false; }
+    $head = 0;
+    fseek($fp, 0, SEEK_END);
+    $tail = ftell($fp);
+    $finger = 0;
+    $finger_rev = 0;
+
+    // find chunk
+    while ($tail-$head>$chunk_size) {
+      $finger = $head+floor(($tail-$head)/2.0);
+      fseek($fp, $finger);
+      fgets($fp); // slip the finger forward to a new line
+      $finger = ftell($fp);
+      $tmp = fgets($fp); // then read at that location
+      $tmp = parseChangelogLine($tmp);
+      $finger_rev = $tmp['date'];
+      if ($finger==$head || $finger==$tail) { break; }
+      if ($finger_rev>$rev) {
+        $tail = $finger;
+      } else {
+        $head = $finger;
       }
     }
+
+    if ($tail-$head<1) {
+      // cound not find chunk, assume requested rev is missing
+      fclose($fp);
+      return false;
+    }
+
+    // read chunk
+    $chunk = '';
+    $chunk_size = max($tail-$head, 0); // found chunk size
+    $got = 0;
+    fseek($fp, $head);
+    while ($got<$chunk_size && !feof($fp)) {
+      $tmp = fread($fp, max($chunk_size-$got, 0));
+      if ($tmp===false) { break; } //error state
+      $got += strlen($tmp);
+      $chunk .= $tmp;
+    }
+    $lines = explode("\n", $chunk);
+    array_pop($lines); // remove trailing newline
+    fclose($fp);
+  }
+
+  // parse and cache changelog lines
+  foreach ($lines as $value) {
+    $tmp = parseChangelogLine($value);
+    if ($tmp!==false) {
+      $cache[$id][$tmp['date']] = $tmp;
+    }
+  }
+  if (!isset($cache[$id][$rev])) { return false; }
+  return $cache[$id][$rev];
+}
+
+/**
+ * Return a list of page revisions numbers
+ * Does not guarantee that the revision exists in the attic,
+ * only that a line with the date exists in the changelog.
+ * By default the current revision is skipped.
+ *
+ * id:    the page of interest
+ * first: skip the first n changelog lines
+ * num:   number of revisions to return
+ *
+ * The current revision is automatically skipped when the page exists.
+ * See $INFO['meta']['last_change'] for the current revision.
+ *
+ * For efficiency, the log lines are parsed and cached for later
+ * calls to getRevisionInfo. Large changelog files are read
+ * backwards in chunks untill the requested number of changelog
+ * lines are recieved.
+ *
+ * @author Ben Coburn <btcoburn@silicodon.net>
+ */
+function getRevisions($id, $first, $num, $chunk_size=8192) {
+  global $cache_revinfo;
+  $cache =& $cache_revinfo;
+  if (!isset($cache[$id])) { $cache[$id] = array(); }
+
+  $revs = array();
+  $lines = array();
+  $count  = 0;
+  $file = metaFN($id, '.changes');
+  $num = max($num, 0);
+  $chunk_size = max($chunk_size, 0);
+  if ($first<0) { $first = 0; }
+  else if (file_exists(wikiFN($id))) {
+     // skip current revision if the page exists
+    $first = max($first+1, 0);
+  }
+
+  if (!file_exists($file)) { return $revs; }
+  if (filesize($file)<$chunk_size || $chunk_size==0) {
+    // read whole file
+    $lines = file($file);
+    if ($lines===false) { return $revs; }
   } else {
-    // load and cache all the lines with the right id
-    if(!is_array($cache)) { $cache = array(); }
-    if (!isset($cache[$id])) { $cache[$id] = array(); }
-    foreach ($loglines as $logline) {
-      $start = strpos($logline, "\t", strpos($logline, "\t")+1)+1;
-      $end = strpos($logline, "\t", $start);
-      if (substr($logline, $start, $end-$start)==$id) {
-        $line = explode("\t", $logline);
-        $info = array();
-        $info['date']  = $line[0];
-        $info['ip']    = $line[1];
-        $info['user']  = $line[3];
-        $info['sum']   = $line[4];
-        $info['minor'] = isMinor($info['sum']);
-        $cache[$id][$info['date']] = $info;
+    // read chunks backwards
+    $fp = fopen($file, 'rb'); // "file pointer"
+    if ($fp===false) { return $revs; }
+    fseek($fp, 0, SEEK_END);
+    $tail = ftell($fp);
+
+    // chunk backwards
+    $finger = max($tail-$chunk_size, 0);
+    while ($count<$num+$first) {
+      fseek($fp, $finger);
+      if ($finger>0) {
+        fgets($fp); // slip the finger forward to a new line
+        $finger = ftell($fp);
+      }
+
+      // read chunk
+      if ($tail<=$finger) { break; }
+      $chunk = '';
+      $read_size = max($tail-$finger, 0); // found chunk size
+      $got = 0;
+      while ($got<$read_size && !feof($fp)) {
+        $tmp = fread($fp, max($read_size-$got, 0));
+        if ($tmp===false) { break; } //error state
+        $got += strlen($tmp);
+        $chunk .= $tmp;
+      }
+      $tmp = explode("\n", $chunk);
+      array_pop($tmp); // remove trailing newline
+
+      // combine with previous chunk
+      $count += count($tmp);
+      $lines = array_merge($tmp, $lines);
+
+      // next chunk
+      if ($finger==0) { break; } // already read all the lines
+      else {
+        $tail = $finger;
+        $finger = max($tail-$chunk_size, 0);
       }
     }
-    $info = $cache[$id][$rev];
+    fclose($fp);
   }
 
