%PDF-
%PDF-
Mini Shell
Mini Shell
<?php
/**
* Object caching using a SQL database.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
* @ingroup Cache
*/
/**
* Class to store objects in the database
*
* @ingroup Cache
*/
class SqlBagOStuff extends BagOStuff {
/** @var LoadBalancer */
protected $lb;
protected $serverInfos;
/** @var array */
protected $serverNames;
/** @var int */
protected $numServers;
/** @var array */
protected $conns;
/** @var int */
protected $lastExpireAll = 0;
/** @var int */
protected $purgePeriod = 100;
/** @var int */
protected $shards = 1;
/** @var string */
protected $tableName = 'objectcache';
/** @var array UNIX timestamps */
protected $connFailureTimes = array();
/** @var array Exceptions */
protected $connFailureErrors = array();
/**
* Constructor. Parameters are:
* - server: A server info structure in the format required by each
* element in $wgDBServers.
*
* - servers: An array of server info structures describing a set of
* database servers to distribute keys to. If this is
* specified, the "server" option will be ignored.
*
* - purgePeriod: The average number of object cache requests in between
* garbage collection operations, where expired entries
* are removed from the database. Or in other words, the
* reciprocal of the probability of purging on any given
* request. If this is set to zero, purging will never be
* done.
*
* - tableName: The table name to use, default is "objectcache".
*
* - shards: The number of tables to use for data storage on each server.
* If this is more than 1, table names will be formed in the style
* objectcacheNNN where NNN is the shard index, between 0 and
* shards-1. The number of digits will be the minimum number
* required to hold the largest shard index. Data will be
* distributed across all tables by key hash. This is for
* MySQL bugs 61735 and 61736.
*
* @param array $params
*/
public function __construct( $params ) {
parent::__construct( $params );
if ( isset( $params['servers'] ) ) {
$this->serverInfos = $params['servers'];
$this->numServers = count( $this->serverInfos );
$this->serverNames = array();
foreach ( $this->serverInfos as $i => $info ) {
$this->serverNames[$i] = isset( $info['host'] ) ? $info['host'] : "#$i";
}
} elseif ( isset( $params['server'] ) ) {
$this->serverInfos = array( $params['server'] );
$this->numServers = count( $this->serverInfos );
} else {
$this->serverInfos = false;
$this->numServers = 1;
}
if ( isset( $params['purgePeriod'] ) ) {
$this->purgePeriod = intval( $params['purgePeriod'] );
}
if ( isset( $params['tableName'] ) ) {
$this->tableName = $params['tableName'];
}
if ( isset( $params['shards'] ) ) {
$this->shards = intval( $params['shards'] );
}
}
/**
* Get a connection to the specified database
*
* @param int $serverIndex
* @return DatabaseBase
* @throws MWException
*/
protected function getDB( $serverIndex ) {
global $wgDebugDBTransactions;
if ( !isset( $this->conns[$serverIndex] ) ) {
if ( $serverIndex >= $this->numServers ) {
throw new MWException( __METHOD__ . ": Invalid server index \"$serverIndex\"" );
}
# Don't keep timing out trying to connect for each call if the DB is down
if ( isset( $this->connFailureErrors[$serverIndex] )
&& ( time() - $this->connFailureTimes[$serverIndex] ) < 60
) {
throw $this->connFailureErrors[$serverIndex];
}
# If server connection info was given, use that
if ( $this->serverInfos ) {
if ( $wgDebugDBTransactions ) {
$this->logger->debug( "Using provided serverInfo for SqlBagOStuff" );
