Github user joewitt commented on a diff in the pull request:
https://github.com/apache/nifi/pull/3178#discussion_r235107847
--- Diff:
nifi-nar-bundles/nifi-pulsar-bundle/nifi-pulsar-processors/src/main/java/org/apache/nifi/processors/pulsar/pubsub/ConsumePulsar.java
---
@@ -0,0 +1,141 @@
+/*
+ * 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.pulsar.pubsub;
+
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.SeeAlso;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processors.pulsar.AbstractPulsarConsumerProcessor;
+import org.apache.pulsar.client.api.Consumer;
+import org.apache.pulsar.client.api.Message;
+import org.apache.pulsar.client.api.PulsarClientException;
+
+@SeeAlso({PublishPulsar.class, ConsumePulsarRecord.class,
PublishPulsarRecord.class})
+@Tags({"Pulsar", "Get", "Ingest", "Ingress", "Topic", "PubSub", "Consume"})
+@CapabilityDescription("Consumes messages from Apache Pulsar. The
complementary NiFi processor for sending messages is PublishPulsar.")
+@InputRequirement(InputRequirement.Requirement.INPUT_FORBIDDEN)
+public class ConsumePulsar extends AbstractPulsarConsumerProcessor<byte[]>
{
+
+ @Override
+ public void onTrigger(ProcessContext context, ProcessSession session)
throws ProcessException {
+ try {
+ Consumer<byte[]> consumer = getConsumer(context,
getConsumerId(context, session.get()));
+
+ if (consumer == null) {
+ context.yield();
+ return;
+ }
+
+ if (context.getProperty(ASYNC_ENABLED).asBoolean()) {
+ consumeAsync(consumer, context, session);
+ handleAsync(consumer, context, session);
+ } else {
+ consume(consumer, context, session);
+ }
+ } catch (PulsarClientException e) {
+ getLogger().error("Unable to consume from Pulsar Topic ", e);
+ context.yield();
+ throw new ProcessException(e);
+ }
+ }
+
+ private void handleAsync(final Consumer<byte[]> consumer,
ProcessContext context, ProcessSession session) {
+ try {
+ Future<Message<byte[]>> done = getConsumerService().poll(50,
TimeUnit.MILLISECONDS);
+
+ if (done != null) {
+ Message<byte[]> msg = done.get();
+
+ if (msg != null) {
+ FlowFile flowFile = null;
+ final byte[] value = msg.getData();
+ if (value != null && value.length > 0) {
+ flowFile = session.create();
+ flowFile = session.write(flowFile, out -> {
+ out.write(value);
+ });
+
+ session.getProvenanceReporter().receive(flowFile,
getPulsarClientService().getPulsarBrokerRootURL() + "/" + consumer.getTopic());
+ session.transfer(flowFile, REL_SUCCESS);
+ session.commit();
+ }
+ // Acknowledge consuming the message
+ getAckService().submit(new Callable<Object>() {
+ @Override
+ public Object call() throws Exception {
+ return consumer.acknowledgeAsync(msg).get();
+ }
+ });
+ }
+ } else {
+ // Check if the processor is stopped and if so gracefully
stop processing.
+ }
+
+ } catch (InterruptedException | ExecutionException e) {
+ getLogger().error("Trouble consuming messages ", e);
+ }
+ }
+
+ private void consume(Consumer<byte[]> consumer, ProcessContext
context, ProcessSession session) throws PulsarClientException {
+ try {
+ /* If we do not provide a timeout value, this call will block
indefinitely, which will
+ * cause the processor to hang when we try to stop it
consuming from an empty topic.
+ * Therefore, we chose a 2 second timeout to handle this
situation gracefully.
+ */
+ final Message<byte[]> msg = consumer.receive(2,
TimeUnit.SECONDS);
+
+ if (msg == null) {
+ return;
+ }
+
+ final byte[] value = msg.getData();
+
+ if (value != null && value.length > 0) {
+ FlowFile flowFile = session.create();
+ flowFile = session.write(flowFile, out -> {
+ out.write(value);
--- End diff --
performance of a single flowfile per poll cycle will be poor relative to
doing batched reads. I am guessing pulsar pulls more than a single message at
a time too. We have the demarcator approach for the kafka processors and
performance there is extremely high because then we're aligning nifi and the
messaging systems strengths. That said, the record processors are an even
better path for this so maybe dont worry about that for now. not sure.
---
