AMQ-7055 - Optimization on SequenceSet to prevent iterating through the whole set when a value bigger than the last value is added

Signed-off-by: gtully <gary.tully@gmail.com>
(cherry picked from commit 8f88dcda09)

activemq-kahadb-store/src/main/java/org/apache/activemq/store/kahadb/disk/util/Sequence.java

@@ -38,6 +38,10 @@ public class Sequence extends LinkedNode<Sequence> {
         return last + 1 == value;
     }
 
+    public boolean isBiggerButNotAdjacentToLast(long value) {
+        return last + 1 < value;
+    }
+
     public boolean isAdjacentToFirst(long value) {
         return first - 1 == value;
     }

activemq-kahadb-store/src/main/java/org/apache/activemq/store/kahadb/disk/util/SequenceSet.java

@@ -114,6 +114,13 @@ public class SequenceSet extends LinkedNodeList<Sequence> implements Iterable<Lo
             return true;
         }
 
+        // check if the value is greater than the bigger sequence value and if it's not adjacent to it
+        // in this case, we are sure that the value should be add to the tail of the sequence.
+        if (sequence.isBiggerButNotAdjacentToLast(value)) {
+            addLast(new Sequence(value));
+            return true;
+        }
+
         sequence = getHead();
         while (sequence != null) {
 

activemq-kahadb-store/src/test/java/org/apache/activemq/store/kahadb/disk/util/SequenceSetTest.java

@@ -85,6 +85,37 @@ public class SequenceSetTest {
         assertFalse(set.contains(11));
     }
 
+    @Test
+    public void testAddValuesToTail() {
+        SequenceSet set = new SequenceSet();
+        set.add(new Sequence(0, 10));
+        set.add(new Sequence(21, 42));
+        set.add(new Sequence(142, 512));
+
+        set.add(513);
+
+        for (int i = 600; i < 650; i++) {
+            set.add(i);
+        }
+
+        for (int i = 0; i < 10; i++) {
+            set.add(i * 100);
+        }
+
+        assertTrue(set.contains(0));
+        assertTrue(set.contains(25));
+
+        assertTrue(set.contains(513));
+        assertTrue(!set.contains(514));
+        assertFalse(set.contains(599));
+        assertTrue(set.contains(625));
+        assertFalse(set.contains(651));
+
+        for (int i = 0; i < 10; i++) {
+            assertTrue(set.contains(i * 100));
+        }
+    }
+
     @Test
     public void testRemove() {
         SequenceSet set = new SequenceSet();