1 files changed, 99 insertions, 0 deletions
diff --git a/extender/src/main/java/org/eclipse/gemini/blueprint/extender/internal/activator/listeners/BaseListener.java b/extender/src/main/java/org/eclipse/gemini/blueprint/extender/internal/activator/listeners/BaseListener.java
new file mode 100644
index 0000000..566c96a
--- /dev/null
+++ b/extender/src/main/java/org/eclipse/gemini/blueprint/extender/internal/activator/listeners/BaseListener.java
@@ -0,0 +1,99 @@
+/******************************************************************************
+ * Copyright (c) 2006, 2010 VMware Inc.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * and Apache License v2.0 which accompanies this distribution.
+ * The Eclipse Public License is available at
+ * http://www.eclipse.org/legal/epl-v10.html and the Apache License v2.0
+ * is available at http://www.opensource.org/licenses/apache2.0.php.
+ * You may elect to redistribute this code under either of these licenses.
+ *
+ * Contributors:
+ *   VMware Inc.
+ *****************************************************************************/
+
+package org.eclipse.gemini.blueprint.extender.internal.activator.listeners;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.eclipse.gemini.blueprint.util.OsgiStringUtils;
+import org.osgi.framework.Bundle;
+import org.osgi.framework.BundleEvent;
+import org.osgi.framework.SynchronousBundleListener;
+
+import java.util.Map;
+import java.util.WeakHashMap;
+
+/**
+ * Common base class for {@link org.eclipse.gemini.blueprint.extender.internal.activator.ContextLoaderListener} listeners.
+ *
+ * @author Costin Leau
+ */
+public abstract class BaseListener implements SynchronousBundleListener {
+    public static final int LAZY_ACTIVATION_EVENT_TYPE = 0x00000200;
+
+    protected final Log log = LogFactory.getLog(getClass());
+
+    /**
+     * flag indicating whether the context is down or not - useful during shutdown
+     */
+    private volatile boolean isClosed = false;
+
+    /**
+     * common cache used for tracking down bundles started lazily so they don't get processed twice (once when
+     * started lazy, once when started fully)
+     */
+    protected final Map<Bundle, Object> lazyBundleCache = new WeakHashMap<Bundle, Object>();
+    /**
+     * dummy value for the bundle cache
+     */
+    private final Object VALUE = new Object();
+
+    // caches the bundle
+    protected void push(Bundle bundle) {
+        synchronized (lazyBundleCache) {
+            lazyBundleCache.put(bundle, VALUE);
+        }
+    }
+
+    // checks the presence of the bundle as well as removing it
+    protected boolean pop(Bundle bundle) {
+        synchronized (lazyBundleCache) {
+            return (lazyBundleCache.remove(bundle) != null);
+        }
+    }
+
+    /**
+     * A bundle has been started, stopped, resolved, or unresolved. This method is a synchronous callback, do not do
+     * any long-running work in this thread.
+     *
+     * @see org.osgi.framework.SynchronousBundleListener#bundleChanged
+     */
+    public void bundleChanged(BundleEvent event) {
+
+        boolean trace = log.isTraceEnabled();
+
+        // check if the listener is still alive
+        if (isClosed) {
+            if (trace)
+                log.trace("Listener is closed; events are being ignored");
+            return;
+        }
+        if (trace) {
+            log.trace("Processing bundle event [" + OsgiStringUtils.nullSafeToString(event) + "] for bundle ["
+                    + OsgiStringUtils.nullSafeSymbolicName(event.getBundle()) + "]");
+        }
+        try {
+            handleEvent(event);
+        } catch (Exception ex) {
+            /* log exceptions before swallowing */
+            log.warn("Got exception while handling event " + event, ex);
+        }
+    }
+
+    protected abstract void handleEvent(BundleEvent event);
+
+    public void close() {
+        this.isClosed = true;
+    }
+}