dmemcache.inc 41.5 KB
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<?php

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/**
 * @file
 * A memcache API for Drupal.
 *
 * This file contains core dmemcache functions required by:
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 *   memcache.inc
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 *   memcache-lock.inc
 *   memcache-lock-code.inc
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 */

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define('MEMCACHED_E2BIG', 37);

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global $_dmemcache_stats;
$_dmemcache_stats = array('all' => array(), 'ops' => array());
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/**
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 * Place an item into memcache.
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 *
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 * @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 $mc
 *   Optionally pass in the memcache object.  Normally this value is determined
 *   automatically based on the bin the object is being stored to.
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 *
 * @return bool
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 *   TRUE on succes, FALSE otherwise.
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 */
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function dmemcache_set($key, $value, $exp = 0, $bin = 'cache', $mc = NULL) {
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  $collect_stats = dmemcache_stats_init();

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  $full_key = dmemcache_key($key, $bin);
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  $rc = FALSE;
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  if ($mc || ($mc = dmemcache_object($bin))) {
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    if ($mc instanceof Memcached) {
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      $rc = $mc->set($full_key, $value, $exp);
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      if (empty($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);
        }
      }
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    }
    else {
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      // 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');
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      $rc = $mc->set($full_key, $value, MEMCACHE_COMPRESSED, $exp);
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      // Restore the Drupal error handler.
      restore_error_handler();
      if (empty($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, $mc);
        }
      }
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    }
  }
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  if ($collect_stats) {
    dmemcache_stats_write('set', $bin, array($full_key => $rc));
  }

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  _dmemcache_write_debug('set', $bin, $full_key, $rc);
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  return $rc;
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}

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/**
 * 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 {
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    $serialize_function = dmemcache_serialize();
    $data = $serialize_function($value);
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    $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)) {
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    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);
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  }

  $recursion--;

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

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/**
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 * Add an item into memcache.
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 *
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 * @param string $key
 *   The string with which you will retrieve this item later.
 * @param mixed $value
 *   The item to be stored.
 * @param int $exp
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 *   (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).
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 * @param string $bin
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 *   (optional) The name of the Drupal subsystem that is making this call.
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 *   Examples could be 'cache', 'alias', 'taxonomy term' etc. It is possible
 *   to map different $bin values to different memcache servers.
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 * @param object $mc
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 *   (optional) The memcache object. Normally this value is
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 *   determined automatically based on the bin the object is being stored to.
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 * @param bool $flag
 *   (optional) If using the older memcache PECL extension as opposed to the
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 *   newer memcached PECL extension, the MEMCACHE_COMPRESSED flag can be set
 *   to use zlib to store a compressed copy of the item.  This flag option is
 *   completely ignored when using the newer memcached PECL extension.
 *
 * @return bool
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 *   FALSE if placing the item into memcache failed.
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 */
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function dmemcache_add($key, $value, $exp = 0, $bin = 'cache', $mc = NULL, $flag = FALSE) {
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  $collect_stats = dmemcache_stats_init();

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  $full_key = dmemcache_key($key, $bin);
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  $rc = FALSE;
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  if ($mc || ($mc = dmemcache_object($bin))) {
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    if ($mc instanceof Memcached) {
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      $rc = $mc->add($full_key, $value, $exp);
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    }
    else {
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      $rc = $mc->add($full_key, $value, $flag, $exp);
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    }
  }
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  if ($collect_stats) {
    dmemcache_stats_write('add', $bin, array($full_key => $rc));
  }

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  _dmemcache_write_debug('add', $bin, $full_key, $rc);
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  return $rc;
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}

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/**
 * Retrieve a value from the cache.
 *
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 * @param string $key
 *   The key with which the item was stored.
 * @param string $bin
 *   The bin in which the item was stored.
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 *
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 * @return mixed
 *   The item which was originally saved or FALSE
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 */
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function dmemcache_get($key, $bin = 'cache', $mc = NULL) {
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  $collect_stats = dmemcache_stats_init();

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  $result = FALSE;
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  $full_key = dmemcache_key($key, $bin);
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  if ($mc || $mc = dmemcache_object($bin)) {
    $track_errors = ini_set('track_errors', '1');
    $php_errormsg = '';

