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<?php
/**
* File: Cache_Memcached.php
*
* @package W3TC
*/
namespace W3TC;
/**
* Class Cache_Memcached
*
* PECL Memcached class
* Preferred upon Memcache
*
* phpcs:disable PSR2.Classes.PropertyDeclaration.Underscore
* phpcs:disable PSR2.Methods.MethodDeclaration.Underscore
* phpcs:disable WordPress.PHP.NoSilencedErrors.Discouraged
* phpcs:disable Universal.CodeAnalysis.ConstructorDestructorReturn.ReturnValueFound
*/
class Cache_Memcached extends Cache_Base {
/**
* Memcache object
*
* @var Memcache
*/
private $_memcache = null;
/**
* Used for faster flushing
*
* @var integer $_key_version
*/
private $_key_version = array();
/**
* Configuration used to reinitialize persistent object
*
* @var integer $_key_version
*/
private $_config = null;
/**
* Constructor to initialize the Memcached client with provided configuration.
*
* @param array $config {
* Configuration settings for the Memcached client, including server details, options, and credentials.
*
* @type bool $persistent Whether to use persistent connections.
* }
*
* @return bool True on successful initialization, false on failure.
*/
public function __construct( $config ) {
parent::__construct( $config );
if ( isset( $config['persistent'] ) && $config['persistent'] ) {
$this->_config = $config;
$this->_memcache = new \Memcached( $this->_get_key_version_key( '' ) );
$server_list = $this->_memcache->getServerList();
if ( empty( $server_list ) ) {
return $this->initialize( $config );
} else {
return true;
}
} else {
$this->_memcache = new \Memcached();
return $this->initialize( $config );
}
}
/**
* Initializes the Memcached client with the given configuration.
*
* @param array $config {
* Configuration settings for the Memcached client, including server details, options, and credentials.
*
* @type array|string $servers List of Memcached server endpoints (host:port).
* @type bool $binary_protocol Enable binary protocol if true.
* @type bool $aws_autodiscovery Enable AWS autodiscovery if true.
* @type string $username Username for SASL authentication.
* @type string $password Password for SASL authentication.
* @type string $key_version_mode Key versioning mode (disabled to skip versioning).
* }
*
* @return bool True on successful initialization, false on failure.
*/
private function initialize( $config ) {
if ( empty( $config['servers'] ) ) {
return false;
}
if ( defined( '\Memcached::OPT_REMOVE_FAILED_SERVERS' ) ) {
$this->_memcache->setOption( \Memcached::OPT_REMOVE_FAILED_SERVERS, true );
}
if ( isset( $config['binary_protocol'] ) && ! empty( $config['binary_protocol'] ) && defined( '\Memcached::OPT_BINARY_PROTOCOL' ) ) {
$this->_memcache->setOption( \Memcached::OPT_BINARY_PROTOCOL, true );
}
if ( defined( '\Memcached::OPT_TCP_NODELAY' ) ) {
$this->_memcache->setOption( \Memcached::OPT_TCP_NODELAY, true );
}
if (
isset( $config['aws_autodiscovery'] ) &&
$config['aws_autodiscovery'] &&
defined( '\Memcached::OPT_CLIENT_MODE' ) &&
defined( '\Memcached::DYNAMIC_CLIENT_MODE' )
) {
$this->_memcache->setOption( \Memcached::OPT_CLIENT_MODE, \Memcached::DYNAMIC_CLIENT_MODE );
}
foreach ( (array) $config['servers'] as $server ) {
list( $ip, $port ) = Util_Content::endpoint_to_host_port( $server );
$this->_memcache->addServer( $ip, $port );
}
if ( isset( $config['username'] ) && ! empty( $config['username'] ) && method_exists( $this->_memcache, 'setSaslAuthData' ) ) {
$this->_memcache->setSaslAuthData( $config['username'], $config['password'] );
}
// when disabled - no extra requests are made to obtain key version, but flush operations not supported as a result
// group should be always empty.
if ( isset( $config['key_version_mode'] ) && 'disabled' === $config['key_version_mode'] ) {
$this->_key_version[''] = 1;
}
return true;
}
/**
* Adds a new key-value pair to the Memcached server, or updates it if it already exists.
*
* @param string $key The key under which the data will be stored.
* @param mixed $value The data to store.
