[jboss-jira] [JBoss JIRA] (WFCORE-2111) Fix incorrect usage of AtomicMapFieldUpdater.putAtomic()

[Kabir Khan (JIRA)]

Kabir Khan created WFCORE-2111:
----------------------------------

             Summary: Fix incorrect usage of AtomicMapFieldUpdater.putAtomic()
                 Key: WFCORE-2111
                 URL: https://issues.jboss.org/browse/WFCORE-2111
             Project: WildFly Core
          Issue Type: Bug
          Components: Domain Management
    Affects Versions: 3.0.0.Alpha15
            Reporter: Kabir Khan
            Assignee: Kabir Khan


The javadoc for the copy of AtomicMapFieldUpdater used in core specifies that if putAtomic() returns a value, that the put did not succeed. The transformer and notification registries are full of code checking the return value like https://github.com/kabir/wildfly-core/blob/3396609db1eebf7af382133b7d22fa1828643895/controller/src/main/java/org/jboss/as/controller/registry/GlobalTransformerRegistry.java#L270 : 
{code}
    SubRegistry getOrCreate(final String key) {
        for (;;) {
            final Map<String, SubRegistry> subRegistries = subRegistriesUpdater.get(this);
            SubRegistry registry = subRegistries.get(key);
            if(registry == null) {
                registry = new SubRegistry();
                SubRegistry existing = subRegistriesUpdater.putAtomic(this, key, registry, subRegistries);
                if(existing == null) {
                    return registry;
                } else if (existing != registry) {
                    return existing; // Problematic
                }
            }
            return registry;
        }
    }
{code}
This calling code assumes that if 'existing' is returned and is not the same as the created 'registry' that the put succeeded, and it was added to 'existing'. However, this is not what happens, when 'existing' is returned, its value is actually the same as the 'subRegistries' snapshot, and no insertion has happened.

To clear up the confusion, make AtomicMapFieldUpdater return a boolean where 'true' is returned if the put succeeded, and 'false' when it did not. If 'false' is returned the caller needs to retry the put as implied today.



--
This message was sent by Atlassian JIRA
(v7.2.3#72005)