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-rw-r--r--includes/db/LoadBalancer.php147
1 files changed, 68 insertions, 79 deletions
diff --git a/includes/db/LoadBalancer.php b/includes/db/LoadBalancer.php
index d9584e14..52dca087 100644
--- a/includes/db/LoadBalancer.php
+++ b/includes/db/LoadBalancer.php
@@ -60,8 +60,6 @@ class LoadBalancer {
private $mLastError = 'Unknown error';
/** @var integer Total connections opened */
private $connsOpened = 0;
- /** @var ProcessCacheLRU */
- private $mProcCache;
/** @var integer Warn when this many connection are held */
const CONN_HELD_WARN_THRESHOLD = 10;
@@ -113,8 +111,6 @@ class LoadBalancer {
}
}
}
-
- $this->mProcCache = new ProcessCacheLRU( 30 );
}
/**
@@ -214,7 +210,7 @@ class LoadBalancer {
* @return bool|int|string
*/
public function getReaderIndex( $group = false, $wiki = false ) {
- global $wgReadOnly, $wgDBtype;
+ global $wgDBtype;
# @todo FIXME: For now, only go through all this for mysql databases
if ( $wgDBtype != 'mysql' ) {
@@ -258,7 +254,7 @@ class LoadBalancer {
# meets our criteria
$currentLoads = $nonErrorLoads;
while ( count( $currentLoads ) ) {
- if ( $wgReadOnly || $this->mAllowLagged || $laggedSlaveMode ) {
+ if ( $this->mAllowLagged || $laggedSlaveMode ) {
$i = ArrayUtils::pickRandom( $currentLoads );
} else {
$i = false;
@@ -277,8 +273,6 @@ class LoadBalancer {
if ( $i === false && count( $currentLoads ) != 0 ) {
# All slaves lagged. Switch to read-only mode
wfDebugLog( 'replication', "All slaves lagged. Switch to read-only mode" );
- $wgReadOnly = 'The database has been automatically locked ' .
- 'while the slave database servers catch up to the master';
$i = ArrayUtils::pickRandom( $currentLoads );
$laggedSlaveMode = true;
}
@@ -293,8 +287,8 @@ class LoadBalancer {
return false;
}
- wfDebugLog( 'connect', __METHOD__ .
- ": Using reader #$i: {$this->mServers[$i]['host']}..." );
+ $serverName = $this->getServerName( $i );
+ wfDebugLog( 'connect', __METHOD__ . ": Using reader #$i: $serverName..." );
$conn = $this->openConnection( $i, $wiki );
if ( !$conn ) {
@@ -330,6 +324,10 @@ class LoadBalancer {
}
if ( $this->mReadIndex <= 0 && $this->mLoads[$i] > 0 && $group === false ) {
$this->mReadIndex = $i;
+ # Record if the generic reader index is in "lagged slave" mode
+ if ( $laggedSlaveMode ) {
+ $this->mLaggedSlaveMode = true;
+ }
}
$serverName = $this->getServerName( $i );
wfDebug( __METHOD__ . ": using server $serverName for group '$group'\n" );
@@ -357,6 +355,37 @@ class LoadBalancer {
}
/**
+ * Set the master wait position and wait for a "generic" slave to catch up to it
+ *
+ * This can be used a faster proxy for waitForAll()
+ *
+ * @param DBMasterPos $pos
+ * @param int $timeout Max seconds to wait; default is mWaitTimeout
+ * @return bool Success (able to connect and no timeouts reached)
+ * @since 1.26
+ */
+ public function waitForOne( $pos, $timeout = null ) {
+ $this->mWaitForPos = $pos;
+
+ $i = $this->mReadIndex;
+ if ( $i <= 0 ) {
+ // Pick a generic slave if there isn't one yet
+ $readLoads = $this->mLoads;
+ unset( $readLoads[$this->getWriterIndex()] ); // slaves only
+ $readLoads = array_filter( $readLoads ); // with non-zero load
+ $i = ArrayUtils::pickRandom( $readLoads );
+ }
+
+ if ( $i > 0 ) {
+ $ok = $this->doWait( $i, true, $timeout );
+ } else {
+ $ok = true; // no applicable loads
+ }
+
+ return $ok;
+ }
+
+ /**
* Set the master wait position and wait for ALL slaves to catch up to it
* @param DBMasterPos $pos
* @param int $timeout Max seconds to wait; default is mWaitTimeout
@@ -429,7 +458,7 @@ class LoadBalancer {
if ( $result == -1 || is_null( $result ) ) {
# Timed out waiting for slave, use master instead
- $server = $this->mServers[$index]['host'];
+ $server = $server = $this->getServerName( $index );
$msg = __METHOD__ . ": Timed out waiting on $server pos {$this->mWaitForPos}";
wfDebug( "$msg\n" );
wfDebugLog( 'DBPerformance', "$msg:\n" . wfBacktrace( true ) );
@@ -505,7 +534,6 @@ class LoadBalancer {
# Now we have an explicit index into the servers array
$conn = $this->openConnection( $i, $wiki );
if ( !$conn ) {
-
return $this->reportConnectionError();
}
@@ -618,25 +646,32 @@ class LoadBalancer {
public function openConnection( $i, $wiki = false ) {
if ( $wiki !== false ) {
$conn = $this->openForeignConnection( $i, $wiki );
-
- return $conn;
- }
- if ( isset( $this->mConns['local'][$i][0] ) ) {
+ } elseif ( isset( $this->mConns['local'][$i][0] ) ) {
$conn = $this->mConns['local'][$i][0];
} else {
$server = $this->mServers[$i];
$server['serverIndex'] = $i;
$conn = $this->reallyOpenConnection( $server, false );
+ $serverName = $this->getServerName( $i );
if ( $conn->isOpen() ) {
- wfDebug( "Connected to database $i at {$this->mServers[$i]['host']}\n" );
+ wfDebug( "Connected to database $i at $serverName\n" );
$this->mConns['local'][$i][0] = $conn;
} else {
- wfDebug( "Failed to connect to database $i at {$this->mServers[$i]['host']}\n" );
+ wfDebug( "Failed to connect to database $i at $serverName\n" );
$this->mErrorConnection = $conn;
$conn = false;
}
}
+ if ( $conn && !$conn->isOpen() ) {
+ // Connection was made but later unrecoverably lost for some reason.
