YARN-4525. Fix bug in RLESparseResourceAllocation.getRangeOverlapping(). (Ishai Menache and Carlo Curino via asuresh)

(cherry picked from commit 3a154f75ed85d864b3ffd35818992418f2b6aa59)

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/reservation/RLESparseResourceAllocation.java

@@ -510,7 +510,11 @@ public class RLESparseResourceAllocation {
           long previous = a.floorKey(start);
           a = a.tailMap(previous, true);
         }
-        a = a.headMap(end, true);
+
+        if (end < a.lastKey()) {
+          a = a.headMap(end, true);
+        }
+
       }
       RLESparseResourceAllocation ret =
           new RLESparseResourceAllocation(a, resourceCalculator);

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/reservation/TestRLESparseResourceAllocation.java

@@ -282,6 +282,28 @@ public class TestRLESparseResourceAllocation {
 
   }
 
+  @Test
+  public void testRangeOverlapping() {
+    ResourceCalculator resCalc = new DefaultResourceCalculator();
+
+    RLESparseResourceAllocation r =
+        new RLESparseResourceAllocation(resCalc);
+    int[] alloc = {10, 10, 10, 10, 10, 10};
+    int start = 100;
+    Set<Entry<ReservationInterval, Resource>> inputs =
+        generateAllocation(start, alloc, false).entrySet();
+    for (Entry<ReservationInterval, Resource> ip : inputs) {
+      r.addInterval(ip.getKey(), ip.getValue());
+    }
+    long s = r.getEarliestStartTime();
+    long d = r.getLatestNonNullTime();
+
+    // tries to trigger "out-of-range" bug
+    r =  r.getRangeOverlapping(s, d);
+    r = r.getRangeOverlapping(s-1, d-1);
+    r = r.getRangeOverlapping(s+1, d+1);
+  }
+
   @Test
   public void testBlocks() {
     ResourceCalculator resCalc = new DefaultResourceCalculator();