    $result = @$mc->get($full_key);
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    // This is a multi-part value.
    if (is_object($result) && !empty($result->multi_part_data)) {
      $result = _dmemcache_get_pieces($result->data, $result->cid, $bin, $mc);
    }
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    if (!empty($php_errormsg)) {
      register_shutdown_function('watchdog', 'memcache', 'Exception caught in dmemcache_get: !msg', array('!msg' => $php_errormsg), WATCHDOG_WARNING);
      $php_errormsg = '';
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    }
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    ini_set('track_errors', $track_errors);
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  }
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  if ($collect_stats) {
    dmemcache_stats_write('get', $bin, array($full_key => (bool) $result));
  }

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  _dmemcache_write_debug('get', $bin, $full_key, (bool) $result);
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  return $result;
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}

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/**
 * 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.
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  if (empty($item->serialized)) {
    return $data;
  }
  else {
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    $unserialize_function = dmemcache_unserialize();
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    return $unserialize_function($data);
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  }
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}

/**
 * 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");
}

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/**
 * Retrieve multiple values from the cache.
 *
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 * @param array $keys
 *   The keys with which the items were stored.
 * @param string $bin
 *   The bin in which the item was stored.
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 *
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 * @return mixed
 *   The item which was originally saved or FALSE
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 */
function dmemcache_get_multi($keys, $bin = 'cache', $mc = NULL) {
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  $collect_stats = dmemcache_stats_init();
  $multi_stats = array();

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  $full_keys = array();
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  foreach ($keys as $key => $cid) {
    $full_key = dmemcache_key($cid, $bin);
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    $full_keys[$cid] = $full_key;
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    if ($collect_stats) {
      $multi_stats[$full_key] = FALSE;
    }
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  }
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  $results = array();
  if ($mc || ($mc = dmemcache_object($bin))) {
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    if ($mc instanceof Memcached) {
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      if (PHP_MAJOR_VERSION >= 7) {
        // See https://www.drupal.org/node/2728427
        $results = $mc->getMulti($full_keys, Memcached::GET_PRESERVE_ORDER);
      }
      else {
        $cas_tokens = NULL;
        $results = $mc->getMulti($full_keys, $cas_tokens, Memcached::GET_PRESERVE_ORDER);
      }
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    }
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    elseif ($mc instanceof Memcache) {
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      $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', $track_errors);
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      // Order is not guaranteed, map responses to order of requests.
      if (is_array($results)) {
        $keys = array_fill_keys($full_keys, NULL);
        $results = array_merge($keys, $results);
      }
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    }
  }
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  // If $results is FALSE, convert it to an empty array.
  if (!$results) {
    $results = array();
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    _dmemcache_write_debug('getMulti', $bin, implode(',', $full_keys), FALSE);
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  }
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  if ($collect_stats) {
    foreach ($multi_stats as $key => $value) {
      $multi_stats[$key] = isset($results[$key]) ? TRUE : FALSE;
    }
  }

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  // Convert the full keys back to the cid.
  $cid_results = array();
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  $cid_lookup = array_flip($full_keys);
  foreach ($results as $key => $value) {
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    // This is a multi-part value.
    if (is_object($value) && !empty($value->multi_part_data)) {
      $value = _dmemcache_get_pieces($value->data, $value->cid, $bin, $mc);
    }
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    $cid_results[$cid_lookup[$key]] = $value;
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    _dmemcache_write_debug('getMulti', $bin, $key, TRUE);
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  }
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  if ($collect_stats) {
    dmemcache_stats_write('getMulti', $bin, $multi_stats);
  }

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  return $cid_results;
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}

/**
 * Deletes an item from the cache.
 *
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 * @param string $key
 *   The key with which the item was stored.
 * @param string $bin
 *   The bin in which the item was stored.
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 *
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 * @return bool
 *   Returns TRUE on success or FALSE on failure.
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 */
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function dmemcache_delete($key, $bin = 'cache', $mc = NULL) {
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  $collect_stats = dmemcache_stats_init();

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  $full_keys = dmemcache_key($key, $bin, TRUE);
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  $rc = FALSE;
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  if ($mc || ($mc = dmemcache_object($bin))) {
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    foreach ($full_keys as $fk) {
      $rc = $mc->delete($fk, 0);

      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($fk)) {
          // First, remove from the piece_cache so we don't try and delete it
          // again in another thread, then delete the actual cache data pieces.
          dmemcache_piece_cache_set($fk, NULL);
          $next_id = 0;
          do {
            if ($inner_rc) {
              _dmemcache_write_debug("delete", $bin, $full_key, $inner_rc);
            }
            // 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 ($inner_rc = $mc->delete($full_key, 0));
          _dmemcache_write_debug("delete", $bin, $full_key, $inner_rc);

