From 9c62e3d05c5ab37d60423d2822c636fe161b6d9c Mon Sep 17 00:00:00 2001
From: chris-lumigrow <cschaefer@lumigrow.com>
Date: Thu, 10 Nov 2016 14:19:43 -0800
Subject: [PATCH] a bit of defensive programming in the case of negative
 reference values

---
 .../java/io/moquette/spi/persistence/MapDBMessagesStore.java | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/broker/src/main/java/io/moquette/spi/persistence/MapDBMessagesStore.java b/broker/src/main/java/io/moquette/spi/persistence/MapDBMessagesStore.java
index 4eb497e0..f8c3d583 100644
--- a/broker/src/main/java/io/moquette/spi/persistence/MapDBMessagesStore.java
+++ b/broker/src/main/java/io/moquette/spi/persistence/MapDBMessagesStore.java
@@ -110,7 +110,10 @@ class MapDBMessagesStore implements IMessagesStore {
     void removeStoredMessage(MessageGUID guid) {
         //remove only the not retained and no more referenced
         StoredMessage storedMessage = m_persistentMessageStore.get(guid);
-        if (!storedMessage.isRetained() && storedMessage.getReferenceCounter() == 0) {
+        if (!storedMessage.isRetained() && storedMessage.getReferenceCounter() <= 0) {
+            if(storedMessage.getReferenceCounter() < 0) {
+                LOG.error("we should never have gotten a reference count less than zero");
+            }
             LOG.debug("Cleaning not retained message guid {}", guid);
             m_persistentMessageStore.remove(guid);
         }