markap14 commented on a change in pull request #4730:
URL: https://github.com/apache/nifi/pull/4730#discussion_r555182063



##########
File path: 
nifi-external/nifi-kafka-connect/nifi-kafka-connector/src/main/java/org/apache/nifi/kafka/connect/StatelessNiFiSourceTask.java
##########
@@ -0,0 +1,275 @@
+/*
+ * 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.kafka.connect;
+
+import org.apache.kafka.clients.producer.RecordMetadata;
+import org.apache.kafka.common.config.ConfigException;
+import org.apache.kafka.connect.data.Schema;
+import org.apache.kafka.connect.errors.RetriableException;
+import org.apache.kafka.connect.header.Header;
+import org.apache.kafka.connect.source.SourceRecord;
+import org.apache.kafka.connect.source.SourceTask;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.stateless.flow.DataflowTrigger;
+import org.apache.nifi.stateless.flow.StatelessDataflow;
+import org.apache.nifi.stateless.flow.TriggerResult;
+import org.apache.nifi.util.FormatUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicLong;
+import java.util.regex.Pattern;
+
+public class StatelessNiFiSourceTask extends SourceTask {
+    private static final Logger logger = 
LoggerFactory.getLogger(StatelessNiFiSourceTask.class);
+
+    private StatelessDataflow dataflow;
+    private String outputPortName;
+    private String topicName;
+    private String topicNameAttribute;
+    private TriggerResult triggerResult;
+    private String keyAttributeName;
+    private Pattern headerAttributeNamePattern;
+    private long timeoutMillis;
+    private String dataflowName;
+
+    private final AtomicLong unacknowledgedRecords = new AtomicLong(0L);
+
+    @Override
+    public String version() {
+        return StatelessKafkaConnectorUtil.getVersion();
+    }
+
+    @Override
+    public void start(final Map<String, String> properties) {
+        logger.info("Starting Source Task with properties {}", properties);
+
+        final String timeout = 
properties.getOrDefault(StatelessKafkaConnectorUtil.DATAFLOW_TIMEOUT, 
StatelessKafkaConnectorUtil.DEFAULT_DATAFLOW_TIMEOUT);
+        timeoutMillis = (long) FormatUtils.getPreciseTimeDuration(timeout, 
TimeUnit.MILLISECONDS);
+
+        topicName = properties.get(StatelessNiFiSourceConnector.TOPIC_NAME);
+        topicNameAttribute = 
properties.get(StatelessNiFiSourceConnector.TOPIC_NAME_ATTRIBUTE);
+        keyAttributeName = 
properties.get(StatelessNiFiSourceConnector.KEY_ATTRIBUTE);
+
+        if (topicName == null && topicNameAttribute == null) {
+            throw new ConfigException("Either the topic.name or 
topic.name.attribute configuration must be specified");
+        }
+
+        final String headerRegex = 
properties.get(StatelessNiFiSourceConnector.HEADER_REGEX);
+        headerAttributeNamePattern = headerRegex == null ? null : 
Pattern.compile(headerRegex);
+
+        dataflow = StatelessKafkaConnectorUtil.createDataflow(properties);
+
+        // Determine the name of the Output Port to retrieve data from
+        dataflowName = properties.get("name");
+        outputPortName = 
properties.get(StatelessNiFiSourceConnector.OUTPUT_PORT_NAME);
+        if (outputPortName == null) {
+            final Set<String> outputPorts = dataflow.getOutputPortNames();
+            if (outputPorts.isEmpty()) {
+                throw new ConfigException("The dataflow specified for <" + 
dataflowName + "> does not have an Output Port at the root level. Dataflows 
used for a Kafka Connect Source Task "
+                    + "must have at least one Output Port at the root level.");
+            }
+
+            if (outputPorts.size() > 1) {
+                throw new ConfigException("The dataflow specified for <" + 
dataflowName + "> has multiple Output Ports at the root level (" + 
outputPorts.toString()
+                    + "). The " + 