          // 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' => $gc_counter), WATCHDOG_WARNING);
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          }
        }
      }
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      if ($collect_stats) {
        dmemcache_stats_write('delete', $bin, array($fk => $rc));
      }
      _dmemcache_write_debug('delete', $bin, $fk, $rc);
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    }
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  }
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  return $rc;
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}

/**
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 * 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.
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 *
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 * @param string $bin
 *   The bin to flush. Note that this will flush all bins mapped to the same
 *   server as $bin. There is no way at this time to empty just one bin.
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 *
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 * @return bool
 *   Returns TRUE on success or FALSE on failure.
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 */
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function dmemcache_flush($bin = 'cache', $mc = NULL) {
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  $collect_stats = dmemcache_stats_init();

  $rc = FALSE;
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  if ($mc || ($mc = dmemcache_object($bin))) {
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    $rc = $mc->flush();
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  }

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

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/**
 * 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 $aggregate
 *   Whether to aggregate statistics.
 */
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function dmemcache_stats($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.
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  $slab = (int) $stats_type;
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  $stats = array();
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  foreach ($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 $stats_type is 'default', then no parameter should be
        // passed to the Memcache memcache_get_extended_stats() function.
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        elseif ($mc instanceof Memcache) {
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          if ($stats_type == 'default' || $stats_type == '') {
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            $rc = $mc->getExtendedStats();
            if (is_array($rc)) {
              foreach ($rc as $server => $data) {
                if (empty($data)) {
                  unset($rc[$server]);
                }
              }
              if (!empty($rc)) {
                $stats[$bin] = $rc;
              }
            }
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          }
          // If $slab isn't zero, then we are dumping the contents of a
          // specific cache slab.
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          elseif (!empty($slab)) {
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            $stats[$bin] = $mc->getStats('cachedump', $slab);
          }
          else {
            $stats[$bin] = $mc->getExtendedStats($stats_type);
          }
        }
      }
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    }
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  }
  // Optionally calculate a sum-total for all servers in the current bin.
  if ($aggregate) {
    // Some variables don't logically aggregate.
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    $no_aggregate = array(
      'pid',
      'time',
      'version',
      'pointer_size',
      'accepting_conns',
      'listen_disabled_num',
    );
    foreach ($stats as $bin => $servers) {
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      if (is_array($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;
                }
              }
            }
          }
        }
      }
634
    }
635
  }
636
  return $stats;
637 638 639
}

/**
640
 * Determine which memcache extension to use: memcache or memcached.
641
 *
642 643
 * By default prefer the 'Memcache' PHP extension, though the default can be
 * overridden by setting memcache_extension in settings.php.
644
 */
645 646 647
function dmemcache_extension() {
  static $extension = NULL;
  if ($extension === NULL) {
648 649
    // If an extension is specified in settings.php, use that when available.
    $preferred = variable_get('memcache_extension', NULL);
650
    if (isset($preferred) && class_exists($preferred, FALSE)) {
651
      $extension = ucfirst(strtolower($preferred));
652 653
    }
    // If no extension is set, default to Memcache.
654
    elseif (class_exists('Memcache', FALSE)) {
655 656
      $extension = 'Memcache';
    }
657
    elseif (class_exists('Memcached', FALSE)) {
658 659
      $extension = 'Memcached';
    }
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    else {
      $extension = FALSE;
    }
  }
  return $extension;
}

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/**
 * Determine which serialize extension to use: serialize (none), igbinary,
 * or msgpack.
 *
 * By default we prefer the igbinary extension, then the msgpack extension,
 * then the core serialize functions. This can be overridden in settings.php.
 */
function dmemcache_serialize_extension() {
  static $extension = NULL;
  if ($extension === NULL) {
    $preferred = strtolower(variable_get('memcache_serialize', NULL));
    // Fastpath if we're forcing php's own serialize function.
    if ($preferred == 'serialize') {
      $extension = $preferred;
    }
    // Otherwise, find an available extension favoring configuration.
    else {
      $igbinary_available = extension_loaded('igbinary');
      $msgpack_available = extension_loaded('msgpack');
      if ($preferred == 'igbinary' && $igbinary_available) {
        $extension = $preferred;
      }
      elseif ($preferred == 'msgpack' && $msgpack_available) {
        $extension = $preferred;
      }
      else {
        // No (valid) serialize extension specified, try igbinary.
        if ($igbinary_available) {
          $extension = 'igbinary';
        }
        // Next try msgpack.
        else if ($msgpack_available) {
          $extension = 'msgpack';
        }
        // Finally fall back to core serialize.
        else {
          $extension = 'serialize';
        }
      }
    }
  }
  return $extension;
}

