public function getLagTimes($serverIndexes, $wiki)
{
if (count($serverIndexes) == 1 && reset($serverIndexes) == 0) {
// Single server only, just return zero without caching
return array(0 => 0);
}
$expiry = 5;
$requestRate = 10;
$cache = $this->cache;
$masterName = $this->parent->getServerName(0);
$memcKey = wfMemcKey('lag_times', $masterName);
$times = $cache->get($memcKey);
if (is_array($times)) {
# Randomly recache with probability rising over $expiry
$elapsed = time() - $times['timestamp'];
$chance = max(0, ($expiry - $elapsed) * $requestRate);
if (mt_rand(0, $chance) != 0) {
unset($times['timestamp']);
// hide from caller
return $times;
}
wfIncrStats('lag_cache.miss.expired');
} else {
wfIncrStats('lag_cache.miss.absent');
}
# Cache key missing or expired
if ($cache->lock($memcKey, 0, 10)) {
# Let this process alone update the cache value
$unlocker = new ScopedCallback(function () use($cache, $memcKey) {
$cache->unlock($memcKey);
});
} elseif (is_array($times)) {
# Could not acquire lock but an old cache exists, so use it
unset($times['timestamp']);
// hide from caller
return $times;
}
$times = array();
foreach ($serverIndexes as $i) {
if ($i == 0) {
# Master
$times[$i] = 0;
} elseif (false !== ($conn = $this->parent->getAnyOpenConnection($i))) {
$times[$i] = $conn->getLag();
} elseif (false !== ($conn = $this->parent->openConnection($i, $wiki))) {
$times[$i] = $conn->getLag();
// Close the connection to avoid sleeper connections piling up.
// Note that the caller will pick one of these DBs and reconnect,
// which is slightly inefficient, but this only matters for the lag
// time cache miss cache, which is far less common that cache hits.
$this->parent->closeConnection($conn);
}
}
# Add a timestamp key so we know when it was cached
$times['timestamp'] = time();
$cache->set($memcKey, $times, $expiry + 10);
unset($times['timestamp']);
// hide from caller
return $times;
}
public function getLagTimes($serverIndexes, $wiki)
{
if (count($serverIndexes) == 1 && reset($serverIndexes) == 0) {
// Single server only, just return zero without caching
return array(0 => 0);
}
$section = new ProfileSection(__METHOD__);
$expiry = 5;
$requestRate = 10;
global $wgMemc;
if (empty($wgMemc)) {
$wgMemc = wfGetMainCache();
}
$masterName = $this->parent->getServerName(0);
$memcKey = wfMemcKey('lag_times', $masterName);
$times = $wgMemc->get($memcKey);
if (is_array($times)) {
# Randomly recache with probability rising over $expiry
$elapsed = time() - $times['timestamp'];
$chance = max(0, ($expiry - $elapsed) * $requestRate);
if (mt_rand(0, $chance) != 0) {
unset($times['timestamp']);
// hide from caller
return $times;
}
wfIncrStats('lag_cache_miss_expired');
} else {
wfIncrStats('lag_cache_miss_absent');
}
# Cache key missing or expired
if ($wgMemc->add("{$memcKey}:lock", 1, 10)) {
# Let this process alone update the cache value
$unlocker = new ScopedCallback(function () use($wgMemc, $memcKey) {
$wgMemc->delete($memcKey);
});
} elseif (is_array($times)) {
# Could not acquire lock but an old cache exists, so use it
unset($times['timestamp']);
// hide from caller
return $times;
}
$times = array();
foreach ($serverIndexes as $i) {
if ($i == 0) {
# Master
$times[$i] = 0;
} elseif (false !== ($conn = $this->parent->getAnyOpenConnection($i))) {
$times[$i] = $conn->getLag();
} elseif (false !== ($conn = $this->parent->openConnection($i, $wiki))) {
$times[$i] = $conn->getLag();
}
}
# Add a timestamp key so we know when it was cached
$times['timestamp'] = time();
$wgMemc->set($memcKey, $times, $expiry + 10);
unset($times['timestamp']);
// hide from caller
return $times;
}
/**
* @param $serverIndexes
* @param $wiki
* @return array
*/
function getLagTimes($serverIndexes, $wiki)
{
if (count($serverIndexes) == 1 && reset($serverIndexes) == 0) {
// Single server only, just return zero without caching
return array(0 => 0);
}
wfProfileIn(__METHOD__);
$expiry = 5;
