xref: /dokuwiki/inc/cache.php (revision b4f2363aa1360136c8a826f09aaebc6505211c73) 
1<?php
2/**
3 * Generic class to handle caching
4 *
5 * @license    GPL 2 (http://www.gnu.org/licenses/gpl.html)
6 * @author     Chris Smith <chris@jalakai.co.uk>
7 */
8
9/**
10 * Generic handling of caching
11 */
12class cache {
13    public $key = '';          // primary identifier for this item
14    public $ext = '';          // file ext for cache data, secondary identifier for this item
15    public $cache = '';        // cache file name
16    public $depends = array(); // array containing cache dependency information,
17                               //   used by _useCache to determine cache validity
18
19    public $_event = '';       // event to be triggered during useCache
20    public $_time;
21    public $_nocache = false;  // if set to true, cache will not be used or stored
22
23    /**
24     * @param string $key primary identifier
25     * @param string $ext file extension
26     */
27    public function __construct($key,$ext) {
28        $this->key = $key;
29        $this->ext = $ext;
30        $this->cache = getCacheName($key,$ext);
31    }
32
33    /**
34     * public method to determine whether the cache can be used
35     *
36     * to assist in centralisation of event triggering and calculation of cache statistics,
37     * don't override this function override _useCache()
38     *
39     * @param  array   $depends   array of cache dependencies, support dependecies:
40     *                            'age'   => max age of the cache in seconds
41     *                            'files' => cache must be younger than mtime of each file
42     *                                       (nb. dependency passes if file doesn't exist)
43     *
44     * @return bool    true if cache can be used, false otherwise
45     */
46    public function useCache($depends=array()) {
47        $this->depends = $depends;
48        $this->_addDependencies();
49
50        if ($this->_event) {
51            return $this->_stats(trigger_event($this->_event, $this, array($this,'_useCache')));
52        } else {
53            return $this->_stats($this->_useCache());
54        }
55    }
56
57    /**
58     * private method containing cache use decision logic
59     *
60     * this function processes the following keys in the depends array
61     *   purge - force a purge on any non empty value
62     *   age   - expire cache if older than age (seconds)
63     *   files - expire cache if any file in this array was updated more recently than the cache
64     *
65     * Note that this function needs to be public as it is used as callback for the event handler
66     *
67     * can be overridden
68     *
69     * @return bool               see useCache()
70     */
71    public function _useCache() {
72
73        if ($this->_nocache) return false;                              // caching turned off
74        if (!empty($this->depends['purge'])) return false;              // purge requested?
75        if (!($this->_time = @filemtime($this->cache))) return false;   // cache exists?
76
77        // cache too old?
78        if (!empty($this->depends['age']) && ((time() - $this->_time) > $this->depends['age'])) return false;
79
80        if (!empty($this->depends['files'])) {
81            foreach ($this->depends['files'] as $file) {
82                if ($this->_time <= @filemtime($file)) return false;         // cache older than files it depends on?
83            }
84        }
85
86        return true;
87    }
88
89    /**
90     * add dependencies to the depends array
91     *
92     * this method should only add dependencies,
93     * it should not remove any existing dependencies and
94     * it should only overwrite a dependency when the new value is more stringent than the old
95     */
96    protected function _addDependencies() {
97        global $INPUT;
98        if ($INPUT->has('purge')) $this->depends['purge'] = true;   // purge requested
99    }
100
101    /**
102     * retrieve the cached data
103     *
104     * @param   bool   $clean   true to clean line endings, false to leave line endings alone
105     * @return  string          cache contents
106     */
107    public function retrieveCache($clean=true) {
108        return io_readFile($this->cache, $clean);
109    }
110
111    /**
112     * cache $data
113     *
114     * @param   string $data   the data to be cached
115     * @return  bool           true on success, false otherwise
116     */
117    public function storeCache($data) {
118        if ($this->_nocache) return false;
119
120        return io_savefile($this->cache, $data);
121    }
122
123    /**
124     * remove any cached data associated with this cache instance
125     */
126    public function removeCache() {
127        @unlink($this->cache);
128    }
129
130    /**
131     * Record cache hits statistics.
132     * (Only when debugging allowed, to reduce overhead.)