}
$info = $this->serverInfos[$serverIndex];
$type = isset( $info['type'] ) ? $info['type'] : 'mysql';
$host = isset( $info['host'] ) ? $info['host'] : '[unknown]';
$this->logger->debug( __CLASS__ . ": connecting to $host" );
// Use a blank trx profiler to ignore expections as this is a cache
$info['trxProfiler'] = new TransactionProfiler();
$db = DatabaseBase::factory( $type, $info );
$db->clearFlag( DBO_TRX );
} else {
/*
* We must keep a separate connection to MySQL in order to avoid deadlocks
* However, SQLite has an opposite behavior. And PostgreSQL needs to know
* if we are in transaction or no
*/
if ( wfGetDB( DB_MASTER )->getType() == 'mysql' ) {
$this->lb = wfGetLBFactory()->newMainLB();
$db = $this->lb->getConnection( DB_MASTER );
$db->clearFlag( DBO_TRX ); // auto-commit mode
} else {
$db = wfGetDB( DB_MASTER );
}
}
if ( $wgDebugDBTransactions ) {
$this->logger->debug( sprintf( "Connection %s will be used for SqlBagOStuff", $db ) );
}
$this->conns[$serverIndex] = $db;
}
return $this->conns[$serverIndex];
}
/**
* Get the server index and table name for a given key
* @param string $key
* @return array Server index and table name
*/
protected function getTableByKey( $key ) {
if ( $this->shards > 1 ) {
$hash = hexdec( substr( md5( $key ), 0, 8 ) ) & 0x7fffffff;
$tableIndex = $hash % $this->shards;
} else {
$tableIndex = 0;
}
if ( $this->numServers > 1 ) {
$sortedServers = $this->serverNames;
ArrayUtils::consistentHashSort( $sortedServers, $key );
reset( $sortedServers );
$serverIndex = key( $sortedServers );
} else {
$serverIndex = 0;
}
return array( $serverIndex, $this->getTableNameByShard( $tableIndex ) );
}
/**
* Get the table name for a given shard index
* @param int $index
* @return string
*/
protected function getTableNameByShard( $index ) {
if ( $this->shards > 1 ) {
$decimals = strlen( $this->shards - 1 );
return $this->tableName .
sprintf( "%0{$decimals}d", $index );
} else {
return $this->tableName;
}
}
/**
* @param string $key
* @param mixed $casToken [optional]
* @return mixed
*/
public function get( $key, &$casToken = null ) {
$values = $this->getMulti( array( $key ) );
if ( array_key_exists( $key, $values ) ) {
$casToken = $values[$key];
return $values[$key];
}
return false;
}
/**
* @param array $keys
* @return array
*/
public function getMulti( array $keys ) {
$values = array(); // array of (key => value)
$keysByTable = array();
foreach ( $keys as $key ) {
list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
$keysByTable[$serverIndex][$tableName][] = $key;
}
$this->garbageCollect(); // expire old entries if any
$dataRows = array();
foreach ( $keysByTable as $serverIndex => $serverKeys ) {
try {
$db = $this->getDB( $serverIndex );
foreach ( $serverKeys as $tableName => $tableKeys ) {
$res = $db->select( $tableName,
array( 'keyname', 'value', 'exptime' ),
array( 'keyname' => $tableKeys ),
__METHOD__,
// Approximate write-on-the-fly BagOStuff API via blocking.
// This approximation fails if a ROLLBACK happens (which is rare).
// We do not want to flush the TRX as that can break callers.
$db->trxLevel() ? array( 'LOCK IN SHARE MODE' ) : array()
);
if ( $res === false ) {
continue;
}
foreach ( $res as $row ) {
$row->serverIndex = $serverIndex;
$row->tableName = $tableName;
$dataRows[$row->keyname] = $row;
}
}
} catch ( DBError $e ) {
$this->handleReadError( $e, $serverIndex );
}
}
foreach ( $keys as $key ) {
if ( isset( $dataRows[$key] ) ) { // HIT?
