Merge "Revert "Use display name in category page subheadings if provided""

[lhc/web/wiklou.git] / includes / libs / objectcache / BagOStuff.php

diff --git a/includes/libs/objectcache/BagOStuff.php b/includes/libs/objectcache/BagOStuff.php
index 5472e83..d0b68bc 100644 (file)
--- 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()
         *