Github user rmetzger commented on a diff in the pull request:
https://github.com/apache/flink/pull/1305#discussion_r45544375
--- Diff:
flink-contrib/flink-streaming-contrib/src/main/java/org/apache/flink/contrib/streaming/state/DbStateHandle.java
---
@@ -0,0 +1,88 @@
+/*
+ * 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.flink.contrib.streaming.state;
+
+import static org.apache.flink.contrib.streaming.state.SQLRetrier.retry;
+
+import java.io.IOException;
+import java.io.Serializable;
+import java.util.concurrent.Callable;
+
+import org.apache.flink.runtime.state.StateHandle;
+import org.apache.flink.util.InstantiationUtil;
+import org.eclipse.jetty.util.log.Log;
+
+/**
+ * State handle implementation for storing checkpoints as byte arrays in
+ * databases using the {@link MySqlAdapter} defined in the {@link
DbBackendConfig}.
+ *
+ */
+public class DbStateHandle<S> implements Serializable, StateHandle<S> {
+
+ private static final long serialVersionUID = 1L;
+
+ private final String jobId;
+ private final DbBackendConfig dbConfig;
+
+ private final long checkpointId;
+ private final long checkpointTs;
+
+ private final long handleId;
+
+ public DbStateHandle(String jobId, long checkpointId, long
checkpointTs, long handleId, DbBackendConfig dbConfig) {
+ this.checkpointId = checkpointId;
+ this.handleId = handleId;
+ this.jobId = jobId;
+ this.dbConfig = dbConfig;
+ this.checkpointTs = checkpointTs;
+ }
+
+ protected byte[] getBytes() throws IOException {
+ return retry(new Callable<byte[]>() {
+ public byte[] call() throws Exception {
+ try (ShardedConnection con =
dbConfig.createShardedConnection()) {
+ return
dbConfig.getDbAdapter().getCheckpoint(jobId, con.getFirst(), checkpointId,
checkpointTs, handleId);
+ }
+ }
+ }, dbConfig.getMaxNumberOfSqlRetries(),
dbConfig.getSleepBetweenSqlRetries());
+ }
+
+ @Override
+ public void discardState() {
+ try {
+ retry(new Callable<Boolean>() {
+ public Boolean call() throws Exception {
+ try (ShardedConnection con =
dbConfig.createShardedConnection()) {
+
dbConfig.getDbAdapter().deleteCheckpoint(jobId, con.getFirst(), checkpointId,
checkpointTs, handleId);
+ }
+ return true;
+ }
+ }, dbConfig.getMaxNumberOfSqlRetries(),
dbConfig.getSleepBetweenSqlRetries());
+ } catch (IOException e) {
+ // We don't want to fail the job here, but log the
error.
+ if (Log.isDebugEnabled()) {
--- End diff --
We could add a checkstyle rule for that, but I would like to solve the
problem in a different way: I recently opened a JIRA for checking whether a
Flink module is only using dependencies it has explicitly declared (forbidding
to rely on transitive dependencies). WIth that check, we would also identify
cases like this one.
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