$requestRate = 10;
global $wgMemc;
if (empty($wgMemc)) {
$wgMemc = wfGetMainCache();
}
$masterName = $this->parent->getServerName(0);
$memcKey = wfMemcKey('lag_times', $masterName);
$times = $wgMemc->get($memcKey);
if ($times) {
# Randomly recache with probability rising over $expiry
$elapsed = time() - $times['timestamp'];
$chance = max(0, ($expiry - $elapsed) * $requestRate);
if (mt_rand(0, $chance) != 0) {
unset($times['timestamp']);
wfProfileOut(__METHOD__);
return $times;
}
wfIncrStats('lag_cache_miss_expired');
} else {
wfIncrStats('lag_cache_miss_absent');
}
# Cache key missing or expired
$times = array();
foreach ($serverIndexes as $i) {
if ($i == 0) {
# Master
$times[$i] = 0;
} elseif (false !== ($conn = $this->parent->getAnyOpenConnection($i))) {
$times[$i] = $conn->getLag();
} elseif (false !== ($conn = $this->parent->openConnection($i, $wiki))) {
$times[$i] = $conn->getLag();
}
}
# Add a timestamp key so we know when it was cached
$times['timestamp'] = time();
$wgMemc->set($memcKey, $times, $expiry);
# But don't give the timestamp to the caller
unset($times['timestamp']);
$lagTimes = $times;
wfProfileOut(__METHOD__);
return $lagTimes;
}
/**
* Notify the ChronologyProtector that the LoadBalancer is about to shut
* down. Saves replication positions.
*
* @param LoadBalancer $lb
* @return void
*/
public function shutdownLB(LoadBalancer $lb)
{
if (session_id() == '' || $lb->getServerCount() <= 1) {
return;
// don't start a session; don't bother with non-replicated setups
}
$masterName = $lb->getServerName(0);
if (isset($this->shutdownPositions[$masterName])) {
return;
// already done
}
// Only save the position if writes have been done on the connection
$db = $lb->getAnyOpenConnection(0);
$info = $lb->parentInfo();
if (!$db || !$db->doneWrites()) {
wfDebug(__METHOD__ . ": LB {$info['id']}, no writes done\n");
return;
}
$pos = $db->getMasterPos();
wfDebug(__METHOD__ . ": LB {$info['id']} has master pos {$pos}\n");
$this->shutdownPositions[$masterName] = $pos;
}
/**
* Notify the ChronologyProtector that the LoadBalancer is about to shut
* down. Saves replication positions.
*
* @param LoadBalancer $lb
* @return void
*/
public function shutdownLB(LoadBalancer $lb)
{
if (!$this->enabled || $lb->getServerCount() <= 1) {
return;
// non-replicated setup or disabled
}
$info = $lb->parentInfo();
$masterName = $lb->getServerName($lb->getWriterIndex());
// Only save the position if writes have been done on the connection
$db = $lb->getAnyOpenConnection($lb->getWriterIndex());
if (!$db || !$db->doneWrites()) {
wfDebugLog('replication', __METHOD__ . ": LB {$info['id']}, no writes done\n");
return;
// nothing to do
}
$pos = $db->getMasterPos();
wfDebugLog('replication', __METHOD__ . ": LB {$info['id']} has master pos {$pos}\n");
$this->shutdownPositions[$masterName] = $pos;
}
private function getLagTimeCacheKey()
{
# Lag is per-server, not per-DB, so key on the master DB name
return wfGlobalCacheKey('lag-times', $this->parent->getServerName(0));
}
private function getLagTimeCacheKey()
{
$writerIndex = $this->parent->getWriterIndex();
// Lag is per-server, not per-DB, so key on the master DB name
return $this->srvCache->makeGlobalKey('lag-times', $this->parent->getServerName($writerIndex));
}
private function getLagTimeCacheKey()
{
# Lag is per-server, not per-DB, so key on the master DB name
return wfForeignMemcKey($this->parent->getServerName(0), '', 'lag_times');
}
/**
* Notify the ChronologyProtector that the LoadBalancer is about to shut
* down. Saves replication positions.
*
* @param LoadBalancer $lb
*/
function shutdownLB($lb)
{
if (session_id() != '' && $lb->getServerCount() > 1) {
$masterName = $lb->getServerName(0);
if (!isset($this->shutdownPos[$masterName])) {
$pos = $lb->getMasterPos();
$info = $lb->parentInfo();
wfDebug(__METHOD__ . ": LB " . $info['id'] . " has master pos {$pos}\n");
$this->shutdownPos[$masterName] = $pos;
}
}
}
