Checkin of remaining files for ALF-8793: "RSOLR 036: Update IndexChecker to call SOLR check APIs"

git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@29244 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/repo/solr/SolrTrackingMethodInterceptor.java

@@ -0,0 +1,66 @@
+package org.alfresco.repo.solr;
+
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock.WriteLock;
+
+import org.aopalliance.intercept.MethodInterceptor;
+import org.aopalliance.intercept.MethodInvocation;
+import org.springframework.context.ApplicationEventPublisher;
+import org.springframework.context.ApplicationEventPublisherAware;
+
+/**
+ * A method interceptor that intercepts method calls on the {@link SOLRTrackingComponent} 
+ * in order to determine if a remote Solr instance is active. If so, an application event
+ * is generated to indicate this.
+ * 
+ * This is used by the Solr JMX code to export Solr mbeans only if the remote Solr instance
+ * is active.
+ * 
+ * since 4.0
+ *
+ */
+public class SolrTrackingMethodInterceptor implements MethodInterceptor, ApplicationEventPublisherAware
+{
+    private final WriteLock writeLock;
+	private boolean solrActive = false;
+    private ApplicationEventPublisher applicationEventPublisher;
+
+    public SolrTrackingMethodInterceptor()
+    {
+        ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
+        writeLock = lock.writeLock();
+    }
+    
+    private void broadcastSolrActive()
+    {
+    	applicationEventPublisher.publishEvent(new SolrActiveEvent(this));
+    	solrActive = true;
+    }
+    
+	@Override
+	public void setApplicationEventPublisher(ApplicationEventPublisher applicationEventPublisher)
+	{
+		this.applicationEventPublisher = applicationEventPublisher;
+	}
+	
+    public Object invoke(MethodInvocation mi) throws Throwable
+    {
+        writeLock.lock();
+        try
+        {
+        	if(!solrActive)
+        	{
+        		broadcastSolrActive();
+        		solrActive = true;
+        	}
+        }
+        finally
+        {
+            writeLock.unlock();
+        }
+
+        return mi.proceed();
+    }
+
+}