BUG-4514: clear oldModule/oldInstance when no longer needed

[controller.git] / opendaylight / config / config-api / src / main / java / org / opendaylight / controller / config / spi / AbstractModule.java

diff --git a/opendaylight/config/config-api/src/main/java/org/opendaylight/controller/config/spi/AbstractModule.java b/opendaylight/config/config-api/src/main/java/org/opendaylight/controller/config/spi/AbstractModule.java
index b0fda1eacf936a392718371238399f15a7666e6d..e60a047379ee73b9399807f232a08592123d0d5c 100644 (file)
--- a/opendaylight/config/config-api/src/main/java/org/opendaylight/controller/config/spi/AbstractModule.java
+++ b/opendaylight/config/config-api/src/main/java/org/opendaylight/controller/config/spi/AbstractModule.java
@@ -21,11 +21,12 @@ public abstract class AbstractModule<M extends AbstractModule<M>> implements org
 
     private static final Logger LOG = LoggerFactory.getLogger(AbstractModule.class);
 
-    private final M oldModule;
-    private final AutoCloseable oldInstance;
+    protected final DependencyResolver dependencyResolver;
     protected final ModuleIdentifier identifier;
+
+    private AutoCloseable oldInstance;
+    private M oldModule;
     private AutoCloseable instance;
-    protected final DependencyResolver dependencyResolver;
 
     /**
      * Called when module is configured.
@@ -33,7 +34,7 @@ public abstract class AbstractModule<M extends AbstractModule<M>> implements org
      * @param identifier id of current instance.
      * @param dependencyResolver resolver used in dependency injection and validation.
      */
-    public AbstractModule(ModuleIdentifier identifier, DependencyResolver dependencyResolver) {
+    public AbstractModule(final ModuleIdentifier identifier, final DependencyResolver dependencyResolver) {
         this(identifier, dependencyResolver, null, null);
     }
 
@@ -45,7 +46,7 @@ public abstract class AbstractModule<M extends AbstractModule<M>> implements org
      * @param oldModule old instance of module that is being reconfigred(replaced) by current instance. The old instance can be examined for reuse.
      * @param oldInstance old instance wrapped by the old module. This is the resource that is actually being reused if possible or closed otherwise.
      */
-    public AbstractModule(ModuleIdentifier identifier, DependencyResolver dependencyResolver, M oldModule, AutoCloseable oldInstance) {
+    public AbstractModule(final ModuleIdentifier identifier, final DependencyResolver dependencyResolver, final M oldModule, final AutoCloseable oldInstance) {
         this.identifier = identifier;
         this.dependencyResolver = dependencyResolver;
         this.oldModule = oldModule;
@@ -65,15 +66,15 @@ public abstract class AbstractModule<M extends AbstractModule<M>> implements org
      */
     @Override
     public final AutoCloseable getInstance() {
-        if(instance==null) {
-            if(oldInstance!=null && canReuseInstance(oldModule)) {
+        if (instance == null) {
+            if (oldInstance != null && canReuseInstance(oldModule)) {
                 resolveDependencies();
                 instance = reuseInstance(oldInstance);
             } else {
-                if(oldInstance!=null) {
+                if (oldInstance != null) {
                     try {
                         oldInstance.close();
-                    } catch(Exception e) {
+                    } catch (Exception e) {
                         LOG.error("An error occurred while closing old instance {} for module {}", oldInstance, getIdentifier(), e);
                     }
                 }
@@ -83,7 +84,12 @@ public abstract class AbstractModule<M extends AbstractModule<M>> implements org
                     throw new IllegalStateException("Error in createInstance - null is not allowed as return value. Module: " + getIdentifier());
                 }
             }
+
+            // Prevent serial memory leak: clear these references as we will not use them again.
+            oldInstance = null;
+            oldModule = null;
         }
+
         return instance;
     }
 
@@ -93,7 +99,7 @@ public abstract class AbstractModule<M extends AbstractModule<M>> implements org
     protected abstract AutoCloseable createInstance();
 
     @Override
-    public final boolean canReuse(Module oldModule) {
+    public final boolean canReuse(final Module oldModule) {
         // Just cast into a specific instance
         // TODO unify this method with canReuseInstance (required Module interface to be generic which requires quite a lot of changes)
         return getClass().isInstance(oldModule) ? canReuseInstance((M) oldModule) : false;
@@ -115,7 +121,7 @@ public abstract class AbstractModule<M extends AbstractModule<M>> implements org
      * @param oldInstance old instance of a class wrapped by the module
      * @return reused instance
      */
-    protected AutoCloseable reuseInstance(AutoCloseable oldInstance) {
+    protected AutoCloseable reuseInstance(final AutoCloseable oldInstance) {
         // implement if instance reuse should be supported. Override canReuseInstance to change the criteria.
         return oldInstance;
     }