Index: oak-solr-core/pom.xml
===================================================================
--- oak-solr-core/pom.xml	(revision 1574838)
+++ oak-solr-core/pom.xml	(working copy)
@@ -121,12 +121,6 @@
       <classifier>tests</classifier>
     </dependency>
     <dependency>
-      <groupId>javax.servlet</groupId>
-      <artifactId>servlet-api</artifactId>
-      <version>2.5</version>
-      <scope>test</scope>
-    </dependency>
-    <dependency>
       <groupId>org.apache.jackrabbit</groupId>
       <artifactId>oak-mk</artifactId>
       <version>${project.version}</version>
Index: oak-solr-core/src/main/java/org/apache/jackrabbit/oak/plugins/index/solr/server/RequestCachingSolrServer.java
===================================================================
--- oak-solr-core/src/main/java/org/apache/jackrabbit/oak/plugins/index/solr/server/RequestCachingSolrServer.java	(revision 0)
+++ oak-solr-core/src/main/java/org/apache/jackrabbit/oak/plugins/index/solr/server/RequestCachingSolrServer.java	(working copy)
@@ -0,0 +1,128 @@
+/*
+ * 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.
+ */
+package org.apache.jackrabbit.oak.plugins.index.solr.server;
+
+import java.io.IOException;
+import java.util.Queue;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ConcurrentLinkedQueue;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Future;
+import org.apache.solr.client.solrj.SolrRequest;
+import org.apache.solr.client.solrj.SolrServer;
+import org.apache.solr.client.solrj.SolrServerException;
+import org.apache.solr.common.util.NamedList;
+
+/**
+ * A {@link org.apache.solr.client.solrj.SolrServer} wrapper which caches requests if the Solr instance / cluster,
+ * represented by a 'root' {@link org.apache.solr.client.solrj.SolrServer}, is not reachable.
+ */
+public class RequestCachingSolrServer extends SolrServer {
+    private final SolrServer solrServer;
+    private final ExecutorService executorService;
+    private final Queue<SolrServerCommand> queue = new ConcurrentLinkedQueue<SolrServerCommand>();
+    private final boolean blocking;
+
+    public RequestCachingSolrServer(SolrServer solrServer, ExecutorService executorService, boolean blocking) {
+        this.solrServer = solrServer;
+        this.executorService = executorService;
+        this.blocking = blocking;
+    }
+
+    public RequestCachingSolrServer(SolrServer solrServer, ExecutorService executorService) {
+        this.solrServer = solrServer;
+        this.executorService = executorService;
+        blocking = true;
+    }
+
+    private boolean isSolrReachable() {
+        try {
+            return 0 == solrServer.ping().getStatus();
+        } catch (Exception e) {
+            return false;
+        }
+    }
+
+    @Override
+    public NamedList<Object> request(final SolrRequest request) throws SolrServerException, IOException {
+        NamedList<Object> response = null;
+        synchronized (queue) {
+            if (queue.isEmpty() && isSolrReachable()) {
+                response = solrServer.request(request);
+            } else {
+                SolrServerCommand<NamedList<Object>> command = new SolrServerCommand<NamedList<Object>>() {
+                    @Override
+                    public NamedList<Object> execute() throws Exception {
+                        return solrServer.request(request);
+                    }
+                };
+                queue.add(command);
+                try {
+                    Future<NamedList<Object>> future = executorService.submit(new SolrServerCommandCallable<NamedList<Object>>(command));
+                    if (blocking) {
+                        response = future.get();
+                    }
+                } catch (Exception e) {
+                    // do nothing
+                }
+            }
+        }
+        return response;
+    }
+
+    @Override
+    public void shutdown() {
+        executorService.shutdown();
+        queue.clear();
+        solrServer.shutdown();
+    }
+
+    private interface SolrServerCommand<T> {
+        T execute() throws Exception;
+    }
+
+    private class SolrServerCommandCallable<T> implements Callable<T> {
+
+        private SolrServerCommand<T> solrServerCommand;
+
