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<?php
/**
* File: UsageStatistics_Sources_Memcached.php
*
* @package W3TC
*/
namespace W3TC;
/**
* Class UsageStatistics_Sources_Memcached
*/
class UsageStatistics_Sources_Memcached {
/**
* Stores server configurations indexed by host and port.
*
* @var array
*/
private $servers;
/**
* Constructor for initializing the Memcached server configurations.
*
* This method takes an array of server descriptors, processes each one to extract
* necessary information, and stores the server configuration in the `$servers`
* attribute, ensuring that the configuration for each unique host-port pair is
* only added once.
*
* @param array $server_descriptors Array of server descriptors containing server details.
* Each item should contain 'servers', 'username', 'password', and 'name' attributes.
*
* @return void
*/
public function __construct( $server_descriptors ) {
$this->servers = array();
foreach ( $server_descriptors as $i ) {
foreach ( $i['servers'] as $host_port ) {
if ( ! isset( $this->servers[ $host_port ] ) ) {
$this->servers[ $host_port ] = array(
'username' => $i['username'],
'password' => $i['password'],
'module_names' => array( $i['name'] ),
);
} else {
$this->servers[ $host_port ]['module_names'][] = $i['name'];
}
}
}
}
/**
* Retrieves a snapshot of the Memcached statistics across all servers.
*
* This method iterates over the list of servers, collects Memcached statistics
* (such as memory usage and cache hits), and accumulates the data. The method
* returns an array containing the total memory usage, total 'get' commands, and
* total cache hits across all servers.
*
* @return array An associative array containing the total 'size_used', 'get_calls', and 'get_hits'.
*/
public function get_snapshot() {
$size_used = 0;
$get_calls = 0;
$get_hits = 0;
foreach ( $this->servers as $host_port => $i ) {
$cache = Cache::instance(
'memcached',
array(
'servers' => array( $host_port ),
'username' => $i['username'],
'password' => $i['password'],
)
);
$stats = $cache->get_statistics();
$size_used += Util_UsageStatistics::v( $stats, 'bytes' );
$get_calls += Util_UsageStatistics::v( $stats, 'cmd_get' );
$get_hits += Util_UsageStatistics::v( $stats, 'get_hits' );
}
return array(
'size_used' => $size_used,
'get_calls' => $get_calls,
'get_hits' => $get_hits,
);
}
/**
* Retrieves a summary of Memcached statistics across all servers.
*
* This method iterates over the list of servers, gathers various Memcached statistics
* (such as total memory used, maximum memory limit, cache hits, and uptime), and
* calculates additional derived metrics such as hit rate and evictions per second.
* The method returns a summary of these metrics, including the list of module names.
*
* @return array An associative array containing summary metrics such as 'module_names',
* 'size_percent', 'size_used', 'get_hit_rate', and 'evictions_per_second'.
*/
public function get_summary() {
$sum = array(
'module_names' => array(),
'size_used' => 0,
'size_maxbytes' => 0,
'get_total' => 0,
'get_hits' => 0,
'evictions' => 0,
'uptime' => 0,
);
foreach ( $this->servers as $host_port => $i ) {
$cache = Cache::instance(
'memcached',
array(
'servers' => array( $host_port ),
'username' => $i['username'],
'password' => $i['password'],
)
);
$stats = $cache->get_statistics();
$sum['module_names'] = array_merge( $sum['module_names'], $i['module_names'] );
$sum['size_used'] += Util_UsageStatistics::v3( $stats, 'bytes' );
$sum['size_maxbytes'] += Util_UsageStatistics::v3( $stats, 'limit_maxbytes' );
$sum['get_total'] += Util_UsageStatistics::v3( $stats, 'cmd_get' );
$sum['get_hits'] += Util_UsageStatistics::v3( $stats, 'get_hits' );
$sum['evictions'] += Util_UsageStatistics::v3( $stats, 'evictions' );
$sum['uptime'] += Util_UsageStatistics::v3( $stats, 'uptime' );
}
$summary = array(
'module_names' => implode( ',', $sum['module_names'] ),
'size_percent' => Util_UsageStatistics::percent2( $sum, 'size_used', 'size_maxbytes' ),
'size_used' => Util_UsageStatistics::bytes_to_size2( $sum, 'size_used' ),
'get_hit_rate' => Util_UsageStatistics::percent2( $sum, 'get_hits', 'get_total' ),
'evictions_per_second' => Util_UsageStatistics::value_per_second( $sum, 'evictions', 'uptime' ),
);
return $summary;
}
}