RedisBagOStuff.php
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RedisBagOStuff.php
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	<?php
	/**
	* 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
	*/
	namespace Wikimedia\ObjectCache;

	use ArrayUtils;
	use Exception;
	use Redis;
	use RedisException;

	/**
	* Store data in Redis.
	*
	* This requires the php-redis PECL extension (2.2.4 or later) and
	* a Redis server (2.6.12 or later).
	*
	* @see http://redis.io/
	* @see https://github.com/phpredis/phpredis/blob/d310ed7c8/Changelog.md
	*
	* @note Avoid use of Redis::MULTI transactions for twemproxy support
	*
	* @ingroup Cache
	* @ingroup Redis
	* @phan-file-suppress PhanTypeComparisonFromArray It's unclear whether exec() can return false
	*/
	class RedisBagOStuff extends MediumSpecificBagOStuff {
	/** @var RedisConnectionPool */
	protected $redisPool;
	/** @var array List of server names */
	protected $servers;
	/** @var array Map of (tag => server name) */
	protected $serverTagMap;
	/** @var bool */
	protected $automaticFailover;

	/**
	* Construct a RedisBagOStuff object. Parameters are:
	*
	* - servers: An array of server names. A server name may be a hostname,
	* a hostname/port combination or the absolute path of a UNIX socket.
	* If a hostname is specified but no port, the standard port number
	* 6379 will be used. Arrays keys can be used to specify the tag to
	* hash on in place of the host/port. Required.
	*
	* - connectTimeout: The timeout for new connections, in seconds. Optional,
	* default is 1 second.
	*
	* - persistent: Set this to true to allow connections to persist across
	* multiple web requests. False by default.
	*
	* - password: The authentication password, will be sent to Redis in
	* clear text. Optional, if it is unspecified, no AUTH command will be
	* sent.
	*
	* - automaticFailover: If this is false, then each key will be mapped to
	* a single server, and if that server is down, any requests for that key
	* will fail. If this is true, a connection failure will cause the client
	* to immediately try the next server in the list (as determined by a
	* consistent hashing algorithm). True by default. This has the
	* potential to create consistency issues if a server is slow enough to
	* flap, for example if it is in swap death.
	*
	* @param array $params
	*/
	public function __construct( $params ) {
	parent::__construct( $params );
	$redisConf = [ 'serializer' => 'none' ]; // manage that in this class
	foreach ( [ 'connectTimeout', 'persistent', 'password' ] as $opt ) {
	if ( isset( $params[$opt] ) ) {
	$redisConf[$opt] = $params[$opt];
	}
	}
	$this->redisPool = RedisConnectionPool::singleton( $redisConf );

	$this->servers = $params['servers'];
	foreach ( $this->servers as $key => $server ) {
	$this->serverTagMap[is_int( $key ) ? $server : $key] = $server;
	}

	$this->automaticFailover = $params['automaticFailover'] ?? true;

	// ...and uses rdb snapshots (redis.conf default)
	$this->attrMap[self::ATTR_DURABILITY] = self::QOS_DURABILITY_DISK;
	}

	protected function doGet( $key, $flags = 0, &$casToken = null ) {
	$getToken = ( $casToken === self::PASS_BY_REF );
	$casToken = null;

	$conn = $this->getConnection( $key );
	if ( !$conn ) {
	return false;
	}

	$e = null;
	try {
	$blob = $conn->get( $key );
	if ( $blob !== false ) {
	$value = $this->unserialize( $blob );
	$valueSize = strlen( $blob );
	} else {
	$value = false;
	$valueSize = false;
	}
	if ( $getToken && $value !== false ) {
	$casToken = $blob;
	}
	} catch ( RedisException $e ) {
	$value = false;
	$valueSize = false;
	$this->handleException( $conn, $e );
	}

	$this->logRequest( 'get', $key, $conn->getServer(), $e );

	$this->updateOpStats( self::METRIC_OP_GET, [ $key => [ 0, $valueSize ] ] );

	return $value;
	}

	protected function doSet( $key, $value, $exptime = 0, $flags = 0 ) {
	$conn = $this->getConnection( $key );
	if ( !$conn ) {
	return false;
	}

	$ttl = $this->getExpirationAsTTL( $exptime );
	$serialized = $this->getSerialized( $value, $key );
	$valueSize = strlen( $serialized );

	$e = null;
	try {
	if ( $ttl ) {
	$result = $conn->setex( $key, $ttl, $serialized );
	} else {
	$result = $conn->set( $key, $serialized );
	}
	} catch ( RedisException $e ) {
	$result = false;
	$this->handleException( $conn, $e );
	}

