Aaron Schulz has uploaded a new change for review.
https://gerrit.wikimedia.org/r/181209
Change subject: Moved "nowait:" key code to PoolCounter in core
......................................................................
Moved "nowait:" key code to PoolCounter in core
Change-Id: I5286e6c6052289e1107314a04d72703b44a8fbc6
---
M includes/poolcounter/PoolCounter.php
M includes/poolcounter/PoolCounterRedis.php
2 files changed, 70 insertions(+), 1 deletion(-)
git pull ssh://gerrit.wikimedia.org:29418/mediawiki/core
refs/changes/09/181209/1
diff --git a/includes/poolcounter/PoolCounter.php
b/includes/poolcounter/PoolCounter.php
index e77ffd7..5692d73 100644
--- a/includes/poolcounter/PoolCounter.php
+++ b/includes/poolcounter/PoolCounter.php
@@ -34,7 +34,10 @@
* minutes and hundreds of read hits.
*
* The PoolCounter provides semaphore semantics for restricting the number
- * of workers that may be concurrently performing such single task.
+ * of workers that may be concurrently performing such single task. Only one
+ * key can be locked by any PoolCounter instance of a process, except for keys
+ * that start with "nowait:". However, only 0 timeouts (non-blocking requests)
+ * can be used with "nowait:" keys.
*
* By default PoolCounter_Stub is used, which provides no locking. You
* can get a useful one in the PoolCounter extension.
@@ -68,6 +71,15 @@
protected $timeout;
/**
+ * @var boolean Whether the key is a "might wait" key
+ */
+ private $isMightWaitKey;
+ /**
+ * @var boolean Whether this process holds a "might wait" lock key
+ */
+ private static $acquiredMightWaitKey = 0;
+
+ /**
* @param array $conf
* @param string $type
* @param string $key
@@ -84,6 +96,7 @@
$key = $this->hashKeyIntoSlots( $key, $this->slots );
}
$this->key = $key;
+ $this->isMightWaitKey = !preg_match( '/^nowait:/', $this->key );
}
/**
@@ -137,6 +150,48 @@
abstract public function release();
/**
+ * Checks that the lock request is sane.
+ * @return Status - good for sane requests fatal for insane
+ * @since 1.25
+ */
+ final protected function precheckAcquire() {
+ if ( $this->isMightWaitKey ) {
+ if ( self::$acquiredMightWaitKey ) {
+ /*
+ * The poolcounter itself is quite happy to
allow you to wait
+ * on another lock while you have a lock you
waited on already
+ * but we think that it is unlikely to be a
good idea. So we
+ * made it an error. If you are _really_
_really_ sure it is a
+ * good idea then feel free to implement an
unsafe flag or
+ * something.
+ */
+ return Status::newFatal(
'poolcounter-usage-error',
+ 'You may only aquire a single
non-nowait lock.' );
+ }
+ } elseif ( $this->timeout !== 0 ) {
+ return Status::newFatal( 'poolcounter-usage-error',
+ 'Locks starting in nowait: must have 0
timeout.' );
+ }
+ return Status::newGood();
+ }
+
+ /**
+ * Update any lock tracking information when the lock is acquired
+ * @since 1.25
+ */
+ final protected function onAcquire() {
+ self::$acquiredMightWaitKey |= $this->isMightWaitKey;
+ }
+
+ /**
+ * Update any lock tracking information when the lock is released
+ * @since 1.25
+ */
+ final protected function onRelease() {
+ self::$acquiredMightWaitKey &= !$this->isMightWaitKey;
+ }
+
+ /**
* Given a key (any string) and the number of lots, returns a slot
number (an integer from the [0..($slots-1)] range).
* This is used for a global limit on the number of instances of a
given type that can acquire a lock.
* The hashing is deterministic so that PoolCounter::$workers is always
an upper limit of how many instances with
diff --git a/includes/poolcounter/PoolCounterRedis.php
b/includes/poolcounter/PoolCounterRedis.php
index d609f61..0f025f3 100644
--- a/includes/poolcounter/PoolCounterRedis.php
+++ b/includes/poolcounter/PoolCounterRedis.php
@@ -123,11 +123,21 @@
function acquireForMe() {
$section = new ProfileSection( __METHOD__ );
+ $status = $this->precheckAcquire();
+ if ( !$status->isGood() ) {
+ return $status;
+ }
+
return $this->waitForSlotOrNotif( self::AWAKE_ONE );
}
function acquireForAnyone() {
$section = new ProfileSection( __METHOD__ );
+
+ $status = $this->precheckAcquire();
+ if ( !$status->isGood() ) {
+ return $status;
+ }
return $this->waitForSlotOrNotif( self::AWAKE_ALL );
}
@@ -207,6 +217,8 @@
$this->onRelease = null;
unset( self::$active[$this->session] );
+ $this->onRelease();
+
return Status::newGood( PoolCounter::RELEASED );
}
@@ -266,6 +278,8 @@
self::$active[$this->session] = $this;
}
+ $this->onAcquire();
+
return Status::newGood( $slot === 'w' ? PoolCounter::DONE :
PoolCounter::LOCKED );
}
--
To view, visit https://gerrit.wikimedia.org/r/181209
To unsubscribe, visit https://gerrit.wikimedia.org/r/settings
Gerrit-MessageType: newchange
Gerrit-Change-Id: I5286e6c6052289e1107314a04d72703b44a8fbc6
Gerrit-PatchSet: 1
Gerrit-Project: mediawiki/core
Gerrit-Branch: master
Gerrit-Owner: Aaron Schulz <asch...@wikimedia.org>
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