MemcLockManager::freeLocksOnServer() - Code Metrics - Inspection of "Daily Inspection: Merge "Remove cruft from interwi..." - wikimedia/mediawiki - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Branch — master (e770d9)

unknown

created 2016-10-03 17:03 UTC

MemcLockManager::freeLocksOnServer() C

↳ Parent: MemcLockManager

Complexity

Conditions	11
Paths	32

Size

Total Lines	64
Code Lines	38

Duplication

Lines	0
Ratio	0 %

Importance

Changes

Metric	Value
cc	11
eloc	38
nc	32
nop	2
dl	0
loc	64
rs	6.0563
c	0
b	0
f	0

How to fix Long Method Complexity

<?php
/**
 * Version of LockManager based on using memcached servers.
 *
 * This program 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 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 * @ingroup LockManager
 */
use Wikimedia\WaitConditionLoop;

/**
 * Manage locks using memcached servers.
 *
 * Version of LockManager based on using memcached servers.
 * This is meant for multi-wiki systems that may share files.
 * All locks are non-blocking, which avoids deadlocks.
 *
 * All lock requests for a resource, identified by a hash string, will map to one
 * bucket. Each bucket maps to one or several peer servers, each running memcached.
 * A majority of peers must agree for a lock to be acquired.
 *
 * @ingroup LockManager
 * @since 1.20
 */
class MemcLockManager extends QuorumLockManager {
	/** @var array Mapping of lock types to the type actually used */
	protected $lockTypeMap = [
		self::LOCK_SH => self::LOCK_SH,
		self::LOCK_UW => self::LOCK_SH,
		self::LOCK_EX => self::LOCK_EX
	];

	/** @var MemcachedBagOStuff[] Map of (server name => MemcachedBagOStuff) */
	protected $cacheServers = [];
	/** @var HashBagOStuff Server status cache */
	protected $statusCache;

	/**
	 * Construct a new instance from configuration.
	 *
	 * @param array $config Parameters include:
	 *   - lockServers  : Associative array of server names to "<IP>:<port>" strings.
	 *   - srvsByBucket : Array of 1-16 consecutive integer keys, starting from 0,
	 *                    each having an odd-numbered list of server names (peers) as values.
	 *   - memcConfig   : Configuration array for MemcachedBagOStuff::construct() with an
	 *                    additional 'class' parameter specifying which MemcachedBagOStuff
	 *                    subclass to use. The server names will be injected. [optional]
	 * @throws Exception
	 */
	public function __construct( array $config ) {
		parent::__construct( $config );

		// Sanitize srvsByBucket config to prevent PHP errors
		$this->srvsByBucket = array_filter( $config['srvsByBucket'], 'is_array' );
		$this->srvsByBucket = array_values( $this->srvsByBucket ); // consecutive

		$memcConfig = isset( $config['memcConfig'] ) ? $config['memcConfig'] : [];
		$memcConfig += [ 'class' => 'MemcachedPhpBagOStuff' ]; // default

		$class = $memcConfig['class'];
		if ( !is_subclass_of( $class, 'MemcachedBagOStuff' ) ) {
			throw new InvalidArgumentException( "$class is not of type MemcachedBagOStuff." );
		}

		foreach ( $config['lockServers'] as $name => $address ) {
			$params = [ 'servers' => [ $address ] ] + $memcConfig;
			$this->cacheServers[$name] = new $class( $params );
		}

		$this->statusCache = new HashBagOStuff();
	}

	protected function getLocksOnServer( $lockSrv, array $pathsByType ) {
		$status = StatusValue::newGood();

		$memc = $this->getCache( $lockSrv );
		// List of affected paths
		$paths = call_user_func_array( 'array_merge', array_values( $pathsByType ) );
		$paths = array_unique( $paths );
		// List of affected lock record keys
		$keys = array_map( [ $this, 'recordKeyForPath' ], $paths );

		// Lock all of the active lock record keys...
		if ( !$this->acquireMutexes( $memc, $keys ) ) {
/** @return stdClass|null */
function mayReturnNull() { }

function doesNotAcceptNull(stdClass $x) { }

// With potential error.
function withoutCheck() {
    $x = mayReturnNull();
    doesNotAcceptNull($x); // Potential error here.
}

