added ref min/max history control - refs #138

2 files changed, 48 insertions, 1 deletions

diff --git a/src/jvm/clojure/lang/LockingTransaction.java b/src/jvm/clojure/lang/LockingTransaction.java
index 66a262e7..4976d169 100644
--- a/src/jvm/clojure/lang/LockingTransaction.java
+++ b/src/jvm/clojure/lang/LockingTransaction.java
@@ -281,11 +281,14 @@ Object run(Callable fn) throws Exception{
 					Ref ref = e.getKey();
 					Object oldval = ref.tvals == null ? null : ref.tvals.val;
 					Object newval = e.getValue();
+					int hcount = ref.histCount();
+
 					if(ref.tvals == null)
 						{
 						ref.tvals = new Ref.TVal(newval, commitPoint, msecs);
 						}
-					else if(ref.faults.get() > 0)
+					else if((ref.faults.get() > 0 && hcount < ref.maxHistory)
+							|| hcount < ref.minHistory)
 						{
 						ref.tvals = new Ref.TVal(newval, commitPoint, msecs, ref.tvals);
 						ref.faults.set(0);
diff --git a/src/jvm/clojure/lang/Ref.java b/src/jvm/clojure/lang/Ref.java
index 90faedcc..fef7c439 100644
--- a/src/jvm/clojure/lang/Ref.java
+++ b/src/jvm/clojure/lang/Ref.java
@@ -26,6 +26,24 @@ public class Ref extends ARef implements IFn, Comparable<Ref>, IRef{
             return 1;
     }
 
+public int getMinHistory(){
+	return minHistory;
+}
+
+public Ref setMinHistory(int minHistory){
+	this.minHistory = minHistory;
+	return this;
+}
+
+public int getMaxHistory(){
+	return maxHistory;
+}
+
+public Ref setMaxHistory(int maxHistory){
+	this.maxHistory = maxHistory;
+	return this;
+}
+
 public static class TVal{
 	Object val;
 	long point;
@@ -60,6 +78,9 @@ LockingTransaction.Info tinfo;
 //IFn validator;
 final long id;
 
+volatile int minHistory = 0;
+volatile int maxHistory = 10;
+
 static final AtomicLong ids = new AtomicLong();
 
 public Ref(Object initVal) throws Exception{
@@ -187,6 +208,29 @@ public void trimHistory(){
 		}
 }
 
+public int getHistoryCount(){
+	try
+		{
+		lock.writeLock().lock();
+		return histCount();
+		}
+	finally
+		{
+		lock.writeLock().unlock();
+		}	
+}
+
+int histCount(){
+	if(tvals == null)
+		return 0;
+	else
+		{
+		int count = 0;
+		for(TVal tv = tvals.next;tv != tvals;tv = tv.next)
+			count++;
+		return count;
+		}
+}
 
 final public IFn fn(){
 	return (IFn) deref();