Github user revans2 commented on a diff in the pull request:
https://github.com/apache/storm/pull/1693#discussion_r97423227
--- Diff:
examples/storm-starter/src/jvm/org/apache/storm/starter/streams/StateQueryExample.java
---
@@ -0,0 +1,110 @@
+/**
+ * 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.storm.starter.streams;
+
+import org.apache.storm.Config;
+import org.apache.storm.LocalCluster;
+import org.apache.storm.StormSubmitter;
+import org.apache.storm.spout.SpoutOutputCollector;
+import org.apache.storm.streams.Pair;
+import org.apache.storm.streams.Stream;
+import org.apache.storm.streams.StreamBuilder;
+import org.apache.storm.streams.StreamState;
+import org.apache.storm.streams.operations.mappers.ValueMapper;
+import org.apache.storm.task.TopologyContext;
+import org.apache.storm.testing.TestWordSpout;
+import org.apache.storm.topology.OutputFieldsDeclarer;
+import org.apache.storm.topology.base.BaseRichSpout;
+import org.apache.storm.tuple.Fields;
+import org.apache.storm.tuple.Values;
+import org.apache.storm.utils.Utils;
+
+import java.util.Map;
+
+/**
+ * An example that uses {@link Stream#stateQuery(StreamState)} to query
the state
+ * <p>
+ * You should start a local redis instance before running the 'storm jar'
command. By default
+ * the connection will be attempted at localhost:6379. The default
+ * RedisKeyValueStateProvider parameters can be overridden in
conf/storm.yaml, for e.g.
+ * <p/>
+ * <pre>
+ * topology.state.provider.config: '{"keyClass":"...", "valueClass":"...",
+ * "keySerializerClass":"...", "valueSerializerClass":"...",
+ * "jedisPoolConfig":{"host":"localhost", "port":6379,
+ * "timeout":2000, "database":0, "password":"xyz"}}'
+ * </pre>
+ */
+public class StateQueryExample {
+ public static void main(String[] args) throws Exception {
+ StreamBuilder builder = new StreamBuilder();
+ StreamState<String, Long> ss = builder.newStream(new
TestWordSpout(), new ValueMapper<String>(0), 2)
+ .mapToPair(w -> Pair.of(w, 1))
+ .updateStateByKey(0L, (count, val) -> count + 1);
+
+ /*
+ * A stream of words emitted by the QuerySpout is used as
+ * the keys to query the state.
+ */
+ builder.newStream(new QuerySpout(), new ValueMapper<String>(0))
+ /*
+ * Queries the state and emits the
+ * matching (key, value) as results. The stream state
returned
+ * by the updateStateByKey is passed as the argument to
stateQuery.
+ */
+ .stateQuery(ss).print();
+
+ Config config = new Config();
+ // use redis based state store for persistence
+ config.put(Config.TOPOLOGY_STATE_PROVIDER,
"org.apache.storm.redis.state.RedisKeyValueStateProvider");
+
+ if (args.length > 0) {
+ config.setNumWorkers(1);
+ StormSubmitter.submitTopologyWithProgressBar(args[0], config,
builder.build());
+ } else {
+ LocalCluster cluster = new LocalCluster();
+ cluster.submitTopology("test", config, builder.build());
--- End diff --
Again minor nit of AutoCloseable
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