parser caching update

This patch primarily updates p_cached_xhtml() and p_cached_instructions() to
allow their caching logic to be surrounded by an event trigger.

p_cached_xhtml() has been rewritten as the more general p_cached_output() to
support other render output formats besides 'xhtml'. All calls to
p_cached_xhtml() have been changed to refer to the new function.

New event:

name:        PARSER_CACHE_USE
data:        cache object (see below)
action:      determine if cache file can be used
preventable: yes
result:      bool, true to use cache file, false otherwise

Cache operations have been generalised in a new class, cache, extended to
cache_parser, cache_renderer & cache_instructions. Details can be found in
inc/cache.php

For handling of above event, key properties are:
- page, if present the wiki page id,
        may not always be present, e.g. when called for locale xhtml files
- file, source file
- mode, renderer mode (e.g. 'xhtml') or 'i' for instructions

Other changes:
- cache class counts cache hits against attempts, results are stored in
  {cache_dir}/cache_stats.txt
- adds metadata dependency to renderer page cache
- replaces purgefile dependency for renderer cache with metadata
  'relation references' (internal link) dependency for wiki pages only

darcs-hash:20060911021418-9b6ab-19601ed194b8c8e45236ab72c3e23d78bf777e6c.gz

1 files changed, 221 insertions, 0 deletions

diff --git a/inc/cache.php b/inc/cache.php
new file mode 100644
index 000000000..19d431560
--- /dev/null
+++ b/inc/cache.php
@@ -0,0 +1,221 @@
+<?php
+/**
+ * Generic class to handle caching
+ *
+ * @license    GPL 2 (http://www.gnu.org/licenses/gpl.html)
+ * @author     Chris Smith <chris@jalakai.co.uk>
+ */
+
+if(!defined('DOKU_INC')) define('DOKU_INC',realpath(dirname(__FILE__).'/../').'/');
+
+require_once(DOKU_INC.'inc/io.php');
+require_once(DOKU_INC.'inc/pageutils.php');
+require_once(DOKU_INC.'inc/parserutils.php');
+
+class cache {
+  var $key = '';        // primary identifier for this item
+  var $ext = '';        // file ext for cache data, secondary identifier for this item
+  var $cache = '';      // cache file name
+
+  var $_event = '';      // event to be triggered during useCache
+
+  function cache($key,$ext) {
+    $this->key = $key;
+    $this->ext = $ext;
+    $this->cache = getCacheName($key,$ext);
+  }
+
+  /**
+   * public method to determine whether the cache can be used
+   *
+   * to assist in cetralisation of event triggering and calculation of cache statistics, 
+   * don't override this function override _useCache()
+   *
+   * @param  array   $depends   array of cache dependencies, support dependecies:
+   *                            'age'   => max age of the cache in seconds
+   *                            'files' => cache must be younger than mtime of each file
+   *
+   * @return bool    true if cache can be used, false otherwise
+   */
+  function useCache($depends=array()) {
+    $this->depends = $depends;
+
+    if ($this->_event) {
+      return $this->_stats(trigger_event($this->_event,$this,array($this,'_useCache')));
+    } else {
+      return $this->_stats($this->_useCache());
+    }
+  }
+
+  /*
+   * private method containing cache use decision logic
+   *
+   * this function can be overridden
+   *
+   * @return bool               see useCache()
+   */
+  function _useCache() {
+
+    if (isset($_REQUEST['purge'])) return false;                    // purge requested?
+    if (!($this->_time = @filemtime($this->cache))) return false;   // cache exists?
+
+    // cache too old?
+    if (!empty($this->depends['age']) && ((time() - $this->_time) > $this->depends['age'])) return false;
+
+    if (!empty($this->depends['files'])) {
+      foreach ($this->depends['files'] as $file) {
+        if ($this->_time < @filemtime($file)) return false;         // cache older than files it depends on?
+      }
+    }
+
+    return true;
+  }
+
+  /**
+   * retrieve the cached data
+   *
+   * @param   bool   $clean   true to clean line endings, false to leave line endings alone
