includes/libs/objectcache/RESTBagOStuff.php

   1 <?php
   2
   3 /**
   4  * Interface to key-value storage behind an HTTP server.
   5  *
   6  * Uses URL of the form "baseURL/{KEY}" to store, fetch, and delete values.
   7  *
   8  * E.g., when base URL is `/v1/sessions/`, then the store would do:
   9  *
  10  * `PUT /v1/sessions/12345758`
  11  *
  12  * and fetch would do:
  13  *
  14  * `GET /v1/sessions/12345758`
  15  *
  16  * delete would do:
  17  *
  18  * `DELETE /v1/sessions/12345758`
  19  *
  20  * Configure with:
  21  *
  22  * @code
  23  * $wgObjectCaches['sessions'] = array(
  24  *      'class' => 'RESTBagOStuff',
  25  *      'url' => 'http://localhost:7231/wikimedia.org/v1/sessions/'
  26  * );
  27  * @endcode
  28  */
  29 class RESTBagOStuff extends BagOStuff {
  30
  31         /**
  32          * @var MultiHttpClient
  33          */
  34         private $client;
  35
  36         /**
  37          * REST URL to use for storage.
  38          * @var string
  39          */
  40         private $url;
  41
  42         public function __construct( $params ) {
  43                 if ( empty( $params['url'] ) ) {
  44                         throw new InvalidArgumentException( 'URL parameter is required' );
  45                 }
  46                 parent::__construct( $params );
  47                 if ( empty( $params['client'] ) ) {
  48                         $this->client = new MultiHttpClient( [] );
  49                 } else {
  50                         $this->client = $params['client'];
  51                 }
  52                 // Make sure URL ends with /
  53                 $this->url = rtrim( $params['url'], '/' ) . '/';
  54                 // Default config, R+W > N; no locks on reads though; writes go straight to state-machine
  55                 $this->attrMap[self::ATTR_SYNCWRITES] = self::QOS_SYNCWRITES_QC;
  56         }
  57
  58         /**
  59          * @param string  $key
  60          * @param integer $flags Bitfield of BagOStuff::READ_* constants [optional]
  61          * @return mixed Returns false on failure and if the item does not exist
  62          */
  63         protected function doGet( $key, $flags = 0 ) {
  64                 $req = [
  65                         'method' => 'GET',
  66                         'url' => $this->url . rawurlencode( $key ),
  67                 ];
  68
  69                 list( $rcode, $rdesc, $rhdrs, $rbody, $rerr ) = $this->client->run( $req );
  70                 if ( $rcode === 200 ) {
  71                         if ( is_string( $rbody ) ) {
  72                                 return unserialize( $rbody );
  73                         }
  74                         return false;
  75                 }
  76                 if ( $rcode === 0 || ( $rcode >= 400 && $rcode != 404 ) ) {
  77                         return $this->handleError( "Failed to fetch $key", $rcode, $rerr );
  78                 }
  79                 return false;
  80         }
  81
  82         /**
  83          * Handle storage error
  84          * @param string $msg Error message
  85          * @param int    $rcode Error code from client
  86          * @param string $rerr Error message from client
  87          * @return false
  88          */
  89         protected function handleError( $msg, $rcode, $rerr ) {
  90                 $this->logger->error( "$msg : ({code}) {error}", [
  91                         'code' => $rcode,
  92                         'error' => $rerr
  93                 ] );
  94                 $this->setLastError( $rcode === 0 ? self::ERR_UNREACHABLE : self::ERR_UNEXPECTED );
  95                 return false;
  96         }
  97
  98         /**
  99          * Set an item
 100          *
 101          * @param string $key
 102          * @param mixed  $value
 103          * @param int    $exptime Either an interval in seconds or a unix timestamp for expiry
 104          * @param int    $flags Bitfield of BagOStuff::WRITE_* constants
 105          * @return bool Success
 106          */
 107         public function set( $key, $value, $exptime = 0, $flags = 0 ) {
 108                 $req = [
 109                         'method' => 'PUT',
 110                         'url' => $this->url . rawurlencode( $key ),
 111                         'body' => serialize( $value )
 112                 ];
 113                 list( $rcode, $rdesc, $rhdrs, $rbody, $rerr ) = $this->client->run( $req );
 114                 if ( $rcode === 200 || $rcode === 201 ) {
 115                         return true;
 116                 }
 117                 return $this->handleError( "Failed to store $key", $rcode, $rerr );
 118         }
 119
 120         /**
 121          * Delete an item.
 122          *
 123          * @param string $key
 124          * @return bool True if the item was deleted or not found, false on failure
 125          */
 126         public function delete( $key ) {
 127                 $req = [
 128                         'method' => 'DELETE',
 129                         'url' => $this->url . rawurlencode( $key ),
 130                 ];
 131                 list( $rcode, $rdesc, $rhdrs, $rbody, $rerr ) = $this->client->run( $req );
 132                 if ( $rcode === 200 || $rcode === 204 || $rcode === 205 ) {
 133                         return true;
 134                 }
 135                 return $this->handleError( "Failed to delete $key", $rcode, $rerr );
 136         }
 137 }