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PoolCounter.php
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1 <?php
45 abstract class PoolCounter {
46  /* Return codes */
47  const LOCKED = 1; /* Lock acquired */
48  const RELEASED = 2; /* Lock released */
49  const DONE = 3; /* Another worker did the work for you */
50 
51  const ERROR = -1; /* Indeterminate error */
52  const NOT_LOCKED = -2; /* Called release() with no lock held */
53  const QUEUE_FULL = -3; /* There are already maxqueue workers on this lock */
54  const TIMEOUT = -4; /* Timeout exceeded */
55  const LOCK_HELD = -5; /* Cannot acquire another lock while you have one lock held */
56 
58  protected $key;
60  protected $workers;
67  protected $slots = 0;
69  protected $maxqueue;
71  protected $timeout;
72 
76  private $isMightWaitKey;
80  private static $acquiredMightWaitKey = 0;
81 
87  protected function __construct( $conf, $type, $key ) {
88  $this->workers = $conf['workers'];
89  $this->maxqueue = $conf['maxqueue'];
90  $this->timeout = $conf['timeout'];
91  if ( isset( $conf['slots'] ) ) {
92  $this->slots = $conf['slots'];
93  }
94 
95  if ( $this->slots ) {
96  $key = $this->hashKeyIntoSlots( $type, $key, $this->slots );
97  }
98 
99  $this->key = $key;
100  $this->isMightWaitKey = !preg_match( '/^nowait:/', $this->key );
101  }
102 
111  public static function factory( $type, $key ) {
112  global $wgPoolCounterConf;
113  if ( !isset( $wgPoolCounterConf[$type] ) ) {
114  return new PoolCounterNull;
115  }
116  $conf = $wgPoolCounterConf[$type];
117  $class = $conf['class'];
118 
119  return new $class( $conf, $type, $key );
120  }
121 
125  public function getKey() {
126  return $this->key;
127  }
128 
134  abstract public function acquireForMe();
135 
142  abstract public function acquireForAnyone();
143 
151  abstract public function release();
152 
158  final protected function precheckAcquire() {
159  if ( $this->isMightWaitKey ) {
160  if ( self::$acquiredMightWaitKey ) {
161  /*
162  * The poolcounter itself is quite happy to allow you to wait
163  * on another lock while you have a lock you waited on already
164  * but we think that it is unlikely to be a good idea. So we
165  * made it an error. If you are _really_ _really_ sure it is a
166  * good idea then feel free to implement an unsafe flag or
167  * something.
168  */
169  return Status::newFatal( 'poolcounter-usage-error',
170  'You may only aquire a single non-nowait lock.' );
171  }
172  } elseif ( $this->timeout !== 0 ) {
173  return Status::newFatal( 'poolcounter-usage-error',
174  'Locks starting in nowait: must have 0 timeout.' );
175  }
176  return Status::newGood();
177  }
178 
183  final protected function onAcquire() {
184  self::$acquiredMightWaitKey |= $this->isMightWaitKey;
185  }
186 
191  final protected function onRelease() {
192  self::$acquiredMightWaitKey &= !$this->isMightWaitKey;
193  }
194 
207  protected function hashKeyIntoSlots( $type, $key, $slots ) {
208  return $type . ':' . ( hexdec( substr( sha1( $key ), 0, 4 ) ) % $slots );
209  }
210 }
A default PoolCounter, which provides no locking.
acquireForMe()
I want to do this task and I need to do it myself.
precheckAcquire()
Checks that the lock request is sane.
const LOCKED
Definition: PoolCounter.php:47
onRelease()
Update any lock tracking information when the lock is released.
$wgPoolCounterConf
Configuration for processing pool control, for use in high-traffic wikis.
release()
I have successfully finished my task.
either a unescaped string or a HtmlArmor object after in associative array form externallinks including delete and has completed for all link tables whether this was an auto creation use $formDescriptor instead default is conds Array Extra conditions for the No matching items in log is displayed if loglist is empty msgKey Array If you want a nice box with a set this to the key of the message First element is the message key
Definition: hooks.txt:2138
int $maxqueue
If this number of workers are already working/waiting, fail instead of wait.
Definition: PoolCounter.php:69
const NOT_LOCKED
Definition: PoolCounter.php:52
acquireForAnyone()
I want to do this task, but if anyone else does it instead, it&#39;s also fine for me.
static newFatal( $message)
Factory function for fatal errors.
Definition: StatusValue.php:68
int $workers
Maximum number of workers working on tasks with the same key simultaneously.
Definition: PoolCounter.php:60
bool $isMightWaitKey
Whether the key is a "might wait" key.
Definition: PoolCounter.php:76
static bool $acquiredMightWaitKey
Whether this process holds a "might wait" lock key.
Definition: PoolCounter.php:80
string $key
All workers with the same key share the lock.
Definition: PoolCounter.php:58
static newGood( $value=null)
Factory function for good results.
Definition: StatusValue.php:81
__construct( $conf, $type, $key)
Definition: PoolCounter.php:87
int $slots
Maximum number of workers working on this task type, regardless of key.
Definition: PoolCounter.php:67
injection txt This is an overview of how MediaWiki makes use of dependency injection The design described here grew from the discussion of RFC T384 The term dependency this means that anything an object needs to operate should be injected from the the object itself should only know narrow no concrete implementation of the logic it relies on The requirement to inject everything typically results in an architecture that based on two main types of and essentially stateless service objects that use other service objects to operate on the value objects As of the beginning MediaWiki is only starting to use the DI approach Much of the code still relies on global state or direct resulting in a highly cyclical dependency which acts as the top level factory for services in MediaWiki which can be used to gain access to default instances of various services MediaWikiServices however also allows new services to be defined and default services to be redefined Services are defined or redefined by providing a callback the instantiator that will return a new instance of the service When it will create an instance of MediaWikiServices and populate it with the services defined in the files listed by thereby bootstrapping the DI framework Per $wgServiceWiringFiles lists includes ServiceWiring php
Definition: injection.txt:35
static factory( $type, $key)
Create a Pool counter.
const QUEUE_FULL
Definition: PoolCounter.php:53
When you have many workers (threads/servers) giving service, and a cached item expensive to produce e...
Definition: PoolCounter.php:45
float $timeout
Maximum time in seconds to wait for the lock.
Definition: PoolCounter.php:71
const TIMEOUT
Definition: PoolCounter.php:54
hashKeyIntoSlots( $type, $key, $slots)
Given a key (any string) and the number of lots, returns a slot key (a prefix with a suffix integer f...
onAcquire()
Update any lock tracking information when the lock is acquired.
const RELEASED
Definition: PoolCounter.php:48
const LOCK_HELD
Definition: PoolCounter.php:55