	$this->logRequest( 'set', $key, $conn->getServer(), $e );

	$this->updateOpStats( self::METRIC_OP_SET, [ $key => [ $valueSize, 0 ] ] );

	return $result;
	}

	protected function doDelete( $key, $flags = 0 ) {
	$conn = $this->getConnection( $key );
	if ( !$conn ) {
	return false;
	}

	$e = null;
	try {
	// Note that redis does not return false if the key was not there
	$result = ( $conn->del( $key ) !== false );
	} catch ( RedisException $e ) {
	$result = false;
	$this->handleException( $conn, $e );
	}

	$this->logRequest( 'delete', $key, $conn->getServer(), $e );

	$this->updateOpStats( self::METRIC_OP_DELETE, [ $key ] );

	return $result;
	}

	protected function doGetMulti( array $keys, $flags = 0 ) {
	$blobsFound = [];

	[ $keysByServer, $connByServer ] = $this->getConnectionsForKeys( $keys );
	foreach ( $keysByServer as $server => $batchKeys ) {
	$conn = $connByServer[$server];

	$e = null;
	try {
	// Avoid mget() to reduce CPU hogging from a single request
	$conn->multi( Redis::PIPELINE );
	foreach ( $batchKeys as $key ) {
	$conn->get( $key );
	}
	$batchResult = $conn->exec();
	if ( $batchResult === false ) {
	$this->logRequest( 'get', implode( ',', $batchKeys ), $server, true );
	continue;
	}

	foreach ( $batchResult as $i => $blob ) {
	if ( $blob !== false ) {
	$blobsFound[$batchKeys[$i]] = $blob;
	}
	}
	} catch ( RedisException $e ) {
	$this->handleException( $conn, $e );
	}

	$this->logRequest( 'get', implode( ',', $batchKeys ), $server, $e );
	}

	// Preserve the order of $keys
	$result = [];
	$valueSizesByKey = [];
	foreach ( $keys as $key ) {
	if ( array_key_exists( $key, $blobsFound ) ) {
	$blob = $blobsFound[$key];
	$value = $this->unserialize( $blob );
	if ( $value !== false ) {
	$result[$key] = $value;
	}
	$valueSize = strlen( $blob );
	} else {
	$valueSize = false;
	}
	$valueSizesByKey[$key] = [ 0, $valueSize ];
	}

	$this->updateOpStats( self::METRIC_OP_GET, $valueSizesByKey );

	return $result;
	}

	protected function doSetMulti( array $data, $exptime = 0, $flags = 0 ) {
	$ttl = $this->getExpirationAsTTL( $exptime );
	$op = $ttl ? 'setex' : 'set';

	$keys = array_keys( $data );
	$valueSizesByKey = [];

	[ $keysByServer, $connByServer, $result ] = $this->getConnectionsForKeys( $keys );
	foreach ( $keysByServer as $server => $batchKeys ) {
	$conn = $connByServer[$server];

	$e = null;
	try {
	// Avoid mset() to reduce CPU hogging from a single request
	$conn->multi( Redis::PIPELINE );
	foreach ( $batchKeys as $key ) {
	$serialized = $this->getSerialized( $data[$key], $key );
	if ( $ttl ) {
	$conn->setex( $key, $ttl, $serialized );
	} else {
	$conn->set( $key, $serialized );
	}
	$valueSizesByKey[$key] = [ strlen( $serialized ), 0 ];
	}
	$batchResult = $conn->exec();
	if ( $batchResult === false ) {
	$result = false;
	$this->logRequest( $op, implode( ',', $batchKeys ), $server, true );
	continue;
	}

	$result = $result && !in_array( false, $batchResult, true );
	} catch ( RedisException $e ) {
	$this->handleException( $conn, $e );
	$result = false;
	}

	$this->logRequest( $op, implode( ',', $batchKeys ), $server, $e );
	}

	$this->updateOpStats( self::METRIC_OP_SET, $valueSizesByKey );

	return $result;
	}

	protected function doDeleteMulti( array $keys, $flags = 0 ) {
	[ $keysByServer, $connByServer, $result ] = $this->getConnectionsForKeys( $keys );
	foreach ( $keysByServer as $server => $batchKeys ) {
	$conn = $connByServer[$server];

