dmemcache.inc 34.3 KB
Newer Older
1 2
<?php

3 4 5 6 7
/**
 * @file
 * A memcache API for Drupal.
 *
 * This file contains core dmemcache functions required by:
8
 *   memcache.inc
9 10 11
 *   memcache-lock.inc
 *   memcache-lock-code.inc
 *   memcache-session.inc
12 13
 */

14 15
define('MEMCACHED_E2BIG', 37);

16 17
global $_dmemcache_stats;
$_dmemcache_stats = array('all' => array(), 'ops' => array());
18 19

/**
20
 * Place an item into memcache.
21
 *
22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37
 * @param string $key
 *   The string with which you will retrieve this item later.
 * @param mixed $value
 *   The item to be stored.
 * @param int $exp
 *   Parameter expire is expiration time in seconds. If it's 0, the item never
 *   expires (but memcached server doesn't guarantee this item to be stored all
 *   the time, it could be deleted from the cache to make place for other
 *   items).
 * @param string $bin
 *   The name of the Drupal subsystem that is making this call. Examples could
 *   be 'cache', 'alias', 'taxonomy term' etc. It is possible to map different
 *   $bin values to different memcache servers.
 * @param object $mc
 *   Optionally pass in the memcache object.  Normally this value is determined
 *   automatically based on the bin the object is being stored to.
38 39
 *
 * @return bool
40
 *   TRUE on succes, FALSE otherwise.
41
 */
42
function dmemcache_set($key, $value, $exp = 0, $bin = 'cache', $mc = NULL) {
43 44
  $collect_stats = dmemcache_stats_init();

45
  $full_key = dmemcache_key($key, $bin);
46 47

  $rc = FALSE;
48
  if ($mc || ($mc = dmemcache_object($bin))) {
49
    if ($mc instanceof Memcached) {
50
      $rc = $mc->set($full_key, $value, $exp);
51 52 53 54 55 56 57
      if (empty($rc)) {
        // If there was a MEMCACHED_E2BIG error, split the value into pieces
        // and cache them individually.
        if ($mc->getResultCode() == MEMCACHED_E2BIG) {
          $rc = _dmemcache_set_pieces($key, $value, $exp, $bin, $mc);
        }
      }
58 59
    }
    else {
60 61 62 63 64
      // The PECL Memcache library throws an E_NOTICE level error, which
      // $php_errormsg doesn't catch, so we need to log it ourselves.
      // Catch it with our own error handler.
      drupal_static_reset('_dmemcache_error_handler');
      set_error_handler('_dmemcache_error_handler');
65
      $rc = $mc->set($full_key, $value, MEMCACHE_COMPRESSED, $exp);
66 67 68 69 70 71 72 73 74 75
      // Restore the Drupal error handler.
      restore_error_handler();
      if (empty($rc)) {
        // If the object was too big, split the value into pieces and cache
        // them individually.
        $dmemcache_errormsg = &drupal_static('_dmemcache_error_handler');
        if (!empty($dmemcache_errormsg) && (strpos($dmemcache_errormsg, 'SERVER_ERROR object too large for cache') !== FALSE || strpos($dmemcache_errormsg, 'SERVER_ERROR out of memory storing object') !== FALSE)) {
          $rc = _dmemcache_set_pieces($key, $value, $exp, $bin, $mc);
        }
      }
76 77
    }
  }
78 79 80 81 82 83

  if ($collect_stats) {
    dmemcache_stats_write('set', $bin, array($full_key => $rc));
  }

  return $rc;
84 85
}

86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186
/**
 * A temporary error handler which keeps track of the most recent error.
 */
function _dmemcache_error_handler($errno, $errstr) {
  $dmemcache_errormsg = &drupal_static(__FUNCTION__);
  $dmemcache_errormsg = $errstr;
  return TRUE;
}

/**
 *  Split a large item into pieces and place them into memcache
 *
 * @param string $key
 *   The string with which you will retrieve this item later.
 * @param mixed $value
 *   The item to be stored.
 * @param int $exp
 *   (optional) Expiration time in seconds. If it's 0, the item never expires
 *   (but memcached server doesn't guarantee this item to be stored all the
 *   time, it could be deleted from the cache to make place for other items).
 * @param string $bin
 *   (optional) The name of the Drupal subsystem that is making this call.
 *   Examples could be 'cache', 'alias', 'taxonomy term' etc. It is possible to
 *   map different $bin values to different memcache servers.
 * @param object $mc
 *   (optional) The memcache object. Normally this value is
 *   determined automatically based on the bin the object is being stored to.
 *
 * @return bool
 */
function _dmemcache_set_pieces($key, $value, $exp = 0, $bin = 'cache', $mc = NULL) {
  static $recursion = 0;
  if (!empty($value->multi_part_data) || !empty($value->multi_part_pieces)) {
    // Prevent an infinite loop.
    return FALSE;
  }

