dmemcache.inc in Memcache API and Integration 6
Same filename and directory in other branches
File
dmemcache.incView source
<?php
/*
* Core dmemcache functions required by:
* memcache.inc
* memcache.db.inc
* session-memcache.inc
* session-memcache.db.inc
*/
define('MEMCACHED_E2BIG', 37);
global $_dmemcache_stats;
$_dmemcache_stats = array(
'all' => array(),
'ops' => array(),
);
/*
* A memcache API for Drupal.
*/
/**
* Place an item into memcache
*
* @param $key The string with with you will retrieve this item later.
* @param $value The item to be stored.
* @param $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 $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 $bin values to
* different memcache servers.
*
* @return bool
*/
function dmemcache_set($key, $value, $exp = 0, $bin = 'cache') {
$collect_stats = dmemcache_stats_init();
$full_key = dmemcache_key($key, $bin);
$rc = FALSE;
if ($mc = dmemcache_object($bin)) {
if ($mc instanceof Memcached) {
$rc = $mc
->set($full_key, $value, $exp);
if (empty($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, $mc);
}
}
}
elseif ($mc instanceof Memcache) {
// 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.
dmemcache_static_reset('_dmemcache_error_handler');
set_error_handler('_dmemcache_error_handler');
$rc = $mc
->set($full_key, $value, MEMCACHE_COMPRESSED, $exp);
// Restore the Drupal error handler.
restore_error_handler();
if (empty($rc)) {
// If the object was too big, split the value into pieces and cache
// them individually.
$dmemcache_errormsg =& dmemcache_static('_dmemcache_error_handler');
if (!empty($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, $mc);
}
}
}
}
if ($collect_stats) {
dmemcache_stats_write('set', $bin, array(
$full_key => $rc,
));
}
return $rc;
}
/**
* A temporary error handler which keeps track of the most recent error.
*/
function _dmemcache_error_handler($errno, $errstr) {
$dmemcache_errormsg =& dmemcache_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).
$piece_cache =& dmemcache_static('dmemcache_piece_cache', array());
register_shutdown_function('watchdog', 'memcache', 'Too many over-sized cache items (!count) has caused the dmemcache_piece_cache to exceed the maximum memcache object size (default of 1 MiB). Now relying on memcache auto-expiration to eventually clean up over-sized cache pieces upon deletion.', array(
'!count' => count($piece_cache),
), WATCHDOG_ERROR);
}
if (variable_get('memcache_log_data_pieces', 2)) {
timer_start('memcache_split_data');
}
// We need to split the item into pieces, so convert it into a string.
if (is_string($value)) {
$data = $value;
$serialized = FALSE;
}
else {
$data = serialize($value);
$serialized = TRUE;
}
// Account for any metadata stored alongside the data.
$max_len = variable_get('memcache_data_max_length', 1048576) - (512 + strlen($full_key));
$pieces = str_split($data, $max_len);
$piece_count = count($pieces);
// Create a placeholder item containing data about the pieces.
$cache = new stdClass();
// $key gets run through dmemcache_key() later inside dmemcache_set().
$cache->cid = $key;
$cache->created = $_SERVER['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 = $_SERVER['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) && $piece_count >= variable_get('memcache_log_data_pieces', 2)) {
register_shutdown_function('watchdog', 'memcache', 'Spent !time ms splitting !bytes object into !pieces pieces, cid = !key', array(
'!time' => timer_read('memcache_split_data'),
'!bytes' => format_size(strlen($data)),
'!pieces' => $piece_count,
'!key' => dmemcache_key($key, $bin),
), WATCHDOG_WARNING);
}
$recursion--;
// TRUE if all pieces were saved correctly.
return $result;
}
/**
* Add an item into memcache
*
* @param $key The string with which you will retrieve this item later.
* @param $value The item to be stored.
* @param $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 $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 $mc
* (optional) The memcache object. Normally this value is
* determined automatically based on the bin the object is being stored to.
* @param $flag
* (optional) If using the older memcache PECL extension as opposed to the
* newer memcached PECL extension, the MEMCACHE_COMPRESSED flag can be set
* to use zlib to store a compressed copy of the item. This flag option is
* completely ignored when using the newer memcached PECL extension.
