fix logic bug in handling of multi-confirms

The code was assuming that there would be a contiguous sequence
between the first pending confirm and the received confirm, which
isn't the case since previous confirms can have punched holes into
that sequence.

Author: rade

test/src/com/rabbitmq/client/test/functional/Confirm.java

@@ -58,11 +58,7 @@ protected void setUp() throws IOException {
         channel.setAckListener(new AckListener() {
                 public void handleAck(long seqNo,
                                       boolean multiple) {
-                    if (multiple) {
-                        Confirm.this.gotAckForMultiple(seqNo);
-                    } else {
-                        Confirm.this.gotAckFor(seqNo);
-                    }
+                    Confirm.this.handleAck(seqNo, multiple);
                 }
             });
         channel.confirmSelect();
@@ -271,16 +267,15 @@ private void publish(String exchangeName, String queueName,
                              "nop".getBytes());
     }
 
-    private void gotAckForMultiple(long msgSeqNo) {
-        for (long i = ackSet.first(); i <= msgSeqNo; ++i)
-            gotAckFor(i);
-    }
-
-    private void gotAckFor(long msgSeqNo) {
+    private void handleAck(long msgSeqNo, boolean multiple) {
         if (!ackSet.contains(msgSeqNo)) {
             fail("got duplicate ack: " + msgSeqNo);
         }
-        ackSet.remove(msgSeqNo);
+        if (multiple) {
+            ackSet.headSet(msgSeqNo + 1).clear();
+        } else {
+            ackSet.remove(msgSeqNo);
+        }
     }
 
     private void basicRejectCommon(boolean requeue)