-  return $info;
-}
+  // skip parsing extra lines
+  $num = max(min(count($lines)-$first, $num), 0);
+  if      ($first>0 && $num>0)  { $lines = array_slice($lines, max(count($lines)-$first-$num, 0), $num); }
+  else if ($first>0 && $num==0) { $lines = array_slice($lines, 0, max(count($lines)-$first, 0)); }
+  else if ($first==0 && $num>0) { $lines = array_slice($lines, max(count($lines)-$num, 0)); }
 
+  // handle lines in reverse order
+  for ($i = count($lines)-1; $i >= 0; $i--) {
+    $tmp = parseChangelogLine($lines[$i]);
+    if ($tmp!==false) {
+      $cache[$id][$tmp['date']] = $tmp;
+      $revs[] = $tmp['date'];
+    }
+  }
+
+  return $revs;
+}
 
 /**
  * Saves a wikitext by calling io_writeWikiPage
  *
  * @author Andreas Gohr <andi@splitbrain.org>
+ * @author Ben Coburn <btcoburn@silicodon.net>
  */
 function saveWikiText($id,$text,$summary,$minor=false){
   global $conf;
   global $lang;
+  global $REV;
   // ignore if no changes were made
   if($text == rawWiki($id,'')){
     return;
@@ -1033,14 +1080,19 @@ function saveWikiText($id,$text,$summary,$minor=false){
 
   $file = wikiFN($id);
   $old  = saveOldRevision($id);
+  $wasRemoved = empty($text);
+  $wasCreated = !file_exists($file);
+  $wasReverted = ($REV==true);
 
-  if (empty($text)){
+  if ($wasRemoved){
     // remove empty file
     @unlink($file);
-    // remove any meta info
+    // remove old meta info...
     $mfiles = metaFiles($id);
+    $changelog = metaFN($id, '.changes');
     foreach ($mfiles as $mfile) {
-      if (file_exists($mfile)) @unlink($mfile);
+      // but keep per-page changelog to preserve page history
+      if (file_exists($mfile) && $mfile!==$changelog) { @unlink($mfile); }
     }
     $del = true;
     // autoset summary on deletion
@@ -1051,11 +1103,21 @@ function saveWikiText($id,$text,$summary,$minor=false){
   }else{
     // save file (namespace dir is created in io_writeWikiPage)
     io_writeWikiPage($file, $text, $id);
-    saveMetadata($id, $file, $minor);
     $del = false;
   }
 
