MediaWiki REL1_33
PoolCounter.php
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1<?php
45abstract 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
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}
$wgPoolCounterConf
Configuration for processing pool control, for use in high-traffic wikis.
A default PoolCounter, which provides no locking.
When you have many workers (threads/servers) giving service, and a cached item expensive to produce e...
const QUEUE_FULL
int $workers
Maximum number of workers working on tasks with the same key simultaneously.
static factory( $type, $key)
Create a Pool counter.
__construct( $conf, $type, $key)
bool $isMightWaitKey
Whether the key is a "might wait" key.
float $timeout
Maximum time in seconds to wait for the lock.
onAcquire()
Update any lock tracking information when the lock is acquired.
int $maxqueue
If this number of workers are already working/waiting, fail instead of wait.
string $key
All workers with the same key share the lock.
int $slots
Maximum number of workers working on this task type, regardless of key.
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...
release()
I have successfully finished my task.
precheckAcquire()
Checks that the lock request is sane.
static bool $acquiredMightWaitKey
Whether this process holds a "might wait" lock key.
acquireForMe()
I want to do this task and I need to do it myself.
const NOT_LOCKED
acquireForAnyone()
I want to do this task, but if anyone else does it instead, it's also fine for me.
const LOCK_HELD
onRelease()
Update any lock tracking information when the lock is released.
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Definition hooks.txt:2163
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:37