/**
 * Return proper serialize function.
 */
function dmemcache_serialize() {
  switch (dmemcache_serialize_extension()) {
    case 'igbinary':
      return 'igbinary_serialize';
    case 'msgpack':
      return 'msgpack_pack';
    default:
      return 'serialize';
  }
}

/**
 * Return proper unserialize function.
 */
function dmemcache_unserialize() {
  switch (dmemcache_serialize_extension()) {
    case 'igbinary':
      return 'igbinary_unserialize';
    case 'msgpack':
      return 'msgpack_unpack';
    default:
      return 'unserialize';
  }
}

739 740 741
/**
 * Return a new memcache instance.
 */
742
function dmemcache_instance($bin = 'cache') {
743 744 745
  static $error = FALSE;
  $extension = dmemcache_extension();
  if ($extension == 'Memcache') {
746
    return new Memcache();
747 748
  }
  elseif ($extension == 'Memcached') {
749 750 751 752 753 754
    if (variable_get('memcache_persistent', TRUE)) {
      $memcache = new Memcached($bin);
    }
    else {
      $memcache = new Memcached;
    }
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    $default_opts = array(
      Memcached::OPT_COMPRESSION => FALSE,
      Memcached::OPT_DISTRIBUTION => Memcached::DISTRIBUTION_CONSISTENT,
    );
    foreach ($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, $value);
    }
768
    if (($sasl_username = variable_get('memcache_sasl_username', '')) && ($sasl_password = variable_get('memcache_sasl_password', ''))) {
769 770
      $memcache->setSaslAuthData($sasl_username, $sasl_password);
    }
771 772 773 774 775 776 777 778 779 780 781 782 783 784
    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.
 *
785 786 787 788
 * @param object $memcache
 *   A memcache instance obtained through dmemcache_instance.
 * @param string $server
 *   A server string of the format "localhost:11211" or
789
 *   "unix:///path/to/socket".
790 791
 * @param integer $weight
 *   Weighted probability of talking to this server.
792
 *
793 794
 * @return bool
 *   TRUE or FALSE if connection was successful.
795
 */
796
function dmemcache_connect($memcache, $server, $weight) {
797
  static $memcache_persistent = NULL;
798

799 800
  $extension = dmemcache_extension();

801 802 803 804
  @list($host, $port) = explode(':', trim($server));
  if (empty($host)) {
    register_shutdown_function('watchdog', 'memcache', 'You have specified an invalid address of "!server" in settings.php. Please review README.txt for proper configuration.', array('!server' => $server, '!ip' => t('127.0.0.1:11211'), '!host' => t('localhost:11211'), '!socket' => t('unix:///path/to/socket')), WATCHDOG_WARNING);
  }
805

806 807 808 809
  if (!isset($memcache_persistent)) {
    $memcache_persistent = variable_get('memcache_persistent', TRUE);
  }

810
  $port_error = FALSE;
811 812 813 814 815 816 817
  if ($extension == 'Memcache') {
    // 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;
      $port = 0;
    }
818
    else if (!isset($port)) {
819
      $port_error = TRUE;
820 821
    }
  }
822
  elseif ($extension == 'Memcached') {
823 824 825 826 827 828
    // Support unix sockets of the format 'unix:///path/to/socket'.
    if ($host == 'unix') {
      // Strip 'unix://' as expected by Memcached extension.
      $host = substr($server, 7);
      $port = 0;
    }
829
    else if (!isset($port)) {
830
      $port_error = TRUE;
831
    }
832 833 834 835 836 837 838 839 840 841 842
  }

  if ($port_error) {
    register_shutdown_function('watchdog', 'memcache', 'You have specified an invalid address of "!server" in settings.php which does not include a port. Please review README.txt for proper configuration. You must specify both a server address and port such as "!ip" or "!host", or a unix socket such as "!socket".', array('!server' => $server, '!ip' => t('127.0.0.1:11211'), '!host' => t('localhost:11211'), '!socket' => t('unix:///path/to/socket')), WATCHDOG_WARNING);
  }

