dmemcache.inc 41.6 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 == '') {
            $stats[$bin] = $mc->getExtendedStats();
          }
          // 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;
                }
              }
            }
          }
        }
      }
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    }
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  }
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  return $stats;
627 628 629
}

/**
630
 * Determine which memcache extension to use: memcache or memcached.
631
 *
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 * By default prefer the 'Memcache' PHP extension, though the default can be
 * overridden by setting memcache_extension in settings.php.
634
 */
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function dmemcache_extension() {
  static $extension = NULL;
  if ($extension === NULL) {
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    // If an extension is specified in settings.php, use that when available.
    $preferred = variable_get('memcache_extension', NULL);
640
    if (isset($preferred) && class_exists($preferred)) {
641
      $extension = ucfirst(strtolower($preferred));
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    }
    // If no extension is set, default to Memcache.
644
    elseif (class_exists('Memcache')) {
645 646
      $extension = 'Memcache';
    }
647
    elseif (class_exists('Memcached')) {
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      $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';
  }
}

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/**
 * Return a new memcache instance.
 */
732
function dmemcache_instance($bin = 'cache') {
733 734 735
  static $error = FALSE;
  $extension = dmemcache_extension();
  if ($extension == 'Memcache') {
736
    return new Memcache();
737 738
  }
  elseif ($extension == 'Memcached') {
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    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, $value);
    }
758
    if (($sasl_username = variable_get('memcache_sasl_username', '')) && ($sasl_password = variable_get('memcache_sasl_password', ''))) {
759 760
      $memcache->setSaslAuthData($sasl_username, $sasl_password);
    }
761 762 763 764 765 766 767 768 769 770 771 772 773 774
    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.
 *
775 776 777 778
 * @param object $memcache
 *   A memcache instance obtained through dmemcache_instance.
 * @param string $server
 *   A server string of the format "localhost:11211" or
779
 *   "unix:///path/to/socket".
780 781 782
 * @param bool $connection
 *   TRUE or FALSE, whether the $memcache instance already has at least one
 *   open connection.
783
 *
784 785
 * @return bool
 *   TRUE or FALSE if connection was successful.
786 787 788
 */
function dmemcache_connect($memcache, $server, $connection) {
  static $memcache_persistent = NULL;
789

790 791
  $extension = dmemcache_extension();

792 793 794 795
  @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' => $server, '!ip' => t('127.0.0.1:11211'), '!host' => t('localhost:11211'), '!socket' => t('unix:///path/to/socket')), WATCHDOG_WARNING);
  }
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797 798 799 800
  if (!isset($memcache_persistent)) {
    $memcache_persistent = variable_get('memcache_persistent', TRUE);
  }

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  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;
      $port = 0;
    }
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    else if (!isset($port)) {
      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' => $server, '!ip' => t('127.0.0.1:11211'), '!host' => t('localhost:11211'), '!socket' => t('unix:///path/to/socket')), WATCHDOG_WARNING);
    }
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    // When using the PECL memcache extension, we must use ->(p)connect
    // for the first connection.
    if (!$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)) {
828
        register_shutdown_function('watchdog', 'memcache', 'Exception caught in dmemcache_connect while connecting to !host:!port: !msg', array('!host' => $host, '!port' => $port, '!msg' => $php_errormsg), WATCHDOG_WARNING);
829 830 831 832 833 834 835 836
        $php_errormsg = '';
      }
      ini_set('track_errors', $track_errors);
    }
    else {
      $rc = $memcache->addServer($host, $port, $memcache_persistent);
    }
  }
837
  elseif ($extension == 'Memcached') {
838 839 840 841 842 843
    // Support unix sockets of the format 'unix:///path/to/socket'.
    if ($host == 'unix') {
      // Strip 'unix://' as expected by Memcached extension.
      $host = substr($server, 7);
      $port = 0;
    }
844 845 846
    else if (!isset($port)) {
      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' => $server, '!ip' => t('127.0.0.1:11211'), '!host' => t('localhost:11211'), '!socket' => t('unix:///path/to/socket')), WATCHDOG_WARNING);
    }
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    if ($memcache_persistent) {
      $servers = $memcache->getServerList();
      $match = FALSE;
      foreach ($servers as $s) {
        if ($s['host'] == $host && $s['port'] == $port) {
          $match = TRUE;
          break;
        }
      }
      if (!$match) {
        $rc = $memcache->addServer($host, $port);
      }
      else {
        $rc = TRUE;
      }
    }
    else {
      $rc = $memcache->addServer($host, $port);
    }
866 867 868 869 870 871 872 873 874 875 876 877 878 879 880
  }
  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;
  }
881
  elseif ($extension == 'Memcached' && $memcache instanceof Memcached) {
882
    $rc = @$memcache->quit;
883
  }
884 885 886 887 888 889 890 891 892 893 894 895 896 897
  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.
 *
898 899 900 901
 * @param string $bin
 *   The bin which is to be used.
 * @param bool $flush
 *   Defaults to FALSE. Rebuild the bin/server/cache mapping.
902
 *
903 904
 * @return mixed
 *   A Memcache object, or FALSE on failure.
905 906
 */
function dmemcache_object($bin = NULL, $flush = FALSE) {
907
  static $memcache_cache = array();
908 909 910
  static $memcache_servers = array();
  static $memcache_bins = array();
  static $failed_connections = array();
911 912