// Safe - Alternative 1
function withCheck1() {
    $x = mayReturnNull();
    if ( ! $x instanceof stdClass) {
        throw new \LogicException('$x must be defined.');
    }
    doesNotAcceptNull($x);
}

// Safe - Alternative 2
function withCheck2() {
    $x = mayReturnNull();
    if ($x instanceof stdClass) {
        doesNotAcceptNull($x);
    }
}
			foreach ( $paths as $path ) {
				$status->fatal( 'lockmanager-fail-acquirelock', $path );
			}

			return $status;
		}

		// Fetch all the existing lock records...
		$lockRecords = $memc->getMulti( $keys );

		$now = time();
		// Check if the requested locks conflict with existing ones...
		foreach ( $pathsByType as $type => $paths ) {
			foreach ( $paths as $path ) {
				$locksKey = $this->recordKeyForPath( $path );
				$locksHeld = isset( $lockRecords[$locksKey] )
					? self::sanitizeLockArray( $lockRecords[$locksKey] )
					: self::newLockArray(); // init
				foreach ( $locksHeld[self::LOCK_EX] as $session => $expiry ) {
					if ( $expiry < $now ) { // stale?
						unset( $locksHeld[self::LOCK_EX][$session] );
					} elseif ( $session !== $this->session ) {
						$status->fatal( 'lockmanager-fail-acquirelock', $path );
					}
				}
				if ( $type === self::LOCK_EX ) {
					foreach ( $locksHeld[self::LOCK_SH] as $session => $expiry ) {
						if ( $expiry < $now ) { // stale?
							unset( $locksHeld[self::LOCK_SH][$session] );
						} elseif ( $session !== $this->session ) {
							$status->fatal( 'lockmanager-fail-acquirelock', $path );
						}
					}
				}
				if ( $status->isOK() ) {
					// Register the session in the lock record array
					$locksHeld[$type][$this->session] = $now + $this->lockTTL;
					// We will update this record if none of the other locks conflict
					$lockRecords[$locksKey] = $locksHeld;
				}
			}
		}

		// If there were no lock conflicts, update all the lock records...
		if ( $status->isOK() ) {
			foreach ( $paths as $path ) {
				$locksKey = $this->recordKeyForPath( $path );
				$locksHeld = $lockRecords[$locksKey];
				$ok = $memc->set( $locksKey, $locksHeld, self::MAX_LOCK_TTL );
				if ( !$ok ) {
					$status->fatal( 'lockmanager-fail-acquirelock', $path );
				} else {
					$this->logger->debug( __METHOD__ . ": acquired lock on key $locksKey.\n" );
				}
			}
		}

		// Unlock all of the active lock record keys...
		$this->releaseMutexes( $memc, $keys );
/** @return stdClass|null */
function mayReturnNull() { }

function doesNotAcceptNull(stdClass $x) { }

// With potential error.
function withoutCheck() {
    $x = mayReturnNull();
    doesNotAcceptNull($x); // Potential error here.
}

// Safe - Alternative 1
function withCheck1() {
    $x = mayReturnNull();
    if ( ! $x instanceof stdClass) {
        throw new \LogicException('$x must be defined.');
    }
    doesNotAcceptNull($x);
}

// Safe - Alternative 2
function withCheck2() {
    $x = mayReturnNull();
    if ($x instanceof stdClass) {
        doesNotAcceptNull($x);
    }
}

		return $status;
	}

	protected function freeLocksOnServer( $lockSrv, array $pathsByType ) {
		$status = StatusValue::newGood();

		$memc = $this->getCache( $lockSrv );
		// List of affected paths
		$paths = call_user_func_array( 'array_merge', array_values( $pathsByType ) );
		$paths = array_unique( $paths );
		// List of affected lock record keys
		$keys = array_map( [ $this, 'recordKeyForPath' ], $paths );

		// Lock all of the active lock record keys...
		if ( !$this->acquireMutexes( $memc, $keys ) ) {
/** @return stdClass|null */
function mayReturnNull() { }

function doesNotAcceptNull(stdClass $x) { }

// With potential error.
function withoutCheck() {
    $x = mayReturnNull();
    doesNotAcceptNull($x); // Potential error here.
}