*
* NOTE: dmemcache_get calls dmemcache_add when grabbing a semaphore. For that
* reason, dmemcache_add can't call dmemcache_get for any reason or you'll end
* up in an infinite loop.
*
* @return bool
*/
function dmemcache_add($key, $value, $exp = 0, $bin = 'cache', $mc = NULL, $flag = FALSE) {
$collect_stats = dmemcache_stats_init();
$full_key = dmemcache_key($key, $bin);
$rc = FALSE;
if ($mc || ($mc = dmemcache_object($bin))) {
if ($mc instanceof Memcached) {
$rc = $mc
->add($full_key, $value, $exp);
}
elseif ($mc instanceof Memcache) {
$rc = $mc
->add($full_key, $value, $flag, $exp);
}
}
if ($collect_stats) {
dmemcache_stats_write('add', $bin, array(
$full_key => $rc,
));
}
return $rc;
}
/**
* Retrieve a value from the cache.
*
* @param $key The key with which the item was stored.
* @param $bin The bin in which the item was stored.
*
* @return The item which was originally saved or FALSE
*/
function dmemcache_get($key, $bin = 'cache') {
$collect_stats = dmemcache_stats_init();
$result = FALSE;
$full_key = dmemcache_key($key, $bin);
if ($mc = dmemcache_object($bin)) {
$track_errors = ini_set('track_errors', '1');
$php_errormsg = '';
$result = @$mc
->get($full_key);
if (is_object($result) && !empty($result->multi_part_data)) {
// This is a multi-part value.
$result = _dmemcache_get_pieces($result->data, $result->cid, $bin, $mc);
}
if (!empty($php_errormsg)) {
register_shutdown_function('watchdog', 'memcache', 'Exception caught in dmemcache_get: !msg', array(
'!msg' => $php_errormsg,
), WATCHDOG_WARNING);
$php_errormsg = '';
}
ini_set('track_errors', $track_errors);
}
if ($collect_stats) {
dmemcache_stats_write('get', $bin, array(
$full_key => (bool) $result,
));
}
return $result;
}
/**
* Retrieve a value from the cache.
*
* @param $item
* The placeholder cache item from _dmemcache_set_pieces().
* @param $key
* The key with which the item was stored.
* @param string $bin
* (optional) The bin in which the item was stored.
* @param object $mc
* (optional) The memcache object. Normally this value is
* determined automatically based on the bin the object is being stored to.
*
* @return object|bool
* The item which was originally saved or FALSE.
*/
function _dmemcache_get_pieces($item, $key, $bin = 'cache', $mc = NULL) {
// Create a list of keys for the pieces of data.
for ($id = 0; $id < $item->piece_count; $id++) {
$keys[] = _dmemcache_key_piece($key, $id);
}
// Retrieve all the pieces of data.
$pieces = dmemcache_get_multi($keys, $bin, $mc);
if (count($pieces) != $item->piece_count) {
// Some of the pieces don't exist, so our data cannot be reconstructed.
return FALSE;
}
// Append all of the pieces together.
$data = '';
foreach ($pieces as $piece) {
$data .= $piece->data;
}
unset($pieces);
// If necessary unserialize the item.
return empty($item->serialized) ? $data : unserialize($data);
}
/**
* Generates a key name for a multi-part data piece based on the sequence ID.
*
* @param int $id
* The sequence ID of the data piece.
* @param int $key
* The original CID of the cache item.
*
* @return string
*/
function _dmemcache_key_piece($key, $id) {
return dmemcache_key('_multi' . (string) $id . "-{$key}");
}
/**
* Retrieve multiple values from the cache.
*
* @param $keys The keys with which the items were stored.
* @param $bin The bin in which the item was stored.
