Github user mattf-horton commented on a diff in the pull request:
https://github.com/apache/metron/pull/530#discussion_r133530431
--- Diff:
bundles-lib/src/main/java/org/apache/metron/bundles/ExtensionManager.java ---
@@ -103,61 +104,52 @@ private ExtensionManager(){}
/**
* @return The singleton instance of the ExtensionManager
*/
- public static ExtensionManager getInstance() {
- ExtensionManager result = extensionManager;
- if (result == null) {
- synchronized (ExtensionManager.class) {
- result = extensionManager;
- if (result == null) {
- extensionManager = new ExtensionManager();
- result = extensionManager;
- }
+ public static ExtensionManager getInstance() throws
NotInitializedException {
+ synchronized (ExtensionManager.class) {
+ if (extensionManager == null) {
+ throw new NotInitializedException("ExtensionManager not
initialized");
}
+ return extensionManager;
}
- return result;
}
/**
* Uninitializes the ExtensionManager.
* TESTING ONLY
*/
+ @VisibleForTesting
public static void reset() {
synchronized (ExtensionManager.class) {
- getInstance().forgetExtensions();
+ initContext = null;
extensionManager = null;
}
}
- private void forgetExtensions() {
- initContext = null;
- }
-
-
/**
* Loads all extension class types that can be found on the bootstrap
classloader and by creating
* classloaders for all BUNDLES found within the classpath.
*
* @param bundles the bundles to scan through in search of extensions
*/
- public void init(final List<Class> classes, final Bundle systemBundle,
final Set<Bundle> bundles)
+ public static void init(final List<Class> classes, final Bundle
systemBundle, final Set<Bundle> bundles)
throws NotInitializedException {
- InitContext ic = initContext;
- if (ic == null) {
- synchronized (this) {
- ic = initContext;
- if (ic == null) {
- initContext = discoverExtensions(classes, systemBundle, bundles);
- ic = initContext;
- }
+ if (systemBundle == null) {
+ throw new IllegalArgumentException("systemBundle is required");
+ }
+
+ synchronized (ExtensionManager.class) {
+ if (extensionManager != null) {
+ throw new IllegalStateException("ExtensionManager already exists");
}
+ extensionManager = new ExtensionManager();
+ initContext = extensionManager.discoverExtensions(classes,
systemBundle, bundles);
--- End diff --
And to protect unsynchronized getInstance():
```java
ExtensionManager em = new ExtensionManager();
InitContext ic = em.discoverExtensions(classes, systemBundle,
bundles);
initContext = ic;
extensionManager = em;
```
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