$row = $dataRows[$key];
$this->debug( "get: retrieved data; expiry time is " . $row->exptime );
try {
$db = $this->getDB( $row->serverIndex );
if ( $this->isExpired( $db, $row->exptime ) ) { // MISS
$this->debug( "get: key has expired, deleting" );
# Put the expiry time in the WHERE condition to avoid deleting a
# newly-inserted value
$db->delete( $row->tableName,
array( 'keyname' => $key, 'exptime' => $row->exptime ),
__METHOD__ );
} else { // HIT
$values[$key] = $this->unserialize( $db->decodeBlob( $row->value ) );
}
} catch ( DBQueryError $e ) {
$this->handleWriteError( $e, $row->serverIndex );
}
} else { // MISS
$this->debug( 'get: no matching rows' );
}
}
return $values;
}
/**
* @param array $data
* @param int $expiry
* @return bool
*/
public function setMulti( array $data, $expiry = 0 ) {
$keysByTable = array();
foreach ( $data as $key => $value ) {
list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
$keysByTable[$serverIndex][$tableName][] = $key;
}
$this->garbageCollect(); // expire old entries if any
$result = true;
$exptime = (int)$expiry;
foreach ( $keysByTable as $serverIndex => $serverKeys ) {
try {
$db = $this->getDB( $serverIndex );
} catch ( DBError $e ) {
$this->handleWriteError( $e, $serverIndex );
$result = false;
continue;
}
if ( $exptime < 0 ) {
$exptime = 0;
}
if ( $exptime == 0 ) {
$encExpiry = $this->getMaxDateTime( $db );
} else {
$exptime = $this->convertExpiry( $exptime );
$encExpiry = $db->timestamp( $exptime );
}
foreach ( $serverKeys as $tableName => $tableKeys ) {
$rows = array();
foreach ( $tableKeys as $key ) {
$rows[] = array(
'keyname' => $key,
'value' => $db->encodeBlob( $this->serialize( $data[$key] ) ),
'exptime' => $encExpiry,
);
}
try {
$db->replace(
$tableName,
array( 'keyname' ),
$rows,
__METHOD__
);
} catch ( DBError $e ) {
$this->handleWriteError( $e, $serverIndex );
$result = false;
}
}
}
return $result;
}
/**
* @param string $key
* @param mixed $value
* @param int $exptime
* @return bool
*/
public function set( $key, $value, $exptime = 0 ) {
list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
try {
$db = $this->getDB( $serverIndex );
$exptime = intval( $exptime );
if ( $exptime < 0 ) {
$exptime = 0;
}
if ( $exptime == 0 ) {
$encExpiry = $this->getMaxDateTime( $db );
} else {
$exptime = $this->convertExpiry( $exptime );
$encExpiry = $db->timestamp( $exptime );
}
// (bug 24425) use a replace if the db supports it instead of
// delete/insert to avoid clashes with conflicting keynames
$db->replace(
$tableName,
array( 'keyname' ),
array(
'keyname' => $key,
'value' => $db->encodeBlob( $this->serialize( $value ) ),
'exptime' => $encExpiry
), __METHOD__ );
} catch ( DBError $e ) {
$this->handleWriteError( $e, $serverIndex );
return false;
}
return true;
}
/**
* @param mixed $casToken
* @param string $key
* @param mixed $value
* @param int $exptime
* @return bool
*/
protected function cas( $casToken, $key, $value, $exptime = 0 ) {
list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
try {
$db = $this->getDB( $serverIndex );
$exptime = intval( $exptime );
if ( $exptime < 0 ) {
$exptime = 0;
}
if ( $exptime == 0 ) {
$encExpiry = $this->getMaxDateTime( $db );
} else {
$exptime = $this->convertExpiry( $exptime );
$encExpiry = $db->timestamp( $exptime );
}
// (bug 24425) use a replace if the db supports it instead of
// delete/insert to avoid clashes with conflicting keynames
$db->update(
$tableName,
array(
'keyname' => $key,
'value' => $db->encodeBlob( $this->serialize( $value ) ),
'exptime' => $encExpiry
),
array(
'keyname' => $key,
'value' => $db->encodeBlob( $this->serialize( $casToken ) )
),
__METHOD__
);
} catch ( DBQueryError $e ) {
$this->handleWriteError( $e, $serverIndex );
return false;
}
return (bool)$db->affectedRows();
}
/**
* @param string $key
* @return bool
*/
public function delete( $key ) {
list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
try {
$db = $this->getDB( $serverIndex );
$db->delete(
$tableName,
array( 'keyname' => $key ),
__METHOD__ );
} catch ( DBError $e ) {
$this->handleWriteError( $e, $serverIndex );
return false;
}
return true;
}
/**
* @param string $key
* @param int $step
* @return int|null
*/
public function incr( $key, $step = 1 ) {
list( $serverIndex, $tableName ) = $this->getTableByKey( $key );
try {
$db = $this->getDB( $serverIndex );
$step = intval( $step );
$row = $db->selectRow(
$tableName,
array( 'value', 'exptime' ),
array( 'keyname' => $key ),
__METHOD__,
array( 'FOR UPDATE' ) );
if ( $row === false ) {
// Missing
return null;
}
$db->delete( $tableName, array( 'keyname' => $key ), __METHOD__ );
if ( $this->isExpired( $db, $row->exptime ) ) {
// Expired, do not reinsert
return null;
}
$oldValue = intval( $this->unserialize( $db->decodeBlob( $row->value ) ) );
$newValue = $oldValue + $step;
$db->insert( $tableName,
array(
'keyname' => $key,
'value' => $db->encodeBlob( $this->serialize( $newValue ) ),
'exptime' => $row->exptime
), __METHOD__, 'IGNORE' );
if ( $db->affectedRows() == 0 ) {
// Race condition. See bug 28611
$newValue = null;
}
} catch ( DBError $e ) {
$this->handleWriteError( $e, $serverIndex );
return null;
}
return $newValue;
}
public function merge( $key, $callback, $exptime = 0, $attempts = 10 ) {
if ( !is_callable( $callback ) ) {
throw new Exception( "Got invalid callback." );
}
return $this->mergeViaCas( $key, $callback, $exptime, $attempts );
}
/**
* @param DatabaseBase $db
* @param string $exptime
* @return bool
*/
protected function isExpired( $db, $exptime ) {
return $exptime != $this->getMaxDateTime( $db ) && wfTimestamp( TS_UNIX, $exptime ) < time();
}
/**
* @param DatabaseBase $db
* @return string
*/
protected function getMaxDateTime( $db ) {
if ( time() > 0x7fffffff ) {
return $db->timestamp( 1 << 62 );
} else {
return $db->timestamp( 0x7fffffff );
}
}
protected function garbageCollect() {
if ( !$this->purgePeriod ) {
// Disabled
return;
}
// Only purge on one in every $this->purgePeriod requests.