*
* @return The item which was originally saved or FALSE
*/
function dmemcache_get_multi($keys, $bin = 'cache', $mc = NULL) {
$collect_stats = dmemcache_stats_init();
$multi_stats = array();
$full_keys = array();
foreach ($keys as $key => $cid) {
$full_key = dmemcache_key($cid, $bin);
$full_keys[$cid] = $full_key;
if ($collect_stats) {
$multi_stats[$full_key] = FALSE;
}
}
$results = array();
if ($mc || ($mc = dmemcache_object($bin))) {
if ($mc instanceof Memcached) {
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, $cas_tokens, Memcached::GET_PRESERVE_ORDER);
}
}
elseif ($mc instanceof Memcache) {
$track_errors = ini_set('track_errors', '1');
$php_errormsg = '';
$results = @$mc
->get($full_keys);
// Order is not guaranteed, map responses to order of requests.
$keys = array_fill_keys($full_keys, NULL);
$results = array_merge($keys, $results);
if (!empty($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);
}
}
// If $results is FALSE, convert it to an empty array.
if (!$results) {
$results = array();
}
if ($collect_stats) {
foreach ($multi_stats as $key => $value) {
$multi_stats[$key] = isset($results[$key]) ? TRUE : FALSE;
}
}
// Convert the full keys back to the cid.
$cid_results = array();
$cid_lookup = array_flip($full_keys);
foreach ($results as $key => $value) {
if (is_object($value) && !empty($value->multi_part_data)) {
// This is a multi-part value.
$value = _dmemcache_get_pieces($value->data, $value->cid, $bin, $mc);
}
$cid_results[$cid_lookup[$key]] = $value;
}
if ($collect_stats) {
dmemcache_stats_write('getMulti', $bin, $multi_stats);
}
return $cid_results;
}
/**
* Deletes an item from the cache.
*
* @param $key The key with which the item was stored.
* @param $bin The bin in which the item was stored.
*
* @return Returns TRUE on success or FALSE on failure.
*/
function dmemcache_delete($key, $bin = 'cache') {
$collect_stats = dmemcache_stats_init();
$full_key = dmemcache_key($key, $bin);
$rc = FALSE;
if ($mc = dmemcache_object($bin)) {
$rc = $mc
->delete($full_key, 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($full_key)) {
// First, remove from the piece_cache so we don't try and delete it
// again in another thread, then delete the actual cache data pieces.
dmemcache_piece_cache_set($full_key, NULL);
$next_id = 0;
do {
// Generate the cid of the next data piece.
$piece_key = _dmemcache_key_piece($key, $next_id);
$full_key = dmemcache_key($piece_key, $bin);
$next_id++;
// Keep deleting pieces until the operation fails. We accept that
// this could lead to orphaned pieces as memcache will auto-expire
// them eventually.
} while ($mc
->delete($full_key, 0));
// Perform garbage collection for keys memcache has auto-expired. If we
// don't do this, this variable could grow over enough time as a slow
// memory leak.
// @todo: Consider moving this to hook_cron() and requiring people to
// enable the memcache module.
timer_start('memcache_gc_piece_cache');
$gc_counter = 0;
$piece_cache =& dmemcache_static('dmemcache_piece_cache', array());
foreach ($piece_cache as $cid => $expires) {
if ($_SERVER['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' => $gc_counter,
), WATCHDOG_WARNING);
}
}
}
}
if ($collect_stats) {
dmemcache_stats_write('delete', $bin, array(
$full_key => $rc,
));
}
return $rc;
}
/**
* 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.
*
* @param $bin The bin to flush. Note that this will flush all bins mapped to the same server
* as $bin. There is no way at this time to empty just one bin.
*
* @return Returns TRUE on success or FALSE on failure.
*/
function dmemcache_flush($bin = 'cache') {
$collect_stats = dmemcache_stats_init();
$rc = FALSE;
if ($mc = dmemcache_object($bin)) {
$rc = $mc
->flush();
}
if ($collect_stats) {
dmemcache_stats_write('flush', $bin, array(
'' => $rc,
));
}
return $rc;
}
function dmemcache_stats($stats_bin = 'cache', $stats_type = 'default', $aggregate = FALSE) {
$memcache_bins = variable_get('memcache_bins', array(
'cache' => 'default',
));
if (!isset($memcache_bins['cache'])) {
$memcache_bins['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.