* @param int $expire The expiration time in seconds (default is 0 for no expiration).
* @param string $group The group to which the item belongs (default is an empty string).
*
* @return bool True on success, false on failure.
*/
public function add( $key, &$value, $expire = 0, $group = '' ) {
return $this->set( $key, $value, $expire, $group );
}
/**
* Sets a key-value pair in the Memcached server, or updates it if it already exists.
*
* @param string $key The key under which the data will be stored.
* @param mixed $value The data to store.
* @param int $expire The expiration time in seconds (default is 0 for no expiration).
* @param string $group The group to which the item belongs (default is an empty string).
*
* @return bool True on success, false on failure.
*/
public function set( $key, $value, $expire = 0, $group = '' ) {
if ( ! isset( $value['key_version'] ) ) {
$value['key_version'] = $this->_get_key_version( $group );
}
$storage_key = $this->get_item_key( $key );
return @$this->_memcache->set( $storage_key, $value, $expire );
}
/**
* Retrieves a value from Memcached along with a flag indicating if old data was found.
*
* Checks for data associated with the given key and ensures the version is up-to-date.
*
* @param string $key The key to fetch from the Memcached server.
* @param string $group The group the item belongs to (default is an empty string).
*
* @return array An array containing the fetched data (or null) and a flag indicating whether old data was returned.
*/
public function get_with_old( $key, $group = '' ) {
$has_old_data = false;
$storage_key = $this->get_item_key( $key );
$v = @$this->_memcache->get( $storage_key );
if ( ! is_array( $v ) || ! isset( $v['key_version'] ) ) {
return array( null, $has_old_data );
}
$key_version = $this->_get_key_version( $group );
if ( $v['key_version'] === $key_version ) {
return array( $v, $has_old_data );
}
if ( $v['key_version'] > $key_version ) {
if ( ! empty( $v['key_version_at_creation'] ) && $v['key_version_at_creation'] !== $key_version ) {
$this->_set_key_version( $v['key_version'], $group );
}
return array( $v, $has_old_data );
}
// key version is old.
if ( ! $this->_use_expired_data ) {
return array( null, $has_old_data );
}
// if we have expired data - update it for future use and let current process recalculate it.
$expires_at = isset( $v['expires_at'] ) ? $v['expires_at'] : null;
if ( null === $expires_at || time() > $expires_at ) {
$v['expires_at'] = time() + 30;
@$this->_memcache->set( $storage_key, $v, 0 );
$has_old_data = true;
return array( null, $has_old_data );
}
// return old version.
return array( $v, $has_old_data );
}
/**
* Replaces an existing key-value pair in Memcached if it already exists.
*
* @param string $key The key under which the data will be stored.
* @param mixed $value The data to store.
* @param int $expire The expiration time in seconds (default is 0 for no expiration).
* @param string $group The group to which the item belongs (default is an empty string).
*
* @return bool True on success, false on failure.
*/
public function replace( $key, &$value, $expire = 0, $group = '' ) {
return $this->set( $key, $value, $expire, $group );
}
/**
* Deletes a key-value pair from Memcached.
*
* @param string $key The key to delete from the Memcached server.
* @param string $group The group the item belongs to (default is an empty string).
*
* @return bool True on success, false on failure.
*/
public function delete( $key, $group = '' ) {
$storage_key = $this->get_item_key( $key );
if ( $this->_use_expired_data ) {
$v = @$this->_memcache->get( $storage_key );
if ( is_array( $v ) ) {
$v['key_version'] = 0;
@$this->_memcache->set( $storage_key, $v, 0 );
return true;
}
}
return @$this->_memcache->delete( $storage_key );
}
/**
* Deletes an item from the Memcached storage.
*
* @param string $key The cache key to delete.
* @param string $group The cache group. Default is an empty string.
*
* @return bool True if the item was successfully deleted, false otherwise.
*/
public function hard_delete( $key, $group = '' ) {
$storage_key = $this->get_item_key( $key );
return @$this->_memcache->delete( $storage_key );
}
/**
* Flushes all items in the Memcached storage.
*
* This method resets the server list if persistent connections are used, and reinitializes the Memcached object with the new
* configuration.
*
* @param string $group The cache group to flush. Default is an empty string.
*
* @return bool Always returns true.
