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https://issues.apache.org/jira/browse/STORM-1175?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15068514#comment-15068514
]
ASF GitHub Bot commented on STORM-1175:
---------------------------------------
Github user Parth-Brahmbhatt commented on a diff in the pull request:
https://github.com/apache/storm/pull/939#discussion_r48282204
--- Diff: storm-core/src/jvm/backtype/storm/spout/CheckpointSpout.java ---
@@ -0,0 +1,280 @@
+/**
+ * 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 backtype.storm.spout;
+
+import backtype.storm.Config;
+import backtype.storm.state.KeyValueState;
+import backtype.storm.state.StateFactory;
+import backtype.storm.task.TopologyContext;
+import backtype.storm.topology.OutputFieldsDeclarer;
+import backtype.storm.topology.base.BaseRichSpout;
+import backtype.storm.tuple.Fields;
+import backtype.storm.tuple.Tuple;
+import backtype.storm.tuple.Values;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.Map;
+import static backtype.storm.spout.CheckPointState.State.COMMITTED;
+import static backtype.storm.spout.CheckPointState.State.COMMITTING;
+import static backtype.storm.spout.CheckPointState.State.PREPARING;
+
+/**
+ * Emits checkpoint tuples which is used to save the state of the {@link
backtype.storm.topology.IStatefulComponent}
+ * across the topology. If a topology contains Stateful bolts, Checkpoint
spouts are automatically added
+ * to the topology. There is only one Checkpoint task per topology.
+ * <p/>
+ * Checkpoint spout stores its internal state in a {@link KeyValueState}.
The state transitions are as follows.
+ * <p/>
+ * <pre>
+ * ROLLBACK(tx2)
+ * <------------- PREPARE(tx2)
COMMIT(tx2)
+ * COMMITTED(tx1)-------------> PREPARING(tx2) -------------->
COMMITTING(tx2) -----------------> COMMITTED (tx2)
+ *
+ *
+ * </pre>
+ */
+public class CheckpointSpout extends BaseRichSpout {
+ private static final Logger LOG =
LoggerFactory.getLogger(CheckpointSpout.class);
+
+ public static final String CHECKPOINT_STREAM_ID = "$checkpoint";
+ public static final String CHECKPOINT_COMPONENT_ID =
"$checkpointspout";
+ public static final String CHECKPOINT_FIELD_TXID = "txid";
+ public static final String CHECKPOINT_FIELD_ACTION = "action";
+ public static final String CHECKPOINT_ACTION_PREPARE = "prepare";
+ public static final String CHECKPOINT_ACTION_COMMIT = "commit";
+ public static final String CHECKPOINT_ACTION_ROLLBACK = "rollback";
+ public static final String CHECKPOINT_ACTION_INITSTATE = "initstate";
+
+ private static final String TX_STATE_KEY = "__state";
+ private static final int DEFAULT_CHECKPOINT_INTERVAL = 1000; // every
sec
+
+ private TopologyContext context;
+ private SpoutOutputCollector collector;
+ private long lastCheckpointTs;
+ private int checkpointInterval;
+ private boolean recoveryStepInProgress;
+ private boolean checkpointStepInProgress;
+ private boolean recovering;
+ private KeyValueState<String, CheckPointState> checkpointState;
+
+ @Override
+ public void open(Map conf, TopologyContext context,
SpoutOutputCollector collector) {
+ open(context, collector, loadCheckpointInterval(conf),
loadCheckpointState(conf, context));
+ }
+
+ // package access for unit test
+ void open(TopologyContext context, SpoutOutputCollector collector,
+ int checkpointInterval, KeyValueState<String,
CheckPointState> checkpointState) {
+ this.context = context;
+ this.collector = collector;
+ this.checkpointInterval = checkpointInterval;
+ this.checkpointState = checkpointState;
+ lastCheckpointTs = 0;
+ recoveryStepInProgress = false;
+ checkpointStepInProgress = false;
+ recovering = true;
+ }
+
+ @Override
+ public void nextTuple() {
+ if (shouldRecover()) {
+ LOG.debug("In recovery");
+ handleRecovery();
+ startProgress();
+ } else if (shouldCheckpoint()) {
+ LOG.debug("In checkpoint");
+ doCheckpoint();
+ startProgress();
+ }
+ }
+
+ @Override
+ public void ack(Object msgId) {
+ CheckPointState txState = getTxState();
+ LOG.debug("Got ack with txid {}, current txState {}", msgId,
txState);
+ if (txState.txid == ((Number) msgId).longValue()) {
+ if (recovering) {
+ handleRecoveryAck();
+ } else {
+ handleCheckpointAck();
+ }
+ } else {
+ LOG.warn("Ack msgid {}, txState.txid {} mismatch", msgId,
txState.txid);
+ }
+ resetProgress();
+ }
+
+ @Override
+ public void fail(Object msgId) {
+ LOG.debug("Got fail with msgid {}", msgId);
+ resetProgress();
+ }
+
+ @Override
+ public void declareOutputFields(OutputFieldsDeclarer declarer) {
+ declarer.declareStream(CHECKPOINT_STREAM_ID, new
Fields(CHECKPOINT_FIELD_TXID, CHECKPOINT_FIELD_ACTION));
+ }
+
+ @Override
+ public Map<String, Object> getComponentConfiguration() {
+ Config conf = new Config();
+ conf.put(Config.TOPOLOGY_SLEEP_SPOUT_WAIT_STRATEGY_TIME_MS, 100);
+ return conf;
+ }
+
+ public static boolean isCheckpoint(Tuple input) {
+ return CHECKPOINT_STREAM_ID.equals(input.getSourceStreamId());
+ }
+
+ /**
+ * Loads the last saved checkpoint state the from persistent storage.
