Github user rmetzger commented on a diff in the pull request:
https://github.com/apache/flink/pull/1771#discussion_r58557862
--- Diff:
flink-streaming-connectors/flink-connector-cassandra/src/main/java/org/apache/flink/streaming/connectors/cassandra/CassandraSink.java
---
@@ -0,0 +1,313 @@
+/**
+ * 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
+ * <p/>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p/>
+ * 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.streaming.connectors.cassandra;
+
+import com.datastax.driver.core.Cluster;
+import org.apache.flink.api.common.typeinfo.TypeInformation;
+import org.apache.flink.api.common.typeutils.TypeSerializer;
+import org.apache.flink.api.java.tuple.Tuple;
+import org.apache.flink.api.java.typeutils.TupleTypeInfo;
+import org.apache.flink.streaming.api.datastream.DataStream;
+import org.apache.flink.streaming.api.datastream.DataStreamSink;
+import
org.apache.flink.streaming.api.datastream.SingleOutputStreamOperator;
+import org.apache.flink.streaming.api.operators.ChainingStrategy;
+import org.apache.flink.streaming.api.transformations.SinkTransformation;
+import org.apache.flink.streaming.api.transformations.StreamTransformation;
+import org.apache.flink.streaming.runtime.operators.CheckpointCommitter;
+
+import java.util.UUID;
+
+/**
+ * This class wraps different Cassandra sink implementations to provide a
common interface for all of them.
+ *
+ * @param <IN> input type
+ */
+public class CassandraSink<IN> {
+ private static final String jobID =
UUID.randomUUID().toString().replace("-", "_");
+ private final boolean useDataStreamSink;
+ private DataStreamSink<IN> sink1;
+ private SingleOutputStreamOperator<IN> sink2;
+
+ private CassandraSink(DataStreamSink<IN> sink) {
+ sink1 = sink;
+ useDataStreamSink = true;
+ }
+
+ private CassandraSink(SingleOutputStreamOperator<IN> sink) {
+ sink2 = sink;
+ useDataStreamSink = false;
+ }
+
+ private SinkTransformation<IN> getSinkTransformation() {
+ return sink1.getTransformation();
+ }
+
+ private StreamTransformation<IN> getStreamTransformation() {
+ return sink2.getTransformation();
+ }
+
+ /**
+ * Sets the name of this sink. This name is
+ * used by the visualization and logging during runtime.
+ *
+ * @return The named sink.
+ */
+ public CassandraSink<IN> name(String name) {
+ if (useDataStreamSink) {
+ getSinkTransformation().setName(name);
+ } else {
+ getStreamTransformation().setName(name);
+ }
+ return this;
+ }
+
+ /**
+ * Sets an ID for this operator.
+ * <p/>
+ * <p>The specified ID is used to assign the same operator ID across job
+ * submissions (for example when starting a job from a savepoint).
+ * <p/>
+ * <p><strong>Important</strong>: this ID needs to be unique per
+ * transformation and job. Otherwise, job submission will fail.
+ *
+ * @param uid The unique user-specified ID of this transformation.
+ * @return The operator with the specified ID.
+ */
+ public CassandraSink<IN> uid(String uid) {
+ if (useDataStreamSink) {
+ getSinkTransformation().setUid(uid);
+ } else {
+ getStreamTransformation().setUid(uid);
+ }
+ return this;
+ }
+
+ /**
+ * Sets the parallelism for this sink. The degree must be higher than
zero.
+ *
+ * @param parallelism The parallelism for this sink.
+ * @return The sink with set parallelism.
+ */
+ public CassandraSink<IN> setParallelism(int parallelism) {
+ if (useDataStreamSink) {
+ getSinkTransformation().setParallelism(parallelism);
+ } else {
+ getStreamTransformation().setParallelism(parallelism);
+ }
+ return this;
+ }
+
+ /**
+ * Turns off chaining for this operator so thread co-location will not
be
+ * used as an optimization.
+ * <p/>
+ * <p/>
+ * Chaining can be turned off for the whole
+ * job by {@link
org.apache.flink.streaming.api.environment.StreamExecutionEnvironment#disableOperatorChaining()}
+ * however it is not advised for performance considerations.
+ *
+ * @return The sink with chaining disabled
+ */
+ public CassandraSink<IN> disableChaining() {
+ if (useDataStreamSink) {
+
getSinkTransformation().setChainingStrategy(ChainingStrategy.NEVER);
+ } else {
+
getStreamTransformation().setChainingStrategy(ChainingStrategy.NEVER);
+ }
+ return this;
+ }
+
+ /**
+ * Sets the slot sharing group of this operation. Parallel instances of
+ * operations that are in the same slot sharing group will be
co-located in the same
+ * TaskManager slot, if possible.
