Github user olegz commented on a diff in the pull request: https://github.com/apache/nifi/pull/392#discussion_r63908853 --- Diff: nifi-nar-bundles/nifi-mqtt-bundle/nifi-mqtt-processors/src/main/java/org/apache/nifi/processors/mqtt/PublishMQTT.java --- @@ -0,0 +1,237 @@ +/* + * 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.mqtt; + +import org.apache.nifi.annotation.behavior.SupportsBatching; +import org.apache.nifi.annotation.lifecycle.OnStopped; +import org.apache.nifi.components.PropertyDescriptor; +import org.apache.nifi.expression.AttributeExpression; +import org.apache.nifi.flowfile.FlowFile; +import org.apache.nifi.annotation.lifecycle.OnScheduled; +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.processor.ProcessContext; +import org.apache.nifi.processor.ProcessorInitializationContext; +import org.apache.nifi.processor.Relationship; +import org.apache.nifi.processor.exception.ProcessException; +import org.apache.nifi.processor.ProcessSession; +import org.apache.nifi.processor.io.InputStreamCallback; +import org.apache.nifi.annotation.behavior.InputRequirement; +import org.apache.nifi.annotation.behavior.InputRequirement.Requirement; + +import org.apache.nifi.processor.util.StandardValidators; +import org.apache.nifi.processors.mqtt.common.AbstractMQTTProcessor; +import org.apache.nifi.stream.io.StreamUtils; +import org.eclipse.paho.client.mqttv3.MqttCallback; +import org.eclipse.paho.client.mqttv3.MqttException; +import org.eclipse.paho.client.mqttv3.MqttMessage; +import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken; + +import java.util.Arrays; +import java.util.Collections; +import java.util.HashSet; +import java.util.List; +import java.util.Set; +import java.io.InputStream; +import java.io.IOException; + +@SupportsBatching +@InputRequirement(Requirement.INPUT_REQUIRED) +@Tags({"publish", "MQTT", "IOT"}) +@CapabilityDescription("Publishes a message to an MQTT topic") +@SeeAlso({ConsumeMQTT.class}) +public class PublishMQTT extends AbstractMQTTProcessor { + + public static final PropertyDescriptor PROP_TOPIC = new PropertyDescriptor.Builder() + .name("Topic") + .description("The topic to publish the message to.") + .expressionLanguageSupported(true) + .required(true) + .addValidator(StandardValidators.createAttributeExpressionLanguageValidator(AttributeExpression.ResultType.STRING, true)) + .addValidator(StandardValidators.NON_BLANK_VALIDATOR) + .build(); + + public static final PropertyDescriptor PROP_QOS = new PropertyDescriptor.Builder() + .name("Quality of Service(QoS)") + .description("The Quality of Service(QoS) to send the message with. Accepts three values '0', '1' and '2'; '0' for 'at most once', '1' for 'at least once', '2' for 'exactly once'. " + + "Expression language is allowed in order to support publishing messages with different QoS but the end value of the property must be either '0', '1' or '2'. ") + .required(true) + .expressionLanguageSupported(true) + .addValidator(QOS_VALIDATOR) + .build(); + + public static final PropertyDescriptor PROP_RETAIN = new PropertyDescriptor.Builder() + .name("Retain Message") + .description("Whether or not the retain flag should be set on the MQTT message.") + .required(true) + .expressionLanguageSupported(true) + .addValidator(RETAIN_VALIDATOR) + .build(); + + public static final Relationship REL_SUCCESS = new Relationship.Builder() + .name("success") + .description("FlowFiles that are sent successfully to the destination are transferred to this relationship.") + .build(); + public static final Relationship REL_FAILURE = new Relationship.Builder() + .name("failure") + .description("FlowFiles that failed to send to the destination are transferred to this relationship.") + .build(); + + private static final List<PropertyDescriptor> descriptors; + private static final Set<Relationship> relationships; + + static { + final List<PropertyDescriptor> innerDescriptorsList = getAbstractPropertyDescriptors(); + innerDescriptorsList.add(PROP_TOPIC); + innerDescriptorsList.add(PROP_QOS); + innerDescriptorsList.add(PROP_RETAIN); + descriptors = Collections.unmodifiableList(innerDescriptorsList); + + final Set<Relationship> innerRelationshipsSet = new HashSet<>(); + innerRelationshipsSet.add(REL_SUCCESS); + innerRelationshipsSet.add(REL_FAILURE); + relationships = Collections.unmodifiableSet(innerRelationshipsSet); + } + + @Override + protected void init(final ProcessorInitializationContext context) { + logger = getLogger(); + } + + @Override + public Set<Relationship> getRelationships() { + return relationships; + } + + @Override + public final List<PropertyDescriptor> getSupportedPropertyDescriptors() { + return descriptors; + } + + @OnScheduled + public void onScheduled(final ProcessContext context) { + buildClient(context); + } + + @OnStopped + public void onStop(final ProcessContext context) { + try { + synchronized (mqttClientConnectLock) { + if (mqttClient != null && mqttClient.isConnected()) { + mqttClient.disconnect(); + logger.info("Disconnected the MQTT client."); + } + } + } catch(MqttException me) { + logger.error("Failed when disconnecting the MQTT client.", me); + } + } + + @Override + public void onTrigger(final ProcessContext context, final ProcessSession session) throws ProcessException { + FlowFile flowfile = session.get(); + if (flowfile == null) { + return; + } + + if(mqttClient == null || !mqttClient.isConnected()){ + logger.info("Was disconnected from client or was never connected, attempting to connect."); + synchronized (mqttClientConnectLock){ --- End diff -- Assuming you are synchronizing for _reconnect_ purposes only, but _reconnect_ is already synchronized internally. Any reason for having nesting these synch blocks?
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