zentol commented on code in PR #3:
URL:
https://github.com/apache/flink-connector-cassandra/pull/3#discussion_r1087821967
##########
flink-connector-cassandra/src/main/java/org/apache/flink/connector/cassandra/source/split/CassandraSplit.java:
##########
@@ -48,6 +52,30 @@ public CassandraSplitState toSplitState() {
return new CassandraSplitState(new HashSet<>(ringRanges), splitId());
}
+ public void serialize(ObjectOutputStream objectOutputStream) throws
IOException {
Review Comment:
let's make this package private. Personally I'd move all of it into the
serializer, but I can see why it could be useful to have it here.
For symmetry I'd prefer this method to be static and accept a CassandraSplit
instance.
##########
flink-connector-cassandra/src/main/java/org/apache/flink/connector/cassandra/source/split/CassandraSplit.java:
##########
@@ -48,6 +52,30 @@ public CassandraSplitState toSplitState() {
return new CassandraSplitState(new HashSet<>(ringRanges), splitId());
}
+ public void serialize(ObjectOutputStream objectOutputStream) throws
IOException {
+ objectOutputStream.writeInt(ringRanges.size());
+ for (RingRange ringRange : ringRanges) {
+ objectOutputStream.writeObject(ringRange.getStart());
+ objectOutputStream.writeObject(ringRange.getEnd());
+ }
+ }
+
+ public static CassandraSplit deserialize(ObjectInputStream
objectInputStream)
+ throws IOException {
+ try {
+ final int nbRingRanges = objectInputStream.readInt();
+ Set<RingRange> ringRanges = new HashSet<>(nbRingRanges);
Review Comment:
note: Passing npRingRanges won't have the desired effect of avoiding
allocations, since the backing map is resized when the map is filled to a
certain load. In fact you've guaranteed that the map will be resized at least
once.
##########
flink-connector-cassandra/src/main/java/org/apache/flink/connector/cassandra/source/reader/CassandraSplitReader.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 org.apache.flink.connector.cassandra.source.reader;
+
+import org.apache.flink.annotation.VisibleForTesting;
+import org.apache.flink.connector.base.source.reader.RecordsBySplits;
+import org.apache.flink.connector.base.source.reader.RecordsWithSplitIds;
+import org.apache.flink.connector.base.source.reader.splitreader.SplitReader;
+import org.apache.flink.connector.base.source.reader.splitreader.SplitsChange;
+import org.apache.flink.connector.cassandra.source.split.CassandraSplit;
+import org.apache.flink.connector.cassandra.source.split.CassandraSplitState;
+import org.apache.flink.connector.cassandra.source.split.RingRange;
+import org.apache.flink.streaming.connectors.cassandra.ClusterBuilder;
+
+import com.datastax.driver.core.Cluster;
+import com.datastax.driver.core.ColumnMetadata;
+import com.datastax.driver.core.Metadata;
+import com.datastax.driver.core.PreparedStatement;
+import com.datastax.driver.core.ResultSet;
+import com.datastax.driver.core.Session;
+import com.datastax.driver.core.Token;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.annotation.Nullable;
+
+import java.math.BigInteger;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import java.util.stream.Collectors;
+
+/**
+ * {@link SplitReader} for Cassandra source. This class is responsible for
fetching the records as
+ * {@link CassandraRow}. For that, it executes a range query (query that
outputs records belonging
+ * to a {@link RingRange}) based on the user specified query. This class
manages the Cassandra
+ * cluster and session.
+ */
+public class CassandraSplitReader implements SplitReader<CassandraRow,
CassandraSplit> {
+
+ private static final Logger LOG =
LoggerFactory.getLogger(CassandraSplitReader.class);
+ public static final String SELECT_REGEXP = "(?i)select .+ from
(\\w+)\\.(\\w+).*;$";
+
+ private final Cluster cluster;
+ private final Session session;
+ private final Set<CassandraSplitState> unprocessedSplits;
+ private final AtomicBoolean wakeup = new AtomicBoolean(false);
+ private final String query;
+
+ public CassandraSplitReader(ClusterBuilder clusterBuilder, String query) {
+ // need a thread safe set
+ this.unprocessedSplits = ConcurrentHashMap.newKeySet();
+ this.query = query;
+ cluster = clusterBuilder.getCluster();
+ session = cluster.connect();
+ }
+
+ @Override
+ public RecordsWithSplitIds<CassandraRow> fetch() {
+ Map<String, Collection<CassandraRow>> recordsBySplit = new HashMap<>();
+ Set<String> finishedSplits = new HashSet<>();
+ Metadata clusterMetadata = cluster.getMetadata();
+
+ String partitionKey = getPartitionKey(clusterMetadata);
+ String finalQuery = generateRangeQuery(query, partitionKey);
+ PreparedStatement preparedStatement = session.prepare(finalQuery);
+ // Set wakeup to false to start consuming.
+ wakeup.compareAndSet(true, false);
+ for (CassandraSplitState cassandraSplitState : unprocessedSplits) {
Review Comment:
Of course the splits are scoped to the reader.
But say, if parallelism=1, then you're reading all records from all splits
into memory.
Even with a higher parallelism cases I don't see this working very well for
larger tables.
While the split reader API docs are a bit unclear on this, you _are_ allowed
to exist the fetch call early. If you adjust the splits accordingly fetch()
will be called again later on and you can continue where you left off.
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