+ * <p/>
+ * <p>Operations inherit the slot sharing group of input operations if
all input operations
+ * are in the same slot sharing group and no slot sharing group was
explicitly specified.
+ * <p/>
+ * <p>Initially an operation is in the default slot sharing group. An
operation can be put into
+ * the default group explicitly by setting the slot sharing group to
{@code "default"}.
+ *
+ * @param slotSharingGroup The slot sharing group name.
+ */
+ public CassandraSink<IN> slotSharingGroup(String slotSharingGroup) {
+ if (useDataStreamSink) {
+
getSinkTransformation().setSlotSharingGroup(slotSharingGroup);
+ } else {
+
getStreamTransformation().setSlotSharingGroup(slotSharingGroup);
+ }
+ return this;
+ }
+
+ /**
+ * Writes a DataStream into a Cassandra database.
+ *
+ * @param input input DataStream
+ * @param <IN> input type
+ * @return CassandraSinkBuilder, to further configure the sink
+ */
+ public static <IN, T extends Tuple> CassandraSinkBuilder<IN>
addSink(DataStream<IN> input) {
+ if (input.getType() instanceof TupleTypeInfo) {
+ DataStream<T> tupleInput = (DataStream<T>) input;
+ return (CassandraSinkBuilder<IN>) new
CassandraTupleSinkBuilder<>(tupleInput, tupleInput.getType(),
tupleInput.getType().createSerializer(tupleInput.getExecutionEnvironment().getConfig()));
+ } else {
+ return new CassandraPojoSinkBuilder<>(input,
input.getType(),
input.getType().createSerializer(input.getExecutionEnvironment().getConfig()));
+ }
+ }
+
+ public abstract static class CassandraSinkBuilder<IN> {
+ protected final DataStream<IN> input;
+ protected final TypeSerializer<IN> serializer;
+ protected final TypeInformation<IN> typeInfo;
+ protected ClusterBuilder builder;
+ protected String query;
+ protected CheckpointCommitter committer;
+ protected boolean isWriteAheadLogEnabled;
+
+ public CassandraSinkBuilder(DataStream<IN> input,
TypeInformation<IN> typeInfo, TypeSerializer<IN> serializer) {
+ this.input = input;
+ this.typeInfo = typeInfo;
+ this.serializer = serializer;
+ }
+
+ /**
+ * Sets the query that is to be executed for every record.
+ *
+ * @param query query to use
+ * @return this builder
+ */
+ public CassandraSinkBuilder<IN> setQuery(String query) {
+ this.query = query;
+ return this;
+ }
+
+ /**
+ * Sets the cassandra host to connect to.
+ *
+ * @param host host to connect to
+ * @return this builder
+ */
+ public CassandraSinkBuilder<IN> setHost(String host) {
+ return setHost(host, 9042);
+ }
+
+ /**
+ * Sets the cassandra host/port to connect to.
+ *
+ * @param host host to connect to
+ * @param port port to connect to
+ * @return this builder
+ */
+ public CassandraSinkBuilder<IN> setHost(final String host,
final int port) {
+ builder = new ClusterBuilder() {
+ @Override
+ protected Cluster buildCluster(Cluster.Builder
builder) {
+ return
builder.addContactPoint(host).withPort(port).build();
+ }
+ };
+ return this;
+ }
+
+ /**
+ * Sets the ClusterBuilder for this sink. A ClusterBuilder is
used to configure the connection to cassandra.
+ *
+ * @param builder ClusterBuilder to configure the connection to
cassandra
+ * @return this builder
+ */
+ public CassandraSinkBuilder<IN>
setClusterBuilder(ClusterBuilder builder) {
+ this.builder = builder;
+ return this;
+ }
+
+ /**
+ * Enables the write-ahead log, which allows exactly-once
processing for non-deterministic algorithms that use
+ * idempotent updates.
+ *
+ * @return this builder
+ */
+ public CassandraSinkBuilder<IN> enableWriteAheadLog() {
+ this.isWriteAheadLogEnabled = true;
+ return this;
+ }
+
+ /**
+ * Enables the write-ahead log, which allows exactly-once
processing for non-deterministic algorithms that use
+ * idempotent updates.
+ *
+ * @param committer CheckpointCommitter, that stores
informationa bout completed checkpoints in an external
+ * resource. By default this information is
stored within a separate table within Cassandra.
+ * @return this builder
+ */
+ public CassandraSinkBuilder<IN>
enableWriteAheadLog(CheckpointCommitter committer) {
+ this.isWriteAheadLogEnabled = true;
+ this.committer = committer;
+ return this;
+ }
+
+ /**
+ * Finalizes the configuration of this sink.
+ *
+ * @return finalized sink
+ * @throws Exception
+ */
+ public abstract CassandraSink<IN> build() throws Exception;
+
+ protected void sanityCheck() {
--- End diff --
very good!
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