+ */
+ private KeyValueState<String, CheckPointState> loadCheckpointState(Map
conf, TopologyContext ctx) {
+ String namespace = ctx.getThisComponentId() + "-" +
ctx.getThisTaskId();
+ KeyValueState<String, CheckPointState> state =
+ (KeyValueState<String, CheckPointState>)
StateFactory.getState(namespace, conf, ctx);
+ if (state.get(TX_STATE_KEY) == null) {
+ CheckPointState txState = new CheckPointState(-1, COMMITTED);
+ state.put(TX_STATE_KEY, txState);
+ state.commit();
+ LOG.debug("Initialized checkpoint spout state with txState
{}", txState);
+ } else {
+ LOG.debug("Got checkpoint spout state {}",
state.get(TX_STATE_KEY));
+ }
+ return state;
+ }
+
+ private int loadCheckpointInterval(Map stormConf) {
+ int interval;
+ if
(stormConf.containsKey(Config.TOPOLOGY_STATE_CHECKPOINT_INTERVAL)) {
+ interval = ((Number)
stormConf.get(Config.TOPOLOGY_STATE_CHECKPOINT_INTERVAL)).intValue();
+ } else {
+ interval = DEFAULT_CHECKPOINT_INTERVAL;
+ }
+ return interval;
+ }
+
+ private boolean shouldRecover() {
+ return recovering && !recoveryStepInProgress;
+ }
+
+ private boolean shouldCheckpoint() {
+ return !recovering && !checkpointStepInProgress
+ && (System.currentTimeMillis() - lastCheckpointTs) >
checkpointInterval;
+ }
+
+ private boolean shouldRollback(CheckPointState txState) {
+ return txState.state == PREPARING;
+ }
+
+ private boolean shouldCommit(CheckPointState txState) {
+ return txState.state == COMMITTING;
+ }
+
+ private boolean shouldInitState(CheckPointState txState) {
+ return txState.state == COMMITTED;
+ }
+
+ private void handleRecovery() {
+ CheckPointState txState = getTxState();
+ LOG.debug("Current txState is {}", txState);
+ if (shouldRollback(txState)) {
+ LOG.debug("Emitting rollback with txid {}", txState.txid);
+ collector.emit(CHECKPOINT_STREAM_ID, new Values(txState.txid,
CHECKPOINT_ACTION_ROLLBACK), txState.txid);
+ } else if (shouldCommit(txState)) {
+ LOG.debug("Emitting commit with txid {}", txState.txid);
+ collector.emit(CHECKPOINT_STREAM_ID, new Values(txState.txid,
CHECKPOINT_ACTION_COMMIT), txState.txid);
+ } else if (shouldInitState(txState)) {
+ LOG.debug("Emitting init state with txid {}", txState.txid);
+ collector.emit(CHECKPOINT_STREAM_ID, new Values(txState.txid,
CHECKPOINT_ACTION_INITSTATE), txState.txid);
+ }
+ startProgress();
+ }
+
+ private void handleRecoveryAck() {
--- End diff --
the state transition code seems to be repeating in handleCheckpointAck,
doCheckpoint and handleRecoveryAck. Do you think we can capture the nextState
and prevState for each state in the CheckPointState class it self so in all
these methods we can just call netxt/prevState followed by saveTxState(txState).
> State store for windowing operations
> ------------------------------------
>
> Key: STORM-1175
> URL: https://issues.apache.org/jira/browse/STORM-1175
> Project: Apache Storm
> Issue Type: Sub-task
> Reporter: Arun Mahadevan
> Assignee: Arun Mahadevan
>
> Windowing operations should be able to save the results of partial
> computations in a state store. This should persist across restarts and bolts
> should be able to look up the values from the store.
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