ExternalStore.php

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<?php
class ExternalStore {
        var $mParams;

        function __construct( $params = array() ) {
                $this->mParams = $params;
        }

        static function fetchFromURL( $url, $params = array() ) {
                global $wgExternalStores;

                if( !$wgExternalStores ) {
                        return false;
                }

                $parts = explode( '://', $url, 2 );

                if ( count( $parts ) != 2 ) {
                        return false;
                }

                list( $proto, $path ) = $parts;

                if ( $path == '' ) { // Bad URL
                        return false;
                }

                $store = self::getStoreObject( $proto, $params );
                if ( $store === false ) {
                        return false;
                }

                return $store->fetchFromURL( $url );
        }

        static function getStoreObject( $proto, $params = array() ) {
                global $wgExternalStores;
                if( !$wgExternalStores ) {
                        return false;
                }

                /* Protocol not enabled */
                if( !in_array( $proto, $wgExternalStores ) ) {
                        return false;
                }

                $class = 'ExternalStore' . ucfirst( $proto );
                /* Any custom modules should be added to $wgAutoLoadClasses for on-demand loading */
                if( !MWInit::classExists( $class ) ) {
                        return false;
                }

                return new $class($params);
        }

        static function insert( $url, $data, $params = array() ) {
                list( $proto, $params ) = explode( '://', $url, 2 );
                $store = self::getStoreObject( $proto, $params );
                if ( $store === false ) {
                        return false;
                } else {
                        return $store->store( $params, $data );
                }
        }

        public static function insertToDefault( $data, $storageParams = array() ) {
                global $wgDefaultExternalStore;
                $tryStores = (array)$wgDefaultExternalStore;
                $error = false;
                while ( count( $tryStores ) > 0 ) {
                        $index = mt_rand(0, count( $tryStores ) - 1);
                        $storeUrl = $tryStores[$index];
                        wfDebug( __METHOD__.": trying $storeUrl\n" );
                        list( $proto, $params ) = explode( '://', $storeUrl, 2 );
                        $store = self::getStoreObject( $proto, $storageParams );
                        if ( $store === false ) {
                                throw new MWException( "Invalid external storage protocol - $storeUrl" );
                        }
                        try {
                                $url = $store->store( $params, $data ); // Try to save the object
                        } catch ( DBConnectionError $error ) {
                                $url = false;
                        } catch( DBQueryError $error ) {
                                $url = false;
                        }
                        if ( $url ) {
                                return $url; // Done!
                        } else {
                                unset( $tryStores[$index] ); // Don't try this one again!
                                $tryStores = array_values( $tryStores ); // Must have consecutive keys
                                wfDebugLog( 'ExternalStorage', "Unable to store text to external storage $storeUrl" );
                        }
                }
                // All stores failed
                if ( $error ) {
                        // Rethrow the last connection error
                        throw $error;
                } else {
                        throw new MWException( "Unable to store text to external storage" );
                }
        }

        public static function insertToForeignDefault( $data, $wiki ) {
                return self::insertToDefault( $data, array( 'wiki' => $wiki ) );
        }
}