jdyer1 commented on code in PR #2805:
URL: https://github.com/apache/solr/pull/2805#discussion_r1822683918
##########
solr/solrj/src/test/org/apache/solr/client/solrj/impl/LBHttp2SolrClientIntegrationTest.java:
##########
@@ -337,8 +349,27 @@ public void startJetty() throws Exception {
fail("TESTING FAILURE: could not grab requested port.");
}
this.port = newPort;
- // System.out.println("waiting.........");
- // Thread.sleep(5000);
+ }
+ }
+
+ private static class LBClientHolder implements AutoCloseable {
Review Comment:
The holder is just to avoid copy/paste in these test methods. I'd rather
test the actual class and not a subclass.
##########
solr/solrj/src/java/org/apache/solr/client/solrj/impl/LBHttpSolrClientBase.java:
##########
@@ -0,0 +1,288 @@
+/*
+ * 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.solr.client.solrj.impl;
+
+import static org.apache.solr.common.params.CommonParams.ADMIN_PATHS;
+
+import java.io.IOException;
+import java.net.ConnectException;
+import java.net.SocketException;
+import java.net.SocketTimeoutException;
+import java.util.Arrays;
+import java.util.Set;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicReference;
+import org.apache.solr.client.solrj.ResponseParser;
+import org.apache.solr.client.solrj.SolrClient;
+import org.apache.solr.client.solrj.SolrServerException;
+import org.apache.solr.client.solrj.request.IsUpdateRequest;
+import org.apache.solr.client.solrj.request.RequestWriter;
+import org.apache.solr.common.SolrException;
+import org.apache.solr.common.util.NamedList;
+import org.slf4j.MDC;
+
+/**
+ * LBHttp2SolrClient or "LoadBalanced LBHttp2SolrClient" is a load balancing
wrapper around {@link
+ * Http2SolrClient}. This is useful when you have multiple Solr endpoints and
requests need to be
+ * Load Balanced among them.
+ *
+ * <p>Do <b>NOT</b> use this class for indexing in leader/follower scenarios
since documents must be
+ * sent to the correct leader; no inter-node routing is done.
+ *
+ * <p>In SolrCloud (leader/replica) scenarios, it is usually better to use
{@link CloudSolrClient},
+ * but this class may be used for updates because the server will forward them
to the appropriate
+ * leader.
+ *
+ * <p>It offers automatic failover when a server goes down, and it detects
when the server comes
+ * back up.
+ *
+ * <p>Load balancing is done using a simple round-robin on the list of
endpoints. Endpoint URLs are
+ * expected to point to the Solr "root" path (i.e. "/solr").
+ *
+ * <blockquote>
+ *
+ * <pre>
+ * SolrClient client = new LBHttp2SolrClient.Builder(http2SolrClient,
+ * new LBSolrClient.Endpoint("http://host1:8080/solr";), new
LBSolrClient.Endpoint("http://host2:8080/solr";))
+ * .build();
+ * </pre>
+ *
+ * </blockquote>
+ *
+ * Users who wish to balance traffic across a specific set of replicas or
cores may specify each
+ * endpoint as a root-URL and core-name pair. For example:
+ *
+ * <blockquote>
+ *
+ * <pre>
+ * SolrClient client = new LBHttp2SolrClient.Builder(http2SolrClient,
+ * new LBSolrClient.Endpoint("http://host1:8080/solr";, "coreA"),
+ * new LBSolrClient.Endpoint("http://host2:8080/solr";, "coreB"))
+ * .build();
+ * </pre>
+ *
+ * </blockquote>
+ *
+ * <p>If a request to an endpoint fails by an IOException due to a connection
timeout or read
+ * timeout then the host is taken off the list of live endpoints and moved to
a 'dead endpoint list'
+ * and the request is resent to the next live endpoint. This process is
continued till it tries all
+ * the live endpoints. If at least one endpoint is alive, the request
succeeds, and if not it fails.
+ *
+ * <p>Dead endpoints are periodically healthchecked on a fixed interval
controlled by {@link
+ * LBHttp2SolrClient.Builder#setAliveCheckInterval(int, TimeUnit)}. The
default is set to one
+ * minute.
+ *
+ * <p><b>When to use this?</b><br>
+ * This can be used as a software load balancer when you do not wish to set up
an external load
+ * balancer. Alternatives to this code are to use a dedicated hardware load
balancer or using Apache
+ * httpd with mod_proxy_balancer as a load balancer. See <a
+ * href="http://en.wikipedia.org/wiki/Load_balancing_(computing)">Load
balancing on Wikipedia</a>
+ *
+ * @since solr 8.0
+ */
+public abstract class LBHttpSolrClientBase<C extends HttpSolrClientBase>
extends LBSolrClient {
Review Comment:
Yes, we do not need to subclass and I agree a generic LBHttpSolrClient would
be better than this. Doing this would be an API change, and although we can
change APIs with 10.0 coming, I wonder if it is worth annoying our users for
what seems like a very slight improvement?
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