  // Recursion happens when __dmemcache_piece_cache outgrows the largest
  // memcache slice (1 MiB by default) -- prevent an infinite loop and later
  // generate a watchdog error.
  if ($recursion) {
    return FALSE;
  }
  $recursion++;

  $full_key = dmemcache_key($key);

  // Cache the name of this key so if it is deleted later we know to also
  // delete the cache pieces.
  if (!dmemcache_piece_cache_set($full_key, $exp)) {
    // We're caching a LOT of large items. Our piece_cache has exceeded the
    // maximum memcache object size (default of 1 MiB).
    $piece_cache = &drupal_static('dmemcache_piece_cache', array());
    register_shutdown_function('watchdog', 'memcache', 'Too many over-sized cache items (!count) has caused the dmemcache_piece_cache to exceed the maximum memcache object size (default of 1 MiB). Now relying on memcache auto-expiration to eventually clean up over-sized cache pieces upon deletion.', array('!count' => count($piece_cache)), WATCHDOG_ERROR);
  }

  if (variable_get('memcache_log_data_pieces', 2)) {
    timer_start('memcache_split_data');
  }

  // We need to split the item into pieces, so convert it into a string.
  if (is_string($value)) {
    $data = $value;
    $serialized = FALSE;
  }
  else {
    $data = serialize($value);
    $serialized = TRUE;
  }

  // Account for any metadata stored alongside the data.
  $max_len = variable_get('memcache_data_max_length', 1048576) - (512 + strlen($full_key));
  $pieces = str_split($data, $max_len);

  $piece_count = count($pieces);

  // Create a placeholder item containing data about the pieces.
  $cache = new stdClass;
  // $key gets run through dmemcache_key() later inside dmemcache_set().
  $cache->cid = $key;
  $cache->created = REQUEST_TIME;
  $cache->expire = $exp;
  $cache->data = new stdClass;
  $cache->data->serialized = $serialized;
  $cache->data->piece_count = $piece_count;
  $cache->multi_part_data = TRUE;
  $result = dmemcache_set($cache->cid, $cache, $exp, $bin, $mc);

  // Create a cache item for each piece of data.
  foreach ($pieces as $id => $piece) {
    $cache = new stdClass;
    $cache->cid = _dmemcache_key_piece($key, $id);
    $cache->created = REQUEST_TIME;
    $cache->expire = $exp;
    $cache->data = $piece;
    $cache->multi_part_piece = TRUE;

    $result &= dmemcache_set($cache->cid, $cache, $exp, $bin, $mc);
  }

  if (variable_get('memcache_log_data_pieces', 2) && $piece_count >= variable_get('memcache_log_data_pieces', 2)) {
187 188 189 190 191 192 193
    if (function_exists('format_size')) {
      $data_size = format_size(strlen($data));
    }
    else {
      $data_size = number_format(strlen($data)) . ' byte';
    }
    register_shutdown_function('watchdog', 'memcache', 'Spent !time ms splitting !bytes object into !pieces pieces, cid = !key', array('!time' => timer_read('memcache_split_data'), '!bytes' => $data_size, '!pieces' => $piece_count, '!key' => dmemcache_key($key, $bin)), WATCHDOG_WARNING);
194 195 196 197 198 199 200 201
  }

  $recursion--;

  // TRUE if all pieces were saved correctly.
  return $result;
}

202
/**
203
 * Add an item into memcache.
204
 *
205 206 207 208 209
 * @param string $key
 *   The string with which you will retrieve this item later.
 * @param mixed $value
 *   The item to be stored.
 * @param int $exp
210 211 212
 *   (optional) Expiration time in seconds. If it's 0, the item never expires
 *   (but memcached server doesn't guarantee this item to be stored all the
 *   time, it could be deleted from the cache to make place for other items).
213
 * @param string $bin
214
 *   (optional) The name of the Drupal subsystem that is making this call.
215 216
 *   Examples could be 'cache', 'alias', 'taxonomy term' etc. It is possible
 *   to map different $bin values to different memcache servers.
217
 * @param object $mc
218
 *   (optional) The memcache object. Normally this value is
219
 *   determined automatically based on the bin the object is being stored to.
220 221
 * @param bool $flag
 *   (optional) If using the older memcache PECL extension as opposed to the
222 223 224 225 226
 *   newer memcached PECL extension, the MEMCACHE_COMPRESSED flag can be set
 *   to use zlib to store a compressed copy of the item.  This flag option is
 *   completely ignored when using the newer memcached PECL extension.
 *
 * @return bool
227
 *   FALSE if placing the item into memcache failed.
228
 */
229
function dmemcache_add($key, $value, $exp = 0, $bin = 'cache', $mc = NULL, $flag = FALSE) {
230 231
  $collect_stats = dmemcache_stats_init();

