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https://issues.apache.org/jira/browse/STORM-1175?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15070019#comment-15070019
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ASF GitHub Bot commented on STORM-1175:
---------------------------------------
Github user harshach commented on a diff in the pull request:
https://github.com/apache/storm/pull/939#discussion_r48368972
--- 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
--- End diff --
@arunmahadevan well if you add that to defaults.yaml it will be set and
thats how the defaults has been used so far in storm. Incase if we need to
change default in the future its .yaml file change than the code change.
> 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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