	$e = null;
	try {
	// Avoid delete() with array to reduce CPU hogging from a single request
	$conn->multi( Redis::PIPELINE );
	foreach ( $batchKeys as $key ) {
	$conn->del( $key );
	}
	$batchResult = $conn->exec();
	if ( $batchResult === false ) {
	$result = false;
	$this->logRequest( 'delete', implode( ',', $batchKeys ), $server, true );
	continue;
	}
	// Note that redis does not return false if the key was not there
	$result = $result && !in_array( false, $batchResult, true );
	} catch ( RedisException $e ) {
	$this->handleException( $conn, $e );
	$result = false;
	}

	$this->logRequest( 'delete', implode( ',', $batchKeys ), $server, $e );
	}

	$this->updateOpStats( self::METRIC_OP_DELETE, array_values( $keys ) );

	return $result;
	}

	public function doChangeTTLMulti( array $keys, $exptime, $flags = 0 ) {
	$relative = $this->isRelativeExpiration( $exptime );
	$op = ( $exptime == self::TTL_INDEFINITE )
	? 'persist'
	: ( $relative ? 'expire' : 'expireAt' );

	[ $keysByServer, $connByServer, $result ] = $this->getConnectionsForKeys( $keys );
	foreach ( $keysByServer as $server => $batchKeys ) {
	$conn = $connByServer[$server];

	$e = null;
	try {
	$conn->multi( Redis::PIPELINE );
	foreach ( $batchKeys as $key ) {
	if ( $exptime == self::TTL_INDEFINITE ) {
	$conn->persist( $key );
	} elseif ( $relative ) {
	$conn->expire( $key, $this->getExpirationAsTTL( $exptime ) );
	} else {
	$conn->expireAt( $key, $this->getExpirationAsTimestamp( $exptime ) );
	}
	}
	$batchResult = $conn->exec();
	if ( $batchResult === false ) {
	$result = false;
	$this->logRequest( $op, implode( ',', $batchKeys ), $server, true );
	continue;
	}
	$result = in_array( false, $batchResult, true ) ? false : $result;
	} catch ( RedisException $e ) {
	$this->handleException( $conn, $e );
	$result = false;
	}

	$this->logRequest( $op, implode( ',', $batchKeys ), $server, $e );
	}

	$this->updateOpStats( self::METRIC_OP_CHANGE_TTL, array_values( $keys ) );

	return $result;
	}

	protected function doAdd( $key, $value, $exptime = 0, $flags = 0 ) {
	$conn = $this->getConnection( $key );
	if ( !$conn ) {
	return false;
	}

	$ttl = $this->getExpirationAsTTL( $exptime );
	$serialized = $this->getSerialized( $value, $key );
	$valueSize = strlen( $serialized );

	try {
	$result = $conn->set(
	$key,
	$serialized,
	$ttl ? [ 'nx', 'ex' => $ttl ] : [ 'nx' ]
	);
	} catch ( RedisException $e ) {
	$result = false;
	$this->handleException( $conn, $e );
	}

	$this->logRequest( 'add', $key, $conn->getServer(), $result );

	$this->updateOpStats( self::METRIC_OP_ADD, [ $key => [ $valueSize, 0 ] ] );

	return $result;
	}

	protected function doIncrWithInit( $key, $exptime, $step, $init, $flags ) {
	$conn = $this->getConnection( $key );
	if ( !$conn ) {
	return false;
	}

	$ttl = $this->getExpirationAsTTL( $exptime );
	try {
	static $script =
	/** @lang Lua */
	<<<LUA
	local key = KEYS[1]
	local ttl, step, init = unpack( ARGV )
	if redis.call( 'exists', key ) == 1 then
	return redis.call( 'incrBy', key, step )
	end
	if 1 * ttl ~= 0 then
	redis.call( 'setex', key, ttl, init )
	else
	redis.call( 'set', key, init )
	end
	return 1 * init
	LUA;
	$result = $conn->luaEval( $script, [ $key, $ttl, $step, $init ], 1 );
	} catch ( RedisException $e ) {
	$result = false;
	$this->handleException( $conn, $e );
	}
	$this->logRequest( 'incrWithInit', $key, $conn->getServer(), $result );

	return $result;
	}

	protected function doChangeTTL( $key, $exptime, $flags ) {
	$conn = $this->getConnection( $key );
	if ( !$conn ) {
	return false;
	}

	$relative = $this->isRelativeExpiration( $exptime );
	try {
	if ( $exptime == self::TTL_INDEFINITE ) {
	$result = $conn->persist( $key );
	$this->logRequest( 'persist', $key, $conn->getServer(), $result );
	} elseif ( $relative ) {
	$result = $conn->expire( $key, $this->getExpirationAsTTL( $exptime ) );
	$this->logRequest( 'expire', $key, $conn->getServer(), $result );
	} else {
	$result = $conn->expireAt( $key, $this->getExpirationAsTimestamp( $exptime ) );
	$this->logRequest( 'expireAt', $key, $conn->getServer(), $result );
	}
	} catch ( RedisException $e ) {
	$result = false;
	$this->handleException( $conn, $e );
	}