232
  $full_key = dmemcache_key($key, $bin);
233 234

  $rc = FALSE;
235
  if ($mc || ($mc = dmemcache_object($bin))) {
236
    if ($mc instanceof Memcached) {
237
      $rc = $mc->add($full_key, $value, $exp);
238 239
    }
    else {
240
      $rc = $mc->add($full_key, $value, $flag, $exp);
241 242
    }
  }
243 244 245 246 247 248

  if ($collect_stats) {
    dmemcache_stats_write('add', $bin, array($full_key => $rc));
  }

  return $rc;
249 250
}

251 252 253
/**
 * Retrieve a value from the cache.
 *
254 255 256 257
 * @param string $key
 *   The key with which the item was stored.
 * @param string $bin
 *   The bin in which the item was stored.
258
 *
259 260
 * @return mixed
 *   The item which was originally saved or FALSE
261
 */
262
function dmemcache_get($key, $bin = 'cache', $mc = NULL) {
263 264
  $collect_stats = dmemcache_stats_init();

265
  $result = FALSE;
266

267
  $full_key = dmemcache_key($key, $bin);
268 269 270 271 272
  if ($mc || $mc = dmemcache_object($bin)) {
    $track_errors = ini_set('track_errors', '1');
    $php_errormsg = '';

    $result = @$mc->get($full_key);
273 274 275 276
    // This is a multi-part value.
    if (is_object($result) && !empty($result->multi_part_data)) {
      $result = _dmemcache_get_pieces($result->data, $result->cid, $bin, $mc);
    }
277 278 279 280

    if (!empty($php_errormsg)) {
      register_shutdown_function('watchdog', 'memcache', 'Exception caught in dmemcache_get: !msg', array('!msg' => $php_errormsg), WATCHDOG_WARNING);
      $php_errormsg = '';
281
    }
282
    ini_set('track_errors', $track_errors);
283
  }
284

285 286 287 288
  if ($collect_stats) {
    dmemcache_stats_write('get', $bin, array($full_key => (bool) $result));
  }

289
  return $result;
290 291
}

292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345
/**
 * Retrieve a value from the cache.
 *
 * @param $item
 *   The placeholder cache item from _dmemcache_set_pieces().
 * @param $key
 *   The key with which the item was stored.
 * @param string $bin
 *   (optional) The bin in which the item was stored.
 * @param object $mc
 *   (optional) The memcache object. Normally this value is
 *   determined automatically based on the bin the object is being stored to.
 *
 * @return object|bool
 *   The item which was originally saved or FALSE.
 */
function _dmemcache_get_pieces($item, $key, $bin = 'cache', $mc = NULL) {
  // Create a list of keys for the pieces of data.
  for ($id = 0; $id < $item->piece_count; $id++) {
    $keys[] = _dmemcache_key_piece($key, $id);
  }

  // Retrieve all the pieces of data.
  $pieces = dmemcache_get_multi($keys, $bin, $mc);
  if (count($pieces) != $item->piece_count) {
    // Some of the pieces don't exist, so our data cannot be reconstructed.
    return FALSE;
  }

  // Append all of the pieces together.
  $data = '';
  foreach ($pieces as $piece) {
    $data .= $piece->data;
  }
  unset($pieces);

  // If necessary unserialize the item.
  return empty($item->serialized) ? $data : unserialize($data);
}

/**
 * Generates a key name for a multi-part data piece based on the sequence ID.
 *
 * @param int $id
 *   The sequence ID of the data piece.
 * @param int $key
 *   The original CID of the cache item.
 *
 * @return string
 */
function _dmemcache_key_piece($key, $id) {
  return dmemcache_key('_multi'. (string)$id . "-$key");
}

346 347 348
/**
 * Retrieve multiple values from the cache.
 *
349 350 351 352
 * @param array $keys
 *   The keys with which the items were stored.
 * @param string $bin
 *   The bin in which the item was stored.
353
 *
354 355
 * @return mixed
 *   The item which was originally saved or FALSE
356 357
 */
function dmemcache_get_multi($keys, $bin = 'cache', $mc = NULL) {
358 359 360
  $collect_stats = dmemcache_stats_init();
  $multi_stats = array();

361
  $full_keys = array();
362

363 364
  foreach ($keys as $key => $cid) {
    $full_key = dmemcache_key($cid, $bin);
365
    $full_keys[$cid] = $full_key;
366 367 368 369

    if ($collect_stats) {
      $multi_stats[$full_key] = FALSE;
    }
370
  }
371

372 373
  $results = array();
  if ($mc || ($mc = dmemcache_object($bin))) {
374
    if ($mc instanceof Memcached) {
375 376
      $null = NULL;
      $results = $mc->getMulti($full_keys, $null, Memcached::GET_PRESERVE_ORDER);
377
    }
378
    elseif ($mc instanceof Memcache) {
379 380 381 382 383 384 385 386 387 388
      $track_errors = ini_set('track_errors', '1');
      $php_errormsg = '';

      $results = @$mc->get($full_keys);

      if (!empty($php_errormsg)) {
        register_shutdown_function('watchdog', 'memcache', 'Exception caught in dmemcache_get_multi: !msg', array('!msg' => $php_errormsg), WATCHDOG_WARNING);
        $php_errormsg = '';
      }
      ini_set('track_errors', $track_errors);
389 390
    }
  }
391 392 393 394
  // If $results is FALSE, convert it to an empty array.
  if (!$results) {
    $results = array();
  }
395

