AMQ-8012 - Improve thread safety of SubQueueSelectorCacheBroker
When returning a copy of the set of selectors we need to synchronize
diff --git a/activemq-broker/src/main/java/org/apache/activemq/plugin/SubQueueSelectorCacheBroker.java b/activemq-broker/src/main/java/org/apache/activemq/plugin/SubQueueSelectorCacheBroker.java
index dbd9ad7..0e48830 100644
--- a/activemq-broker/src/main/java/org/apache/activemq/plugin/SubQueueSelectorCacheBroker.java
+++ b/activemq-broker/src/main/java/org/apache/activemq/plugin/SubQueueSelectorCacheBroker.java
@@ -69,7 +69,7 @@
* The subscription's selector cache. We cache compiled expressions keyed
* by the target destination.
*/
- private ConcurrentMap<String, Set<String>> subSelectorCache = new ConcurrentHashMap<String, Set<String>>();
+ private ConcurrentMap<String, Set<String>> subSelectorCache = new ConcurrentHashMap<>();
private final File persistFile;
private boolean singleSelectorPerDestination = false;
@@ -275,8 +275,11 @@
@SuppressWarnings("unchecked")
public Set<String> getSelectorsForDestination(String destinationName) {
- if (subSelectorCache.containsKey(destinationName)) {
- return new HashSet<String>(subSelectorCache.get(destinationName));
+ final Set<String> cachedSelectors = subSelectorCache.get(destinationName);
+ synchronized(cachedSelectors) {
+ if (cachedSelectors != null) {
+ return new HashSet<>(cachedSelectors);
+ }
}
return Collections.EMPTY_SET;
@@ -291,17 +294,13 @@
}
public boolean deleteSelectorForDestination(String destinationName, String selector) {
- if (subSelectorCache.containsKey(destinationName)) {
- Set<String> cachedSelectors = subSelectorCache.get(destinationName);
- return cachedSelectors.remove(selector);
- }
-
- return false;
+ final Set<String> cachedSelectors = subSelectorCache.get(destinationName);
+ return cachedSelectors != null ? cachedSelectors.remove(selector) : false;
}
public boolean deleteAllSelectorsForDestination(String destinationName) {
- if (subSelectorCache.containsKey(destinationName)) {
- Set<String> cachedSelectors = subSelectorCache.get(destinationName);
+ final Set<String> cachedSelectors = subSelectorCache.get(destinationName);
+ if (cachedSelectors != null) {
cachedSelectors.clear();
}
return true;