$slab = (int) $stats_type;
$stats = array();
foreach ($memcache_bins as $bin => $target) {
if ($stats_bin == $bin) {
if ($mc = dmemcache_object($bin)) {
if ($mc instanceof Memcached) {
$stats[$bin] = $mc
->getStats();
}
else {
if ($mc instanceof Memcache) {
if ($stats_type == 'default' || $stats_type == '') {
$stats[$bin] = $mc
->getExtendedStats();
}
else {
if (!empty($slab)) {
$stats[$bin] = $mc
->getStats('cachedump', $slab);
}
else {
$stats[$bin] = $mc
->getExtendedStats($stats_type);
}
}
}
}
}
}
}
// Optionally calculate a sum-total for all servers in the current bin.
if ($aggregate) {
// Some variables don't logically aggregate.
$no_aggregate = array(
'pid',
'time',
'version',
'pointer_size',
'accepting_conns',
'listen_disabled_num',
);
foreach ($stats as $bin => $servers) {
if (is_array($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;
}
}
}
}
}
}
}
}
return $stats;
}
/**
* Initiate a connection to memcache.
*
* @param object $memcache
* A memcache instance obtained through dmemcache_instance.
* @param string $server
* A server string of the format "localhost:11211" or
* "unix:///path/to/socket".
* @param bool $connection
* TRUE or FALSE, whether the $memcache instance already has at least one
* open connection.
*
* @return bool
* TRUE or FALSE if connection was successful.
*/
function dmemcache_connect($memcache, $server, $connection) {
static $memcache_persistent = NULL;
$extension = dmemcache_extension();
@(list($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' => $server,
'!ip' => t('127.0.0.1:11211'),
'!host' => t('localhost:11211'),
'!socket' => t('unix:///path/to/socket'),
), WATCHDOG_WARNING);
}
if ($extension == 'Memcache') {
// Allow persistent connection via Memcache extension -- note that this
// module currently doesn't support persistent connections with the
// Memcached extension. See http://drupal.org/node/822316#comment-4427676
// for details.
if (!isset($memcache_persistent)) {
$memcache_persistent = variable_get('memcache_persistent', FALSE);
}
// Support unix sockets of the format 'unix:///path/to/socket'.
if ($host == 'unix') {
// Use full protocol and path as expected by Memcache extension.
$host = $server;
$port = 0;
}
else {
if (!isset($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' => $server,
'!ip' => t('127.0.0.1:11211'),
'!host' => t('localhost:11211'),
'!socket' => t('unix:///path/to/socket'),
), WATCHDOG_WARNING);
}
}
// When using the PECL memcache extension, we must use ->(p)connect
// for the first connection.
if (!$connection) {
$track_errors = ini_set('track_errors', '1');
$php_errormsg = '';
// The Memcache extension requires us to use (p)connect for the first
// server we connect to.
if ($memcache_persistent) {
$rc = @$memcache
->pconnect($host, $port);
}
else {
$rc = @$memcache
->connect($host, $port);
}
if (!empty($php_errormsg)) {
register_shutdown_function('watchdog', 'memcache', 'Exception caught in dmemcache_connect while connecting to !host:!port: !msg', array(
'!host' => $host,
'!port' => $port,
'!msg' => $php_errormsg,
), WATCHDOG_WARNING);
$php_errormsg = '';
}
ini_set('track_errors', $track_errors);
}
else {
$rc = $memcache
->addServer($host, $port, $memcache_persistent);
}
}
elseif ($extension == 'Memcached') {
// Support unix sockets of the format 'unix:///path/to/socket'.
if ($host == 'unix') {
// Strip 'unix://' as expected by Memcached extension.
$host = substr($server, 7);
$port = 0;
}
else {
if (!isset($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);
}
}
$rc = $memcache
->addServer($host, $port);
}
else {
$rc = FALSE;
}
return $rc;
}
/**
* Close the connection to the memcache instance.
*/
function dmemcache_close($memcache) {
$extension = dmemcache_extension();
if ($extension == 'Memcache' && $memcache instanceof Memcache) {
$rc = @$memcache->close;
}
elseif ($extension == 'Memcached' && $memcache instanceof Memcached) {
$rc = @$memcache->quit;
}
else {
$rc = FALSE;
}
return $rc;
}
/**
* Returns an Memcache object based on the bin requested. 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.