+        private SolrServerCommandCallable(SolrServerCommand<T> solrServerCommand) {
+            this.solrServerCommand = solrServerCommand;
+        }
+
+        @Override
+        public T call() throws Exception {
+            synchronized (queue) {
+                while (true) {
+                    if (solrServerCommand.equals(queue.element()) && isSolrReachable()) {
+                        T result = null;
+                        try {
+                            result = solrServerCommand.execute();
+                        } catch (Exception e) {
+                            // could not execute the command
+                        }
+                        if (result != null) {
+                            queue.remove();
+                            return result;
+                        }
+                    } else {
+                        Thread.sleep(3000);
+                    }
+                }
+            }
+        }
+    }
+}
\ No newline at end of file

Property changes on: oak-solr-core/src/main/java/org/apache/jackrabbit/oak/plugins/index/solr/server/RequestCachingSolrServer.java
___________________________________________________________________
Added: svn:eol-style
## -0,0 +1 ##
+native
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Index: oak-solr-core/src/test/java/org/apache/jackrabbit/oak/plugins/index/solr/server/RequestCachingSolrServerTest.java
===================================================================
--- oak-solr-core/src/test/java/org/apache/jackrabbit/oak/plugins/index/solr/server/RequestCachingSolrServerTest.java	(revision 0)
+++ oak-solr-core/src/test/java/org/apache/jackrabbit/oak/plugins/index/solr/server/RequestCachingSolrServerTest.java	(working copy)
@@ -0,0 +1,75 @@
+/*
+ * 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.
+ */
+package org.apache.jackrabbit.oak.plugins.index.solr.server;
+
+import java.util.Collection;
+import java.util.LinkedList;
+import java.util.concurrent.Executors;
+import org.apache.solr.client.solrj.SolrQuery;
+import org.apache.solr.client.solrj.SolrServer;
+import org.apache.solr.client.solrj.embedded.JettySolrRunner;
+import org.apache.solr.client.solrj.impl.HttpSolrServer;
+import org.apache.solr.common.SolrInputDocument;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * Testcase for {@link org.apache.jackrabbit.oak.plugins.index.solr.server.RequestCachingSolrServer}
+ */
+public class RequestCachingSolrServerTest {
+
+    @Test
+    public void testResilience() throws Exception {
+
+        JettySolrRunner jettySolrRunner = new JettySolrRunner(getClass().getResource("/solr").getFile(), "/solr", 8983, "solrconfig.xml", null, true, null, null);
+        jettySolrRunner.start();
+
+        SolrServer httpSolrServer = new HttpSolrServer("http://localhost:8983/solr/oak");
+
+        Collection<SolrInputDocument> docs = new LinkedList<SolrInputDocument>();
+        SolrInputDocument doc = new SolrInputDocument();
+        doc.addField("path_exact", "/a");
+        doc.addField("text", "foo");
+        docs.add(doc);
+        doc = new SolrInputDocument();
+        doc.addField("path_exact", "/b");
+        doc.addField("text", "bar");
+        docs.add(doc);
+
+        RequestCachingSolrServer requestCachingSolrServer = new RequestCachingSolrServer(httpSolrServer, Executors.newCachedThreadPool(), false);
+        requestCachingSolrServer.add(docs);
+        requestCachingSolrServer.commit();
+
+        assertEquals(2, httpSolrServer.query(new SolrQuery("text:(foo bar)")).getResults().size());
+
+        jettySolrRunner.stop();
+
+        docs.clear();
+        doc = new SolrInputDocument();
+        doc.addField("path_exact", "/c");
+        doc.addField("text", "xyz");
+        docs.add(doc);
+        requestCachingSolrServer.add(docs);
+        requestCachingSolrServer.commit();
+
+        jettySolrRunner.start();
+
+        Thread.sleep(10000);
+        assertEquals(1, httpSolrServer.query(new SolrQuery("text:xyz")).getResults().size());
+    }
+}

Property changes on: oak-solr-core/src/test/java/org/apache/jackrabbit/oak/plugins/index/solr/server/RequestCachingSolrServerTest.java
___________________________________________________________________
Added: svn:eol-style
## -0,0 +1 ##
+native
\ No newline at end of property