SOLR-2718: allow for lazy loaded response writers; clean up test hack for VelocityResponseWriter

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1189958 13f79535-47bb-0310-9956-ffa450edef68

solr/CHANGES.txt

@@ -347,6 +347,9 @@ Other Changes
 
 * SOLR-2588: Moved VelocityResponseWriter back to contrib module in order to 
   remove it as a mandatory core dependency.  (ehatcher)
+  
+* SOLR-2718: Add ability to lazy load response writers, defined with startup="lazy".
+  (ehatcher)
 
 Documentation
 ----------------------

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

@@ -55,10 +55,7 @@ import org.xml.sax.SAXException;
 
 import javax.xml.parsers.ParserConfigurationException;
 
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.IOException;
-import java.io.InputStream;
+import java.io.*;
 import java.util.*;
 import java.util.concurrent.*;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -292,8 +289,8 @@ public final class SolrCore implements SolrInfoMBean {
    * 
    * @see SolrCoreAware
    */
-  public void registerResponseWriter( String name, QueryResponseWriter responseWriter ){
-    responseWriters.put(name, responseWriter);
+  public QueryResponseWriter registerResponseWriter( String name, QueryResponseWriter responseWriter ){
+    return responseWriters.put(name, responseWriter);
   }
   
   public SolrCore reload(SolrResourceLoader resourceLoader) throws IOException,
@@ -477,6 +474,10 @@ public final class SolrCore implements SolrInfoMBean {
   private UpdateHandler createUpdateHandler(String className, UpdateHandler updateHandler) {
     return createReloadedUpdateHandler(className, UpdateHandler.class, "Update Handler", updateHandler);
   }
+
+  private QueryResponseWriter createQueryResponseWriter(String className) {
+    return createInstance(className, QueryResponseWriter.class, "Query Response Writer");
+  }
   
   /**
    * 
@@ -1532,7 +1533,54 @@ public final class SolrCore implements SolrInfoMBean {
   /** Configure the query response writers. There will always be a default writer; additional
    * writers may also be configured. */
   private void initWriters() {
-    defaultResponseWriter = initPlugins(responseWriters, QueryResponseWriter.class);
+    // use link map so we iterate in the same order
+    Map<PluginInfo,QueryResponseWriter> writers = new LinkedHashMap<PluginInfo,QueryResponseWriter>();
+    for (PluginInfo info : solrConfig.getPluginInfos(QueryResponseWriter.class.getName())) {
+      try {
+        QueryResponseWriter writer;
+        String startup = info.attributes.get("startup") ;
+        if( startup != null ) {
+          if( "lazy".equals(startup) ) {
+            log.info("adding lazy queryResponseWriter: " + info.className);
+            writer = new LazyQueryResponseWriterWrapper(this, info.className, info.initArgs );
+          } else {
+            throw new Exception( "Unknown startup value: '"+startup+"' for: "+info.className );
+          }
+        } else {
+          writer = createQueryResponseWriter(info.className);
+        }
+        writers.put(info,writer);
+        QueryResponseWriter old = registerResponseWriter(info.name, writer);
+        if(old != null) {
+          log.warn("Multiple queryResponseWriter registered to the same name: " + info.name + " ignoring: " + old.getClass().getName());
+        }
+        if(info.isDefault()){
+          defaultResponseWriter = writer;
+          if(defaultResponseWriter != null)
+            log.warn("Multiple default queryResponseWriter registered ignoring: " + old.getClass().getName());
+        }
+        log.info("created "+info.name+": " + info.className);
+      } catch (Exception ex) {
+          SolrConfig.severeErrors.add( ex );
+          SolrException e = new SolrException
+            (SolrException.ErrorCode.SERVER_ERROR, "QueryResponseWriter init failure", ex);
+          SolrException.logOnce(log,null,e);
+          throw e;
+      }
+    }
+
+    // we've now registered all handlers, time to init them in the same order
+    for (Map.Entry<PluginInfo,QueryResponseWriter> entry : writers.entrySet()) {
+      PluginInfo info = entry.getKey();
+      QueryResponseWriter writer = entry.getValue();
+      responseWriters.put(info.name, writer);
+      if (writer instanceof PluginInfoInitialized) {
+        ((PluginInfoInitialized) writer).init(info);
+      } else{
+        writer.init(info.initArgs);
+      }
+    }
+
     for (Map.Entry<String, QueryResponseWriter> entry : DEFAULT_RESPONSE_WRITERS.entrySet()) {
       if(responseWriters.get(entry.getKey()) == null) responseWriters.put(entry.getKey(), entry.getValue());
     }
@@ -1784,6 +1832,50 @@ public final class SolrCore implements SolrInfoMBean {
     return codecProvider;
   }
 
+  public final class LazyQueryResponseWriterWrapper implements QueryResponseWriter {
+    private SolrCore _core;
+    private String _className;
+    private NamedList _args;
+    private QueryResponseWriter _writer;
+
+    public LazyQueryResponseWriterWrapper(SolrCore core, String className, NamedList args) {
+      _core = core;
+      _className = className;
+      _args = args;
+      _writer = null;
+    }
+
+    public synchronized QueryResponseWriter getWrappedWriter()
+    {
+      if( _writer == null ) {
+        try {
+          QueryResponseWriter writer = createQueryResponseWriter(_className);
+          writer.init( _args );
+          _writer = writer;
+        }
+        catch( Exception ex ) {
+          throw new SolrException( SolrException.ErrorCode.SERVER_ERROR, "lazy loading error", ex );
+        }
+      }
+      return _writer;
+    }
+
+
+    @Override
+    public void init(NamedList args) {
+      // do nothing
+    }
+
+    @Override
+    public void write(Writer writer, SolrQueryRequest request, SolrQueryResponse response) throws IOException {
+      getWrappedWriter().write(writer, request, response);
+    }
+
+    @Override
+    public String getContentType(SolrQueryRequest request, SolrQueryResponse response) {
+      return getWrappedWriter().getContentType(request, response);
+    }
+  }
 }
 
