Ensure ActionFRequency does reset if time ran backwards.

NCPCommons/src/main/java/fr/neatmonster/nocheatplus/utilities/ActionFrequency.java

@@ -10,6 +10,7 @@ public class ActionFrequency {
 
     /** Reference time for filling in. */
     private long time = 0;
+    private long lastUpdate = 0;
 
     /**
      * Buckets to fill weights in, each represents an interval of durBucket duration, 
@@ -21,7 +22,7 @@ public class ActionFrequency {
     /** Duration in milliseconds that oe bucket covers. */
     private final long durBucket;
 
- 	public ActionFrequency(final int nBuckets, final long durBucket){
+    public ActionFrequency(final int nBuckets, final long durBucket) {
         this.buckets = new float[nBuckets];
         this.durBucket = durBucket;
     }
@@ -31,7 +32,7 @@ public class ActionFrequency {
      * @param now
      * @param amount
      */
-	public final void add(final long now, final float amount){
+    public final void add(final long now, final float amount) {
         update(now);
         buckets[0] += amount;
     }
@@ -40,42 +41,43 @@ public class ActionFrequency {
      * Unchecked addition of amount to the first bucket.
      * @param amount
      */
-	public final void add(final float amount){
+    public final void add(final float amount) {
         buckets[0] += amount;
     }
 
     /**
-	 * Update without adding, also updates time.
+     * Update without adding, also updates time. Detects time running backwards.
      * @param now
      */
     public final void update(final long now) {
         final long diff = now - time;
-		if (diff < durBucket){
-			// No update (first bucket).
-			return; 
-		}
-		else if (diff >= durBucket * buckets.length || diff < 0){
+        if (now < lastUpdate || diff >= durBucket * buckets.length) {
             // Clear (beyond range).
             clear(now);
             return;
         }
+        else if (diff < durBucket) {
+            // No update (first bucket).
+            return; 
+        }
         final int shift = (int) ((float) diff / (float) durBucket);
         // Update buckets.
-		for (int i = 0; i < buckets.length - shift; i++){
+        for (int i = 0; i < buckets.length - shift; i++) {
             buckets[buckets.length - (i + 1)] = buckets[buckets.length - (i + 1 + shift)];
         }
-		for (int i = 0; i < shift; i++){
+        for (int i = 0; i < shift; i++) {
             buckets[i] = 0;
         }
         // Set time according to bucket duration (!).
         time += durBucket * shift;
+        lastUpdate = now;
     }
 
     public final void clear(final long now) {
-		for (int i = 0; i < buckets.length; i++){
+        for (int i = 0; i < buckets.length; i++) {
             buckets[i] = 0f;
         }
-		time = now;
+        time = lastUpdate = now;
     }
 
     /**
@@ -83,7 +85,7 @@ public class ActionFrequency {
      * @param factor
      * @return
      */
-	public final float getScore(final float factor){
+    public final float getScore(final float factor) {
         return score(factor);
     }
 
@@ -92,7 +94,7 @@ public class ActionFrequency {
      * @param factor
      * @return
      */
-	public final float getScore(final int bucket){
+    public final float getScore(final int bucket) {
         return bucketScore(bucket);
     }
 
@@ -101,7 +103,7 @@ public class ActionFrequency {
      * @param factor
      * @return
      */
-	public final float score(final float factor){
+    public final float score(final float factor) {
         return sliceScore(0, buckets.length, factor);
     }
 
@@ -110,7 +112,7 @@ public class ActionFrequency {
      * @param bucket
      * @return
      */
-	public final float bucketScore(final int bucket){
+    public final float bucketScore(final int bucket) {
         return buckets[bucket];
     }
 
@@ -120,7 +122,7 @@ public class ActionFrequency {
      * @param factor
      * @return
      */
-	public final float leadingScore(final int end, float factor){
+    public final float leadingScore(final int end, float factor) {
         return sliceScore(0, end, factor);
     }
 
@@ -130,7 +132,7 @@ public class ActionFrequency {
      * @param factor
      * @return
      */
-	public final float trailingScore(final int start, float factor){
+    public final float trailingScore(final int start, float factor) {
         return sliceScore(start, buckets.length, factor);
     }
 
@@ -141,10 +143,10 @@ public class ActionFrequency {
      * @param factor
      * @return
      */
-	public final float sliceScore(final int start, final int end, float factor){
+    public final float sliceScore(final int start, final int end, float factor) {
         float score = buckets[start];
         float cf = factor;
-		for (int i = start + 1; i < end; i++){
+        for (int i = start + 1; i < end; i++) {
             score += buckets[i] * cf;
             cf *= factor;
         }
@@ -156,7 +158,7 @@ public class ActionFrequency {
      * @param n
      * @param value
      */
-	public final void setBucket(final int n, final float value){
+    public final void setBucket(final int n, final float value) {
         buckets[n] = value;
     }
 
@@ -164,23 +166,32 @@ public class ActionFrequency {
      * Set the reference time.
      * @param time
      */
-	public final void setTime(final long time){
+    public final void setTime(final long time) {
         this.time = time;
+        this.lastUpdate = time;
     }
 
     /**
      * Get reference time.
      * @return
      */
-	public final long lastAccess(){
+    public final long lastAccess() { // TODO: Should rename this.
         return time;
     }
     
+    /**
+     * 
+     * @return
+     */
+    public final long lastUpdate() {
+        return lastUpdate;
+    }
+
     /**
      * Get the number of buckets.
      * @return
      */
-	public final int numberOfBuckets(){
+    public final int numberOfBuckets() {
         return buckets.length;
     }
 
@@ -188,7 +199,7 @@ public class ActionFrequency {
      * Get the duration of a bucket in milliseconds.
      * @return
      */
-	public final long bucketDuration(){
+    public final long bucketDuration() {
         return durBucket;
     }
 
@@ -196,10 +207,11 @@ public class ActionFrequency {
      * Serialize to a String line.
      * @return
      */
-	public final String toLine(){
+    public final String toLine() {
+        // TODO: Backwards-compatible lastUpdate ?
         final StringBuilder buffer = new StringBuilder(50);
         buffer.append(buckets.length + ","+durBucket+","+time);
-		for (int i = 0; i < buckets.length; i++){
+        for (int i = 0; i < buckets.length; i++) {
             buffer.append("," + buckets[i]);
         }
         return buffer.toString();
@@ -210,7 +222,8 @@ public class ActionFrequency {
      * @param line
      * @return
      */
-	public static ActionFrequency fromLine(final String line){
+    public static ActionFrequency fromLine(final String line) {
+        // TODO: Backwards-compatible lastUpdate ?
         String[] split = line.split(",");
         if (split.length < 3) throw new RuntimeException("Bad argument length."); // TODO
         final int n = Integer.parseInt(split[0]);
@@ -218,12 +231,12 @@ public class ActionFrequency {
         final long time = Long.parseLong(split[2]);
         final float[] buckets = new float[split.length -3];
         if (split.length - 3 != buckets.length) throw new RuntimeException("Bad argument length."); // TODO
-		for (int i = 3; i < split.length; i ++){
+        for (int i = 3; i < split.length; i ++) {
             buckets[i - 3] = Float.parseFloat(split[i]);
         }
         ActionFrequency freq = new ActionFrequency(n, durBucket);
         freq.setTime(time);
-		for (int i = 0; i < buckets.length; i ++){
+        for (int i = 0; i < buckets.length; i ++) {
             freq.setBucket(i, buckets[i]);
         }
         return freq;