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https://issues.apache.org/jira/browse/STREAMS-478?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15783162#comment-15783162
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ASF GitHub Bot commented on STREAMS-478:
----------------------------------------
Github user steveblackmon commented on a diff in the pull request:
https://github.com/apache/incubator-streams/pull/345#discussion_r94047563
--- Diff:
streams-contrib/streams-persist-cassandra/src/main/java/org/apache/streams/cassandra/CassandraPersistWriter.java
---
@@ -0,0 +1,312 @@
+/*
+ * 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
+ *
+ * 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.streams.cassandra;
+
+import org.apache.streams.config.ComponentConfigurator;
+import org.apache.streams.config.StreamsConfigurator;
+import org.apache.streams.core.StreamsDatum;
+import org.apache.streams.core.StreamsPersistWriter;
+import org.apache.streams.jackson.StreamsJacksonMapper;
+import org.apache.streams.util.GuidUtils;
+
+import com.datastax.driver.core.BatchStatement;
+import com.datastax.driver.core.BoundStatement;
+import com.datastax.driver.core.Cluster;
+import com.datastax.driver.core.DataType;
+import com.datastax.driver.core.KeyspaceMetadata;
+import com.datastax.driver.core.Metadata;
+import com.datastax.driver.core.PreparedStatement;
+import com.datastax.driver.core.Session;
+import com.datastax.driver.core.TableMetadata;
+import com.datastax.driver.core.querybuilder.Insert;
+import com.datastax.driver.core.querybuilder.QueryBuilder;
+import com.datastax.driver.core.schemabuilder.SchemaBuilder;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.google.common.base.Strings;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.Closeable;
+import java.io.Flushable;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Queue;
+import java.util.Random;
+import java.util.concurrent.ConcurrentLinkedQueue;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+
+public class CassandraPersistWriter implements StreamsPersistWriter,
Runnable, Flushable, Closeable {
+
+ public static final String STREAMS_ID = "CassandraPersistWriter";
+
+ private static final Logger LOGGER =
LoggerFactory.getLogger(CassandraPersistWriter.class);
+
+ private static final long MAX_WRITE_LATENCY = 1000;
+
+ protected volatile Queue<StreamsDatum> persistQueue;
+
+ private ObjectMapper mapper = StreamsJacksonMapper.getInstance();
+ private volatile AtomicLong lastWrite = new
AtomicLong(System.currentTimeMillis());
+ private ScheduledExecutorService backgroundFlushTask =
Executors.newSingleThreadScheduledExecutor();
+
+ private CassandraConfiguration config;
+
+ protected Cluster cluster;
+ protected Session session;
+
+ protected String keyspace;
+ protected String table;
+ protected PreparedStatement insertStatement;
+
+ protected List<BoundStatement> insertBatch = new ArrayList<>();
+
+ protected final ReadWriteLock lock = new ReentrantReadWriteLock();
+
+ public CassandraPersistWriter() {
+ this(new ComponentConfigurator<>(CassandraConfiguration.class)
+
.detectConfiguration(StreamsConfigurator.getConfig().getConfig("cassandra")));
+ }
+
+ public CassandraPersistWriter(CassandraConfiguration config) {
+ this.config = config;
+ }
+
+ public void setPersistQueue(Queue<StreamsDatum> persistQueue) {
+ this.persistQueue = persistQueue;
+ }
+
+ public Queue<StreamsDatum> getPersistQueue() {
+ return persistQueue;
+ }
+
+ @Override
+ public String getId() {
+ return STREAMS_ID;
+ }
+
+ @Override
+ public void write(StreamsDatum streamsDatum) {
+
+ ObjectNode node;
+
+ if (streamsDatum.getDocument() instanceof String) {
+ try {
+ node = mapper.readValue((String) streamsDatum.getDocument(),
ObjectNode.class);
+
+ byte[] value = node.toString().getBytes();
+
+ BoundStatement statement =
insertStatement.bind(GuidUtils.generateGuid(node.toString()),
ByteBuffer.wrap(value));
+ insertBatch.add(statement);
+ } catch (IOException ex) {
+ ex.printStackTrace();
+ LOGGER.warn("Failure adding object: {}",
streamsDatum.getDocument().toString());
+ return;
+ }
+ } else {
+ try {
+ node = mapper.valueToTree(streamsDatum.getDocument());
+
+ byte[] value = node.toString().getBytes();
+
+ BoundStatement statement =
insertStatement.bind(GuidUtils.generateGuid(node.toString()),
ByteBuffer.wrap(value));
--- End diff --
consider using streamsDatum.getMetadata().get("id") if it exists, enabling
an stream to get a write-then-overwrite behavior when the id is already known.
> streams persist reader/writer for Apache Cassandra
> --------------------------------------------------
>
> Key: STREAMS-478
> URL: https://issues.apache.org/jira/browse/STREAMS-478
> Project: Streams
> Issue Type: New Feature
> Reporter: Subhobrata Dey
>
> This issue is created to propose the streams persist reader/writer to
> get/post documents from/to apache cassandra.
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