133     *
134     * @param    bool   $success   result of this cache use attempt
135     * @return   bool              pass-thru $success value
136     */
137    protected function _stats($success) {
138        global $conf;
139        static $stats = null;
140        static $file;
141
142        if (!$conf['allowdebug']) { return $success; }
143
144        if (is_null($stats)) {
145            $file = $conf['cachedir'].'/cache_stats.txt';
146            $lines = explode("\n",io_readFile($file));
147
148            foreach ($lines as $line) {
149                $i = strpos($line,',');
150                $stats[substr($line,0,$i)] = $line;
151            }
152        }
153
154        if (isset($stats[$this->ext])) {
155            list($ext,$count,$hits) = explode(',',$stats[$this->ext]);
156        } else {
157            $ext = $this->ext;
158            $count = 0;
159            $hits = 0;
160        }
161
162        $count++;
163        if ($success) $hits++;
164        $stats[$this->ext] = "$ext,$count,$hits";
165
166        io_saveFile($file,join("\n",$stats));
167
168        return $success;
169    }
170}
171
172/**
173 * Parser caching
174 */
175class cache_parser extends cache {
176
177    public $file = '';       // source file for cache
178    public $mode = '';       // input mode (represents the processing the input file will undergo)
179    public $page = '';
180
181    public $_event = 'PARSER_CACHE_USE';
182
183    /**
184     *
185     * @param string $id page id
186     * @param string $file source file for cache
187     * @param string $mode input mode
188     */
189    public function __construct($id, $file, $mode) {
190        if ($id) $this->page = $id;
191        $this->file = $file;
192        $this->mode = $mode;
193
194        parent::__construct($file.$_SERVER['HTTP_HOST'].$_SERVER['SERVER_PORT'],'.'.$mode);
195    }
196
197    /**
198     * method contains cache use decision logic
199     *
200     * @return bool               see useCache()
201     */
202    public function _useCache() {
203
204        if (!file_exists($this->file)) return false;                   // source exists?
205        return parent::_useCache();
206    }
207
208    protected function _addDependencies() {
209
210        // parser cache file dependencies ...
211        $files = array($this->file,                              // ... source
212                DOKU_INC.'inc/parser/parser.php',                // ... parser
213                DOKU_INC.'inc/parser/handler.php',               // ... handler
214                );
215        $files = array_merge($files, getConfigFiles('main'));    // ... wiki settings
216
217        $this->depends['files'] = !empty($this->depends['files']) ? array_merge($files, $this->depends['files']) : $files;
218        parent::_addDependencies();
219    }
220
221}
222
223/**
224 * Caching of data of renderer
225 */
226class cache_renderer extends cache_parser {
227
228    /**
229     * method contains cache use decision logic
230     *
231     * @return bool               see useCache()
232     */
233    public function _useCache() {
234        global $conf;
235
236        if (!parent::_useCache()) return false;
237
238        if (!isset($this->page)) {
239            return true;
240        }
241
242        if ($this->_time < @filemtime(metaFN($this->page,'.meta'))) return false;         // meta cache older than file it depends on?
243
244        // check current link existence is consistent with cache version
245        // first check the purgefile
246        // - if the cache is more recent than the purgefile we know no links can have been updated
247        if ($this->_time >= @filemtime($conf['cachedir'].'/purgefile')) {
248            return true;
249        }
250
251        // for wiki pages, check metadata dependencies
252        $metadata = p_get_metadata($this->page);
253
254        if (!isset($metadata['relation']['references']) ||
255                empty($metadata['relation']['references'])) {
256            return true;
257        }
258
259        foreach ($metadata['relation']['references'] as $id => $exists) {
260            if ($exists != page_exists($id,'',false)) return false;
261        }
262
263        return true;
264    }
265
266    protected function _addDependencies() {
267        global $conf;
268
269        // default renderer cache file 'age' is dependent on 'cachetime' setting, two special values:
270        //    -1 : do not cache (should not be overridden)
271        //    0  : cache never expires (can be overridden) - no need to set depends['age']
272        if ($conf['cachetime'] == -1) {
273            $this->_nocache = true;
274            return;
275        } elseif ($conf['cachetime'] > 0) {
276            $this->depends['age'] = isset($this->depends['age']) ?
277                min($this->depends['age'],$conf['cachetime']) : $conf['cachetime'];
278        }
279
280        // renderer cache file dependencies ...
281        $files = array(
282                DOKU_INC.'inc/parser/'.$this->mode.'.php',       // ... the renderer
283                );
284
285        // page implies metadata and possibly some other dependencies
286        if (isset($this->page)) {
287
288            $valid = p_get_metadata($this->page, 'date valid');         // for xhtml this will render the metadata if needed
289            if (!empty($valid['age'])) {
290                $this->depends['age'] = isset($this->depends['age']) ?
291                    min($this->depends['age'],$valid['age']) : $valid['age'];
292            }
293        }
294
295        $this->depends['files'] = !empty($this->depends['files']) ? array_merge($files, $this->depends['files']) : $files;
296        parent::_addDependencies();
297    }
298}
299
300/**
301 * Caching of parser instructions
302 */
303class cache_instructions extends cache_parser {
304
305    /**
306     * @param string $id page id
307     * @param string $file source file for cache
308     */
309    public function __construct($id, $file) {
310        parent::__construct($id, $file, 'i');
311    }
312
313    /**
314     * retrieve the cached data
315     *
316     * @param   bool   $clean   true to clean line endings, false to leave line endings alone
317     * @return  array          cache contents
318     */
319    public function retrieveCache($clean=true) {
320        $contents = io_readFile($this->cache, false);
321        return !empty($contents) ? unserialize($contents) : array();
322    }
323
324    /**
325     * cache $instructions
326     *
327     * @param   array $instructions  the instruction to be cached
328     * @return  bool                  true on success, false otherwise
329     */
330    public function storeCache($instructions) {
331        if ($this->_nocache) return false;
332
333        return io_savefile($this->cache,serialize($instructions));
334    }
335}
336