// Safe - Alternative 1
function withCheck1() {
    $x = mayReturnNull();
    if ( ! $x instanceof stdClass) {
        throw new \LogicException('$x must be defined.');
    }
    doesNotAcceptNull($x);
}

// Safe - Alternative 2
function withCheck2() {
    $x = mayReturnNull();
    if ($x instanceof stdClass) {
        doesNotAcceptNull($x);
    }
}
			foreach ( $paths as $path ) {
				$status->fatal( 'lockmanager-fail-releaselock', $path );
			}

			return $status;
		}

		// Fetch all the existing lock records...
		$lockRecords = $memc->getMulti( $keys );

		// Remove the requested locks from all records...
		foreach ( $pathsByType as $type => $paths ) {
			foreach ( $paths as $path ) {
				$locksKey = $this->recordKeyForPath( $path ); // lock record
				if ( !isset( $lockRecords[$locksKey] ) ) {
					$status->warning( 'lockmanager-fail-releaselock', $path );
					continue; // nothing to do
				}
				$locksHeld = $this->sanitizeLockArray( $lockRecords[$locksKey] );
				if ( isset( $locksHeld[$type][$this->session] ) ) {
					unset( $locksHeld[$type][$this->session] ); // unregister this session
					$lockRecords[$locksKey] = $locksHeld;
				} else {
					$status->warning( 'lockmanager-fail-releaselock', $path );
				}
			}
		}

		// Persist the new lock record values...
		foreach ( $paths as $path ) {
			$locksKey = $this->recordKeyForPath( $path );
			if ( !isset( $lockRecords[$locksKey] ) ) {
				continue; // nothing to do
			}
			$locksHeld = $lockRecords[$locksKey];
			if ( $locksHeld === $this->newLockArray() ) {
				$ok = $memc->delete( $locksKey );
			} else {
				$ok = $memc->set( $locksKey, $locksHeld, self::MAX_LOCK_TTL );
			}
			if ( $ok ) {
				$this->logger->debug( __METHOD__ . ": released lock on key $locksKey.\n" );
			} else {
				$status->fatal( 'lockmanager-fail-releaselock', $path );
			}
		}

		// Unlock all of the active lock record keys...
		$this->releaseMutexes( $memc, $keys );
/** @return stdClass|null */
function mayReturnNull() { }

function doesNotAcceptNull(stdClass $x) { }

// With potential error.
function withoutCheck() {
    $x = mayReturnNull();
    doesNotAcceptNull($x); // Potential error here.
}

// Safe - Alternative 1
function withCheck1() {
    $x = mayReturnNull();
    if ( ! $x instanceof stdClass) {
        throw new \LogicException('$x must be defined.');
    }
    doesNotAcceptNull($x);
}

// Safe - Alternative 2
function withCheck2() {
    $x = mayReturnNull();
    if ($x instanceof stdClass) {
        doesNotAcceptNull($x);
    }
}

		return $status;
	}

	/**
	 * @see QuorumLockManager::releaseAllLocks()
	 * @return StatusValue
	 */
	protected function releaseAllLocks() {
		return StatusValue::newGood(); // not supported
	}

	/**
	 * @see QuorumLockManager::isServerUp()
	 * @param string $lockSrv
	 * @return bool
	 */
	protected function isServerUp( $lockSrv ) {
		return (bool)$this->getCache( $lockSrv );
	}

	/**
	 * Get the MemcachedBagOStuff object for a $lockSrv
	 *
	 * @param string $lockSrv Server name
	 * @return MemcachedBagOStuff|null
	 */
	protected function getCache( $lockSrv ) {
		if ( !isset( $this->cacheServers[$lockSrv] ) ) {
			throw new InvalidArgumentException( "Invalid cache server '$lockSrv'." );
		}

		$online = $this->statusCache->get( "online:$lockSrv" );
		if ( $online === false ) {
			$online = $this->cacheServers[$lockSrv]->set( __CLASS__ . ':ping', 1, 1 );
			if ( !$online ) { // server down?
				$this->logger->warning( __METHOD__ . ": Could not contact $lockSrv." );
			}
			$this->statusCache->set( "online:$lockSrv", (int)$online, 30 );
		}

		return $online ? $this->cacheServers[$lockSrv] : null;
	}

	/**
	 * @param string $path
	 * @return string
	 */
	protected function recordKeyForPath( $path ) {
		return implode( ':', [ __CLASS__, 'locks', $this->sha1Base36Absolute( $path ) ] );
	}