+ // Do not return a handle that will just throw exceptions on use,
+ // but let the calling code (e.g. getReaderIndex) try another server.
+ // See DatabaseMyslBase::ping() for how this can happen.
+ $this->mErrorConnection = $conn;
+ $conn = false;
+ }
+
return $conn;
}
@@ -812,8 +847,9 @@ class LoadBalancer {
/**
* @return int
+ * @since 1.26
*/
- private function getWriterIndex() {
+ public function getWriterIndex() {
return 0;
}
@@ -854,12 +890,14 @@ class LoadBalancer {
*/
public function getServerName( $i ) {
if ( isset( $this->mServers[$i]['hostName'] ) ) {
- return $this->mServers[$i]['hostName'];
+ $name = $this->mServers[$i]['hostName'];
} elseif ( isset( $this->mServers[$i]['host'] ) ) {
- return $this->mServers[$i]['host'];
+ $name = $this->mServers[$i]['host'];
} else {
- return '';
+ $name = '';
}
+
+ return ( $name != '' ) ? $name : 'localhost';
}
/**
@@ -1096,9 +1134,12 @@ class LoadBalancer {
}
/**
- * @return bool
+ * @return bool Whether the generic connection for reads is highly "lagged"
*/
public function getLaggedSlaveMode() {
+ # Get a generic reader connection
+ $this->getConnection( DB_SLAVE );
+
return $this->mLaggedSlaveMode;
}
@@ -1195,16 +1236,8 @@ class LoadBalancer {
return array( 0 => 0 ); // no replication = no lag
}
- if ( $this->mProcCache->has( 'slave_lag', 'times', 1 ) ) {
- return $this->mProcCache->get( 'slave_lag', 'times' );
- }
-
# Send the request to the load monitor
- $times = $this->getLoadMonitor()->getLagTimes( array_keys( $this->mServers ), $wiki );
-
- $this->mProcCache->set( 'slave_lag', 'times', $times );
-
- return $times;
+ return $this->getLoadMonitor()->getLagTimes( array_keys( $this->mServers ), $wiki );
}
/**
@@ -1231,54 +1264,10 @@ class LoadBalancer {
/**
* Clear the cache for slag lag delay times
+ *
+ * This is only used for testing
*/
public function clearLagTimeCache() {
- $this->mProcCache->clear( 'slave_lag' );
- }
-}
-
-/**
- * Helper class to handle automatically marking connections as reusable (via RAII pattern)
- * as well handling deferring the actual network connection until the handle is used
- *
- * @ingroup Database
- * @since 1.22
- */
-class DBConnRef implements IDatabase {
- /** @var LoadBalancer */
- private $lb;
-
- /** @var DatabaseBase|null */
- private $conn;
-
- /** @var array|null */
- private $params;
-
- /**
- * @param LoadBalancer $lb
- * @param DatabaseBase|array $conn Connection or (server index, group, wiki ID) array
- */
- public function __construct( LoadBalancer $lb, $conn ) {
- $this->lb = $lb;
- if ( $conn instanceof DatabaseBase ) {
- $this->conn = $conn;
- } else {
- $this->params = $conn;
- }
- }
-
- public function __call( $name, $arguments ) {
- if ( $this->conn === null ) {
- list( $db, $groups, $wiki ) = $this->params;
- $this->conn = $this->lb->getConnection( $db, $groups, $wiki );
- }
-
- return call_user_func_array( array( $this->conn, $name ), $arguments );
- }
-
- public function __destruct() {
- if ( $this->conn !== null ) {
- $this->lb->reuseConnection( $this->conn );
- }
+ $this->getLoadMonitor()->clearCaches();
}
}
generated by cgit v1.2.2 (git 2.25.0) at 2024-04-18 04:14:14 +0000