396 397 398 399 400 401
  if ($collect_stats) {
    foreach ($multi_stats as $key => $value) {
      $multi_stats[$key] = isset($results[$key]) ? TRUE : FALSE;
    }
  }

402 403
  // Convert the full keys back to the cid.
  $cid_results = array();
404 405
  $cid_lookup = array_flip($full_keys);
  foreach ($results as $key => $value) {
406 407 408 409
    // This is a multi-part value.
    if (is_object($value) && !empty($value->multi_part_data)) {
      $value = _dmemcache_get_pieces($value->data, $value->cid, $bin, $mc);
    }
410
    $cid_results[$cid_lookup[$key]] = $value;
411
  }
412 413 414 415 416

  if ($collect_stats) {
    dmemcache_stats_write('getMulti', $bin, $multi_stats);
  }

417
  return $cid_results;
418 419 420 421 422
}

/**
 * Deletes an item from the cache.
 *
423 424 425 426
 * @param string $key
 *   The key with which the item was stored.
 * @param string $bin
 *   The bin in which the item was stored.
427
 *
428 429
 * @return bool
 *   Returns TRUE on success or FALSE on failure.
430
 */
431
function dmemcache_delete($key, $bin = 'cache', $mc = NULL) {
432 433
  $collect_stats = dmemcache_stats_init();

434
  $full_key = dmemcache_key($key, $bin);
435 436

  $rc = FALSE;
437
  if ($mc || ($mc = dmemcache_object($bin))) {
438
    $rc = $mc->delete($full_key, 0);
439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479

    if ($rc) {
      // If the delete succeeded, we now check to see if this item has multiple
      // pieces also needing to be cleaned up. If the delete failed, we assume
      // these keys have already expired or been deleted (memcache will
      // auto-expire eventually if we're wrong).
      if ($piece_cache = dmemcache_piece_cache_get($full_key)) {
        // First, remove from the piece_cache so we don't try and delete it
        // again in another thread, then delete the actual cache data pieces.
        dmemcache_piece_cache_set($full_key, NULL);
        $next_id = 0;
        do {
          // Generate the cid of the next data piece.
          $piece_key = _dmemcache_key_piece($key, $next_id);
          $full_key = dmemcache_key($piece_key, $bin);
          $next_id++;

          // Keep deleting pieces until the operation fails. We accept that
          // this could lead to orphaned pieces as memcache will auto-expire
          // them eventually.
        } while ($mc->delete($full_key, 0));

        // Perform garbage collection for keys memcache has auto-expired. If we
        // don't do this, this variable could grow over enough time as a slow
        // memory leak.
        // @todo: Consider moving this to hook_cron() and requiring people to
        // enable the memcache module.
        timer_start('memcache_gc_piece_cache');
        $gc_counter = 0;
        $piece_cache = &drupal_static('dmemcache_piece_cache', array());
        foreach ($piece_cache as $cid => $expires) {
          if (REQUEST_TIME > $expires) {
            $gc_counter++;
            dmemcache_piece_cache_set($cid, NULL);
          }
        }
        if ($gc_counter) {
          register_shutdown_function('watchdog', 'memcache', 'Spent !time ms in garbage collection cleaning !count stale keys from the dmemcache_piece_cache.', array('!time' => timer_read('memcache_gc_piece_cache'), '!count' => $gc_counter), WATCHDOG_WARNING);
        }
      }
    }
480
  }
481 482 483 484 485 486

  if ($collect_stats) {
    dmemcache_stats_write('delete', $bin, array($full_key => $rc));
  }

  return $rc;
487 488 489
}

/**
490 491 492 493 494
 * Flush all stored items.
 *
 * Immediately invalidates all existing items. dmemcache_flush doesn't actually
 * free any resources, it only marks all the items as expired, so occupied
 * memory will be overwritten by new items.
495
 *
496 497 498
 * @param string $bin
 *   The bin to flush. Note that this will flush all bins mapped to the same
 *   server as $bin. There is no way at this time to empty just one bin.
499
 *
500 501
 * @return bool
 *   Returns TRUE on success or FALSE on failure.
502
 */
503
function dmemcache_flush($bin = 'cache', $mc = NULL) {
504 505 506
  $collect_stats = dmemcache_stats_init();

