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Safely add and register the MessageListener to Topic mapping.

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Given addListener(:MessageListener, :Collection<Topic>) could be called concurrently from the addMessageListener(:MessageListener, Collection<Topic>) method by multiple Threads, and the RedisMessageListenerContainer Javadoc specifically states that it is safe to call the addMessageListener(..) method conurrently without any external synchronization, and the registeration (or mapping) of listener to Topics is a componund action, then a race condition is possible.

Closes #2755
This commit is contained in:
John Blum
2023-10-23 12:18:57 -07:00
parent fc9f9d8e5c
commit f28bf61142
1 changed files with 4 additions and 9 deletions
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13
src/main/java/org/springframework/data/redis/listener/RedisMessageListenerContainer.java
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@@ -639,19 +639,14 @@ public class RedisMessageListenerContainer implements InitializingBean, Disposab
private void addListener(MessageListener listener, Collection<? extends Topic> topics) {
Assert.notNull(listener, "a valid listener is required");
Assert.notEmpty(topics, "at least one topic is required");
Assert.notNull(listener, "A valid listener is required");
Assert.notEmpty(topics, "At least one topic is required");
List<byte[]> channels = new ArrayList<>(topics.size());
List<byte[]> patterns = new ArrayList<>(topics.size());
// add listener mapping
Set<Topic> set = listenerTopics.get(listener);
if (set == null) {
set = new CopyOnWriteArraySet<>();
listenerTopics.put(listener, set);
}
// safely lookup or add MessageListener to Topic mapping
Set<Topic> set = listenerTopics.computeIfAbsent(listener, key -> new CopyOnWriteArraySet<>());
set.addAll(topics);