 

solr/core/src/test-files/solr/conf/solrconfig-lazywriter.xml

@@ -0,0 +1,27 @@
+<?xml version="1.0" ?>
+
+<!--
+ 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.
+-->
+
+<!-- a basic solrconfig that tests can use when they want simple minimal solrconfig/schema
+     DO NOT ADD THINGS TO THIS CONFIG! -->
+<config>
+  <luceneMatchVersion>${tests.luceneMatchVersion:LUCENE_CURRENT}</luceneMatchVersion>
+  <requestHandler name="standard" class="solr.StandardRequestHandler"></requestHandler>
+
+  <queryResponseWriter name="velocity" class="solr.VelocityResponseWriter" startup="lazy"/>
+</config>

solr/core/src/test-files/solr/crazy-path-to-config.xml

@@ -67,7 +67,7 @@
   
   
   <queryResponseWriter name="standard" class="solr.XMLResponseWriter"/>
-  <queryResponseWriter name="useless" class="org.apache.solr.OutputWriterTest$UselessOutputWriter"/>
+  <queryResponseWriter name="useless" class="org.apache.solr.OutputWriterTest$UselessOutputWriter" startup="lazy"/>
   <queryResponseWriter name="xslt" class="solr.XSLTResponseWriter"/>
 
 

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

@@ -19,12 +19,16 @@ package org.apache.solr;
 
 import java.io.IOException;
 import java.io.Writer;
+import java.util.List;
 
 import org.apache.solr.common.params.CommonParams;
 import org.apache.solr.common.util.NamedList;
+import org.apache.solr.core.PluginInfo;
+import org.apache.solr.core.SolrCore;
 import org.apache.solr.request.SolrQueryRequest;
 import org.apache.solr.response.QueryResponseWriter;
 import org.apache.solr.response.SolrQueryResponse;
+import org.apache.solr.response.XMLResponseWriter;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
@@ -88,7 +92,15 @@ public class OutputWriterTest extends SolrTestCaseJ4 {
         // System.out.println(out);
         assertTrue(out.contains("DUMMY"));
     }
-    
+
+    public void testLazy() {
+      QueryResponseWriter qrw = h.getCore().getQueryResponseWriter("useless");
+      assertTrue("Should be a lazy class", qrw instanceof SolrCore.LazyQueryResponseWriterWrapper);
+
+      qrw = h.getCore().getQueryResponseWriter("xml");
+      assertTrue("Should not be a lazy class", qrw instanceof XMLResponseWriter);
+
+    }
     
     ////////////////////////////////////////////////////////////////////////////
     /** An output writer that doesn't do anything useful. */

solr/example/solr/conf/solrconfig.xml

@@ -1585,9 +1585,7 @@
   <!--
      Custom response writers can be declared as needed...
     -->
-    <!-- The solr.velocity.enabled flag is used by Solr's test cases so that this response writer is not
-         loaded (causing an error if contrib/velocity has not been built fully) -->
-    <queryResponseWriter name="velocity" class="solr.VelocityResponseWriter" enable="${solr.velocity.enabled:true}"/>
+    <queryResponseWriter name="velocity" class="solr.VelocityResponseWriter" startup="lazy"/>
   
 
   <!-- XSLT response writer transforms the XML output by any xslt file found

solr/solrj/src/test/org/apache/solr/client/solrj/embedded/JettyWebappTest.java

@@ -55,9 +55,6 @@ public class JettyWebappTest extends LuceneTestCase
     System.setProperty("solr.data.dir", dataDir.getCanonicalPath());
     String path = ExternalPaths.WEBAPP_HOME;
 
-    // disable VelocityResponseWriter from example configuration
-    System.setProperty("solr.velocity.enabled", "false");
-
     server = new Server(port);
     // insecure: only use for tests!!!!
     server.setSessionIdManager(new HashSessionIdManager(new Random(random.nextLong())));

solr/test-framework/src/java/org/apache/solr/SolrJettyTestBase.java

@@ -47,9 +47,6 @@ abstract public class SolrJettyTestBase extends SolrTestCaseJ4
     System.setProperty( "solr.solr.home", solrHome);
     System.setProperty( "solr.data.dir", dataDir.getCanonicalPath() );
 
-    // disable VelocityResponseWriter from example configuration
-    System.setProperty("solr.velocity.enabled", "false");
-
     context = context==null ? "/solr" : context;
     SolrJettyTestBase.context = context;
     jetty = new JettySolrRunner( context, 0, configFile );

solr/test-framework/src/java/org/apache/solr/SolrTestCaseJ4.java

@@ -103,7 +103,6 @@ public abstract class SolrTestCaseJ4 extends LuceneTestCase {
     if (solrHome != null) {
       System.setProperty("solr.solr.home", solrHome);
     }
-    System.setProperty("solr.velocity.enabled", "false");
     initCore();
   }