  $rc = FALSE;
507
  if ($mc || ($mc = dmemcache_object($bin))) {
508 509 510 511 512
    $rc = memcache_flush($mc);
  }

  if ($collect_stats) {
    dmemcache_stats_write('flush', $bin, array('' => $rc));
513
  }
514 515

  return $rc;
516 517
}

518 519 520 521 522 523 524 525 526 527
/**
 * Retrieves statistics recorded during memcache operations.
 *
 * @param string $stats_bin
 *   The bin to retrieve statistics for.
 * @param string $stats_type
 *   The type of statistics to retrieve when using the Memcache extension.
 * @param bool $aggregate
 *   Whether to aggregate statistics.
 */
528 529 530 531
function dmemcache_stats($stats_bin = 'cache', $stats_type = 'default', $aggregate = FALSE) {
  $memcache_bins = variable_get('memcache_bins', array('cache' => 'default'));
  // The stats_type can be over-loaded with an integer slab id, if doing a
  // cachedump.  We know we're doing a cachedump if $slab is non-zero.
532
  $slab = (int) $stats_type;
533
  $stats = array();
534 535 536 537 538 539 540 541 542 543 544

  foreach ($memcache_bins as $bin => $target) {
    if ($stats_bin == $bin) {
      if ($mc = dmemcache_object($bin)) {
        if ($mc instanceof Memcached) {
          $stats[$bin] = $mc->getStats();
        }
        // The PHP Memcache extension 3.x version throws an error if the stats
        // type is NULL or not in {reset, malloc, slabs, cachedump, items,
        // sizes}. If $stats_type is 'default', then no parameter should be
        // passed to the Memcache memcache_get_extended_stats() function.
545
        elseif ($mc instanceof Memcache) {
546 547 548 549 550
          if ($stats_type == 'default' || $stats_type == '') {
            $stats[$bin] = $mc->getExtendedStats();
          }
          // If $slab isn't zero, then we are dumping the contents of a
          // specific cache slab.
551
          elseif (!empty($slab)) {
552 553 554 555 556 557 558
            $stats[$bin] = $mc->getStats('cachedump', $slab);
          }
          else {
            $stats[$bin] = $mc->getExtendedStats($stats_type);
          }
        }
      }
559
    }
560 561 562 563
  }
  // Optionally calculate a sum-total for all servers in the current bin.
  if ($aggregate) {
    // Some variables don't logically aggregate.
564 565 566 567 568 569 570 571 572
    $no_aggregate = array(
      'pid',
      'time',
      'version',
      'pointer_size',
      'accepting_conns',
      'listen_disabled_num',
    );
    foreach ($stats as $bin => $servers) {
573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588
      if (is_array($servers)) {
        foreach ($servers as $server) {
          if (is_array($server)) {
            foreach ($server as $key => $value) {
              if (!in_array($key, $no_aggregate)) {
                if (isset($stats[$bin]['total'][$key])) {
                  $stats[$bin]['total'][$key] += $value;
                }
                else {
                  $stats[$bin]['total'][$key] = $value;
                }
              }
            }
          }
        }
      }
589
    }
590
  }
591
  return $stats;
592 593 594
}

/**
595
 * Determine which memcache extension to use: memcache or memcached.
596
 *
597 598
 * By default prefer the 'Memcache' PHP extension, though the default can be
 * overridden by setting memcache_extension in settings.php.
599
 */
600 601 602
function dmemcache_extension() {
  static $extension = NULL;
  if ($extension === NULL) {
603 604 605
    // If an extension is specified in settings.php, use that when available.
    $preferred = variable_get('memcache_extension', NULL);
    if (isset($preferred) && class_exists($preferred)) {
606
      $extension = ucfirst(strtolower($preferred));
607 608 609 610 611 612 613 614
    }
    // If no extension is set, default to Memcache.
    elseif (class_exists('Memcache')) {
      $extension = 'Memcache';
    }
    elseif (class_exists('Memcached')) {
      $extension = 'Memcached';
    }
615 616 617 618 619 620 621 622 623 624 625 626 627 628
    else {
      $extension = FALSE;
    }
  }
  return $extension;
}

/**
 * Return a new memcache instance.
 */
function dmemcache_instance() {
  static $error = FALSE;
  $extension = dmemcache_extension();
  if ($extension == 'Memcache') {
629
    return new Memcache();
630 631
  }
  elseif ($extension == 'Memcached') {
632
    $memcache = new Memcached();
633 634 635 636 637 638 639 640 641 642 643 644 645
    $default_opts = array(
      Memcached::OPT_COMPRESSION => FALSE,
      Memcached::OPT_DISTRIBUTION => Memcached::DISTRIBUTION_CONSISTENT,
    );
    foreach ($default_opts as $key => $value) {
      $memcache->setOption($key, $value);
    }
    // See README.txt for setting custom Memcache options when using the
    // memcached PECL extension.
    $memconf = variable_get('memcache_options', array());
    foreach ($memconf as $key => $value) {
      $memcache->setOption($key, $value);
    }
646 647 648
    if ($sasl_username = variable_get('memcache_sasl_username', '') && $sasl_password = variable_get('memcache_sasl_password', '')) {
      $memcache->setSaslAuthData($sasl_username, $sasl_password);
    }
649 650 651 652 653 654 655 656 657 658 659 660 661 662
    return $memcache;
  }
  else {
    if (!$error) {
      register_shutdown_function('watchdog', 'memcache', 'You must enable the PHP <a href="http://php.net/manual/en/book.memcache.php">memcache</a> (recommended) or <a href="http://php.net/manual/en/book.memcached.php">memcached</a> extension to use memcache.inc.', array(), WATCHDOG_ERROR);
      $error = TRUE;
    }
  }
  return FALSE;
}

