Pool ObjectID objects so only one instance for any given ID is created

Previously, every EMO had its own unique instance of ObjectID. Since
ObjectID is effectively an immutable value class, one instance of a
given ID can be safely shared in all places, so it now uses factory
methods and a map to do so.

Author: rbuch

src/projections/Tools/Timeline/EntryMethodObject.java

@@ -140,9 +140,9 @@ protected EntryMethodObject(Data data,  TimelineEvent tle,
 		EventID = tle.EventID;
 		msglen = tle.MsgLen;
 		if (tle.id != null) {
-			tid = new ObjectId(tle.id);
+			tid = ObjectId.createObjectId(tle.id);
 		} else {
-			tid = new ObjectId();
+			tid = ObjectId.createObjectId();
 		}
 
 		if (tle.UserSpecifiedData != null || tle.memoryUsage > 0 ||

src/projections/analysis/ObjectId.java

@@ -1,43 +1,60 @@
 package projections.analysis;
 
-public class ObjectId implements Comparable
+import java.util.Arrays;
+import java.util.concurrent.ConcurrentHashMap;
+
+public final class ObjectId implements Comparable
 {
     private final static int ID_SIZE = 6;
-    public int id[];
+    public final int id[];
 
-    public ObjectId() {
-        id = new int[ID_SIZE];
-        id[0] = id[1] = id[2] = id[3] = id[4] = id[5] = -1;
-    }
-    public ObjectId(ObjectId d) {
-        if (d!=null) id = d.id.clone();
-        else {
-            id = new int[ID_SIZE];
-            id[0] = id[1] = id[2] = id[3] = id[4] = id[5] = -1;
-        }
-    }
+    private static ConcurrentHashMap<ObjectId, ObjectId> instances = new ConcurrentHashMap<>();
 
-    protected ObjectId(int[] data) {
+    private ObjectId(final int[] data) {
         if (data.length > ID_SIZE)
             throw new IndexOutOfBoundsException("Attempted to assign " + data.length + "elements to ID of size " + ID_SIZE);
         id = new int[ID_SIZE];
-        for (int i = 0; i < data.length; i++) {
+        for (int i = 0; i < ID_SIZE; i++) {
             id[i] = data[i];
         }
     }
 
+    public static ObjectId createObjectId() {
+        final int[] dummy = new int[ID_SIZE];
+        dummy[0] = dummy[1] = dummy[2] = dummy[3] = dummy[4] = dummy[5] = -1;
+        return createObjectId(dummy);
+    }
+
+    public static ObjectId createObjectId(ObjectId d) {
+        if (d == null)
+            return createObjectId();
+        else return d;
+    }
+
+    protected static ObjectId createObjectId(final int[] data) {
+        ObjectId candidate = new ObjectId(data);
+        ObjectId canonical = instances.putIfAbsent(candidate, candidate);
+        if (canonical == null)
+            canonical = candidate;
+        return canonical;
+    }
+
     public boolean equals(ObjectId comp) {
-        System.out.println("EQUALS");
-        return (id[0] == comp.id[0]) && (id[1] == comp.id[1]) && (id[2] == comp.id[2]) &&
-               (id[3] == comp.id[3]) && (id[4] == comp.id[4]) && (id[5] == comp.id[5]);
+        return Arrays.equals(id, comp.id);
     }
 
     public boolean equals(Object o) {
         ObjectId comp = (ObjectId) o;
         return this.equals(comp);
     }
 
+    @Override
+    public int hashCode() {
+        return Arrays.hashCode(id);
+    }
+
     /** Needed for putting these as keys in a TreeSet */
+    @Override
     @SuppressWarnings("ucd")
     public int compareTo(Object o) {
         ObjectId oid = (ObjectId)o;

src/projections/analysis/TimelineEvent.java

@@ -66,7 +66,7 @@ protected TimelineEvent(long bt,long et, int ep,int pe, int mlen, long r,
 	EntryPoint=ep; SrcPe=pe; MsgLen=mlen;
         RecvTime = r;
 
-	id = new ObjectId(d);
+	id = ObjectId.createObjectId(d);
 	EventID = eventid;
 	this.numPapiCounts = numPapiCounts;
 	this.papiCounts = papiCounts;
@@ -85,7 +85,7 @@ protected TimelineEvent(long bt,long et, int ep,int pe, int mlen, long r,
 		EntryPoint=ep; SrcPe=pe; MsgLen=mlen;
 		RecvTime = r;
 
-		id = new ObjectId(d);
+		id = ObjectId.createObjectId(d);
 		EventID = eventid;
 		this.numPapiCounts = numPapiCounts;
 		this.papiCounts = papiCounts;