Github user joewitt commented on a diff in the pull request:
https://github.com/apache/nifi/pull/2181#discussion_r143277153
--- Diff:
nifi-nar-bundles/nifi-druid-bundle/nifi-druid-processors/src/main/java/org/apache/nifi/processors/PutDruid.java
---
@@ -0,0 +1,206 @@
+
+/*
+ * 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.nifi.processors;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import org.apache.nifi.annotation.behavior.SideEffectFree;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.AbstractSessionFactoryProcessor;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.ProcessSessionFactory;
+import org.apache.nifi.processor.ProcessorInitializationContext;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.io.InputStreamCallback;
+import org.apache.nifi.stream.io.StreamUtils;
+
+import org.codehaus.jackson.JsonParseException;
+import org.codehaus.jackson.map.JsonMappingException;
+import org.codehaus.jackson.map.ObjectMapper;
+
+import org.apache.nifi.controller.api.DruidTranquilityService;
+import com.metamx.tranquility.tranquilizer.MessageDroppedException;
+import com.metamx.tranquility.tranquilizer.Tranquilizer;
+import com.twitter.util.Await;
+import com.twitter.util.Future;
+import com.twitter.util.FutureEventListener;
+
+import scala.runtime.BoxedUnit;
+
+@SideEffectFree
+@Tags({"Druid","Timeseries","OLAP","ingest"})
+@CapabilityDescription("Sends events to Apache Druid for Indexing. "
+ + "Leverages Druid Tranquility
Controller service."
+ + "Incoming flow files are
expected to contain 1 or many JSON objects, one JSON object per line")
+public class PutDruid extends AbstractSessionFactoryProcessor {
+
+ private List<PropertyDescriptor> properties;
+ private Set<Relationship> relationships;
+ private final Map<Object,String> messageStatus = new
HashMap<Object,String>();
+
+ public static final PropertyDescriptor DRUID_TRANQUILITY_SERVICE = new
PropertyDescriptor.Builder()
+ .name("druid_tranquility_service")
+ .description("Tranquility Service to use for sending events to
Druid")
+ .required(true)
+ .identifiesControllerService(DruidTranquilityService.class)
+ .build();
+
+ public static final Relationship REL_SUCCESS = new
Relationship.Builder()
+ .name("SUCCESS")
+ .description("Succes relationship")
+ .build();
+
+ public static final Relationship REL_FAIL = new Relationship.Builder()
+ .name("FAIL")
+ .description("FlowFiles are routed to this relationship when
they cannot be parsed")
+ .build();
+
+ public static final Relationship REL_DROPPED = new
Relationship.Builder()
+ .name("DROPPED")
+ .description("FlowFiles are routed to this relationship when
they are outside of the configured time window, timestamp format is invalid,
ect...")
+ .build();
+
+ public void init(final ProcessorInitializationContext context){
+ List<PropertyDescriptor> properties = new ArrayList<>();
+ properties.add(DRUID_TRANQUILITY_SERVICE);
+ this.properties = Collections.unmodifiableList(properties);
+
+ Set<Relationship> relationships = new HashSet<Relationship>();
+ relationships.add(REL_SUCCESS);
+ relationships.add(REL_DROPPED);
+ relationships.add(REL_FAIL);
+ this.relationships = Collections.unmodifiableSet(relationships);
+ }
+
+ @Override
+ public Set<Relationship> getRelationships(){
+ return relationships;
+ }
+
+ @Override
+ protected List<PropertyDescriptor> getSupportedPropertyDescriptors() {
+ return properties;
+ }
+
+ //Method breaks down incoming flow file and sends it to Druid Indexing
servic
+ private void processFlowFile(ProcessContext context, ProcessSession
session){
+ //Get handle on Druid Tranquility session
+ DruidTranquilityService tranquilityController =
context.getProperty(DRUID_TRANQUILITY_SERVICE)
+ .asControllerService(DruidTranquilityService.class);
+ Tranquilizer<Map<String,Object>> tranquilizer =
tranquilityController.getTranquilizer();
+
+ final FlowFile flowFile = session.get();
+ if (flowFile == null || flowFile.getSize() == 0) {
+ return;
+ }
+
+ //Get data from flow file body
+ final byte[] buffer = new byte[(int) flowFile.getSize()];
+ session.read(flowFile, new InputStreamCallback() {
+ @Override
+ public void process(final InputStream in) throws IOException {
+ StreamUtils.fillBuffer(in, buffer);
+ }
+ });
+
+
+ String contentString = new String(buffer, StandardCharsets.UTF_8);
+ Map<String,Object> contentMap = null;
+
+ //Create payload array from flow file content, one element per
line
+ String[] messageArray = contentString.split("\\R");
+
+ //Convert each array element from JSON to HashMap and send to
Druid
+ for(String message: messageArray){
+ try {
+ contentMap = new ObjectMapper().readValue(message,
HashMap.class);
+ //contentMap = new ObjectMapper().readValue(message,
HashMap.class);
+ } catch (JsonParseException e) {
+ getLogger().error("Error parsing incoming message array
in the flowfile body");
+ } catch (JsonMappingException e) {
+ getLogger().error("Error parsing incoming message array
in the flowfile body");
+ } catch (IOException e) {
+ getLogger().error("Error parsing incoming message array
in the flowfile body");
+ }
+
+ getLogger().debug("Tranquilizer Status: " +
tranquilizer.status().toString());
+ messageStatus.put(flowFile, "pending");
+ //Send data element to Druid, Asynch
+ Future<BoxedUnit> future = tranquilizer.send(contentMap);
+ getLogger().debug(" Sent Payload to Druid: " + contentMap);
+
+ //Wait for Druid to call back with status
+ future.addEventListener(new FutureEventListener<Object>() {
+ @Override
+ public void onFailure(Throwable cause) {
+ if (cause instanceof MessageDroppedException) {
+ //This happens when event timestamp
targets a Druid Indexing task that has closed (Late Arriving Data)
+ getLogger().error(" FlowFile Dropped
due to MessageDroppedException: " + cause.getMessage() + " : " + cause);
+ cause.getStackTrace();
+ getLogger().error(" Transfering
FlowFile to DROPPED relationship");
+ session.transfer(flowFile, REL_DROPPED);
+ } else {
+ getLogger().error(" FlowFile Processing
Failed due to: " + cause.getMessage() + " : " + cause);
+ cause.printStackTrace();
+ getLogger().error(" Transfering
FlowFile to FAIL relationship");
+ session.transfer(flowFile, REL_FAIL);
+ }
+ }
+
+ @Override
+ public void onSuccess(Object value) {
+ getLogger().debug(" FlowFile Processing Success
: "+ value.toString());
+ session.transfer(flowFile, REL_SUCCESS);
+ }
+ });
+
+ try {
+ //Wait for result from Druid
+ //This method will be asynch since this is a
SessionFactoryProcessor and OnTrigger will create a new Thread
+ Await.result(future);
+ } catch (Exception e) {
+ e.printStackTrace();
+ }
+ }
+ //session.transfer(flowFile, REL_SUCCESS);
+ session.commit();
+ }
+
+ public void onTrigger(ProcessContext context, ProcessSessionFactory
factory) throws ProcessException {
+ final ProcessSession session = factory.createSession();
+ //Create new Thread to ensure that waiting for callback does
not reduce throughput
+ new Thread(() -> {
--- End diff --
It does not appear that spawning a new thread is necessary and it is
unclear that is desirable. If more throughput is needed we would add threads
to the processor or use the API of druid differently etc.. But we don't want
to spawn a thread per onTrigger/session
---