*/
public function flush( $group = '' ) {
$this->_increment_key_version( $group );
// for persistent connections - apply new config to the object otherwise it will keep old servers list.
if ( ! is_null( $this->_config ) ) {
if ( method_exists( $this->_memcache, 'resetServerList' ) ) {
$this->_memcache->resetServerList();
}
$this->initialize( $this->_config );
}
return true;
}
/**
* Returns an array containing the key version and its version at creation for the specified group.
*
* @param string $group The cache group for which to retrieve version information.
*
* @return array Associative array containing 'key_version' and 'key_version_at_creation'.
*/
public function get_ahead_generation_extension( $group ) {
$v = $this->_get_key_version( $group );
return array(
'key_version' => $v + 1,
'key_version_at_creation' => $v,
);
}
/**
* Updates the key version for a given cache group after ahead generation.
*
* If the provided extension's key version is greater than the current version, it updates the key version.
*
* @param string $group The cache group to update.
* @param array $extension {
* The extension data containing the new key version.
*
* @type string $key_version The new key version to set.
* }
*
* @return void
*/
public function flush_group_after_ahead_generation( $group, $extension ) {
$v = $this->_get_key_version( $group );
if ( $extension['key_version'] > $v ) {
$this->_set_key_version( $extension['key_version'], $group );
}
}
/**
* Checks if Memcached is available for use.
*
* @return bool True if the Memcached class exists and is available, false otherwise.
*/
public function available() {
return class_exists( 'Memcached' );
}
/**
* Retrieves Memcached statistics.
*
* @return array|false Memcached statistics if available, false otherwise.
*/
public function get_statistics() {
$a = $this->_memcache->getStats();
if ( ! empty( $a ) && count( $a ) > 0 ) {
$keys = array_keys( $a );
$key = $keys[0];
return $a[ $key ];
}
return $a;
}
/**
* Retrieves the current key version for a specific cache group.
*
* If the version is not set or is invalid, it attempts to fetch it from Memcached.
*
* @param string $group The cache group to get the key version for. Default is an empty string.
*
* @return int The current key version.
*/
private function _get_key_version( $group = '' ) {
if ( ! isset( $this->_key_version[ $group ] ) || $this->_key_version[ $group ] <= 0 ) {
$v = @$this->_memcache->get( $this->_get_key_version_key( $group ) );
$v = intval( $v );
$this->_key_version[ $group ] = ( $v > 0 ? $v : 1 );
}
return $this->_key_version[ $group ];
}
/**
* Sets the key version for a specific cache group.
*
* The expiration is set to 0, which means the version does not expire.
*
* @param int $v The key version to set.
* @param string $group The cache group to set the version for. Default is an empty string.
*
* @return void
*/
private function _set_key_version( $v, $group = '' ) {
// expiration has to be as long as possible since all cache data expires when key version expires.
@$this->_memcache->set( $this->_get_key_version_key( $group ), $v, 0 );
$this->_key_version[ $group ] = $v;
}
/**
* Increments the key version for a specific cache group.
*
* This method attempts to increment the version in Memcached. If the key does not exist, it sets the version to 2 to initialize it.
*
* @since 0.14.5
*
* @param string $group The cache group to increment the version for. Default is an empty string.
*
* @return void
*/
private function _increment_key_version( $group = '' ) {
$r = @$this->_memcache->increment( $this->_get_key_version_key( $group ), 1 );
if ( $r ) {
$this->_key_version[ $group ] = $r;
} else {
// it doesn't initialize the key if it doesn't exist.
$this->_set_key_version( 2, $group );
}
}
/**
* Retrieves cache statistics size, including the total number of items and bytes.
*
* It checks for timeouts and returns statistics based on the cache server list.
*
* @param int $timeout_time The timestamp to check if the timeout has occurred.
*
* @return array An associative array containing 'bytes', 'items', and 'timeout_occurred'.
