using a ConcurrentHashMap with the new IdentityWrapper to avoid excessive synchronization on markPassingLocks; see bug 3380

java/com.sap.sailing.domain/src/com/sap/sailing/domain/tracking/impl/TrackedRaceImpl.java

@@ -13,7 +13,6 @@ import java.util.ConcurrentModificationException;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.IdentityHashMap;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
 import java.util.LinkedList;
@@ -154,6 +153,7 @@ import com.sap.sse.common.Util.Pair;
 import com.sap.sse.common.impl.MillisecondsTimePoint;
 import com.sap.sse.concurrent.LockUtil;
 import com.sap.sse.concurrent.NamedReentrantReadWriteLock;
+import com.sap.sse.util.IdentityWrapper;
 import com.sap.sse.util.SmartFutureCache;
 import com.sap.sse.util.SmartFutureCache.AbstractCacheUpdater;
 import com.sap.sse.util.SmartFutureCache.EmptyUpdateInterval;
@@ -354,7 +354,7 @@ public abstract class TrackedRaceImpl extends TrackedRaceWithWindEssentials impl
      */
     private final NamedReentrantReadWriteLock loadingFromGPSFixStoreLock;
 
-    private final Map<Iterable<MarkPassing>, NamedReentrantReadWriteLock> locksForMarkPassings;
+    private final ConcurrentHashMap<IdentityWrapper<Iterable<MarkPassing>>, NamedReentrantReadWriteLock> locksForMarkPassings;
     
     /**
      * Caches wind requests for a few seconds to accelerate access in live mode
@@ -412,7 +412,7 @@ public abstract class TrackedRaceImpl extends TrackedRaceWithWindEssentials impl
         rankingMetric = rankingMetricConstructor.apply(this);
         raceStates = new WeakHashMap<>();
         shortTimeWindCache = new ShortTimeWindCache(this, millisecondsOverWhichToAverageWind / 2);
-        locksForMarkPassings = new IdentityHashMap<>();
+        locksForMarkPassings = new ConcurrentHashMap<IdentityWrapper<Iterable<MarkPassing>>, NamedReentrantReadWriteLock>();
         attachedRaceLogs = new ConcurrentHashMap<>();
         attachedRegattaLogs = new ConcurrentHashMap<>();
         attachedRaceExecutionOrderProviders = new ConcurrentHashMap<>();
@@ -2058,15 +2058,19 @@ public abstract class TrackedRaceImpl extends TrackedRaceWithWindEssentials impl
     }
 
     protected NamedReentrantReadWriteLock getMarkPassingsLock(Iterable<MarkPassing> markPassings) {
-        synchronized (locksForMarkPassings) {
-            NamedReentrantReadWriteLock lock = locksForMarkPassings.get(markPassings);
-            if (lock == null) {
-                lock = new NamedReentrantReadWriteLock("mark passings lock for tracked race " + getRace().getName(), /* fair */
-                        false);
-                locksForMarkPassings.put(markPassings, lock);
+        final IdentityWrapper<Iterable<MarkPassing>> markPassingsIdentity = new IdentityWrapper<>(markPassings);
+        NamedReentrantReadWriteLock lock = locksForMarkPassings.get(markPassingsIdentity);
+        if (lock == null) {
+            synchronized (locksForMarkPassings) {
+                lock = locksForMarkPassings.get(markPassingsIdentity);
+                if (lock == null) {
+                    lock = new NamedReentrantReadWriteLock(
+                            "mark passings lock for tracked race " + getRace().getName(), /* fair */false);
+                    locksForMarkPassings.put(markPassingsIdentity, lock);
+                }
             }
-            return lock;
         }
+        return lock;
     }
 
     private void updateStartToNextMarkCacheInvalidationCacheListenersAfterWaypointRemoved(int zeroBasedIndex,

java/com.sap.sse/src/com/sap/sse/util/IdentityWrapper.java

@@ -0,0 +1,31 @@
+package com.sap.sse.util;
+
+/**
+ * Implements {@link Object#equals(Object)} and {@link Object#hashCode()} based on the wrapped object's
+ * identity, no matter what the object itself defines as {@code equals} and {@code hashCode}.
+ * 
+ * @author Axel Uhl (D043530)
+ *
+ */
+public class IdentityWrapper<T> {
+    private final T t;
+    
+    public IdentityWrapper(T t) {
+        this.t = t;
+    }
+
+    @Override
+    public int hashCode() {
+        return System.identityHashCode(t);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        return (obj instanceof IdentityWrapper<?>) ? ((IdentityWrapper<?>) obj).t == this.t : obj == t;
+    }
+
+    @Override
+    public String toString() {
+        return "IdentityWrapper for "+t;
+    }
+}