StatelessNiFiSourceConnector.OUTPUT_PORT_NAME + " property must be set to 
indicate which of these Ports Kafka records should be retrieved from.");
+            }
+
+            outputPortName = outputPorts.iterator().next();
+        }
+    }
+
+    @Override
+    public List<SourceRecord> poll() throws InterruptedException {
+        logger.debug("Triggering dataflow");
+        final long start = System.nanoTime();
+
+        final DataflowTrigger trigger = dataflow.trigger();
+        final Optional<TriggerResult> resultOptional = 
trigger.getResult(timeoutMillis, TimeUnit.MILLISECONDS);
+        if (!resultOptional.isPresent()) {
+            logger.warn("Dataflow timed out after waiting {} milliseconds. 
Will cancel the execution.", timeoutMillis);
+            trigger.cancel();
+            return null;
+        }
+
+        triggerResult = resultOptional.get();
+
+        if (!triggerResult.isSuccessful()) {
+            logger.error("Dataflow {} failed to execute properly", 
dataflowName, triggerResult.getFailureCause().orElse(null));
+            trigger.cancel();
+            return null;
+        }
+
+        // Verify that data was only transferred to the expected Output Port
+        verifyFlowFilesTransferredToProperPort(triggerResult, outputPortName, 
trigger);
+
+        final long nanos = System.nanoTime() - start;
+
+        final List<FlowFile> outputFlowFiles = 
triggerResult.getOutputFlowFiles(outputPortName);
+        final List<SourceRecord> sourceRecords = new 
ArrayList<>(outputFlowFiles.size());
+        for (final FlowFile flowFile : outputFlowFiles) {
+            final byte[] contents = triggerResult.readContent(flowFile);
+            final SourceRecord sourceRecord = createSourceRecord(flowFile, 
contents);
+            sourceRecords.add(sourceRecord);
+        }
+
+        logger.debug("Returning {} records from poll() method (took {} nanos 
to run dataflow)", sourceRecords.size(), nanos);
+
+        // If there is at least one record, we don't want to acknowledge the 
trigger result until Kafka has committed the Record.
+        // This is handled by incrementing the unacknkowledgedRecords count. 
Then, Kafka Connect will call this.commitRecords().
+        // The commitRecords() call will then decrement the number of 
unacknowledgedRecords, and when all unacknowledged Records have been
+        // acknowledged, it will acknowledge the trigger result.
+        //
+        // However, if there are no records, this.commitRecords() will never 
be called. As a result, we need toe nsure that we acknowledge the trigger 
result here.
+        if (sourceRecords.size() > 0) {
+            unacknowledgedRecords.addAndGet(sourceRecords.size());
+        } else {
+            triggerResult.acknowledge();
+        }
+
+        return sourceRecords;
+    }
+
+    private void verifyFlowFilesTransferredToProperPort(final TriggerResult 
triggerResult, final String expectedPortName, final DataflowTrigger trigger) {
+        final Map<String, List<FlowFile>> flowFileOutputMap = 
triggerResult.getOutputFlowFiles();
+
+        for (final Map.Entry<String, List<FlowFile>> entry : 
flowFileOutputMap.entrySet()) {
+            final String portName = entry.getKey();
+            final List<FlowFile> flowFiles = entry.getValue();
+
+            if (!flowFiles.isEmpty() && !expectedPortName.equals(portName)) {
+                logger.error("Dataflow transferred FlowFiles to Port {} but 
was expecting data to be transferred to {}. Rolling back session.", portName, 
expectedPortName);
+                trigger.cancel();
+                throw new RetriableException("Data was transferred to 
unexpected port");
+            }
+        }
+    }
+
+
+    private SourceRecord createSourceRecord(final FlowFile flowFile, final 
byte[] contents) {

