SOLR-423: Add CloseHook notification

git-svn-id: https://svn.apache.org/repos/asf/lucene/solr/trunk@671960 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -297,6 +297,8 @@ New Features
               See http://wiki.apache.org/solr/SpellCheckComponent for more details
               (Shalin Shekhar Mangar, Bojan Smid, gsingers)
 
+54. SOLR-423: Added Request Handler close hook notification so that RequestHandlers can be notified when a core is closing.  (gsingers, ryan)
+    
 Changes in runtime behavior
  1. SOLR-559: use Lucene updateDocument, deleteDocuments methods.  This
    removes the maxBufferedDeletes parameter added by SOLR-310 as Lucene

src/java/org/apache/solr/core/CloseHook.java

@@ -0,0 +1,33 @@
+package org.apache.solr.core;
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+/**
+    * Interface to request notification when the core is closed.
+ *<p/>
+ * Call {@link org.apache.solr.core.SolrCore#addCloseHook(org.apache.solr.core.CloseHook)} during the {@link org.apache.solr.util.plugin.SolrCoreAware#inform(SolrCore)} method to
+ * add a close hook to your object.
+ * <p/>
+ * The close hook can be useful for releasing objects related to the request handler (for instance, if you have a JDBC DataSource or something like that) 
+ *
+ *
+  */
+
+ public interface CloseHook {
+   void close( SolrCore core );
+ }

src/java/org/apache/solr/core/SolrCore.java

@@ -452,6 +452,12 @@ public final class SolrCore {
     return factory;
   }
 
+  /**
+   * Close all resources allocated by the core.
+   *  1. searcher
+   *  2. updateHandler
+   *  3. all CloseHooks will be notified
+   */
   public void close() {
     log.info(logid+" CLOSING SolrCore!");
     try {
@@ -469,6 +475,11 @@ public final class SolrCore {
     } catch (Exception e) {
       SolrException.log(log,e);
     }
+    if( closeHooks != null ) {
+       for( CloseHook hook : closeHooks ) {
+         hook.close( this );
+       }
+     }
   }
 
   public boolean isClosed() {
@@ -478,6 +489,19 @@ public final class SolrCore {
   @Override
   protected void finalize() { close(); }
 
+  private List<CloseHook> closeHooks = null;
+
+   /**
+    * Add a close callback hook
+    */
+   public void addCloseHook( CloseHook hook )
+   {
+     if( closeHooks == null ) {
+       closeHooks = new ArrayList<CloseHook>();
+     }
+     closeHooks.add( hook );
+   }
+
   /**
    * Returns a Request object based on the admin/pingQuery section
    * of the Solr config file.

src/test/org/apache/solr/core/SolrCoreTest.java

@@ -22,6 +22,7 @@ import org.apache.solr.request.SolrQueryRequest;
 import org.apache.solr.request.SolrQueryResponse;
 import org.apache.solr.request.SolrRequestHandler;
 import org.apache.solr.util.AbstractSolrTestCase;
+import org.apache.solr.util.plugin.SolrCoreAware;
 
 public class SolrCoreTest extends AbstractSolrTestCase {
 
@@ -43,8 +44,33 @@ public class SolrCoreTest extends AbstractSolrTestCase {
     assertEquals( old, handler1 ); // should pop out the old one
     assertEquals( core.getRequestHandlers().get( path ), handler2 );
   }
+
+  public void testClose() throws Exception {
+    SolrCore core = h.getCore();
+
+    ClosingRequestHandler handler1 = new ClosingRequestHandler();
+    handler1.inform( core );
+
+    String path = "/this/is A path /that won't be registered!";
+    SolrRequestHandler old = core.registerRequestHandler( path, handler1 );
+    assertNull( old ); // should not be anything...
+    assertEquals( core.getRequestHandlers().get( path ), handler1 );
+    core.close();
+    assertTrue("Handler not closed", handler1.closed == true);
+  }
 }
 
+class ClosingRequestHandler extends EmptyRequestHandler implements SolrCoreAware {
+  boolean closed = false;
+
+  public void inform(SolrCore core) {
+    core.addCloseHook( new CloseHook() {
+      public void close(SolrCore core) {
+        closed = true;
+      }
+    });
+  }
+}
 
 /**
  * An empty handler for testing