-  addLogEntry(@filemtime($file),$id,$summary,$minor);
+  // select changelog line type
+  $extra = '';
+  $type = 'E';
+  if ($wasReverted) {
+    $type = 'R';
+    $extra = $REV;
+  }
+  else if ($wasCreated) { $type = 'C'; }
+  else if ($wasRemoved) { $type = 'D'; }
+  else if ($minor && $conf['useacl'] && $_SERVER['REMOTE_USER']) { $type = 'e'; } //minor edits only for logged in users
+
+  addLogEntry(@filemtime($file), $id, $type, $summary, $extra);
   // send notify mails
   notify($id,'admin',$old,$summary,$minor);
   notify($id,'subscribers',$old,$summary,$minor);
@@ -1067,27 +1129,6 @@ function saveWikiText($id,$text,$summary,$minor=false){
 }
 
 /**
- * saves the metadata for a page
- *
- * @author Esther Brunner <wikidesign@gmail.com>
- */
-function saveMetadata($id, $file, $minor){
-  global $INFO;
-  
-  $user = $_SERVER['REMOTE_USER'];
-  
-  $meta = array();
-  if (!$INFO['exists']){ // newly created
-    $meta['date']['created'] = @filectime($file);
-    if ($user) $meta['creator'] = $INFO['userinfo']['name'];
-  } elseif (!$minor) {   // non-minor modification
-    $meta['date']['modified'] = @filemtime($file);
-    if ($user) $meta['contributor'][$user] = $INFO['userinfo']['name'];
-  }
-  p_set_metadata($id, $meta, true);
-}
-
-/**
  * moves the current version to the attic and returns its
  * revision date
  *
@@ -1178,39 +1219,6 @@ function notify($id,$who,$rev='',$summary='',$minor=false,$replace=array()){
 }
 
 /**
- * Return a list of available page revisons
- *
- * @author Andreas Gohr <andi@splitbrain.org>
- */
-function getRevisions($id){
-  global $conf;
-
-  $id   = cleanID($id);
-  $revd = dirname(wikiFN($id,'foo'));
-  $id   = noNS($id);
-  $id   = utf8_encodeFN($id);
-  $len  = strlen($id);
-  $xlen = 10; // length of timestamp, strlen(time()) would be more correct, 
-              // but i don't expect dokuwiki still running in 287 years ;)
-              // so this will perform better
-
-  $revs = array();
-  if (is_dir($revd) && $dh = opendir($revd)) {
-    while (($file = readdir($dh)) !== false) {
-      if (substr($file,0,$len) === $id) {
-        $time = substr($file,$len+1,$xlen);
-        $time = str_replace('.','FOO',$time); // make sure a dot will make the next test fail
-        $time = (int) $time;
-        if($time) $revs[] = $time;
-      }
-    }
-    closedir($dh);
-  }
-  rsort($revs);
-  return $revs;
-}
-
-/**
  * extracts the query from a google referer
  *
  * @todo   should be more generic and support yahoo et al
@@ -1339,7 +1347,21 @@ function check(){
   if(is_writable($conf['changelog'])){
     msg('Changelog is writable',1);
   }else{
-    msg('Changelog is not writable',-1);
+    if (file_exists($conf['changelog'])) {
+      msg('Changelog is not writable',-1);
+    }
+  }
+
+  if (isset($conf['changelog_old']) && file_exists($conf['changelog_old'])) {
+    msg('Old changelog exists.', 0);
+  }
+
+  if (file_exists($conf['changelog'].'_failed')) {
+    msg('Importing old changelog failed.', -1);
+  } else if (file_exists($conf['changelog'].'_importing')) {
+    msg('Importing old changelog now.', 0);
+  } else if (file_exists($conf['changelog'].'_import_ok')) {
+    msg('Old changelog imported.', 1);
   }
 
   if(is_writable($conf['datadir'])){