[ML] Fix thread safety issues in ManagedCursorContainer related to "h…

…eap" field access (apache#16049) (cherry picked from commit ec9676f)
dragonls · Aug 30, 2022 · 402fa2a · 402fa2a
1 parent 06114c5
commit 402fa2a
Showing 1 changed file with 12 additions and 2 deletions.
diff --git a/managed-ledger/src/main/java/org/apache/bookkeeper/mledger/impl/ManagedCursorContainer.java b/managed-ledger/src/main/java/org/apache/bookkeeper/mledger/impl/ManagedCursorContainer.java
@@ -105,11 +105,21 @@ private boolean shouldTrackInHeap(ManagedCursor cursor) {
     }
 
     public PositionImpl getSlowestReadPositionForActiveCursors() {
-        return heap.isEmpty() ? null : (PositionImpl) heap.get(0).cursor.getReadPosition();
+        long stamp = rwLock.readLock();
+        try {
+            return heap.isEmpty() ? null : (PositionImpl) heap.get(0).cursor.getReadPosition();
+        } finally {
+            rwLock.unlockRead(stamp);
+        }
     }
 
     public PositionImpl getSlowestMarkDeletedPositionForActiveCursors() {
-        return heap.isEmpty() ? null : (PositionImpl) heap.get(0).cursor.getMarkDeletedPosition();
+        long stamp = rwLock.readLock();
+        try {
+            return heap.isEmpty() ? null : (PositionImpl) heap.get(0).cursor.getMarkDeletedPosition();
+        } finally {
+            rwLock.unlockRead(stamp);
+        }
     }
 
     public ManagedCursor get(String name) {