if ( $this->purgePeriod !== 1 && mt_rand( 0, $this->purgePeriod - 1 ) ) {
return;
}
$now = time();
// Avoid repeating the delete within a few seconds
if ( $now > ( $this->lastExpireAll + 1 ) ) {
$this->lastExpireAll = $now;
$this->expireAll();
}
}
public function expireAll() {
$this->deleteObjectsExpiringBefore( wfTimestampNow() );
}
/**
* Delete objects from the database which expire before a certain date.
* @param string $timestamp
* @param bool|callable $progressCallback
* @return bool
*/
public function deleteObjectsExpiringBefore( $timestamp, $progressCallback = false ) {
for ( $serverIndex = 0; $serverIndex < $this->numServers; $serverIndex++ ) {
try {
$db = $this->getDB( $serverIndex );
$dbTimestamp = $db->timestamp( $timestamp );
$totalSeconds = false;
$baseConds = array( 'exptime < ' . $db->addQuotes( $dbTimestamp ) );
for ( $i = 0; $i < $this->shards; $i++ ) {
$maxExpTime = false;
while ( true ) {
$conds = $baseConds;
if ( $maxExpTime !== false ) {
$conds[] = 'exptime > ' . $db->addQuotes( $maxExpTime );
}
$rows = $db->select(
$this->getTableNameByShard( $i ),
array( 'keyname', 'exptime' ),
$conds,
__METHOD__,
array( 'LIMIT' => 100, 'ORDER BY' => 'exptime' ) );
if ( $rows === false || !$rows->numRows() ) {
break;
}
$keys = array();
$row = $rows->current();
$minExpTime = $row->exptime;
if ( $totalSeconds === false ) {
$totalSeconds = wfTimestamp( TS_UNIX, $timestamp )
- wfTimestamp( TS_UNIX, $minExpTime );
}
foreach ( $rows as $row ) {
$keys[] = $row->keyname;
$maxExpTime = $row->exptime;
}
$db->delete(
$this->getTableNameByShard( $i ),
array(
'exptime >= ' . $db->addQuotes( $minExpTime ),
'exptime < ' . $db->addQuotes( $dbTimestamp ),
'keyname' => $keys
),
__METHOD__ );
if ( $progressCallback ) {
if ( intval( $totalSeconds ) === 0 ) {
$percent = 0;
} else {
$remainingSeconds = wfTimestamp( TS_UNIX, $timestamp )
- wfTimestamp( TS_UNIX, $maxExpTime );
if ( $remainingSeconds > $totalSeconds ) {
$totalSeconds = $remainingSeconds;
}
$processedSeconds = $totalSeconds - $remainingSeconds;
$percent = ( $i + $processedSeconds / $totalSeconds )
/ $this->shards * 100;
}
$percent = ( $percent / $this->numServers )
+ ( $serverIndex / $this->numServers * 100 );
call_user_func( $progressCallback, $percent );
}
}
}
} catch ( DBError $e ) {
$this->handleWriteError( $e, $serverIndex );
return false;
}
}
return true;
}
/**
* Delete content of shard tables in every server.
* Return true if the operation is successful, false otherwise.