	$this->updateOpStats( self::METRIC_OP_CHANGE_TTL, [ $key ] );

	return $result;
	}

	/**
	* @param string[] $keys
	*
	* @return array ((server => redis handle wrapper), (server => key batch), success)
	* @phan-return array{0:array<string,string[]>,1:array<string,RedisConnRef\|Redis>,2:bool}
	*/
	protected function getConnectionsForKeys( array $keys ) {
	$keysByServer = [];
	$connByServer = [];
	$success = true;
	foreach ( $keys as $key ) {
	$candidateTags = $this->getCandidateServerTagsForKey( $key );

	$conn = null;
	// Find a suitable server for this key...
	// phpcs:ignore Generic.CodeAnalysis.AssignmentInCondition.FoundInWhileCondition
	while ( ( $tag = array_shift( $candidateTags ) ) !== null ) {
	$server = $this->serverTagMap[$tag];
	// Reuse connection handles for keys mapping to the same server
	if ( isset( $connByServer[$server] ) ) {
	$conn = $connByServer[$server];
	} else {
	$conn = $this->redisPool->getConnection( $server, $this->logger );
	if ( !$conn ) {
	continue;
	}
	// If automatic failover is enabled, check that the server's link
	// to its master (if any) is up -- but only if there are other
	// viable candidates left to consider. Also, getMasterLinkStatus()
	// does not work with twemproxy, though $candidates will be empty
	// by now in such cases.
	if ( $this->automaticFailover && $candidateTags ) {
	try {
	/** @var string[] $info */
	$info = $conn->info();
	if ( ( $info['master_link_status'] ?? null ) === 'down' ) {
	// If the master cannot be reached, fail-over to the next server.
	// If masters are in data-center A, and replica DBs in data-center B,
	// this helps avoid the case were fail-over happens in A but not
	// to the corresponding server in B (e.g. read/write mismatch).
	continue;
	}
	} catch ( RedisException $e ) {
	// Server is not accepting commands
	$this->redisPool->handleError( $conn, $e );
	continue;
	}
	}
	// Use this connection handle
	$connByServer[$server] = $conn;
	}
	// Use this server for this key
	$keysByServer[$server][] = $key;
	break;
	}

	if ( !$conn ) {
	// No suitable server found for this key
	$success = false;
	$this->setLastError( BagOStuff::ERR_UNREACHABLE );
	}
	}

	return [ $keysByServer, $connByServer, $success ];
	}

	/**
	* @param string $key
	*
	* @return RedisConnRef\|Redis\|null Redis handle wrapper for the key or null on failure
	*/
	protected function getConnection( $key ) {
	[ , $connByServer ] = $this->getConnectionsForKeys( [ $key ] );

	return reset( $connByServer ) ?: null;
	}

	private function getCandidateServerTagsForKey( string $key ): array {
	$candidates = array_keys( $this->serverTagMap );

	if ( count( $this->servers ) > 1 ) {
	ArrayUtils::consistentHashSort( $candidates, $key, '/' );
	if ( !$this->automaticFailover ) {
	$candidates = array_slice( $candidates, 0, 1 );
	}
	}

	return $candidates;
	}

	/**
	* Log a fatal error
	*
	* @param string $msg
	*/
	protected function logError( $msg ) {
	$this->logger->error( "Redis error: $msg" );
	}

	/**
	* The redis extension throws an exception in response to various read, write
	* and protocol errors. Sometimes it also closes the connection, sometimes
	* not. The safest response for us is to explicitly destroy the connection
	* object and let it be reopened during the next request.
	*
	* @param RedisConnRef $conn
	* @param RedisException $e
	*/
	protected function handleException( RedisConnRef $conn, RedisException $e ) {
	$this->setLastError( BagOStuff::ERR_UNEXPECTED );
	$this->redisPool->handleError( $conn, $e );
	}

	/**
	* Send information about a single request to the debug log
	*
	* @param string $op
	* @param string $keys
	* @param string $server
	* @param Exception\|bool\|null $e
	*/
	public function logRequest( $op, $keys, $server, $e = null ) {
	$this->debug( "$op($keys) on $server: " . ( $e ? "failure" : "success" ) );
	}
	}

	/** @deprecated class alias since 1.43 */
	class_alias( RedisBagOStuff::class, 'RedisBagOStuff' );

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