+   * @return  string          cache contents
+   */
+  function retrieveCache($clean=true) {
+    return io_readFile($this->cache, $clean);
+  }
+
+  /**
+   * cache $data
+   *
+   * @param   string $data   the data to be cached
+   * @return  none
+   */
+  function storeCache($data) {
+    io_savefile($this->cache, $data);
+  }
+
+  /**
+   * remove any cached data associated with this cache instance
+   */
+  function removeCache() {
+    @unlink($this->cache);
+  }
+
+  /**
+   * record cache hits statistics
+   *
+   * @param    bool   $success   result of this cache use attempt
+   * @return   bool              pass-thru $success value
+   */
+  function _stats($success) {
+    global $conf;
+    static $stats = NULL;
+    static $file;
+
+    if (is_null($stats)) {
+      $file = $conf['cachedir'].'/cache_stats.txt';
+      $lines = explode("\n",io_readFile($file));
+
+      foreach ($lines as $line) {
+        $i = strpos($line,',');
+	$stats[substr($line,0,$i)] = $line;
+      }
+    }
+
+    if (isset($stats[$this->ext])) {
+      list($ext,$count,$successes) = explode(',',$stats[$this->ext]);
+    } else {
+      $ext = $this->ext;
+      $count = 0;
+      $successes = 0;
+    }
+
+    $count++;
+    $successes += $success ? 1 : 0;
+    $stats[$this->ext] = "$ext,$count,$successes";
+
+    io_saveFile($file,join("\n",$stats));
+
+    return $success;
+  }
+}
+
+class cache_parser extends cache {
+
+  var $file = '';       // source file for cache
+  var $mode = '';       // input mode (represents the processing the input file will undergo)
+
+  var $_event = 'PARSER_CACHE_USE';
+
+  function cache_parser($id, $file, $mode) {
+    if ($id) $this->page = $id;
+    $this->file = $file;
+    $this->mode = $mode;
+
+    parent::cache($file.$_SERVER['HTTP_HOST'].$_SERVER['SERVER_PORT'],'.'.$mode);
+  }
+
+  function _useCache() {
+    global $conf;
+
+    if (!@file_exists($this->file)) return false;                   // source exists?
+
+    if (!isset($this->depends['age'])) $this->depends['age'] = $conf['cachetime'];
+
+    // parser cache file dependencies ...
+    $files = array($this->file,                                     // ... source
+                   DOKU_CONF.'dokuwiki.php',                        // ... config
+                   DOKU_CONF.'local.php',                           // ... local config
+                   DOKU_INC.'inc/parser/parser.php',                // ... parser
+                   DOKU_INC.'inc/parser/handler.php',               // ... handler
+             );
+
+    $this->depends['files'] = !empty($this->depends['files']) ? array_merge($files, $this->depends['files']) : $files;
+    return parent::_useCache($depends);
+  }
+
+}
+
+class cache_renderer extends cache_parser {
+
+  function _useCache() {
+    global $conf;
+
+    // renderer cache file dependencies ...
+    $files = array(
+#                   $conf['cachedir'].'/purgefile',                 // ... purgefile - time of last add
+                   DOKU_INC.'inc/parser/'.$this->mode.'.php',      // ... the renderer
+             );
+
+    if (isset($this->page)) { $files[] = metaFN($this->page,'.meta'); }
+
+    $this->depends['files'] = !empty($this->depends['files']) ? array_merge($files, $this->depends['files']) : $files;
+    if (!parent::_useCache($depends)) return false;
+
+    // for wiki pages, check for internal link status changes
+    if (isset($this->page)) {
+      $links = p_get_metadata($this->page,"relation references");
+
+      if (!empty($links)) {
+        foreach ($links as $id => $exists) {
+          if ($exists != @file_exists(wikiFN($id,'',false))) return false;
+	}
+      }
+    }
+
+    return true;
+  }
+}
+
+class cache_instructions extends cache_parser {
+
+  function cache_instructions($id, $file) {
+    parent::cache_parser($id, $file, 'i');
+  }
+
+  function retrieveCache() {
+    $contents = io_readFile($this->cache, false);
+    return !empty($contents) ? unserialize($contents) : array();
+  }
+
+  function storeCache($instructions) {
+    io_savefile($this->cache,serialize($instructions));
+  }
+}