/**
* @param $sample_rate
* @return BernoulliTrial
*/
private function getProfileSampler($sample_rate)
{
if (!isset($this->sampler) || $this->sampler->getProbability() != $sample_rate) {
$this->sampler = new BernoulliTrial($sample_rate);
}
return $this->sampler;
}
/**
* @param float $probability
* @param float $tolerance
* @param float $trials
* @dataProvider sampleProvider
*/
function testShouldSample($probability, $tolerance, $trials)
{
$total = 0.0;
$trials = (double) $trials;
$tolerance = (double) $tolerance;
$sampler = new BernoulliTrial($probability);
for ($i = 0; $i < $trials; $i++) {
if ($sampler->shouldSample()) {
$total++;
}
}
$actual = $total / $trials;
$this->assertTrue(abs($actual - $probability) < $tolerance, sprintf("percent is %f %d %d", $actual, $total, $trials));
}
/**
* Bind to the last stage of MW response generation and send stats to the storage
*
* @return bool true - it's a hook
*/
public static function onRestInPeace()
{
// obey the sampling
global $wgMemcacheStatsSampling;
$trial = new BernoulliTrial($wgMemcacheStatsSampling / 100);
// normalize percents to 0-1 range
if (!$trial->shouldSample()) {
return true;
}
$stats = self::getStats();
// send generic stats
foreach ($stats['counts'] as $name => $value) {
\Transaction::addEvent(\Transaction::EVENT_MEMCACHE_STATS_COUNTERS, ['name' => $name, 'value' => $value]);
}
// send top keys for misses and hits
foreach ($stats['keys'] as $bucket => $keys) {
foreach ($keys as $key => $count) {
\Transaction::addRawEvent(\Transaction::EVENT_MEMCACHE_STATS_KEYS, ['bucket' => $bucket, 'key' => $key, 'count' => $count]);
}
}
return true;
}