  if ($flush) {
913 914 915 916 917 918 919 920 921 922
    if (!empty($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();
      }
923 924 925
    }
  }

926 927
  $extension = dmemcache_extension();

928
  if (empty($memcache_cache) || empty($memcache_cache[$bin])) {
929
    if (empty($memcache_servers)) {
930
      // Load the variables from settings.php if set.
931
      $memcache_servers = variable_get('memcache_servers', array('127.0.0.1:11211' => 'default'));
932
      $memcache_bins = variable_get('memcache_bins', array('cache' => 'default'));
933 934
    }

935
    // If not manually set, default this cluster to 'default'.
936 937
    $cluster = empty($memcache_bins[$bin]) ? 'default' : $memcache_bins[$bin];

938 939
    // If not manually set, map this bin to 'cache' which maps to the 'default'
    // cluster.
940 941
    if (empty($memcache_bins[$bin]) && !empty($memcache_cache['cache'])) {
      $memcache_cache[$bin] = &$memcache_cache['cache'];
942 943
    }
    else {
944
      // Create a new memcache object for each cluster.
945
      $memcache = dmemcache_instance($bin);
946

947 948
      // Track whether or not we've opened any memcache connections.
      $connection = FALSE;
949

950 951 952 953 954 955 956
      // 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;
957
          }
958
          else {
959 960 961 962 963 964
            // 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;
965
          }
966 967
        }
      }
968
      if ($connection) {
969
        // Map the current bin with the new Memcache object.
970
        $memcache_cache[$bin] = $memcache;
971 972 973 974 975 976

        // 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.
977
            $memcache_cache[$b] = &$memcache_cache[$bin];
978 979 980 981 982 983
          }
        }
      }
    }
  }

984
  return empty($memcache_cache[$bin]) ? FALSE : $memcache_cache[$bin];
985 986
}

987 988 989 990 991 992 993
/**
 * 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.
994 995
 * @param string $multiple
 *   If TRUE will return all possible prefix variations.
996
 *
997 998
 * @return string or array
 *   The prefixed and encoded key(s).
999
 */
1000
function dmemcache_key($key, $bin = 'cache', $multiple = FALSE) {
1001
  $prefix = '';
1002 1003
  if ($prefixes = variable_get('memcache_key_prefix', '')) {
    if (is_array($prefixes)) {
1004 1005 1006 1007
      // If no custom prefix defined for bin, use 'default'.
      if (empty($prefixes[$bin])) {
        $bin = 'default';
      }
1008
      if (!empty($prefixes[$bin])) {
1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022
        // There can be multiple prefixes specified for each bin.
        if (is_array($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] . '-';
          }
        }
1023 1024 1025 1026 1027
      }
    }
    else {
      $prefix = $prefixes . '-';
    }
1028
  }
1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040

  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);
1041 1042
  }

1043 1044 1045 1046 1047 1048 1049 1050
  // 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);
1051 1052 1053 1054 1055 1056

