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WANObjectCache: Change getWithSetCallback() signature to key/ttl/callback/opts

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* Put 'checkKeys' param in opts array instead of as a separate parameter.
  It's neat to not have to skip unnamed/positional arguments that are optional.
* Move TTL to be before callback instead of after. This avoids dangling integers
  toward the bottom of a large code block that have no obvious meaning.
  Matches BagOStuff::getWithSetCallback.

Add unit test for lockTSE to confirm

Change-Id: I60d6b64fc5dff14108741bafe801fd1fde16d1df
This commit is contained in:
Timo Tijhof 2015-10-07 16:21:11 -07:00
parent 14788f9aab
commit 09cbebb224
2 changed files with 60 additions and 21 deletions
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48
includes/libs/objectcache/WANObjectCache.php
View file

@ -621,31 +621,41 @@ class WANObjectCache {
* @see WANObjectCache::set()
*
* @param string $key Cache key
* @param callable $callback Value generation function
* @param integer $ttl Seconds to live for key updates. Special values are:
* - WANObjectCache::TTL_NONE : cache forever
* - WANObjectCache::TTL_UNCACHEABLE : do not cache at all
* @param array $checkKeys List of "check" keys
* - WANObjectCache::TTL_NONE : Cache forever
* - WANObjectCache::TTL_UNCACHEABLE: Do not cache at all
* @param callable $callback Value generation function
* @param array $opts Options map:
* - lowTTL : consider pre-emptive updates when the current TTL (sec)
* of the key is less than this. It becomes more likely
* over time, becoming a certainty once the key is expired.
* [Default: WANObjectCache::LOW_TTL seconds]
* - lockTSE : if the key is tombstoned or expired (by $checkKeys) less
* than this many seconds ago, then try to have a single
* thread handle cache regeneration at any given time.
* Other threads will try to use stale values if possible.
* If, on miss, the time since expiration is low, the assumption
* is that the key is hot and that a stampede is worth avoiding.
* Setting this above WANObjectCache::HOLDOFF_TTL makes no difference.
* The higher this is set, the higher the worst-case staleness can be.
* Use WANObjectCache::TSE_NONE to disable this logic.
* [Default: WANObjectCache::TSE_NONE]
* - checkKeys: List of "check" keys.
* - lowTTL: Consider pre-emptive updates when the current TTL (sec) of the key is less than
* this. It becomes more likely over time, becoming a certainty once the key is expired.
* Default: WANObjectCache::LOW_TTL seconds.
* - lockTSE: If the key is tombstoned or expired (by checkKeys) less than this many seconds
* ago, then try to have a single thread handle cache regeneration at any given time.
* Other threads will try to use stale values if possible. If, on miss, the time since
* expiration is low, the assumption is that the key is hot and that a stampede is worth
* avoiding. Setting this above WANObjectCache::HOLDOFF_TTL makes no difference. The
* higher this is set, the higher the worst-case staleness can be.
* Use WANObjectCache::TSE_NONE to disable this logic. Default: WANObjectCache::TSE_NONE.
* @return mixed Value to use for the key
*/
final public function getWithSetCallback(
$key, $callback, $ttl, array $checkKeys = array(), array $opts = array()
$key, $ttl, $callback, array $opts = array(), $oldOpts = null
) {
// Back-compat with 1.26: Swap $ttl and $callback
if ( is_int( $callback ) ) {
$temp = $ttl;
$ttl = $callback;
$callback = $temp;
}
// Back-compat with 1.26: $checkKeys as separate parameter
if ( $oldOpts || ( is_array( $opts ) && isset( $opts[0] ) ) ) {
$checkKeys = $opts;
$opts = $oldOpts;
} else {
$checkKeys = isset( $opts['checkKeys'] ) ? $opts['checkKeys'] : array();
}
$lowTTL = isset( $opts['lowTTL'] ) ? $opts['lowTTL'] : min( self::LOW_TTL, $ttl );
$lockTSE = isset( $opts['lockTSE'] ) ? $opts['lockTSE'] : self::TSE_NONE;

33
tests/phpunit/includes/objectcache/WANObjectCacheTest.php
View file

@ -13,11 +13,14 @@ class WANObjectCacheTest extends MediaWikiTestCase {
$this->cache = ObjectCache::getWANInstance( $name );
} else {
$this->cache = new WANObjectCache( array(
'cache' => new HashBagOStuff(),
'pool' => 'testcache-hash',
'cache' => new HashBagOStuff(),
'pool' => 'testcache-hash',
'relayer' => new EventRelayerNull( array() )
) );
}
$wanCache = TestingAccessWrapper::newFromObject( $this->cache );
$this->internalCache = $wanCache->cache;
}
/**
@ -145,6 +148,32 @@ class WANObjectCacheTest extends MediaWikiTestCase {
$this->assertLessThanOrEqual( 0, $curTTL, "Value has current TTL < 0 due to check keys" );
}
/**
* @covers WANObjectCache::getWithSetCallback()
*/
public function testLockTSE() {
$cache = $this->cache;
$key = wfRandomString();
$value = wfRandomString();
$calls = 0;
$func = function() use ( &$calls, $value ) {
++$calls;
return $value;
};
$cache->delete( $key );
$ret = $cache->getWithSetCallback( $key, 30, $func, array(), array( 'lockTSE' => 5 ) );
$this->assertEquals( $value, $ret );
$this->assertEquals( 1, $calls, 'Value was populated' );
// Acquire a lock to verify that getWithSetCallback uses lockTSE properly
$this->internalCache->lock( $key, 0 );
$ret = $cache->getWithSetCallback( $key, 30, $func, array(), array( 'lockTSE' => 5 ) );
$this->assertEquals( $value, $ret );
$this->assertEquals( 1, $calls, 'Callback was not used' );
}
/**
* @covers WANObjectCache::getMulti()
*/