X-Git-Url: https://git.heureux-cyclage.org/?a=blobdiff_plain;f=includes%2Flibs%2Fobjectcache%2FBagOStuff.php;h=d0b68bcbd7b26a84ce9115e5479bf4444861f804;hb=61898ad28ed69c5b391eb43e0db9386279b9612c;hp=5472e837d4c0c67fffba10e943d7c53fce69260d;hpb=2e7f4e48735b0e916336d9166cb1ab1756e0fa9f;p=lhc%2Fweb%2Fwiklou.git

diff --git a/includes/libs/objectcache/BagOStuff.php b/includes/libs/objectcache/BagOStuff.php
index 5472e837d4..d0b68bcbd7 100644
--- a/includes/libs/objectcache/BagOStuff.php
+++ b/includes/libs/objectcache/BagOStuff.php
@@ -29,6 +29,8 @@
 use Psr\Log\LoggerAwareInterface;
 use Psr\Log\LoggerInterface;
 use Psr\Log\NullLogger;
+use Wikimedia\ScopedCallback;
+use Wikimedia\WaitConditionLoop;
 
 /**
  * interface is intended to be more or less compatible with
@@ -45,31 +47,29 @@ use Psr\Log\NullLogger;
 abstract class BagOStuff implements IExpiringStore, LoggerAwareInterface {
 	/** @var array[] Lock tracking */
 	protected $locks = [];
-
 	/** @var integer ERR_* class constant */
 	protected $lastError = self::ERR_NONE;
-
 	/** @var string */
 	protected $keyspace = 'local';
-
 	/** @var LoggerInterface */
 	protected $logger;
-
 	/** @var callback|null */
 	protected $asyncHandler;
+	/** @var integer Seconds */
+	protected $syncTimeout;
 
 	/** @var bool */
 	private $debugMode = false;
-
 	/** @var array */
 	private $duplicateKeyLookups = [];
-
 	/** @var bool */
 	private $reportDupes = false;
-
 	/** @var bool */
 	private $dupeTrackScheduled = false;
 
+	/** @var callable[] */
+	protected $busyCallbacks = [];
+
 	/** @var integer[] Map of (ATTR_* class constant => QOS_* class constant) */
 	protected $attrMap = [];
 
@@ -94,6 +94,7 @@ abstract class BagOStuff implements IExpiringStore, LoggerAwareInterface {
 	 *      In CLI mode, it should run the task immediately.
 	 *   - reportDupes: Whether to emit warning log messages for all keys that were
 	 *      requested more than once (requires an asyncHandler).
+	 *   - syncTimeout: How long to wait with WRITE_SYNC in seconds.
 	 * @param array $params
 	 */
 	public function __construct( array $params = [] ) {
@@ -114,6 +115,8 @@ abstract class BagOStuff implements IExpiringStore, LoggerAwareInterface {
 		if ( !empty( $params['reportDupes'] ) && is_callable( $this->asyncHandler ) ) {
 			$this->reportDupes = true;
 		}
+
+		$this->syncTimeout = isset( $params['syncTimeout'] ) ? $params['syncTimeout'] : 3;
 	}
 
 	/**
@@ -409,35 +412,21 @@ abstract class BagOStuff implements IExpiringStore, LoggerAwareInterface {
 		}
 
 		$expiry = min( $expiry ?: INF, self::TTL_DAY );
-
-		$this->clearLastError();
-		$timestamp = microtime( true ); // starting UNIX timestamp
-		if ( $this->add( "{$key}:lock", 1, $expiry ) ) {
-			$locked = true;
-		} elseif ( $this->getLastError() || $timeout <= 0 ) {
-			$locked = false; // network partition or non-blocking
-		} else {
-			// Estimate the RTT (us); use 1ms minimum for sanity
-			$uRTT = max( 1e3, ceil( 1e6 * ( microtime( true ) - $timestamp ) ) );
-			$sleep = 2 * $uRTT; // rough time to do get()+set()
-
-			$attempts = 0; // failed attempts
-			do {
-				if ( ++$attempts >= 3 && $sleep <= 5e5 ) {
-					// Exponentially back off after failed attempts to avoid network spam.
-					// About 2*$uRTT*(2^n-1) us of "sleep" happen for the next n attempts.
-					$sleep *= 2;
-				}
-				usleep( $sleep ); // back off
+		$loop = new WaitConditionLoop(
+			function () use ( $key, $timeout, $expiry ) {
 				$this->clearLastError();
-				$locked = $this->add( "{$key}:lock", 1, $expiry );
-				if ( $this->getLastError() ) {
-					$locked = false; // network partition
-					break;
+				if ( $this->add( "{$key}:lock", 1, $expiry ) ) {
+					return true; // locked!
+				} elseif ( $this->getLastError() ) {
+					return WaitConditionLoop::CONDITION_ABORTED; // network partition?
 				}
-			} while ( !$locked && ( microtime( true ) - $timestamp ) < $timeout );
-		}
 
+				return WaitConditionLoop::CONDITION_CONTINUE;
+			},
+			$timeout
+		);
+
+		$locked = ( $loop->invoke() === $loop::CONDITION_REACHED );
 		if ( $locked ) {
 			$this->locks[$key] = [ 'class' => $rclass, 'depth' => 1 ];
 		}
@@ -642,6 +631,30 @@ abstract class BagOStuff implements IExpiringStore, LoggerAwareInterface {
 		$this->lastError = $err;
 	}
 
+	/**
+	 * Let a callback be run to avoid wasting time on special blocking calls
+	 *
+	 * The callbacks may or may not be called ever, in any particular order.
+	 * They are likely to be invoked when something WRITE_SYNC is used used.
+	 * They should follow a caching pattern as shown below, so that any code
+	 * using the word will get it's result no matter what happens.
+	 * @code
+	 *     $result = null;
+	 *     $workCallback = function () use ( &$result ) {
+	 *         if ( !$result ) {
+	 *             $result = ....
+	 *         }
+	 *         return $result;
+	 *     }
+	 * @endcode
+	 *
+	 * @param callable $workCallback
+	 * @since 1.28
+	 */
+	public function addBusyCallback( callable $workCallback ) {
+		$this->busyCallbacks[] = $workCallback;
+	}
+
 	/**
 	 * Modify a cache update operation array for EventRelayer::notify()
 	 *