*
* @param $bin The bin which is to be used.
*
* @param $flush Rebuild the bin/server/cache mapping.
*
* @return an Memcache object or FALSE.
*/
function dmemcache_object($bin = NULL, $flush = FALSE) {
static $memcache_cache = array();
static $memcache_servers = array();
static $memcache_bins = array();
static $failed_connections = array();
if ($flush) {
foreach ($memcache_cache as $cluster) {
memcache_close($cluster);
}
$memcache_cache = array();
}
$extension = dmemcache_extension();
if (empty($memcache_cache) || empty($memcache_cache[$bin])) {
// $memcache_servers and $memcache_bins originate from settings.php.
// $memcache_servers_custom and $memcache_bins_custom get set by
// memcache.module. They are then merged into $memcache_servers and
// $memcache_bins, which are statically cached for performance.
if (empty($memcache_servers)) {
// Values from settings.php
$memcache_servers = variable_get('memcache_servers', array(
'127.0.0.1:11211' => 'default',
));
$memcache_bins = variable_get('memcache_bins', array(
'cache' => 'default',
));
}
// If there is no cluster for this bin in $memcache_bins, cluster is 'default'.
$cluster = empty($memcache_bins[$bin]) ? 'default' : $memcache_bins[$bin];
// If this bin isn't in our $memcache_bins configuration array, and the
// 'default' cluster is already initialized, map the bin to 'cache' because
// we always map the 'cache' bin to the 'default' cluster.
if (empty($memcache_bins[$bin]) && !empty($memcache_cache['cache'])) {
$memcache_cache[$bin] =& $memcache_cache['cache'];
}
else {
// Create a new memcache object for each cluster.
$memcache = dmemcache_instance();
// Track whether or not we've opened any memcache connections.
$connection = FALSE;
// Link all the servers to this cluster.
foreach ($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;
}
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;
}
}
}
if ($connection) {
// Map the current bin with the new Memcache object.
$memcache_cache[$bin] = $memcache;
// Now that all the servers have been mapped to this cluster, look for
// other bins that belong to the cluster and map them too.
foreach ($memcache_bins as $b => $c) {
if ($c == $cluster && $b != $bin) {
// Map this bin and cluster by reference.
$memcache_cache[$b] =& $memcache_cache[$bin];
}
}
}
}
}
return empty($memcache_cache[$bin]) ? FALSE : $memcache_cache[$bin];
}
function dmemcache_key($key = '', $bin = 'cache', $reset = FALSE) {
static $prefix;
if (!isset($prefix)) {
$prefix = '';
// memcache_key_prefix can be set in settings.php to support site namespaces
// in a multisite environment.
if ($prefix = variable_get('memcache_key_prefix', '')) {
$prefix .= '-';
}
// When simpletest is running, emulate the simpletest database prefix here
// to avoid the child site setting cache entries in the parent site.
if (isset($GLOBALS['drupal_test_info']['test_run_id'])) {
$prefix .= $GLOBALS['drupal_test_info']['test_run_id'];
}
}
$full_key = urlencode($prefix . $bin . '-' . $key);
// Memcache truncates keys longer than 250 characters[*]. This could lead to
// cache collisions, so we hash keys that are longer than this while still
// retaining as much of the key bin and name as possible to aid in debugging.
// The hashing algorithm used is configurable, with sha1 selected by default
// as it performs quickly with minimal collisions. You can enforce shorter
// keys by setting memcache_key_max_length in settings.php.
// [*]https://github.com/memcached/memcached/blob/master/doc/protocol.txt#L47
$maxlen = variable_get('memcache_key_max_length', 250);
if (strlen($full_key) > $maxlen) {
$full_key = urlencode($prefix . $bin) . '-' . hash(variable_get('memcache_key_hash_algorithm', 'sha1'), $key);
$full_key .= '-' . substr(urlencode($key), 0, $maxlen - 1 - strlen($full_key) - 1);
}
return $full_key;
}
/**
* 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 =& dmemcache_static('dmemcache_piece_cache', array());
$piece_cache = dmemcache_get('__dmemcache_piece_cache');
if (!is_array($piece_cache)) {
$piece_cache = array();
}
if (isset($exp)) {
if ($exp <= 0) {
// If no expiration time is set, defaults to 30 days.