/**
 * Initiate a connection to memcache.
 *
663 664 665 666
 * @param object $memcache
 *   A memcache instance obtained through dmemcache_instance.
 * @param string $server
 *   A server string of the format "localhost:11211" or
667
 *   "unix:///path/to/socket".
668 669 670
 * @param bool $connection
 *   TRUE or FALSE, whether the $memcache instance already has at least one
 *   open connection.
671
 *
672 673
 * @return bool
 *   TRUE or FALSE if connection was successful.
674 675 676
 */
function dmemcache_connect($memcache, $server, $connection) {
  static $memcache_persistent = NULL;
677

678 679 680 681 682 683 684 685 686
  $extension = dmemcache_extension();

  list($host, $port) = explode(':', $server);

  if ($extension == 'Memcache') {
    // Allow persistent connection via Memcache extension -- note that this
    // module currently doesn't support persistent connections with the
    // Memcached extension. See http://drupal.org/node/822316#comment-4427676
    // for details.
687 688 689
    if (!isset($memcache_persistent)) {
      $memcache_persistent = variable_get('memcache_persistent', FALSE);
    }
690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721

    // Support unix sockets of the format 'unix:///path/to/socket'.
    if ($host == 'unix') {
      // Use full protocol and path as expected by Memcache extension.
      $host = $server;
      $port = 0;
    }

    // When using the PECL memcache extension, we must use ->(p)connect
    // for the first connection.
    if (!$connection) {
      $track_errors = ini_set('track_errors', '1');
      $php_errormsg = '';

      // The Memcache extension requires us to use (p)connect for the first
      // server we connect to.
      if ($memcache_persistent) {
        $rc = @$memcache->pconnect($host, $port);
      }
      else {
        $rc = @$memcache->connect($host, $port);
      }
      if (!empty($php_errormsg)) {
        register_shutdown_function('watchdog', 'memcache', 'Exception caught in dmemcache_object: !msg', array('!msg' => $php_errormsg), WATCHDOG_WARNING);
        $php_errormsg = '';
      }
      ini_set('track_errors', $track_errors);
    }
    else {
      $rc = $memcache->addServer($host, $port, $memcache_persistent);
    }
  }
722
  elseif ($extension == 'Memcached') {
723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744
    // Support unix sockets of the format 'unix:///path/to/socket'.
    if ($host == 'unix') {
      // Strip 'unix://' as expected by Memcached extension.
      $host = substr($server, 7);
      $port = 0;
    }
    $rc = $memcache->addServer($host, $port);
  }
  else {
    $rc = FALSE;
  }
  return $rc;
}

/**
 * Close the connection to the memcache instance.
 */
function dmemcache_close($memcache) {
  $extension = dmemcache_extension();
  if ($extension == 'Memcache' && $memcache instanceof Memcache) {
    $rc = @$memcache->close;
  }
745
  elseif ($extension == 'Memcached' && $memcache instanceof Memcached) {
746
    $rc = @$memcache->quit;
747
  }
748 749 750 751 752 753 754 755 756 757 758 759 760 761
  else {
    $rc = FALSE;
  }
  return $rc;
}

/**
 * Return a Memcache object for the specified bin.
 *
 * Note that there is nothing preventing developers from calling this function
 * directly to get the Memcache object. Do this if you need functionality not
 * provided by this API or if you need to use legacy code. Otherwise, use the
 * dmemcache (get, set, delete, flush) API functions provided here.
 *
762 763 764 765
 * @param string $bin
 *   The bin which is to be used.
 * @param bool $flush
 *   Defaults to FALSE. Rebuild the bin/server/cache mapping.
766
 *
767 768
 * @return mixed
 *   A Memcache object, or FALSE on failure.
769 770
 */
function dmemcache_object($bin = NULL, $flush = FALSE) {
771
  static $memcache_cache = array();
772 773 774
  static $memcache_servers = array();
  static $memcache_bins = array();
  static $failed_connections = array();
775 776

  if ($flush) {
777
    foreach ($memcache_cache as $cluster) {
778
      memcache_close($cluster);
779
    }
780
    $memcache_cache = array();
781 782
  }

783 784
  $extension = dmemcache_extension();

785
  if (empty($memcache_cache) || empty($memcache_cache[$bin])) {
786
    if (empty($memcache_servers)) {
787
      // Load the variables from settings.php if set.
788
      $memcache_servers = variable_get('memcache_servers', array('127.0.0.1:11211' => 'default'));
789
      $memcache_bins = variable_get('memcache_bins', array('cache' => 'default'));
790 791
    }

792
    // If not manually set, default this cluster to 'default'.
793 794
    $cluster = empty($memcache_bins[$bin]) ? 'default' : $memcache_bins[$bin];

