Github user arunmahadevan commented on a diff in the pull request:
https://github.com/apache/storm/pull/2218#discussion_r129763573
--- 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");
+ } else {
+ statefulWindowedBolt.initState(state);
+ stateInitialized = true;
+ start();
+ }
+ }
+
+ @Override
+ public void prePrepare(long txid) {
+ if (stateInitialized) {
+ LOG.debug("Prepare streamState, txid {}", txid);
+ state.prepareCommit(txid);
+ prePrepared = true;
+ } else {
+ LOG.warn("Cannot prepare before initState");
+ }
+ }
+
+ @Override
+ public void preCommit(long txid) {
+ if (prePrepared) {
+ LOG.debug("Commit streamState, txid {}", txid);
+ state.commit(txid);
+ } else {
+ LOG.debug("Ignoring preCommit and not committing
streamState.");
+ }
+ }
+
+ @Override
+ public void preRollback() {
+ LOG.debug("Rollback streamState, stateInitialized {}",
stateInitialized);
+ state.rollback();
+ }
+
+ @Override
+ protected WindowLifecycleListener<Tuple> newWindowLifecycleListener() {
+ return new WindowLifecycleListener<Tuple>() {
+ @Override
+ public void onExpiry(List<Tuple> events) {
+ /*
+ * NO-OP: the events are ack-ed in execute
+ */
+ }
+
+ @Override
+ public void onActivation(Supplier<Iterator<Tuple>> eventsIt,
+ Supplier<Iterator<Tuple>> newEventsIt,
+ Supplier<Iterator<Tuple>> expiredIt,
+ Long timestamp) {
+ /*
+ * Here we don't set the tuples in
windowedOutputCollector's context and emit un-anchored.
+ * The checkpoint tuple will trigger a checkpoint in the
receiver with the emitted tuples.
+ */
+ boltExecute(eventsIt, newEventsIt, expiredIt, timestamp);
+ state.clearIteratorPins();
+ }
+ };
+ }
+
+ private void init(Map<String, Object> topoConf, TopologyContext
context, OutputCollector collector,
+ KeyValueState<Long, WindowPartition<Tuple>>
windowState,
+ KeyValueState<String, Deque<Long>> partitionState,
+ KeyValueState<String, Optional<?>>
windowSystemState) {
+ topologyContext = context;
+ outputCollector = collector;
+ state = new WindowState<>(windowState, partitionState,
windowSystemState, this::getState,
+ statefulWindowedBolt.maxEventsInMemory());
+ }
+
+ private KeyValueState<Long, WindowPartition<Tuple>>
getWindowState(Map<String, Object> topoConf, TopologyContext context) {
+ String namespace = context.getThisComponentId() + "-" +
context.getThisTaskId() + "-window";
+ return (KeyValueState<Long, WindowPartition<Tuple>>)
StateFactory.getState(namespace, topoConf, context);
+ }
+
+ private KeyValueState<String, Deque<Long>>
getPartitionState(Map<String, Object> topoConf, TopologyContext context) {
+ String namespace = context.getThisComponentId() + "-" +
context.getThisTaskId() + "-window-partitions";
+ return (KeyValueState<String, Deque<Long>>)
StateFactory.getState(namespace, topoConf, context);
+ }
+
+ private KeyValueState<String, Optional<?>>
getWindowSystemState(Map<String, Object> topoConf, TopologyContext context) {
+ String namespace = context.getThisComponentId() + "-" +
context.getThisTaskId() + "-window-systemstate";
+ return (KeyValueState<String, Optional<?>>)
StateFactory.getState(namespace, topoConf, context);
+ }
+
+ // a wrapper around the window related states that are checkpointed
+ private static class WindowState<T> extends
AbstractCollection<Event<T>> {
+ // number of events per window-partition
+ private static final int PARTITION_SZ = 1000;
+ private static final int MIN_PARTITIONS = 10;
+ private static final String PARTITION_IDS_KEY = "pk";
+ private final KeyValueState<String, Deque<Long>> partitionIds;
+ private final KeyValueState<Long, WindowPartition<T>>
windowPartitions;
+ private final KeyValueState<String, Optional<?>> windowSystemState;
+ // ordered partition keys
+ private Deque<Long> pids;
+ private volatile long latestPartitionId;
+ private WindowPartitionCache<Long, WindowPartition<T>> cache;
