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RemoteSchema.php
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RemoteSchema.php
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<?php
namespace MediaWiki\Extension\EventLogging;
use JsonSerializable;
use MediaWiki\Http\HttpRequestFactory;
use MediaWiki\Json\FormatJson;
use MediaWiki\MediaWikiServices;
use stdClass;
use Wikimedia\ObjectCache\BagOStuff;
/**
* Represents a schema revision on a remote wiki.
* Handles retrieval (via HTTP) and local caching.
*/
class RemoteSchema implements JsonSerializable {
public const LOCK_TIMEOUT = 20;
/** @var string */
public $title;
/** @var int */
public $revision;
/** @var BagOStuff */
public $cache;
/** @var HttpRequestFactory */
public $httpRequestFactory;
/** @var string */
public $key;
/** @var array|false */
public $content = false;
/**
* Constructor.
* @param string $title
* @param int $revision
* @param BagOStuff|null $cache (optional) cache client.
* @param HttpRequestFactory|null $httpRequestFactory (optional) HttpRequestFactory client.
*/
public function __construct( $title, $revision, $cache = null, $httpRequestFactory = null ) {
global $wgEventLoggingSchemaApiUri;
$this->title = $title;
$this->revision = $revision;
$this->cache = $cache ?: MediaWikiServices::getInstance()
->getObjectCacheFactory()->getInstance( CACHE_ANYTHING );
$this->httpRequestFactory = $httpRequestFactory ?: MediaWikiServices::getInstance()->getHttpRequestFactory();
$this->key = $this->cache->makeGlobalKey(
'eventlogging-schema',
$wgEventLoggingSchemaApiUri,
$revision
);
}
/**
* Retrieves schema content.
* @return array|bool Schema or false if irretrievable.
*/
public function get() {
if ( $this->content ) {
return $this->content;
}
$this->content = $this->memcGet();
if ( $this->content ) {
return $this->content;
}
$this->content = $this->httpGet();
if ( $this->content ) {
$this->memcSet();
}
return $this->content;
}
/**
* Returns an object containing serializable properties.
* @return array
*/
public function jsonSerialize(): array {
return [
'schema' => $this->get() ?: new stdClass(),
'revision' => $this->revision
];
}
/**
* Retrieves content from memcached.
* @return array|bool Schema or false if not in cache.
*/
protected function memcGet() {
return $this->cache->get( $this->key );
}
/**
* Store content in memcached.
* @return bool
*/
protected function memcSet() {
return $this->cache->set( $this->key, $this->content );
}
/**
* Retrieves the schema using HTTP.
* Uses a memcached lock to avoid cache stampedes.
* @return array|bool Schema or false if unable to fetch.
*/
protected function httpGet() {
$uri = $this->getUri();
if ( !$this->lock() ) {
EventLogging::getLogger()->warning(
'Failed to get lock for requesting {schema_uri}.',
[ 'schema_uri' => $uri ]
);
return false;
}
$raw = $this->httpRequestFactory->get( $uri, [
'timeout' => self::LOCK_TIMEOUT * 0.8
], __METHOD__ );
$content = FormatJson::decode( $raw, true );
if ( !$content ) {
EventLogging::getLogger()->error(
'Request to {schema_uri} failed.',
[ 'schema_uri' => $uri ]
);
}
return $content ?: false;
}
/**
* Acquire a mutex lock for HTTP retrieval.
* @return bool Whether lock was successfully acquired.
*/
protected function lock() {
return $this->cache->add( $this->key . ':lock', 1, self::LOCK_TIMEOUT );
}
/**
* Constructs URI for retrieving schema from remote wiki.
* @return string URI.
*/
protected function getUri() {
global $wgEventLoggingSchemaApiUri;
return wfAppendQuery( $wgEventLoggingSchemaApiUri, [
'action' => 'jsonschema',
'revid' => $this->revision,
'formatversion' => 2,
'format' => 'json',
] );
}
}

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Mime Type
text/x-php
Expires
Sat, Oct 3, 10:21 (1 w, 1 d ago)
Storage Engine
local-disk
Storage Format
Raw Data
Storage Handle
c8/af/a995360c7d525df98e5cf73547cd
Default Alt Text
RemoteSchema.php (3 KB)

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