795 796
    // If not manually set, map this bin to 'cache' which maps to the 'default'
    // cluster.
797 798
    if (empty($memcache_bins[$bin]) && !empty($memcache_cache['cache'])) {
      $memcache_cache[$bin] = &$memcache_cache['cache'];
799 800
    }
    else {
801 802
      // Create a new memcache object for each cluster.
      $memcache = dmemcache_instance();
803

804 805
      // Track whether or not we've opened any memcache connections.
      $connection = FALSE;
806

807 808 809 810 811 812 813
      // Link all the servers to this cluster.
      foreach ($memcache_servers as $server => $c) {
        if ($c == $cluster && !isset($failed_connections[$server])) {
          $rc = dmemcache_connect($memcache, $server, $connection);
          if ($rc !== FALSE) {
            // We've made at least one successful connection.
            $connection = TRUE;
814
          }
815
          else {
816 817 818 819 820 821
            // Memcache connection failure. We can't log to watchdog directly
            // because we're in an early Drupal bootstrap phase where watchdog
            // is non-functional. Instead, register a shutdown handler so it
            // gets recorded at the end of the page load.
            register_shutdown_function('watchdog', 'memcache', 'Failed to connect to memcache server: !server', array('!server' => $server), WATCHDOG_ERROR);
            $failed_connections[$server] = FALSE;
822
          }
823 824
        }
      }
825
      if ($connection) {
826
        // Map the current bin with the new Memcache object.
827
        $memcache_cache[$bin] = $memcache;
828 829 830 831 832 833

        // Now that all the servers have been mapped to this cluster, look for
        // other bins that belong to the cluster and map them too.
        foreach ($memcache_bins as $b => $c) {
          if ($c == $cluster && $b != $bin) {
            // Map this bin and cluster by reference.
834
            $memcache_cache[$b] = &$memcache_cache[$bin];
835 836 837 838 839 840
          }
        }
      }
    }
  }

841
  return empty($memcache_cache[$bin]) ? FALSE : $memcache_cache[$bin];
842 843
}

844 845 846 847 848 849 850 851 852 853 854
/**
 * Prefixes a key and ensures it is url safe.
 *
 * @param string $key
 *   The key to prefix and encode.
 * @param string $bin
 *   The cache bin which the key applies to.
 *
 * @return string
 *   The prefixed and encoded key.
 */
855
function dmemcache_key($key, $bin = 'cache') {
856
  $prefix = '';
857 858 859 860 861 862 863 864 865 866 867 868
  if ($prefixes = variable_get('memcache_key_prefix', '')) {
    if (is_array($prefixes)) {
      if (!empty($prefixes[$bin])) {
        $prefix = $prefixes[$bin] . '-';
      } // Support default prefix for site
      elseif (!empty($prefixes['default'])) {
        $prefix = $prefixes['default'] . '-';
      }
    }
    else {
      $prefix = $prefixes . '-';
    }
869 870 871 872 873
  }
  // When simpletest is running, emulate the simpletest database prefix here
  // to avoid the child site setting cache entries in the parent site.
  if (isset($GLOBALS['drupal_test_info']['test_run_id'])) {
    $prefix .= $GLOBALS['drupal_test_info']['test_run_id'];
874 875 876
  }
  $full_key = urlencode($prefix . $bin . '-' . $key);

877 878 879 880 881 882 883 884 885 886 887
  // Memcache truncates keys longer than 250 characters[*]. This could lead to
  // cache collisions, so we hash keys that are longer than this while still
  // retaining as much of the key bin and name as possible to aid in debugging.
  // The hashing algorithm used is configurable, with sha1 selected by default
  // as it performs quickly with minimal collisions. You can enforce shorter
  // keys by setting memcache_key_max_length in settings.php.
  // [*]https://github.com/memcached/memcached/blob/master/doc/protocol.txt#L47
  $maxlen = variable_get('memcache_key_max_length', 250);
  if (strlen($full_key) > $maxlen) {
    $full_key = urlencode($prefix . $bin) . '-' . hash(variable_get('memcache_key_hash_algorithm', 'sha1'), $key);
    $full_key .= '-' . substr(urlencode($key), 0, ($maxlen - 1) - strlen($full_key) - 1);
888
  }
889

890
  return $full_key;
891
}
892

893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962
/**
 * Track active keys with multi-piece values, necessary for efficient cleanup.
 *
 * We can't use variable_get/set for tracking this information because if the
 * variables array grows >1M and has to be split into pieces we'd get stuck in
 * an infinite loop. Storing this information in memcache means it can be lost,
 * but in that case the pieces will still eventually be auto-expired by
 * memcache.
 *
 * @param string $cid
 *   The cid of the root multi-piece value.
 * @param integer $exp
 *   Timestamp when the cached item expires. If NULL, the $cid will be deleted.
 *
 * @return bool
 *   TRUE on succes, FALSE otherwise.
 */
function dmemcache_piece_cache_set($cid, $exp = NULL) {
  // Always refresh cached copy to minimize multi-thread race window.
  $piece_cache = &drupal_static('dmemcache_piece_cache', array());
  $piece_cache = dmemcache_get('__dmemcache_piece_cache');