	/**
	 * @return array An empty lock structure for a key
	 */
	protected function newLockArray() {
		return [ self::LOCK_SH => [], self::LOCK_EX => [] ];
	}

	/**
	 * @param array $a
	 * @return array An empty lock structure for a key
	 */
	protected function sanitizeLockArray( $a ) {
		if ( is_array( $a ) && isset( $a[self::LOCK_EX] ) && isset( $a[self::LOCK_SH] ) ) {
			return $a;
		}

		$this->logger->error( __METHOD__ . ": reset invalid lock array." );

		return $this->newLockArray();
	}

	/**
	 * @param MemcachedBagOStuff $memc
	 * @param array $keys List of keys to acquire
	 * @return bool
	 */
	protected function acquireMutexes( MemcachedBagOStuff $memc, array $keys ) {
		$lockedKeys = [];

		// Acquire the keys in lexicographical order, to avoid deadlock problems.
		// If P1 is waiting to acquire a key P2 has, P2 can't also be waiting for a key P1 has.
		sort( $keys );

		// Try to quickly loop to acquire the keys, but back off after a few rounds.
		// This reduces memcached spam, especially in the rare case where a server acquires
		// some lock keys and dies without releasing them. Lock keys expire after a few minutes.
		$loop = new WaitConditionLoop(
			function () use ( $memc, $keys, &$lockedKeys ) {
				foreach ( array_diff( $keys, $lockedKeys ) as $key ) {
					if ( $memc->add( "$key:mutex", 1, 180 ) ) { // lock record
						$lockedKeys[] = $key;
					}
				}

				return array_diff( $keys, $lockedKeys )
					? WaitConditionLoop::CONDITION_CONTINUE
					: true;
			},
			3.0 // timeout
		);
		$loop->invoke();

		if ( count( $lockedKeys ) != count( $keys ) ) {
			$this->releaseMutexes( $memc, $lockedKeys ); // failed; release what was locked
			return false;
		}

		return true;
	}

	/**
	 * @param MemcachedBagOStuff $memc
	 * @param array $keys List of acquired keys
	 */
	protected function releaseMutexes( MemcachedBagOStuff $memc, array $keys ) {
		foreach ( $keys as $key ) {
			$memc->delete( "$key:mutex" );
		}
	}

	/**
	 * Make sure remaining locks get cleared for sanity
	 */
	function __destruct() {
		while ( count( $this->locksHeld ) ) {
			foreach ( $this->locksHeld as $path => $locks ) {
				$this->doUnlock( [ $path ], self::LOCK_EX );
				$this->doUnlock( [ $path ], self::LOCK_SH );
			}
		}
	}
}