$exp = $_SERVER['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 $dmemcache_static_fast;
if (!isset($dmemcache_static_fast)) {
$dmemcache_static_fast['piece_cache'] =& dmemcache_static('dmemcache_piece_cache', FALSE);
}
$piece_cache =& $dmemcache_static_fast['piece_cache'];
if (!is_array($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;
}
/**
* Collect statistics if enabled.
*
* Optimized function to determine whether or not we should be collecting
* statistics. Also starts a timer to track how long individual memcache
* operations take.
*
* @return bool
* TRUE or FALSE if statistics should be collected.
*/
function dmemcache_stats_init() {
static $drupal_static_fast;
if (!isset($drupal_static_fast)) {
$drupal_static_fast =& dmemcache_static(__FUNCTION__, array(
'variable_checked' => NULL,
'user_access_checked' => NULL,
));
}
$variable_checked =& $drupal_static_fast['variable_checked'];
$user_access_checked =& $drupal_static_fast['user_access_checked'];
// Confirm DRUPAL_BOOTSTRAP_VARIABLES has been reached. We don't use
// drupal_get_bootstrap_phase() as it's buggy. We can use variable_get() here
// because _drupal_bootstrap_variables() includes module.inc immediately
// after it calls variable_initialize().
if (!isset($variable_checked) && function_exists('module_list')) {
$variable_checked = variable_get('show_memcache_statistics', FALSE);
}
// If statistics are enabled we need to check user access.
if (!empty($variable_checked) && !isset($user_access_checked) && !empty($GLOBALS['user']) && function_exists('user_access')) {
// Statistics are enabled and the $user object has been populated, so check
// that the user has access to view them.
$user_access_checked = user_access('access memcache statistics');
}
// Return whether or not statistics are enabled and the user can access them.
if ((!isset($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.
*
* @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)$success. The keys the
* action is being performed on, and whether or not it was a success.
*/
function dmemcache_stats_write($action, $bin, $keys) {
global $_dmemcache_stats;
// 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) {
$_dmemcache_stats['all'][] = array(
number_format($time, 2),
$action,
$bin,
$key,
$success ? 'hit' : 'miss',
);
if (!isset($_dmemcache_stats['ops'][$action])) {
$_dmemcache_stats['ops'][$action] = array(
$action,
0,
0,
0,
);
}
$_dmemcache_stats['ops'][$action][1] += $time;
if ($success) {
$_dmemcache_stats['ops'][$action][2]++;
}
else {
$_dmemcache_stats['ops'][$action][3]++;
}
}
// Reset the dmemcache timer for timing the next memcache operation.
}
/**
* Provides central static variable storage.
*
* Backported from Drupal 7 bootstrap.inc (renamed from drupal_static) to
* minimize changes when backporting patches from the memcache-7.x-1.x.
*
* @param $name
* Globally unique name for the variable. For a function with only one static,
* variable, the function name (e.g. via the PHP magic __FUNCTION__ constant)
* is recommended. For a function with multiple static variables add a
* distinguishing suffix to the function name for each one.
* @param $default_value
* Optional default value.
* @param $reset
* TRUE to reset one or all variables(s). This parameter is only used
* internally and should not be passed in; use drupal_static_reset() instead.
* (This function's return value should not be used when TRUE is passed in.)
*
* @return
* Returns a variable by reference.
*
* @see drupal_static_reset()
*/
function &dmemcache_static($name, $default_value = NULL, $reset = FALSE) {
static $data = array(), $default = array();
// First check if dealing with a previously defined static variable.
if (isset($data[$name]) || array_key_exists($name, $data)) {
// Non-NULL $name and both $data[$name] and $default[$name] statics exist.
if ($reset) {
// Reset pre-existing static variable to its default value.
$data[$name] = $default[$name];
}
return $data[$name];
}
// Neither $data[$name] nor $default[$name] static variables exist.
if (isset($name)) {
if ($reset) {
// Reset was called before a default is set and yet a variable must be
// returned.
return $data;
}
// First call with new non-NULL $name. Initialize a new static variable.
