File: /home/iestorre/moodleAW/moodle405/cache/stores/memcache/lib.php
<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* The library file for the memcache cache store.
*
* This file is part of the memcache cache store, it contains the API for interacting with an instance of the store.
*
* @package cachestore_memcache
* @copyright 2012 Sam Hemelryk
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
defined('MOODLE_INTERNAL') || die();
/**
* The memcache store class.
*
* (Not to be confused with memcached store)
*
* Configuration options:
* servers: string: host:port:weight , ...
*
* @copyright 2012 Sam Hemelryk
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class cachestore_memcache extends cache_store implements cache_is_configurable {
/**
* The name of the store
* @var store
*/
protected $name;
/**
* The memcache connection once established.
* @var Memcache
*/
protected $connection;
/**
* Key prefix for this memcache.
* @var string
*/
protected $prefix;
/**
* An array of servers to use in the connection args.
* @var array
*/
protected $servers = array();
/**
* An array of options used when establishing the connection.
* @var array
*/
protected $options = array();
/**
* Set to true when things are ready to be initialised.
* @var bool
*/
protected $isready = false;
/**
* Set to true once this store instance has been initialised.
* @var bool
*/
protected $isinitialised = false;
/**
* The cache definition this store was initialised for.
* @var cache_definition
*/
protected $definition;
/**
* If true data going in and out will be encoded.
* @var bool
*/
protected $encode = true;
/**
* Default prefix for key names.
* @var string
*/
const DEFAULT_PREFIX = 'mdl_';
/**
* Constructs the store instance.
*
* Noting that this function is not an initialisation. It is used to prepare the store for use.
* The store will be initialised when required and will be provided with a cache_definition at that time.
*
* @param string $name
* @param array $configuration
*/
public function __construct($name, array $configuration = array()) {
$this->name = $name;
if (!array_key_exists('servers', $configuration) || empty($configuration['servers'])) {
// Nothing configured.
return;
}
if (!is_array($configuration['servers'])) {
$configuration['servers'] = array($configuration['servers']);
}
foreach ($configuration['servers'] as $server) {
if (!is_array($server)) {
$server = explode(':', $server, 3);
}
if (!array_key_exists(1, $server)) {
$server[1] = 11211;
$server[2] = 100;
} else if (!array_key_exists(2, $server)) {
$server[2] = 100;
}
$this->servers[] = $server;
}
if (empty($configuration['prefix'])) {
$this->prefix = self::DEFAULT_PREFIX;
} else {
$this->prefix = $configuration['prefix'];
}
$this->connection = new Memcache;
foreach ($this->servers as $server) {
$this->connection->addServer($server[0], (int) $server[1], true, (int) $server[2]);
}
// Test the connection to the pool of servers.
$this->isready = @$this->connection->set($this->parse_key('ping'), 'ping', MEMCACHE_COMPRESSED, 1);
}
/**
* Initialises the cache.
*
* Once this has been done the cache is all set to be used.
*
* @param cache_definition $definition
*/
public function initialise(cache_definition $definition) {
if ($this->is_initialised()) {
throw new coding_exception('This memcache instance has already been initialised.');
}
$this->definition = $definition;
$this->isinitialised = true;
$this->encode = self::require_encoding();
}
/**
* Tests if encoding is going to be required.
*
* Prior to memcache 3.0.3 scalar data types were not preserved.
* For earlier versions of the memcache extension we need to encode and decode scalar types
* to ensure that it is preserved.
*
* @param string $version The version to check, if null it is fetched from PHP.
* @return bool
*/
public static function require_encoding($version = null) {
if (!$version) {
$version = phpversion('memcache');
}
return (version_compare($version, '3.0.3', '<'));
}
/**
* Returns true once this instance has been initialised.
*
* @return bool
*/
public function is_initialised() {
return ($this->isinitialised);
}
/**
* Returns true if this store instance is ready to be used.
* @return bool
*/
public function is_ready() {
return $this->isready;
}
/**
* Returns true if the store requirements are met.
*
* @return bool
*/
public static function are_requirements_met() {
return class_exists('Memcache');
}
/**
* Returns true if the given mode is supported by this store.
*
* @param int $mode One of cache_store::MODE_*
* @return bool
*/
public static function is_supported_mode($mode) {
return ($mode === self::MODE_APPLICATION || $mode === self::MODE_SESSION);
}
/**
* Returns the supported features as a combined int.
*
* @param array $configuration
* @return int
*/
public static function get_supported_features(array $configuration = array()) {
return self::SUPPORTS_NATIVE_TTL;
}
/**
* Returns false as this store does not support multiple identifiers.
* (This optional function is a performance optimisation; it must be
* consistent with the value from get_supported_features.)
*
* @return bool False
*/
public function supports_multiple_identifiers() {
return false;
}
/**
* Returns the supported modes as a combined int.
*
* @param array $configuration
* @return int
*/
public static function get_supported_modes(array $configuration = array()) {
return self::MODE_APPLICATION;
}
/**
* Parses the given key to make it work for this memcache backend.
*
* @param string $key The raw key.
* @return string The resulting key.
*/
protected function parse_key($key) {
if (strlen($key) > 245) {
$key = '_sha1_'.sha1($key);
}
$key = $this->prefix . $key;
return $key;
}
/**
* Retrieves an item from the cache store given its key.
*
* @param string $key The key to retrieve
* @return mixed The data that was associated with the key, or false if the key did not exist.