1		<?php
2		/**
3		* Version of LockManager based on using memcached servers.
4		*
5		* This program is free software; you can redistribute it and/or modify
6		* it under the terms of the GNU General Public License as published by
7		* the Free Software Foundation; either version 2 of the License, or
8		* (at your option) any later version.
9		*
10		* This program is distributed in the hope that it will be useful,
11		* but WITHOUT ANY WARRANTY; without even the implied warranty of
12		* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13		* GNU General Public License for more details.
14		*
15		* You should have received a copy of the GNU General Public License along
16		* with this program; if not, write to the Free Software Foundation, Inc.,
17		* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
18		* http://www.gnu.org/copyleft/gpl.html
19		*
20		* @file
21		* @ingroup LockManager
22		*/
23		use Wikimedia\WaitConditionLoop;
24
25		/**
26		* Manage locks using memcached servers.
27		*
28		* Version of LockManager based on using memcached servers.
29		* This is meant for multi-wiki systems that may share files.
30		* All locks are non-blocking, which avoids deadlocks.
31		*
32		* All lock requests for a resource, identified by a hash string, will map to one
33		* bucket. Each bucket maps to one or several peer servers, each running memcached.
34		* A majority of peers must agree for a lock to be acquired.
35		*
36		* @ingroup LockManager
37		* @since 1.20
38		*/
39		class MemcLockManager extends QuorumLockManager {
40		/** @var array Mapping of lock types to the type actually used */
41		protected $lockTypeMap = [
42		self::LOCK_SH => self::LOCK_SH,
43		self::LOCK_UW => self::LOCK_SH,
44		self::LOCK_EX => self::LOCK_EX
45		];
46
47		/** @var MemcachedBagOStuff[] Map of (server name => MemcachedBagOStuff) */
48		protected $cacheServers = [];
49		/** @var HashBagOStuff Server status cache */
50		protected $statusCache;
51
52		/**
53		* Construct a new instance from configuration.
54		*
55		* @param array $config Parameters include:
56		* - lockServers : Associative array of server names to "<IP>:<port>" strings.
57		* - srvsByBucket : Array of 1-16 consecutive integer keys, starting from 0,
58		* each having an odd-numbered list of server names (peers) as values.
59		* - memcConfig : Configuration array for MemcachedBagOStuff::construct() with an
60		* additional 'class' parameter specifying which MemcachedBagOStuff
61		* subclass to use. The server names will be injected. [optional]
62		* @throws Exception
63		*/
64		public function __construct( array $config ) {
65		parent::__construct( $config );
66
67		// Sanitize srvsByBucket config to prevent PHP errors
68		$this->srvsByBucket = array_filter( $config['srvsByBucket'], 'is_array' );
69		$this->srvsByBucket = array_values( $this->srvsByBucket ); // consecutive
70
71		$memcConfig = isset( $config['memcConfig'] ) ? $config['memcConfig'] : [];
72		$memcConfig += [ 'class' => 'MemcachedPhpBagOStuff' ]; // default
73
74		$class = $memcConfig['class'];
75		if ( !is_subclass_of( $class, 'MemcachedBagOStuff' ) ) {
76		throw new InvalidArgumentException( "$class is not of type MemcachedBagOStuff." );
77		}
78
79		foreach ( $config['lockServers'] as $name => $address ) {
80		$params = [ 'servers' => [ $address ] ] + $memcConfig;
81		$this->cacheServers[$name] = new $class( $params );
82		}
83
84		$this->statusCache = new HashBagOStuff();
85		}
86
87		protected function getLocksOnServer( $lockSrv, array $pathsByType ) {
88		$status = StatusValue::newGood();
89
90		$memc = $this->getCache( $lockSrv );
91		// List of affected paths
92		$paths = call_user_func_array( 'array_merge', array_values( $pathsByType ) );
93		$paths = array_unique( $paths );
94		// List of affected lock record keys
95		$keys = array_map( [ $this, 'recordKeyForPath' ], $paths );
96
97		// Lock all of the active lock record keys...
98		if ( !$this->acquireMutexes( $memc, $keys ) ) {