Review comment:
       That's a very good point. I wanted to revisit this but had forgot about 
it. Will look into how to integrate this well with NiFi StateProvider mechanism 
so that we can store this appropriately.

##########
File path: 
nifi-external/nifi-kafka-connect/nifi-kafka-connector/src/main/java/org/apache/nifi/kafka/connect/StatelessNiFiSinkTask.java
##########
@@ -0,0 +1,289 @@
+/*
+ * 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.kafka.connect;
+
+import org.apache.kafka.clients.consumer.OffsetAndMetadata;
+import org.apache.kafka.common.TopicPartition;
+import org.apache.kafka.common.config.ConfigException;
+import org.apache.kafka.connect.errors.RetriableException;
+import org.apache.kafka.connect.header.Header;
+import org.apache.kafka.connect.sink.SinkRecord;
+import org.apache.kafka.connect.sink.SinkTask;
+import org.apache.nifi.controller.queue.QueueSize;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.stateless.flow.DataflowTrigger;
+import org.apache.nifi.stateless.flow.StatelessDataflow;
+import org.apache.nifi.stateless.flow.TriggerResult;
+import org.apache.nifi.util.FormatUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.nio.charset.StandardCharsets;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.concurrent.TimeUnit;
+import java.util.regex.Pattern;
+
+public class StatelessNiFiSinkTask extends SinkTask {
+    private static final Logger logger = 
LoggerFactory.getLogger(StatelessNiFiSinkTask.class);
+
+    private StatelessDataflow dataflow;
+    private String inputPortName;
+    private Set<String> failurePortNames;
+    private long timeoutMillis;
+    private Pattern headerNameRegex;
+    private String headerNamePrefix;
+    private int batchSize;
+    private long batchBytes;
+    private QueueSize queueSize;
+    private String dataflowName;
+
+    private long backoffMillis = 0L;
+
+    @Override
+    public String version() {
+        return StatelessKafkaConnectorUtil.getVersion();
+    }
+
+    @Override
+    public void start(final Map<String, String> properties) {
+        logger.info("Starting Sink Task with properties {}", 
StatelessKafkaConnectorUtil.getLoggableProperties(properties));
+
+        final String timeout = 
properties.getOrDefault(StatelessKafkaConnectorUtil.DATAFLOW_TIMEOUT, 
StatelessKafkaConnectorUtil.DEFAULT_DATAFLOW_TIMEOUT);
+        timeoutMillis = (long) FormatUtils.getPreciseTimeDuration(timeout, 
TimeUnit.MILLISECONDS);
+
+        dataflowName = 
properties.get(StatelessKafkaConnectorUtil.DATAFLOW_NAME);
+
+        final String regex = 
properties.get(StatelessNiFiSinkConnector.HEADERS_AS_ATTRIBUTES_REGEX);
+        headerNameRegex = regex == null ? null : Pattern.compile(regex);
+        headerNamePrefix = 
properties.getOrDefault(StatelessNiFiSinkConnector.HEADER_ATTRIBUTE_NAME_PREFIX,
 "");
+
+        batchSize = 
Integer.parseInt(properties.getOrDefault(StatelessNiFiSinkConnector.BATCH_SIZE_COUNT,
 "0"));
+        batchBytes = 
Long.parseLong(properties.getOrDefault(StatelessNiFiSinkConnector.BATCH_SIZE_BYTES,
 "0"));
+
+        dataflow = StatelessKafkaConnectorUtil.createDataflow(properties);
+
+        // Determine input port name. If input port is explicitly set, use the 
value given. Otherwise, if only one port exists, use that. Otherwise, throw 
ConfigException.
+        final String dataflowName = 
properties.get(StatelessKafkaConnectorUtil.DATAFLOW_NAME);
+        inputPortName = 
properties.get(StatelessNiFiSinkConnector.INPUT_PORT_NAME);
+        if (inputPortName == null) {
+            final Set<String> inputPorts = dataflow.getInputPortNames();
+            if (inputPorts.isEmpty()) {
+                throw new ConfigException("The dataflow specified for <" + 
dataflowName + "> does not have an Input Port at the root level. Dataflows used 
for a Kafka Connect Sink Task "
+                    + "must have at least one Input Port at the root level.");
+            }
+
+            if (inputPorts.size() > 1) {
+                throw new ConfigException("The dataflow specified for <" + 
dataflowName + "> has multiple Input Ports at the root level (" + 
inputPorts.toString()
+                    + "). The " + StatelessNiFiSinkConnector.INPUT_PORT_NAME + 
" property must be set to indicate which of these Ports Kafka records should be 
sent to.");
+            }
+
+            inputPortName = inputPorts.iterator().next();
+        }
+
+        // Validate the input port
+        if (!dataflow.getInputPortNames().contains(inputPortName)) {
+            throw new ConfigException("The dataflow specified for <" + 
dataflowName + "> does not have Input Port with name <" + inputPortName + "> at 
the root level. Existing Input Port names are "
+                + dataflow.getInputPortNames());
+        }
+
+        // Determine the failure Ports, if any are given.
+        final String failurePortList = 
properties.get(StatelessNiFiSinkConnector.FAILURE_PORTS);
+        if (failurePortList == null || failurePortList.trim().isEmpty()) {
+            failurePortNames = Collections.emptySet();
+        } else {
+            failurePortNames = new HashSet<>();
+
+            final String[] names = failurePortList.split(",");
+            for (final String name : names) {
+                final String trimmed = name.trim();
+                failurePortNames.add(trimmed);
+            }
+        }
+
+        // Validate the failure ports
+        final Set<String> outputPortNames = dataflow.getOutputPortNames();
+        for (final String failurePortName : failurePortNames) {
+            if (!outputPortNames.contains(failurePortName)) {
+                throw new ConfigException("Dataflow was configured with a 
Failure Port of " + failurePortName
+                    + " but there is no Port with that name in the dataflow. 
Valid Port names are " + outputPortNames);
+            }
+        }
+    }
+
+    @Override
+    public void put(final Collection<SinkRecord> records) {
+        if (backoffMillis > 0) {
+            logger.debug("Due to previous failure, will wait {} millis before 
executing dataflow", backoffMillis);
+
+            try {
+                Thread.sleep(backoffMillis);

Review comment:
       Thanks. Will address.




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