  if ($extension == 'Memcache') {
    $rc = $memcache->addServer($host, $port, $memcache_persistent, $weight);
  }
  elseif ($extension == 'Memcached') {
    $match = FALSE;
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    if ($memcache_persistent) {
      $servers = $memcache->getServerList();
      foreach ($servers as $s) {
        if ($s['host'] == $host && $s['port'] == $port) {
          $match = TRUE;
          break;
        }
      }
    }
852
    if (!$match) {
853 854
      $rc = $memcache->addServer($host, $port);
    }
855 856 857
    else {
      $rc = TRUE;
    }
858 859 860 861 862 863 864 865 866 867 868 869 870 871 872
  }
  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;
  }
873
  elseif ($extension == 'Memcached' && $memcache instanceof Memcached) {
874
    $rc = @$memcache->quit;
875
  }
876 877 878 879 880 881 882 883 884 885 886 887 888 889
  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.
 *
890 891 892 893
 * @param string $bin
 *   The bin which is to be used.
 * @param bool $flush
 *   Defaults to FALSE. Rebuild the bin/server/cache mapping.
894
 *
895 896
 * @return mixed
 *   A Memcache object, or FALSE on failure.
897 898
 */
function dmemcache_object($bin = NULL, $flush = FALSE) {
899
  static $memcache_cache = array();
900 901 902
  static $memcache_servers = array();
  static $memcache_bins = array();
  static $failed_connections = array();
903 904

  if ($flush) {
905 906 907 908 909 910 911 912 913 914
    if (!empty($memcache_cache)) {
      foreach ($memcache_cache as $cluster) {
        if ($extension == 'Memcache' && $cluster instanceof Memcache) {
          $rc = @$cluster->close;
        }
        elseif ($extension == 'Memcached' && $cluster instanceof Memcached) {
          $rc = @$cluster->quit;
        }
        $memcache_cache = array();
      }
915 916 917
    }
  }

918 919
  $extension = dmemcache_extension();

920
  if (empty($memcache_cache) || empty($memcache_cache[$bin])) {
921
    if (empty($memcache_servers)) {
922
      // Load the variables from settings.php if set.
923
      $memcache_servers = variable_get('memcache_servers', array('127.0.0.1:11211' => 'default'));
924
      $memcache_bins = variable_get('memcache_bins', array('cache' => 'default'));
925 926
    }

927
    // If not manually set, default this cluster to 'default'.
928 929
    $cluster = empty($memcache_bins[$bin]) ? 'default' : $memcache_bins[$bin];

930 931
    // If not manually set, map this bin to 'cache' which maps to the 'default'
    // cluster.
932 933
    if (empty($memcache_bins[$bin]) && !empty($memcache_cache['cache'])) {
      $memcache_cache[$bin] = &$memcache_cache['cache'];
934 935
    }
    else {
936
      // Create a new memcache object for each cluster.
937
      $memcache = dmemcache_instance($bin);
938

939 940 941
      // Track whether or not we've opened any memcache connections.
      $connection = FALSE;
      // Link all the servers to this cluster.
942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957
      foreach ($memcache_servers as $server => $b) {
        if ($c = dmemcache_object_cluster($b)) {
          if ($c['cluster'] == $cluster && !isset($failed_connections[$server])) {
            $rc = dmemcache_connect($memcache, $server, $c['weight'], $connection);
            if ($rc) {
              // We've made at least one connection.
              $connection = TRUE;
            }
            else {
              // 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;
            }
958
          }
959 960
        }
      }
961
      if ($connection) {
962
        // Map the current bin with the new Memcache object.
963
        $memcache_cache[$bin] = $memcache;
964 965 966 967 968 969

        // 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.
970
            $memcache_cache[$b] = &$memcache_cache[$bin];
971 972 973 974 975 976
          }
        }
      }
    }
  }

977
  return empty($memcache_cache[$bin]) ? FALSE : $memcache_cache[$bin];
978 979
}

980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002
/**
 * Ensure that we're working with a proper cluster array.
 */
function dmemcache_object_cluster($cluster) {
  if (!is_array($cluster)) {
    // Set defaults.
    $cluster = array(
      'cluster' => $cluster,
      'weight' => 1,
    );
  }
  if (!isset($cluster['cluster']) || !is_string($cluster['cluster'])) {
    // Cluster is required, complain if it's missing or invalid.
    register_shutdown_function('watchdog', 'memcache', 'Ignoring invalid or missing cluster definition, review your memcache_servers configuration.', array(), WATCHDOG_ERROR);
    return FALSE;
  }
  if (!isset($cluster['weight']) || !is_int($cluster['weight']) || $cluster['weight'] < 1) {
    // Weight is optional.
    $cluster['weight'] = 1;
  }
  return $cluster;
}