		0 ignored issues – show Bug introduced 2016-02-23 18:13 UTC by Report Bug Copy Issue Report It seems like `$memc` defined by `$this->getCache($lockSrv)` on line `90` can be `null`; however, `MemcLockManager::acquireMutexes()` does not accept `null`, maybe add an additional type check? Unless you are absolutely sure that the expression can never be null because of other conditions, we strongly recommend to add an additional type check to your code: /** @return stdClass\|null */ function mayReturnNull() { } function doesNotAcceptNull(stdClass $x) { } // With potential error. function withoutCheck() { $x = mayReturnNull(); doesNotAcceptNull($x); // Potential error here. } // Safe - Alternative 1 function withCheck1() { $x = mayReturnNull(); if ( ! $x instanceof stdClass) { throw new \LogicException('$x must be defined.'); } doesNotAcceptNull($x); } // Safe - Alternative 2 function withCheck2() { $x = mayReturnNull(); if ($x instanceof stdClass) { doesNotAcceptNull($x); } } Loading history...
99		foreach ( $paths as $path ) {
100		$status->fatal( 'lockmanager-fail-acquirelock', $path );
101		}
102
103		return $status;
104		}
105
106		// Fetch all the existing lock records...
107		$lockRecords = $memc->getMulti( $keys );
108
109		$now = time();
110		// Check if the requested locks conflict with existing ones...
111		foreach ( $pathsByType as $type => $paths ) {
112		foreach ( $paths as $path ) {
113		$locksKey = $this->recordKeyForPath( $path );
114		$locksHeld = isset( $lockRecords[$locksKey] )
115		? self::sanitizeLockArray( $lockRecords[$locksKey] )
116		: self::newLockArray(); // init
117	View Code Duplication	foreach ( $locksHeld[self::LOCK_EX] as $session => $expiry ) {
118		if ( $expiry < $now ) { // stale?
119		unset( $locksHeld[self::LOCK_EX][$session] );
120		} elseif ( $session !== $this->session ) {
121		$status->fatal( 'lockmanager-fail-acquirelock', $path );
122		}
123		}
124		if ( $type === self::LOCK_EX ) {
125	View Code Duplication	foreach ( $locksHeld[self::LOCK_SH] as $session => $expiry ) {
126		if ( $expiry < $now ) { // stale?
127		unset( $locksHeld[self::LOCK_SH][$session] );
128		} elseif ( $session !== $this->session ) {
129		$status->fatal( 'lockmanager-fail-acquirelock', $path );
130		}
131		}
132		}
133		if ( $status->isOK() ) {
134		// Register the session in the lock record array
135		$locksHeld[$type][$this->session] = $now + $this->lockTTL;
136		// We will update this record if none of the other locks conflict
137		$lockRecords[$locksKey] = $locksHeld;
138		}
139		}
140		}
141
142		// If there were no lock conflicts, update all the lock records...
143		if ( $status->isOK() ) {
144		foreach ( $paths as $path ) {
145		$locksKey = $this->recordKeyForPath( $path );
146		$locksHeld = $lockRecords[$locksKey];
147		$ok = $memc->set( $locksKey, $locksHeld, self::MAX_LOCK_TTL );
148		if ( !$ok ) {
149		$status->fatal( 'lockmanager-fail-acquirelock', $path );
150		} else {
151		$this->logger->debug( __METHOD__ . ": acquired lock on key $locksKey.\n" );
152		}
153		}
154		}
155
156		// Unlock all of the active lock record keys...
157		$this->releaseMutexes( $memc, $keys );
		0 ignored issues – show Bug introduced 2016-02-23 18:13 UTC by Report Bug Copy Issue Report It seems like `$memc` defined by `$this->getCache($lockSrv)` on line `90` can be `null`; however, `MemcLockManager::releaseMutexes()` does not accept `null`, maybe add an additional type check? Unless you are absolutely sure that the expression can never be null because of other conditions, we strongly recommend to add an additional type check to your code: /** @return stdClass\|null */ function mayReturnNull() { } function doesNotAcceptNull(stdClass $x) { } // With potential error. function withoutCheck() { $x = mayReturnNull(); doesNotAcceptNull($x); // Potential error here. } // Safe - Alternative 1 function withCheck1() { $x = mayReturnNull(); if ( ! $x instanceof stdClass) { throw new \LogicException('$x must be defined.'); } doesNotAcceptNull($x); } // Safe - Alternative 2 function withCheck2() { $x = mayReturnNull(); if ($x instanceof stdClass) { doesNotAcceptNull($x); } } Loading history...
158
159		return $status;
160		}
161
162		protected function freeLocksOnServer( $lockSrv, array $pathsByType ) {