  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);
    }
1057
  }
1058

1059 1060 1061 1062 1063 1064 1065 1066
  if ($multiple) {
    // An array of prefixed keys.
    return $full_keys;
  }
  else {
    // A single prefixed key.
    return array_shift($full_keys);
  }
1067
}
1068

1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 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
/**
 * 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;
}

1139
/**
1140 1141
 * Collect statistics if enabled.
 *
1142 1143 1144
 * Optimized function to determine whether or not we should be collecting
 * statistics. Also starts a timer to track how long individual memcache
 * operations take.
1145
 *
1146 1147
 * @return bool
 *   TRUE or FALSE if statistics should be collected.
1148
 */
1149
function dmemcache_stats_init() {
1150
  static $drupal_static_fast;
1151

1152 1153 1154 1155 1156 1157 1158
  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
1159 1160 1161
  // 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().
1162 1163 1164 1165
  if (!isset($variable_checked) && function_exists('module_list')) {
    $variable_checked = variable_get('show_memcache_statistics', FALSE);
  }
  // If statistics are enabled we need to check user access.
1166
  if (!empty($variable_checked) && !isset($user_access_checked) && !empty($GLOBALS['user']) && function_exists('user_access')) {
1167 1168 1169 1170 1171
    // Statistics are enabled and the $user object has been populated, so check
    // that the user has access to view them.
    $user_access_checked = user_access('access memcache statistics');
  }
  // Return whether or not statistics are enabled and the user can access them.
1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183
  if ((!isset($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.
 *
1184 1185 1186 1187 1188 1189 1190
 * @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)$success. The keys the
 *   action is being performed on, and whether or not it was a success.
1191 1192
 */
function dmemcache_stats_write($action, $bin, $keys) {
1193
  global $_dmemcache_stats;
1194 1195 1196 1197
  // 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) {
1198 1199 1200 1201 1202 1203 1204
    $_dmemcache_stats['all'][] = array(
      number_format($time, 2),
      $action,
      $bin,
      $key,
      $success ? 'hit' : 'miss',
    );
1205 1206 1207 1208
    if (!isset($_dmemcache_stats['ops'][$action])) {
      $_dmemcache_stats['ops'][$action] = array($action, 0, 0, 0);
    }
    $_dmemcache_stats['ops'][$action][1] += $time;
1209 1210 1211 1212 1213 1214
    if ($success) {
      $_dmemcache_stats['ops'][$action][2]++;
    }
    else {
      $_dmemcache_stats['ops'][$action][3]++;
    }
1215 1216
  }
  // Reset the dmemcache timer for timing the next memcache operation.
1217
}
1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229

/**
 * Write to a debug log when enabled.
 *
 * @param string $action
 *   The action being performed (get, set, etc...).
 * @param string $bin
 *   The memcache bin the action is being performed in.
 * @param array $rc
 *   The return code of the action performed.
 */
function _dmemcache_write_debug($action, $bin, $key, $rc) {
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  static $memcache_debug_log = NULL;
  static $memcache_debug_verbose = NULL;
  if ($memcache_debug_log === NULL) {
    $memcache_debug_log = variable_get('memcache_debug_log', FALSE);
    $memcache_debug_verbose = variable_get('memcache_debug_verbose', FALSE);
  }
  if (($action == 'get' || $action == 'getMulti') && !$memcache_debug_verbose) {
    return;
  }
  else if ($memcache_debug_log) {
    $debug_log = strtr(variable_get('memcache_debug_log_format', "!timestamp|!action|!bin|!cid|!rc\n"), array('!timestamp' => date(variable_get('memcache_debug_time_format', 'U')), '!action' => $action, '!bin' => $bin, '!cid' => $key, '!rc' => (int) $rc));
    if (file_put_contents($memcache_debug_log, $debug_log, FILE_APPEND) === FALSE) {
      // This can lead to a lot of watchdog entries...
      register_shutdown_function('watchdog', 'memcache', 'Unable to write to debug log at !debug_file: !debug_log.', array('!debug_file' => $memcache_debug_file, '!debug_log' => $debug_log), WATCHDOG_ERROR);
    }
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  }
}