*/
public function get($key) {
$result = $this->connection->get($this->parse_key($key));
if ($this->encode && $result !== false) {
return @unserialize($result);
}
return $result;
}
/**
* Retrieves several items from the cache store in a single transaction.
*
* If not all of the items are available in the cache then the data value for those that are missing will be set to false.
*
* @param array $keys The array of keys to retrieve
* @return array An array of items from the cache. There will be an item for each key, those that were not in the store will
* be set to false.
*/
public function get_many($keys) {
$mkeys = array();
foreach ($keys as $key) {
$mkeys[$key] = $this->parse_key($key);
}
$result = $this->connection->get($mkeys);
if (!is_array($result)) {
$result = array();
}
$return = array();
foreach ($mkeys as $key => $mkey) {
if (!array_key_exists($mkey, $result)) {
$return[$key] = false;
} else {
$return[$key] = $result[$mkey];
if ($this->encode && $return[$key] !== false) {
$return[$key] = @unserialize($return[$key]);
}
}
}
return $return;
}
/**
* Sets an item in the cache given its key and data value.
*
* @param string $key The key to use.
* @param mixed $data The data to set.
* @return bool True if the operation was a success false otherwise.
*/
public function set($key, $data) {
if ($this->encode) {
// We must serialise this data.
$data = serialize($data);
}
return $this->connection->set($this->parse_key($key), $data, MEMCACHE_COMPRESSED, $this->definition->get_ttl());
}
/**
* Sets many items in the cache in a single transaction.
*
* @param array $keyvaluearray An array of key value pairs. Each item in the array will be an associative array with two
* keys, 'key' and 'value'.
* @return int The number of items successfully set. It is up to the developer to check this matches the number of items
* sent ... if they care that is.
*/
public function set_many(array $keyvaluearray) {
$count = 0;
foreach ($keyvaluearray as $pair) {
if ($this->set($pair['key'], $pair['value'])) {
$count++;
}
}
return $count;
}
/**
* Deletes an item from the cache store.
*
* @param string $key The key to delete.
* @return bool Returns true if the operation was a success, false otherwise.
*/
public function delete($key) {
return $this->connection->delete($this->parse_key($key));
}
/**
* Deletes several keys from the cache in a single action.
*
* @param array $keys The keys to delete
* @return int The number of items successfully deleted.
*/
public function delete_many(array $keys) {
$count = 0;
foreach ($keys as $key) {
if ($this->delete($key)) {
$count++;
}
}
return $count;
}
/**
* Purges the cache deleting all items within it.
*
* @return boolean True on success. False otherwise.
*/
public function purge() {
if ($this->isready) {
$this->connection->flush();
}
return true;
}
/**
* Given the data from the add instance form this function creates a configuration array.
*
* @param stdClass $data
* @return array
*/
public static function config_get_configuration_array($data) {
$lines = explode("\n", $data->servers);
$servers = array();
foreach ($lines as $line) {
// Trim surrounding colons and default whitespace.
$line = trim(trim($line), ":");
// Skip blank lines.
if ($line === '') {
continue;
}
$servers[] = explode(':', $line, 3);
}
return array(
'servers' => $servers,
'prefix' => $data->prefix,
);
}
/**
* Allows the cache store to set its data against the edit form before it is shown to the user.
*
* @param moodleform $editform
* @param array $config
*/
public static function config_set_edit_form_data(moodleform $editform, array $config) {
$data = array();
if (!empty($config['servers'])) {
$servers = array();
foreach ($config['servers'] as $server) {
$servers[] = join(":", $server);
}
$data['servers'] = join("\n", $servers);
}
if (!empty($config['prefix'])) {
$data['prefix'] = $config['prefix'];
} else {
$data['prefix'] = self::DEFAULT_PREFIX;
}
$editform->set_data($data);
}
/**
* Performs any necessary clean up when the store instance is being deleted.
*/
public function instance_deleted() {
if ($this->connection) {
$connection = $this->connection;
} else {
$connection = new Memcache;
foreach ($this->servers as $server) {
$connection->addServer($server[0], $server[1], true, $server[2]);
}
}
@$connection->flush();
unset($connection);
unset($this->connection);
}
/**
* Generates an instance of the cache store that can be used for testing.
*
* @param cache_definition $definition
* @return cachestore_memcache|false
*/
public static function initialise_test_instance(cache_definition $definition) {
if (!self::are_requirements_met()) {
return false;
}
$config = get_config('cachestore_memcache');
if (empty($config->testservers)) {
return false;
}
$configuration = array();
$configuration['servers'] = explode("\n", $config->testservers);
$store = new cachestore_memcache('Test memcache', $configuration);
$store->initialise($definition);
return $store;
}
/**
* Returns the name of this instance.
* @return string
*/
public function my_name() {
return $this->name;
}
/**
* Used to notify of configuration conflicts.
*
* The warnings returned here will be displayed on the cache configuration screen.
*
* @return string[] Returns an array of warnings (strings)
*/
public function get_warnings() {
global $CFG;
$warnings = array();
if (isset($CFG->session_memcached_save_path) && count($this->servers)) {
$bits = explode(':', $CFG->session_memcached_save_path, 3);
$host = array_shift($bits);
$port = (count($bits)) ? array_shift($bits) : '11211';
foreach ($this->servers as $server) {
if ($server[0] === $host && $server[1] == $port) {
$warnings[] = get_string('sessionhandlerconflict', 'cachestore_memcache', $this->my_name());
break;
}
}
}
return $warnings;
}
}