163		$status = StatusValue::newGood();
164
165		$memc = $this->getCache( $lockSrv );
166		// List of affected paths
167		$paths = call_user_func_array( 'array_merge', array_values( $pathsByType ) );
168		$paths = array_unique( $paths );
169		// List of affected lock record keys
170		$keys = array_map( [ $this, 'recordKeyForPath' ], $paths );
171
172		// Lock all of the active lock record keys...
173		if ( !$this->acquireMutexes( $memc, $keys ) ) {
		0 ignored issues – show Bug introduced 2016-02-23 18:13 UTC by Report Bug Copy Issue Report It seems like `$memc` defined by `$this->getCache($lockSrv)` on line `165` can be `null`; however, `MemcLockManager::acquireMutexes()` does not accept `null`, maybe add an additional type check? Unless you are absolutely sure that the expression can never be null because of other conditions, we strongly recommend to add an additional type check to your code: /** @return stdClass\|null */ function mayReturnNull() { } function doesNotAcceptNull(stdClass $x) { } // With potential error. function withoutCheck() { $x = mayReturnNull(); doesNotAcceptNull($x); // Potential error here. } // Safe - Alternative 1 function withCheck1() { $x = mayReturnNull(); if ( ! $x instanceof stdClass) { throw new \LogicException('$x must be defined.'); } doesNotAcceptNull($x); } // Safe - Alternative 2 function withCheck2() { $x = mayReturnNull(); if ($x instanceof stdClass) { doesNotAcceptNull($x); } } Loading history...
174		foreach ( $paths as $path ) {
175		$status->fatal( 'lockmanager-fail-releaselock', $path );
176		}
177
178		return $status;
179		}
180
181		// Fetch all the existing lock records...
182		$lockRecords = $memc->getMulti( $keys );
183
184		// Remove the requested locks from all records...
185		foreach ( $pathsByType as $type => $paths ) {
186		foreach ( $paths as $path ) {
187		$locksKey = $this->recordKeyForPath( $path ); // lock record
188		if ( !isset( $lockRecords[$locksKey] ) ) {
189		$status->warning( 'lockmanager-fail-releaselock', $path );
190		continue; // nothing to do
191		}
192		$locksHeld = $this->sanitizeLockArray( $lockRecords[$locksKey] );
193		if ( isset( $locksHeld[$type][$this->session] ) ) {
194		unset( $locksHeld[$type][$this->session] ); // unregister this session
195		$lockRecords[$locksKey] = $locksHeld;
196		} else {
197		$status->warning( 'lockmanager-fail-releaselock', $path );
198		}
199		}
200		}
201
202		// Persist the new lock record values...
203		foreach ( $paths as $path ) {
204		$locksKey = $this->recordKeyForPath( $path );
205		if ( !isset( $lockRecords[$locksKey] ) ) {
206		continue; // nothing to do
207		}
208		$locksHeld = $lockRecords[$locksKey];
209		if ( $locksHeld === $this->newLockArray() ) {
210		$ok = $memc->delete( $locksKey );
211		} else {
212		$ok = $memc->set( $locksKey, $locksHeld, self::MAX_LOCK_TTL );
213		}
214		if ( $ok ) {
215		$this->logger->debug( __METHOD__ . ": released lock on key $locksKey.\n" );
216		} else {
217		$status->fatal( 'lockmanager-fail-releaselock', $path );
218		}
219		}
220
221		// Unlock all of the active lock record keys...
222		$this->releaseMutexes( $memc, $keys );
		0 ignored issues – show Bug introduced 2016-02-23 18:13 UTC by Report Bug Copy Issue Report It seems like `$memc` defined by `$this->getCache($lockSrv)` on line `165` can be `null`; however, `MemcLockManager::releaseMutexes()` does not accept `null`, maybe add an additional type check? Unless you are absolutely sure that the expression can never be null because of other conditions, we strongly recommend to add an additional type check to your code: /** @return stdClass\|null */ function mayReturnNull() { } function doesNotAcceptNull(stdClass $x) { } // With potential error. function withoutCheck() { $x = mayReturnNull(); doesNotAcceptNull($x); // Potential error here. } // Safe - Alternative 1 function withCheck1() { $x = mayReturnNull(); if ( ! $x instanceof stdClass) { throw new \LogicException('$x must be defined.'); } doesNotAcceptNull($x); } // Safe - Alternative 2 function withCheck2() { $x = mayReturnNull(); if ($x instanceof stdClass) { doesNotAcceptNull($x); } } Loading history...
223
