[fix][broker]Wrong backlog: expected 0 but got 1 (#24938)

(cherry picked from commit ed31d82)

Author: poorbarcode

managed-ledger/src/main/java/org/apache/bookkeeper/mledger/impl/ManagedCursorImpl.java

@@ -1489,12 +1489,16 @@ public void operationComplete() {
                 // modify mark delete and read position since we are able to persist new position for cursor
                 lock.writeLock().lock();
                 try {
-                    if (markDeletePosition.compareTo(newMarkDeletePosition) >= 0) {
+                    // Correct the variable "messagesConsumedCounter".
+                    // BTW, no need to change "messagesConsumedCounter" if new "markDeletePosition" is the same as the
+                    // old one.
+                    int compareRes = ledger.comparePositions(markDeletePosition, newMarkDeletePosition);
+                    if (compareRes > 0) {
                         MSG_CONSUMED_COUNTER_UPDATER.addAndGet(cursorImpl(), -getNumberOfEntries(
-                                Range.closedOpen(newMarkDeletePosition, markDeletePosition)));
-                    } else {
+                                Range.openClosed(newMarkDeletePosition, markDeletePosition)));
+                    } else if (compareRes < 0) {
                         MSG_CONSUMED_COUNTER_UPDATER.addAndGet(cursorImpl(), getNumberOfEntries(
-                                Range.closedOpen(markDeletePosition, newMarkDeletePosition)));
+                                Range.openClosed(markDeletePosition, newMarkDeletePosition)));
                     }
                     markDeletePosition = newMarkDeletePosition;
                     lastMarkDeleteEntry = new MarkDeleteEntry(newMarkDeletePosition, isCompactionCursor()

managed-ledger/src/main/java/org/apache/bookkeeper/mledger/impl/ManagedLedgerImpl.java

@@ -3831,6 +3831,32 @@ private CompletableFuture<Void> completeLedgerInfoForOffloaded(long ledgerId, UU
                 });
     }
 
+    /**
+     * Compare two positions. It is different with {@link Position#compareTo(Position)} when the params are invalid.
+     * For example: position-1 is "1:{latest entry}", and position-2 is "2:-1", they are the same position.
+     */
+    @VisibleForTesting
+    int comparePositions(Position pos1, Position pos2) {
+        if (pos1 == null || pos2 == null) {
+            throw new IllegalArgumentException("Positions must not be null");
+        }
+        if (ledgers.isEmpty() || pos1.getLedgerId() < getFirstPosition().getLedgerId()
+                || pos2.getLedgerId() < getFirstPosition().getLedgerId()
+                || pos1.getLedgerId() > getLastPosition().getLedgerId()
+                || pos2.getLedgerId() > getLastPosition().getLedgerId()) {
+            log.warn("[{}] Comparing un-exist position {} and {}", name, pos1, pos2,
+                    new IllegalArgumentException("Comparing un-exist position"));
+            return pos1.compareTo(pos2);
+        }
+        if (pos1.getLedgerId() == pos2.getLedgerId()) {
+            return Long.compare(pos1.getEntryId(), pos2.getEntryId());
+        }
+        if (!isValidPosition(pos1) || !isValidPosition(pos2)) {
+            return getNextValidPosition(pos1).compareTo(getNextValidPosition(pos2));
+        }
+        return pos1.compareTo(pos2);
+    }
+
     /**
      * Get the number of entries between a contiguous range of two positions.
      *
@@ -3843,41 +3869,77 @@ public long getNumberOfEntries(Range<Position> range) {
         boolean fromIncluded = range.lowerBoundType() == BoundType.CLOSED;
         Position toPosition = range.upperEndpoint();
         boolean toIncluded = range.upperBoundType() == BoundType.CLOSED;
+        if (comparePositions(fromPosition, toPosition) > 0) {
+            log.warn("[{}] Getting number of entries with an invalid range {} and {}", name, fromPosition, toPosition);
+            throw new IllegalArgumentException("Invalid range " + range);
+        }
+
+        // 1. If the "fromPosition" is after "toPosition", then there is no entry in the range.
+        // 2. If both "formPosition" and "toPosition" have negative entry id amd in the same ledger, then there is no
+        //    entry in the range.
+        if (fromPosition.getLedgerId() > toPosition.getLedgerId()
+            || (fromPosition.getLedgerId() == toPosition.getLedgerId()
+                && fromPosition.getEntryId() > toPosition.getEntryId())
+            || (fromPosition.getLedgerId() == toPosition.getLedgerId()
+                && fromPosition.getEntryId() < 0 && toPosition.getEntryId() < 0)) {
+            return 0;
+        }
 