$default[$name] = $data[$name] = $default_value;
return $data[$name];
}
// Reset all: ($name == NULL). This needs to be done one at a time so that
// references returned by earlier invocations of dmemcache_static() also get
// reset.
foreach ($default as $name => $value) {
$data[$name] = $value;
}
// As the function returns a reference, the return should always be a
// variable.
return $data;
}
/**
* Resets one or all centrally stored static variable(s).
*
* Backported from Drupal 7 bootstrap.inc (renamed from drupal_static) to
* minimize changes when backporting patches from the memcache-7.x-1.x.
*
* @param $name
* Name of the static variable to reset. Omit to reset all variables.
* Resetting all variables should only be used, for example, for running unit
* tests with a clean environment.
*/
function dmemcache_static_reset($name = NULL) {
dmemcache_static($name, NULL, TRUE);
}
/**
* Determine which memcache extension to use: memcache or memcached.
*
* By default prefer the 'Memcache' PHP extension, though the default can be
* overridden by setting memcache_extension in settings.php.
*/
function dmemcache_extension() {
static $extension = NULL;
if ($extension === NULL) {
// If an extension is specified in settings.php, use that when available.
$preferred = variable_get('memcache_extension', NULL);
if (isset($preferred) && class_exists($preferred, FALSE)) {
$extension = ucfirst(strtolower($preferred));
}
elseif (class_exists('Memcache', FALSE)) {
$extension = 'Memcache';
}
elseif (class_exists('Memcached', FALSE)) {
$extension = 'Memcached';
}
else {
$extension = FALSE;
}
}
return $extension;
}
/**
* Return a new memcache instance.
*/
function dmemcache_instance() {
static $error = FALSE;
$extension = dmemcache_extension();
if ($extension == 'Memcache') {
return new Memcache();
}
elseif ($extension == 'Memcached') {
$memcache = new Memcached();
$default_opts = array(
Memcached::OPT_COMPRESSION => FALSE,
Memcached::OPT_DISTRIBUTION => Memcached::DISTRIBUTION_CONSISTENT,
);
foreach ($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, $value);
}
if (($sasl_username = variable_get('memcache_sasl_username', '')) && ($sasl_password = variable_get('memcache_sasl_password', ''))) {
$memcache
->setSaslAuthData($sasl_username, $sasl_password);
}
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;
}Functions
Name |
Description |
|---|---|
| dmemcache_add | Add an item into memcache |
| dmemcache_close | Close the connection to the memcache instance. |
| dmemcache_connect | Initiate a connection to memcache. |
| dmemcache_delete | Deletes an item from the cache. |
| dmemcache_extension | Determine which memcache extension to use: memcache or memcached. |
| dmemcache_flush | 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. |
| dmemcache_get | Retrieve a value from the cache. |
| dmemcache_get_multi | Retrieve multiple values from the cache. |
| dmemcache_instance | Return a new memcache instance. |
| dmemcache_key | |
| dmemcache_object | Returns an Memcache object based on the bin requested. 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… |
| dmemcache_piece_cache_get | Determine if a key has multi-piece values. |
| dmemcache_piece_cache_set | Track active keys with multi-piece values, necessary for efficient cleanup. |
| dmemcache_set | Place an item into memcache |
| dmemcache_static | Provides central static variable storage. |
| dmemcache_static_reset | Resets one or all centrally stored static variable(s). |
| dmemcache_stats | |
| dmemcache_stats_init | Collect statistics if enabled. |
| dmemcache_stats_write | Save memcache statistics to be displayed at end of page generation. |
| _dmemcache_error_handler | A temporary error handler which keeps track of the most recent error. |
| _dmemcache_get_pieces | Retrieve a value from the cache. |
| _dmemcache_key_piece | Generates a key name for a multi-part data piece based on the sequence ID. |
| _dmemcache_set_pieces | Split a large item into pieces and place them into memcache |
Constants
|
Name |
Description |
|---|---|
| MEMCACHED_E2BIG |
Globals
|
Name |
Description |
|---|---|
| $_dmemcache_stats |