wikimedia/mediawiki-core

<?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 MediaWiki\PoolCounter;

use MediaWiki\Status\Status;

/**
 * @since 1.16
 */
class PoolCounterClient extends PoolCounter {
    /**
     * @var ?resource the socket connection to the poolcounterd.  Closing this
     * releases all locks acquired.
     */
    private $conn;

    /**
     * @var string The server host name
     */
    private $hostName;

    /**
     * @var PoolCounterConnectionManager
     */
    private $manager;

    /**
     * @param PoolCounterConnectionManager $manager
     */
    public function setManager( PoolCounterConnectionManager $manager ): void {
        $this->manager = $manager;
    }

    /**
     * @return Status
     */
    public function getConn() {
        if ( !isset( $this->conn ) ) {
            $status = $this->manager->get( $this->key );
            if ( !$status->isOK() ) {
                return $status;
            }
            // @phan-suppress-next-line PhanTypeArraySuspiciousNullable
            $this->conn = $status->value['conn'];
            // @phan-suppress-next-line PhanTypeArraySuspiciousNullable
            $this->hostName = $status->value['hostName'];

            // Set the read timeout to be 1.5 times the pool timeout.
            // This allows the server to time out gracefully before we give up on it.
            stream_set_timeout( $this->conn, 0, (int)( $this->timeout * 1e6 * 1.5 ) );
        }
        // TODO: Convert from Status to StatusValue
        return Status::newGood( $this->conn );
    }

    /**
     * @param string|int|float ...$args
     * @return Status
     */
    public function sendCommand( ...$args ) {
        $args = str_replace( ' ', '%20', $args );
        $cmd = implode( ' ', $args );
        $status = $this->getConn();
        if ( !$status->isOK() ) {
            return $status;
        }
        $conn = $status->value;
        $this->logger->debug( "Sending pool counter command: $cmd" );
        if ( fwrite( $conn, "$cmd\n" ) === false ) {
            return Status::newFatal( 'poolcounter-write-error', $this->hostName );
        }
        $response = fgets( $conn );
        if ( $response === false ) {
            return Status::newFatal( 'poolcounter-read-error', $this->hostName );
        }
        $response = rtrim( $response, "\r\n" );
        $this->logger->debug( "Got pool counter response: $response" );
        $parts = explode( ' ', $response, 2 );
        $responseType = $parts[0];
        switch ( $responseType ) {
            case 'LOCKED':
                $this->onAcquire();
                break;
            case 'RELEASED':
                $this->onRelease();
                break;
            case 'DONE':
            case 'NOT_LOCKED':
            case 'QUEUE_FULL':
            case 'TIMEOUT':
            case 'LOCK_HELD':
                break;
            case 'ERROR':
            default:
                $parts = explode( ' ', $parts[1], 2 );
                $errorMsg = $parts[1] ?? '(no message given)';
                return Status::newFatal( 'poolcounter-remote-error', $errorMsg, $this->hostName );
        }
        return Status::newGood( constant( "PoolCounter::$responseType" ) );
    }

    /**
     * @param int|null $timeout
     * @return Status
     */
    public function acquireForMe( $timeout = null ) {
        $status = $this->precheckAcquire();
        if ( !$status->isGood() ) {
            return $status;
        }
        return $this->sendCommand( 'ACQ4ME', $this->key, $this->workers, $this->maxqueue,
            $timeout ?? $this->timeout );
    }

    /**
     * @param int|null $timeout
     * @return Status
     */
    public function acquireForAnyone( $timeout = null ) {
        $status = $this->precheckAcquire();
        if ( !$status->isGood() ) {
            return $status;
        }
        return $this->sendCommand( 'ACQ4ANY', $this->key, $this->workers, $this->maxqueue,
            $timeout ?? $this->timeout );
    }

    /**
     * @return Status
     */
    public function release() {
        $status = $this->sendCommand( 'RELEASE' );

        if ( $this->conn ) {
            $this->manager->close( $this->conn );
            $this->conn = null;
        }

        return $status;
    }
}