*/
public function get_stats_size( $timeout_time ) {
$size = array(
'bytes' => 0,
'items' => 0,
'timeout_occurred' => false,
);
$key_prefix = $this->get_item_key( '' );
$error_occurred = false;
$server_list = $this->_memcache->getServerList();
$n = 0;
foreach ( $server_list as $server ) {
$loader = new Cache_Memcached_Stats( $server['host'], $server['port'] );
$slabs = $loader->slabs();
if ( ! is_array( $slabs ) ) {
$error_occurred = true;
continue;
}
foreach ( $slabs as $slab_id ) {
$cdump = $loader->cachedump( $slab_id );
if ( ! is_array( $cdump ) ) {
continue;
}
foreach ( $cdump as $line ) {
$key_data = explode( ' ', $line );
if ( ! is_array( $key_data ) || count( $key_data ) < 3 ) {
continue;
}
++$n;
if ( 0 === $n % 10 ) {
$size['timeout_occurred'] = ( time() > $timeout_time );
if ( $size['timeout_occurred'] ) {
return $size;
}
}
$key = $key_data[1];
$bytes = substr( $key_data[2], 1 );
if ( substr( $key, 0, strlen( $key_prefix ) ) === $key_prefix ) {
$size['bytes'] += $bytes;
++$size['items'];
}
}
}
}
if ( $error_occurred && $size['items'] <= 0 ) {
$size['bytes'] = null;
$size['items'] = null;
}
return $size;
}
/**
* Sets a new value for a cache item if the current value matches the specified old value.
*
* This method uses CAS (Compare and Swap) to atomically update the cache item.
*
* @param string $key The cache key to update.
* @param array $old_value {
* The current value to compare against.
*
* @type mixed $content The content to compare in the old value.
* }
* @param array $new_value The new value to set if the old value matches.
*
* @return bool True if the item was updated, false otherwise.
*/
public function set_if_maybe_equals( $key, $old_value, $new_value ) {
$storage_key = $this->get_item_key( $key );
$cas = null;
$value = @$this->_memcache->get( $storage_key, null, $cas );
if ( ! is_array( $value ) ) {
return false;
}
if ( isset( $old_value['content'] ) && $value['content'] !== $old_value['content'] ) {
return false;
}
return @$this->_memcache->cas( $cas, $storage_key, $new_value );
}
/**
* Increments a counter in the cache by the specified value.
*
* If the counter does not exist, it initializes it with 0.
*
* @param string $key The cache key for the counter.
* @param int $value The value to add to the counter.
*
* @return bool True if the counter was incremented successfully, false otherwise.
*/
public function counter_add( $key, $value ) {
if ( 0 === $value ) {
return true;
}
$storage_key = $this->get_item_key( $key );
$r = $this->_memcache->increment( $storage_key, $value, 0, 3600 );
if ( ! $r ) { // it doesnt initialize counter by itself.
$this->counter_set( $key, 0 );
}
return $r;
}
/**
* Sets a counter value in the Memcached storage.
*
* This method sets a specified value for a given key in the Memcached storage. If the key doesn't already exist, it initializes
* it with the provided value. This is typically used to set counters or similar numeric values that need to be stored persistently.
*
* @param string $key The key under which the counter is stored.
* @param int $value The value to set for the counter.
*
* @return bool True on success, false on failure.
*/
public function counter_set( $key, $value ) {
$storage_key = $this->get_item_key( $key );
return @$this->_memcache->set( $storage_key, $value );
}
/**
* Retrieves the counter value from Memcached storage.
*
* This method fetches the stored counter value for the given key. If the key doesn't exist or the value is not a valid integer,
* it returns 0. This is typically used to retrieve counters or similar numeric values stored persistently.
*
* @param string $key The key under which the counter is stored.
*
* @return int The current counter value, or 0 if the key does not exist or is invalid.
*/
public function counter_get( $key ) {
$storage_key = $this->get_item_key( $key );
$v = (int) @$this->_memcache->get( $storage_key );
return $v;
}
/**
* Generates a unique Memcached key for the given item name.
*
* This method generates a unique key for an item to be stored in Memcached. The key is constructed using various instance-specific
* properties (e.g., instance ID, host, blog ID, module) combined with the md5 hash of the item name. This ensures that keys are
* unique and can safely be used in a multi-instance or multi-module environment.
*
* @param string $name The item name to generate a key for.
*
* @return string The generated unique Memcached key.
*/
public function get_item_key( $name ) {
// memcached doesn't survive spaces in a key.
$key = sprintf( 'w3tc_%d_%s_%d_%s_%s', $this->_instance_id, $this->_host, $this->_blog_id, $this->_module, md5( $name ) );
return $key;
}
}