224		return $status;
225		}
226
227		/**
228		* @see QuorumLockManager::releaseAllLocks()
229		* @return StatusValue
230		*/
231		protected function releaseAllLocks() {
232		return StatusValue::newGood(); // not supported
233		}
234
235		/**
236		* @see QuorumLockManager::isServerUp()
237		* @param string $lockSrv
238		* @return bool
239		*/
240		protected function isServerUp( $lockSrv ) {
241		return (bool)$this->getCache( $lockSrv );
242		}
243
244		/**
245		* Get the MemcachedBagOStuff object for a $lockSrv
246		*
247		* @param string $lockSrv Server name
248		* @return MemcachedBagOStuff\|null
249		*/
250		protected function getCache( $lockSrv ) {
251		if ( !isset( $this->cacheServers[$lockSrv] ) ) {
252		throw new InvalidArgumentException( "Invalid cache server '$lockSrv'." );
253		}
254
255		$online = $this->statusCache->get( "online:$lockSrv" );
256		if ( $online === false ) {
257		$online = $this->cacheServers[$lockSrv]->set( __CLASS__ . ':ping', 1, 1 );
258		if ( !$online ) { // server down?
259		$this->logger->warning( __METHOD__ . ": Could not contact $lockSrv." );
260		}
261		$this->statusCache->set( "online:$lockSrv", (int)$online, 30 );
262		}
263
264		return $online ? $this->cacheServers[$lockSrv] : null;
265		}
266
267		/**
268		* @param string $path
269		* @return string
270		*/
271		protected function recordKeyForPath( $path ) {
272		return implode( ':', [ __CLASS__, 'locks', $this->sha1Base36Absolute( $path ) ] );
273		}
274
275		/**
276		* @return array An empty lock structure for a key
277		*/
278		protected function newLockArray() {
279		return [ self::LOCK_SH => [], self::LOCK_EX => [] ];
280		}
281
282		/**
283		* @param array $a
284		* @return array An empty lock structure for a key
285		*/
286		protected function sanitizeLockArray( $a ) {
287		if ( is_array( $a ) && isset( $a[self::LOCK_EX] ) && isset( $a[self::LOCK_SH] ) ) {
288		return $a;
289		}
290
291		$this->logger->error( __METHOD__ . ": reset invalid lock array." );
292
293		return $this->newLockArray();
294		}
295
296		/**
297		* @param MemcachedBagOStuff $memc
298		* @param array $keys List of keys to acquire
299		* @return bool
300		*/
301		protected function acquireMutexes( MemcachedBagOStuff $memc, array $keys ) {
302		$lockedKeys = [];
303
304		// Acquire the keys in lexicographical order, to avoid deadlock problems.
305		// If P1 is waiting to acquire a key P2 has, P2 can't also be waiting for a key P1 has.
306		sort( $keys );
307
308		// Try to quickly loop to acquire the keys, but back off after a few rounds.
309		// This reduces memcached spam, especially in the rare case where a server acquires
310		// some lock keys and dies without releasing them. Lock keys expire after a few minutes.
311		$loop = new WaitConditionLoop(
312		function () use ( $memc, $keys, &$lockedKeys ) {
313		foreach ( array_diff( $keys, $lockedKeys ) as $key ) {
314		if ( $memc->add( "$key:mutex", 1, 180 ) ) { // lock record
315		$lockedKeys[] = $key;
316		}
317		}
318
319		return array_diff( $keys, $lockedKeys )
320		? WaitConditionLoop::CONDITION_CONTINUE
321		: true;
322		},
323		3.0 // timeout
324		);
325		$loop->invoke();
326
327		if ( count( $lockedKeys ) != count( $keys ) ) {
328		$this->releaseMutexes( $memc, $lockedKeys ); // failed; release what was locked
329		return false;
330		}
331
332		return true;
333		}
334
335		/**
336		* @param MemcachedBagOStuff $memc
337		* @param array $keys List of acquired keys
338		*/
339		protected function releaseMutexes( MemcachedBagOStuff $memc, array $keys ) {
340		foreach ( $keys as $key ) {
341		$memc->delete( "$key:mutex" );
342		}
343		}
344
345		/**
346		* Make sure remaining locks get cleared for sanity
347		*/
348		function __destruct() {
349		while ( count( $this->locksHeld ) ) {
350		foreach ( $this->locksHeld as $path => $locks ) {
351		$this->doUnlock( [ $path ], self::LOCK_EX );
352		$this->doUnlock( [ $path ], self::LOCK_SH );
353		}
354		}
355		}
356		}
357

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Branch — master (e770d9)

MemcLockManager::freeLocksOnServer() C

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