+        // If the 2 positions are in the same ledger.
         if (fromPosition.getLedgerId() == toPosition.getLedgerId()) {
             LedgerInfo li = ledgers.get(toPosition.getLedgerId());
             if (li != null) {
                 // If the 2 positions are in the same ledger
                 long count = toPosition.getEntryId() - fromPosition.getEntryId() - 1;
-                count += fromIncluded ? 1 : 0;
-                count += toIncluded ? 1 : 0;
+                count += fromIncluded && fromPosition.getEntryId() >= 0 ? 1 : 0;
+                count += toIncluded && toPosition.getEntryId() >= 0 ? 1 : 0;
                 return count;
             } else {
                 // if the ledgerId is not in the ledgers, it means it has been deleted
                 return 0;
             }
-        } else {
-            long count = 0;
-            // If the from & to are pointing to different ledgers, then we need to :
-            // 1. Add the entries in the ledger pointed by toPosition
-            count += toPosition.getEntryId();
+        }
+
+        // If the "fromPosition.ledgerId" is larger than "toPosition.ledgerId".
+        // 1. Add the entries in the ledger pointed by toPosition.
+        // 2. Add the entries in the ledger pointed by fromPosition.
+        // 3. Add the whole ledgers entries in between.
+        long count = 0;
+
+        // 1. Add the entries in the ledger pointed by toPosition.
+        //    Add nothing if "toPosition" does not exit in "ledgers".
+        //    Add nothing if "toPosition.entryId < 0".
+        LedgerInfo toLedger = ledgers.get(toPosition.getLedgerId());
+        if (toPosition.getEntryId() >= 0 && toLedger != null) {
+            // To support the use case "cursor.getNumberOfEntries()", which will use a "toPosition" that is larger
+            // than the LAC.
+            // To support this case, use "Long.MAX_VALUE" if the ledger is the last one.
+            long entriesInLedger = comparePositions(toPosition, lastConfirmedEntry) >= 0
+                    ? Long.MAX_VALUE : toLedger.getEntries();
+            count += Math.min(toPosition.getEntryId(), entriesInLedger - 1);
             count += toIncluded ? 1 : 0;
+        }
 
-            // 2. Add the entries in the ledger pointed by fromPosition
-            LedgerInfo li = ledgers.get(fromPosition.getLedgerId());
-            if (li != null) {
-                count += li.getEntries() - (fromPosition.getEntryId() + 1);
+        // 2. Add the entries in the ledger pointed by fromPosition.
+        //    Add nothing if "toPosition.entryId < 0".
+        //    Add nothing if "toPosition" does not exit in "ledgers".
+        LedgerInfo formLedger = ledgers.get(fromPosition.getLedgerId());
+        if (formLedger != null) {
+            if (fromPosition.getEntryId() < 0) {
+                count += formLedger.getEntries();
+            } else {
+                count += formLedger.getEntries() - (fromPosition.getEntryId() + 1);
                 count += fromIncluded ? 1 : 0;
             }
+        }
 
-            // 3. Add the whole ledgers entries in between
-            for (LedgerInfo ls : ledgers.subMap(fromPosition.getLedgerId(), false, toPosition.getLedgerId(), false)
-                    .values()) {
-                count += ls.getEntries();
-            }
-
-            return count;
+        // 3. Add the whole ledgers entries in between
+        for (LedgerInfo ls : ledgers.subMap(fromPosition.getLedgerId(), false, toPosition.getLedgerId(), false)
+                .values()) {
+            count += ls.getEntries();
         }
+
+        return count;
     }
 
     /**

managed-ledger/src/test/java/org/apache/bookkeeper/mledger/impl/ManagedCursorListAckTest.java

@@ -33,7 +33,7 @@ public class ManagedCursorListAckTest extends MockedBookKeeperTestCase {
 
     private static final Charset Encoding = StandardCharsets.UTF_8;
 
-    @Test(timeOut = 20000)
+    @Test(timeOut = 20000 * 1000)
     void testMultiPositionDelete() throws Exception {
         ManagedLedger ledger = factory.open("my_test_ledger", new ManagedLedgerConfig().setMaxEntriesPerLedger(2));