Github user arunmahadevan commented on a diff in the pull request:
https://github.com/apache/storm/pull/2218#discussion_r129763468
--- Diff:
storm-client/src/jvm/org/apache/storm/topology/PersistentWindowedBoltExecutor.java
---
@@ -0,0 +1,563 @@
+/**
+ * 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.topology;
+
+import java.util.AbstractCollection;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Deque;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.NoSuchElementException;
+import java.util.Optional;
+import java.util.Set;
+import java.util.concurrent.ConcurrentLinkedQueue;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.function.Supplier;
+
+import org.apache.storm.Config;
+import org.apache.storm.state.KeyValueState;
+import org.apache.storm.state.State;
+import org.apache.storm.state.StateFactory;
+import org.apache.storm.task.OutputCollector;
+import org.apache.storm.task.TopologyContext;
+import org.apache.storm.tuple.Tuple;
+import org.apache.storm.windowing.DefaultEvictionContext;
+import org.apache.storm.windowing.Event;
+import org.apache.storm.windowing.EventImpl;
+import org.apache.storm.windowing.WindowLifecycleListener;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import static java.util.Collections.emptyIterator;
+import static org.apache.storm.topology.WindowPartitionCache.CacheLoader;
+import static org.apache.storm.topology.WindowPartitionCache.RemovalCause;
+import static
org.apache.storm.topology.WindowPartitionCache.RemovalListener;
+
+/**
+ * Wraps a {@link IStatefulWindowedBolt} and handles the execution. Uses
state and the underlying
+ * checkpointing mechanisms to save the tuples in window to state. The
tuples are also kept in-memory
+ * by transparently caching the window partitions and checkpointing them
as needed.
+ */
+public class PersistentWindowedBoltExecutor<T extends State> extends
WindowedBoltExecutor implements IStatefulBolt<T> {
+ private static final Logger LOG =
LoggerFactory.getLogger(PersistentWindowedBoltExecutor.class);
+ private final IStatefulWindowedBolt<T> statefulWindowedBolt;
+ private transient TopologyContext topologyContext;
+ private transient OutputCollector outputCollector;
+ private transient WindowState<Tuple> state;
+ private transient boolean stateInitialized;
+ private transient boolean prePrepared;
+
+ public PersistentWindowedBoltExecutor(IStatefulWindowedBolt<T> bolt) {
+ super(bolt);
+ statefulWindowedBolt = bolt;
+ }
+
+ @Override
+ public void prepare(Map<String, Object> topoConf, TopologyContext
context, OutputCollector collector) {
+ List<String> registrations = (List<String>)
topoConf.getOrDefault(Config.TOPOLOGY_STATE_KRYO_REGISTER, new ArrayList<>());
+ registrations.add(ConcurrentLinkedQueue.class.getName());
+ registrations.add(LinkedList.class.getName());
+ registrations.add(AtomicInteger.class.getName());
+ registrations.add(EventImpl.class.getName());
+ registrations.add(WindowPartition.class.getName());
+ registrations.add(DefaultEvictionContext.class.getName());
+ topoConf.put(Config.TOPOLOGY_STATE_KRYO_REGISTER, registrations);
+ prepare(topoConf, context, collector,
+ getWindowState(topoConf, context),
+ getPartitionState(topoConf, context),
+ getWindowSystemState(topoConf, context));
+ }
+
+ // package access for unit tests
+ void prepare(Map<String, Object> topoConf, TopologyContext context,
OutputCollector collector,
+ KeyValueState<Long, WindowPartition<Tuple>> windowState,
+ KeyValueState<String, Deque<Long>> partitionState,
+ KeyValueState<String, Optional<?>> windowSystemState) {
+ init(topoConf, context, collector, windowState, partitionState,
windowSystemState);
+ doPrepare(topoConf, context, new NoAckOutputCollector(collector),
state, true);
+ Map<String, Optional<?>> wstate = new HashMap<>();
+ windowSystemState.forEach(s -> wstate.put(s.getKey(),
s.getValue()));
+ restoreState(wstate);
+ }
+
+ @Override
+ protected void start() {
+ if (stateInitialized) {
+ super.start();
+ } else {
+ LOG.debug("Will invoke start after state is initialized");
+ }
+ }
+
+ @Override
+ public void execute(Tuple input) {
+ if (!stateInitialized) {
+ throw new IllegalStateException("execute invoked before
initState with input tuple " + input);
+ }
+ super.execute(input);
+ // StatefulBoltExecutor does the actual ack when the state is
saved.
+ outputCollector.ack(input);
+ }
+
+ @Override
+ public void initState(T state) {
+ if (stateInitialized) {
+ LOG.warn("State is already initialized. Ignoring initState");
--- End diff --
If a worker crashes, all worker's state are rolled back and an initState
message is sent across the topology so that crashed workers can initialize
their state. This is already handled in `StatefulBoltExecutor` that wraps the
`PersistentWindowedBoltExecutor` so here its Ok to throw an exception. Will
address this and revisit the others.
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