  if (isset($exp)) {
    if ($exp <= 0) {
      // If no expiration time is set, defaults to 30 days.
      $exp = REQUEST_TIME + 2592000;
    }
    $piece_cache[$cid] = $exp;
  }
  else {
    unset($piece_cache[$cid]);
  }

  return dmemcache_set('__dmemcache_piece_cache', $piece_cache);
}

/**
 * Determine if a key has multi-piece values.
 *
 *
 * @param string $cid
 *   The cid to check for multi-piece values.
 *
 * @return integer
 *   Expiration time if key has multi-piece values, otherwise FALSE.
 */
function dmemcache_piece_cache_get($name) {
  static $drupal_static_fast;
  if (!isset($drupal_static_fast)) {
    $drupal_static_fast['piece_cache'] = &drupal_static('dmemcache_piece_cache', FALSE);
  }
  $piece_cache = &$drupal_static_fast['piece_cache'];

  if (!is_array($piece_cache)) {
    $piece_cache = dmemcache_get('__dmemcache_piece_cache');
    // On a website with no over-sized cache pieces, initialize the variable so
    // we never load it more than once per page versus once per DELETE.
    if (!is_array($piece_cache)) {
      dmemcache_set('__dmemcache_piece_cache', array());
    }
  }

  if (isset($piece_cache[$name])) {
    // Return the expiration time of the multi-piece cache item.
    return $piece_cache[$name];
  }
  // Item doesn't have multiple pieces.
  return FALSE;
}

963
/**
964 965
 * Collect statistics if enabled.
 *
966 967 968
 * Optimized function to determine whether or not we should be collecting
 * statistics. Also starts a timer to track how long individual memcache
 * operations take.
969
 *
970 971
 * @return bool
 *   TRUE or FALSE if statistics should be collected.
972
 */
973
function dmemcache_stats_init() {
974
  static $drupal_static_fast;
975

976 977 978 979 980 981 982
  if (!isset($drupal_static_fast)) {
    $drupal_static_fast = &drupal_static(__FUNCTION__, array('variable_checked' => NULL, 'user_access_checked' => NULL));
  }
  $variable_checked = &$drupal_static_fast['variable_checked'];
  $user_access_checked  = &$drupal_static_fast['user_access_checked'];

  // Confirm DRUPAL_BOOTSTRAP_VARIABLES has been reached. We don't use
983 984 985
  // drupal_get_bootstrap_phase() as it's buggy. We can use variable_get() here
  // because _drupal_bootstrap_variables() includes module.inc immediately
  // after it calls variable_initialize().
986 987 988 989
  if (!isset($variable_checked) && function_exists('module_list')) {
    $variable_checked = variable_get('show_memcache_statistics', FALSE);
  }
  // If statistics are enabled we need to check user access.
990
  if (!empty($variable_checked) && !isset($user_access_checked) && !empty($GLOBALS['user']) && function_exists('user_access')) {
991 992 993 994 995
    // Statistics are enabled and the $user object has been populated, so check
    // that the user has access to view them.
    $user_access_checked = user_access('access memcache statistics');
  }
  // Return whether or not statistics are enabled and the user can access them.
996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007
  if ((!isset($variable_checked) || $variable_checked) && (!isset($user_access_checked) || $user_access_checked)) {
    timer_start('dmemcache');
    return TRUE;
  }
  else {
    return FALSE;
  }
}

/**
 * Save memcache statistics to be displayed at end of page generation.
 *
1008 1009 1010 1011 1012 1013 1014
 * @param string $action
 *   The action being performed (get, set, etc...).
 * @param string $bin
 *   The memcache bin the action is being performed in.
 * @param array $keys
 *   Keyed array in the form (string)$cid => (bool)$success. The keys the
 *   action is being performed on, and whether or not it was a success.
1015 1016
 */
function dmemcache_stats_write($action, $bin, $keys) {
1017
  global $_dmemcache_stats;
1018 1019 1020 1021
  // Determine how much time elapsed to execute this action.
  $time = timer_read('dmemcache');
  // Build the 'all' and 'ops' arrays displayed by memcache_admin.module.
  foreach ($keys as $key => $success) {
1022 1023 1024 1025 1026 1027 1028
    $_dmemcache_stats['all'][] = array(
      number_format($time, 2),
      $action,
      $bin,
      $key,
      $success ? 'hit' : 'miss',
    );
1029 1030 1031 1032
    if (!isset($_dmemcache_stats['ops'][$action])) {
      $_dmemcache_stats['ops'][$action] = array($action, 0, 0, 0);
    }
    $_dmemcache_stats['ops'][$action][1] += $time;
1033 1034 1035 1036 1037 1038
    if ($success) {
      $_dmemcache_stats['ops'][$action][2]++;
    }
    else {
      $_dmemcache_stats['ops'][$action][3]++;
    }
1039 1040
  }
  // Reset the dmemcache timer for timing the next memcache operation.
1041
}