+ private Supplier<Map<String, Optional<?>>>
windowSystemStateSupplier;
+ private final ReentrantLock partitionIdsLock = new
ReentrantLock(true);
+ private final ReentrantLock windowPartitionsLock = new
ReentrantLock(true);
+ private final long maxEventsInMemory;
+ private WindowPartition<T> latestPartition;
+ private Set<Long> iteratorPins = new HashSet<>();
+
+ WindowState(KeyValueState<Long, WindowPartition<T>>
windowPartitions,
+ KeyValueState<String, Deque<Long>> partitionIds,
+ KeyValueState<String, Optional<?>> windowSystemState,
+ Supplier<Map<String, Optional<?>>>
windowSystemStateSupplier,
+ long maxEventsInMemory) {
+ this.windowPartitions = windowPartitions;
+ this.partitionIds = partitionIds;
+ this.windowSystemState = windowSystemState;
+ this.windowSystemStateSupplier = windowSystemStateSupplier;
+ this.maxEventsInMemory = Math.max(PARTITION_SZ *
MIN_PARTITIONS, maxEventsInMemory);
+ initCache();
+ initPartitions();
+ }
+
+ @Override
+ public boolean add(Event<T> event) {
+ if (latestPartition.size() >= PARTITION_SZ) {
+ cache.unpin(latestPartition.getId());
+ latestPartition = getPinnedPartition(getNextPartitionId());
+ }
+ latestPartition.add(event);
+ return true;
+ }
+
+ @Override
+ public Iterator<Event<T>> iterator() {
+
+ return new Iterator<Event<T>>() {
+ private Iterator<Long> ids = getIds();
+ private Iterator<Event<T>> current = emptyIterator();
+ private Iterator<Event<T>> removeFrom;
+ private WindowPartition<T> curPartition;
+
+ private Iterator<Long> getIds() {
+ try {
+ partitionIdsLock.lock();
+ LOG.debug("Iterator pids: {}", pids);
+ return new ArrayList<>(pids).iterator();
+ } finally {
+ partitionIdsLock.unlock();
+ }
+ }
+
+ @Override
+ public void remove() {
+ if (removeFrom == null) {
+ throw new IllegalStateException("No calls to
next() since last call to remove()");
+ }
+ removeFrom.remove();
+ removeFrom = null;
+ }
+
+ @Override
+ public boolean hasNext() {
+ boolean curHasNext = current.hasNext();
+ while (!curHasNext && ids.hasNext()) {
+ if (curPartition != null) {
+ unpin(curPartition.getId());
+ }
+ curPartition = getPinnedPartition(ids.next());
+ iteratorPins.add(curPartition.getId());
+ if (curPartition != null) {
+ current = curPartition.iterator();
+ curHasNext = current.hasNext();
+ }
+ }
+ // un-pin the last partition
+ if (!curHasNext && curPartition != null) {
+ unpin(curPartition.getId());
+ curPartition = null;
+ }
+ return curHasNext;
+ }
+
+ @Override
+ public Event<T> next() {
+ if (!hasNext()) {
+ throw new NoSuchElementException();
+ }
+ removeFrom = current;
+ return current.next();
+ }
+
+ private void unpin(long id) {
+ cache.unpin(id);
+ iteratorPins.remove(id);
+ }
+ };
+ }
+
+ void clearIteratorPins() {
+ LOG.debug("clearIteratorPins '{}'", iteratorPins);
+ Iterator<Long> it = iteratorPins.iterator();
+ while (it.hasNext()) {
+ cache.unpin(it.next());
+ it.remove();
+ }
+ }
+
+ @Override
+ public int size() {
+ throw new UnsupportedOperationException();
+ }
+
+ void prepareCommit(long txid) {
+ flush();
+ partitionIds.prepareCommit(txid);
+ windowPartitions.prepareCommit(txid);
+ windowSystemState.prepareCommit(txid);
+ }
+
+ void commit(long txid) {
+ partitionIds.commit(txid);
+ windowPartitions.commit(txid);
+ windowSystemState.commit(txid);
+ }
+
+ void rollback() {
+ partitionIds.rollback();
+ windowPartitions.rollback();
+ windowSystemState.rollback();
+ }
+
+ private void initPartitions() {
+ pids = partitionIds.get(PARTITION_IDS_KEY, new LinkedList<>());
+ if (pids.isEmpty()) {
+ pids.add(0L);
+ partitionIds.put(PARTITION_IDS_KEY, pids);
+ } else {
+ latestPartitionId = pids.peekLast();
--- End diff --
yes, it was initialized to 0 being a member variable, anyways I will remove
the else to make it clearer.
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