* @return bool
*/
public function deleteAll() {
for ( $serverIndex = 0; $serverIndex < $this->numServers; $serverIndex++ ) {
try {
$db = $this->getDB( $serverIndex );
for ( $i = 0; $i < $this->shards; $i++ ) {
$db->delete( $this->getTableNameByShard( $i ), '*', __METHOD__ );
}
} catch ( DBError $e ) {
$this->handleWriteError( $e, $serverIndex );
return false;
}
}
return true;
}
/**
* Serialize an object and, if possible, compress the representation.
* On typical message and page data, this can provide a 3X decrease
* in storage requirements.
*
* @param mixed $data
* @return string
*/
protected function serialize( &$data ) {
$serial = serialize( $data );
if ( function_exists( 'gzdeflate' ) ) {
return gzdeflate( $serial );
} else {
return $serial;
}
}
/**
* Unserialize and, if necessary, decompress an object.
* @param string $serial
* @return mixed
*/
protected function unserialize( $serial ) {
if ( function_exists( 'gzinflate' ) ) {
wfSuppressWarnings();
$decomp = gzinflate( $serial );
wfRestoreWarnings();
if ( false !== $decomp ) {
$serial = $decomp;
}
}
$ret = unserialize( $serial );
return $ret;
}
/**
* Handle a DBError which occurred during a read operation.
*
* @param DBError $exception
* @param int $serverIndex
*/
protected function handleReadError( DBError $exception, $serverIndex ) {
if ( $exception instanceof DBConnectionError ) {
$this->markServerDown( $exception, $serverIndex );
}
$this->logger->error( "DBError: {$exception->getMessage()}" );
if ( $exception instanceof DBConnectionError ) {
$this->setLastError( BagOStuff::ERR_UNREACHABLE );
$this->logger->debug( __METHOD__ . ": ignoring connection error" );
} else {
$this->setLastError( BagOStuff::ERR_UNEXPECTED );
$this->logger->debug( __METHOD__ . ": ignoring query error" );
}
}
/**
* Handle a DBQueryError which occurred during a write operation.
*
* @param DBError $exception
* @param int $serverIndex
*/
protected function handleWriteError( DBError $exception, $serverIndex ) {
if ( $exception instanceof DBConnectionError ) {
$this->markServerDown( $exception, $serverIndex );
}
if ( $exception->db && $exception->db->wasReadOnlyError() ) {
if ( $exception->db->trxLevel() ) {
try {
$exception->db->rollback( __METHOD__ );
} catch ( DBError $e ) {
}
}
}
$this->logger->error( "DBError: {$exception->getMessage()}" );
if ( $exception instanceof DBConnectionError ) {
$this->setLastError( BagOStuff::ERR_UNREACHABLE );
$this->logger->debug( __METHOD__ . ": ignoring connection error" );
} else {
$this->setLastError( BagOStuff::ERR_UNEXPECTED );
$this->logger->debug( __METHOD__ . ": ignoring query error" );
}
}
/**
* Mark a server down due to a DBConnectionError exception
*
* @param DBError $exception
* @param int $serverIndex
*/
protected function markServerDown( $exception, $serverIndex ) {
if ( isset( $this->connFailureTimes[$serverIndex] ) ) {
if ( time() - $this->connFailureTimes[$serverIndex] >= 60 ) {
unset( $this->connFailureTimes[$serverIndex] );
unset( $this->connFailureErrors[$serverIndex] );
} else {
$this->logger->debug( __METHOD__ . ": Server #$serverIndex already down" );
return;
}
}
$now = time();
$this->logger->info( __METHOD__ . ": Server #$serverIndex down until " . ( $now + 60 ) );
$this->connFailureTimes[$serverIndex] = $now;
$this->connFailureErrors[$serverIndex] = $exception;
}
/**
* Create shard tables. For use from eval.php.
*/
public function createTables() {
for ( $serverIndex = 0; $serverIndex < $this->numServers; $serverIndex++ ) {
$db = $this->getDB( $serverIndex );
if ( $db->getType() !== 'mysql' ) {
throw new MWException( __METHOD__ . ' is not supported on this DB server' );
}
for ( $i = 0; $i < $this->shards; $i++ ) {
$db->query(
'CREATE TABLE ' . $db->tableName( $this->getTableNameByShard( $i ) ) .
' LIKE ' . $db->tableName( 'objectcache' ),
__METHOD__ );
}
}
}
}
Zerion Mini Shell 1.0