1003 1004 1005 1006 1007 1008 1009
/**
 * 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.
1010 1011
 * @param string $multiple
 *   If TRUE will return all possible prefix variations.
1012
 *
1013 1014
 * @return string or array
 *   The prefixed and encoded key(s).
1015
 */
1016
function dmemcache_key($key, $bin = 'cache', $multiple = FALSE) {
1017
  $prefix = '';
1018 1019
  if ($prefixes = variable_get('memcache_key_prefix', '')) {
    if (is_array($prefixes)) {
1020 1021 1022 1023
      // If no custom prefix defined for bin, use 'default'.
      if (empty($prefixes[$bin])) {
        $bin = 'default';
      }
1024
      if (!empty($prefixes[$bin])) {
1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038
        // There can be multiple prefixes specified for each bin.
        if (is_array($prefixes[$bin])) {
          // Optionally return key with all prefixes.
          if ($multiple) {
            $prefix = array();
            foreach ($prefixes[$bin] as $pre) {
              $prefix[] = $pre . '-';
            }
          }
          // Otherwise just return a single prefixed key.
          else {
            $prefix = $prefixes[$bin][0] . '-';
          }
        }
1039 1040 1041 1042 1043
      }
    }
    else {
      $prefix = $prefixes . '-';
    }
1044
  }
1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056

  if (!is_array($prefix)) {
    $prefix = array($prefix);
  }
  $full_keys = array();
  foreach ($prefix as $p) {
    // When simpletest is running, emulate the simpletest database prefix here
    // to avoid the child site setting cache entries in the parent site.
    if (isset($GLOBALS['drupal_test_info']['test_run_id'])) {
      $p .= $GLOBALS['drupal_test_info']['test_run_id'];
    }
    $full_keys[] = urlencode($p . $bin . '-' . $key);
1057 1058
  }

1059 1060 1061 1062 1063 1064 1065 1066
  // 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);
1067 1068 1069 1070 1071 1072

  foreach ($full_keys as $k => $full_key) {
    if (strlen($full_key) > $maxlen) {
      $full_keys[$k] = urlencode($prefix[$k] . $bin) . '-' . hash(variable_get('memcache_key_hash_algorithm', 'sha1'), $key);
      $full_keys[$k] .= '-' . substr(urlencode($key), 0, ($maxlen - 1) - strlen($full_keys[$k]) - 1);
    }
1073
  }
1074

1075 1076 1077 1078 1079 1080 1081 1082
  if ($multiple) {
    // An array of prefixed keys.
    return $full_keys;
  }
  else {
    // A single prefixed key.
    return array_shift($full_keys);
  }
1083
}
1084

1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154
/**
 * 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;
}

1155
/**
1156 1157
 * Collect statistics if enabled.
 *
1158 1159 1160
 * Optimized function to determine whether or not we should be collecting
 * statistics. Also starts a timer to track how long individual memcache
 * operations take.
1161
 *
1162 1163
 * @return bool
 *   TRUE or FALSE if statistics should be collected.
1164
 */
1165
function dmemcache_stats_init() {
1166
  static $drupal_static_fast;
1167

1168 1169 1170 1171 1172 1173 1174
  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
1175 1176 1177
  // 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().
1178 1179 1180 1181
  if (!isset($variable_checked) && function_exists('module_list')) {
    $variable_checked = variable_get('show_memcache_statistics', FALSE);
  }
  // If statistics are enabled we need to check user access.
1182
  if (!empty($variable_checked) && !isset($user_access_checked) && !empty($GLOBALS['user']) && function_exists('user_access')) {
1183 1184 1185 1186 1187
    // Statistics are enabled and the $user object has been populated, so check
    // that the user has access to view them.
    $user_access_checked = user_access('access memcache statistics');
  }
  // Return whether or not statistics are enabled and the user can access them.
1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199
  if ((!isset($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.
 *
1200 1201 1202 1203 1204 1205 1206
 * @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)$success. The keys the
 *   action is being performed on, and whether or not it was a success.
1207 1208
 */
function dmemcache_stats_write($action, $bin, $keys) {
1209
  global $_dmemcache_stats;
1210 1211 1212 1213
  // 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) {
1214 1215 1216 1217 1218