ReplicatedBagOStuff.php

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<?php
use Wikimedia\ObjectCache\BagOStuff;
use Wikimedia\ObjectFactory\ObjectFactory;
 
class ReplicatedBagOStuff extends BagOStuff {
    private $writeStore;
    private $readStore;
 
    private $consistencyWindow;
    private $lastKeyWrites = [];
 
    private const MAX_WRITE_DELAY = 5;
 
    public function __construct( $params ) {
        parent::__construct( $params );
 
        if ( !isset( $params['writeFactory'] ) ) {
            throw new InvalidArgumentException(
                __METHOD__ . ': the "writeFactory" parameter is required' );
        } elseif ( !isset( $params['readFactory'] ) ) {
            throw new InvalidArgumentException(
                __METHOD__ . ': the "readFactory" parameter is required' );
        }
 
        $this->consistencyWindow = $params['sessionConsistencyWindow'] ?? self::MAX_WRITE_DELAY;
        $this->writeStore = ( $params['writeFactory'] instanceof BagOStuff )
            ? $params['writeFactory']
            : ObjectFactory::getObjectFromSpec( $params['writeFactory'] );
        $this->readStore = ( $params['readFactory'] instanceof BagOStuff )
            ? $params['readFactory']
            : ObjectFactory::getObjectFromSpec( $params['readFactory'] );
        $this->attrMap = $this->mergeFlagMaps( [ $this->readStore, $this->writeStore ] );
    }
 
    public function get( $key, $flags = 0 ) {
        $store = (
            $this->hadRecentSessionWrite( [ $key ] ) ||
            $this->fieldHasFlags( $flags, self::READ_LATEST )
        )
            // Try to maintain session consistency and respect READ_LATEST
            ? $this->writeStore
            // Otherwise, just use the default "read" store
            : $this->readStore;
 
        return $store->proxyCall(
            __FUNCTION__,
            self::ARG0_KEY,
            self::RES_NONKEY,
            func_get_args(),
            $this
        );
    }
 
    public function set( $key, $value, $exptime = 0, $flags = 0 ) {
        $this->remarkRecentSessionWrite( [ $key ] );
 
        return $this->writeStore->proxyCall(
            __FUNCTION__,
            self::ARG0_KEY,
            self::RES_NONKEY,
            func_get_args(),
            $this
        );
    }
 
    public function delete( $key, $flags = 0 ) {
        $this->remarkRecentSessionWrite( [ $key ] );
 
        return $this->writeStore->proxyCall(
            __FUNCTION__,
            self::ARG0_KEY,
            self::RES_NONKEY,
            func_get_args(),
            $this
        );
    }
 
    public function add( $key, $value, $exptime = 0, $flags = 0 ) {
        $this->remarkRecentSessionWrite( [ $key ] );
 
        return $this->writeStore->proxyCall(
            __FUNCTION__,
            self::ARG0_KEY,
            self::RES_NONKEY,
            func_get_args(),
            $this
        );
    }
 
    public function merge( $key, callable $callback, $exptime = 0, $attempts = 10, $flags = 0 ) {
        $this->remarkRecentSessionWrite( [ $key ] );
 
        return $this->writeStore->proxyCall(
            __FUNCTION__,
            self::ARG0_KEY,
            self::RES_NONKEY,
            func_get_args(),
            $this
        );
    }
 
    public function changeTTL( $key, $exptime = 0, $flags = 0 ) {
        $this->remarkRecentSessionWrite( [ $key ] );
 
        return $this->writeStore->proxyCall(
            __FUNCTION__,
            self::ARG0_KEY,
            self::RES_NONKEY,
            func_get_args(),
            $this
        );
    }
 
    public function lock( $key, $timeout = 6, $exptime = 6, $rclass = '' ) {
        return $this->writeStore->proxyCall(
            __FUNCTION__,
            self::ARG0_KEY,
            self::RES_NONKEY,
            func_get_args(),
            $this
        );
    }
 
    public function unlock( $key ) {
        return $this->writeStore->proxyCall(
            __FUNCTION__,
            self::ARG0_KEY,
            self::RES_NONKEY,
            func_get_args(),
            $this
        );
    }
 
    public function deleteObjectsExpiringBefore(
        $timestamp,
        callable $progress = null,
        $limit = INF,
        string $tag = null
    ) {
        return $this->writeStore->proxyCall(
            __FUNCTION__,
            self::ARG0_NONKEY,
            self::RES_NONKEY,
            func_get_args(),
            $this
        );
    }
 
    public function getMulti( array $keys, $flags = 0 ) {
        $store = (
            $this->hadRecentSessionWrite( $keys ) ||
            $this->fieldHasFlags( $flags, self::READ_LATEST )
        )
            // Try to maintain session consistency and respect READ_LATEST
            ? $this->writeStore
            // Otherwise, just use the default "read" store
            : $this->readStore;
 
        return $store->proxyCall(
            __FUNCTION__,
            self::ARG0_KEYARR,
            self::RES_KEYMAP,
            func_get_args(),
            $this
        );
    }
 
    public function setMulti( array $valueByKey, $exptime = 0, $flags = 0 ) {
        $this->remarkRecentSessionWrite( array_keys( $valueByKey ) );
 
        return $this->writeStore->proxyCall(
            __FUNCTION__,
            self::ARG0_KEYMAP,
            self::RES_NONKEY,
            func_get_args(),
            $this
        );
    }
 
    public function deleteMulti( array $keys, $flags = 0 ) {
        $this->remarkRecentSessionWrite( $keys );
 
        return $this->writeStore->proxyCall(
            __FUNCTION__,
            self::ARG0_KEYARR,
            self::RES_NONKEY,
            func_get_args(),
            $this
        );
    }
 
    public function changeTTLMulti( array $keys, $exptime, $flags = 0 ) {
        $this->remarkRecentSessionWrite( $keys );
 
        return $this->writeStore->proxyCall(
            __FUNCTION__,
            self::ARG0_KEYARR,
            self::RES_NONKEY,
            func_get_args(),
            $this
        );
    }
 
    public function incrWithInit( $key, $exptime, $step = 1, $init = null, $flags = 0 ) {
        $this->remarkRecentSessionWrite( [ $key ] );
 
        return $this->writeStore->proxyCall(
            __FUNCTION__,
            self::ARG0_KEY,
            self::RES_NONKEY,
            func_get_args(),
            $this
        );
    }
 
    public function setMockTime( &$time ) {
        parent::setMockTime( $time );
        $this->writeStore->setMockTime( $time );
        $this->readStore->setMockTime( $time );
    }
 
    private function hadRecentSessionWrite( array $keys ) {
        $now = $this->getCurrentTime();
        foreach ( $keys as $key ) {
            $ts = $this->lastKeyWrites[$key] ?? 0;
            if ( $ts && ( $now - $ts ) <= $this->consistencyWindow ) {
                return true;
            }
        }
 
        return false;
    }
 
    private function remarkRecentSessionWrite( array $keys ) {
        $now = $this->getCurrentTime();
        foreach ( $keys as $key ) {
            // move to the end
            unset( $this->lastKeyWrites[$key] );
            $this->lastKeyWrites[$key] = $now;
        }
        // Prune out the map if the first key is obsolete
        if ( ( $now - reset( $this->lastKeyWrites ) ) > $this->consistencyWindow ) {
            $this->lastKeyWrites = array_filter(
                $this->lastKeyWrites,
                function ( $timestamp ) use ( $now ) {
                    return ( ( $now - $timestamp ) <= $this->consistencyWindow );
                }
            );
        }
    }
}