Java tutorial
/* * Copyright 2016 ANI Technologies Pvt. Ltd. * * Licensed 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 com.olacabs.fabric.compute.pipeline; import com.google.common.collect.ImmutableMap; import com.google.common.collect.ImmutableSet; import com.google.common.collect.Maps; import com.google.common.collect.Sets; import com.olacabs.fabric.compute.comms.ChannelFactory; import com.olacabs.fabric.compute.comms.CommsChannel; import com.olacabs.fabric.compute.source.PipelineStreamSource; import com.olacabs.fabric.compute.tracking.SimpleBitSet; import com.olacabs.fabric.model.event.EventSet; import lombok.Builder; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.util.Map; import java.util.Properties; import java.util.Set; /** *TODO Add more. */ public class NotificationBus { private static final Logger LOGGER = LoggerFactory.getLogger(NotificationBus.class); private final Map<Long, SimpleBitSet> tracker = Maps.newConcurrentMap(); private Properties properties; private Map<Integer, Connection> connections = Maps.newHashMap(); private Map<Integer, Communicator> comms = Maps.newHashMap(); private Map<Integer, PipelineStreamSource> sources = Maps.newHashMap(); public NotificationBus(final Properties properties) { this.properties = properties; LOGGER.info("Notification bus created..."); } public NotificationBus source(PipelineStreamSource streamSource) { sources.put(streamSource.communicationId(), streamSource); return this; } public NotificationBus connect(MessageSource to, PipelineStage... pipelineStages) { if (!connections.containsKey(to.communicationId())) { connections.put(to.communicationId(), new Connection()); } for (PipelineStage pipelineStage : pipelineStages) { connections.get(to.communicationId()).addConnection(pipelineStage.communicationId()); if (!comms.containsKey(pipelineStage.communicationId())) { comms.put(pipelineStage.communicationId(), Communicator.builder() .commsChannel(ChannelFactory.create(properties, pipelineStage.name(), false, pipelineStage)) .pipelineStage(pipelineStage).build()); } } return this; } public synchronized void publish(PipelineMessage message, int from) { publish(message, from, true); } public synchronized void publish(PipelineMessage message, int from, boolean forward) { switch (message.getMessageType()) { case TIMER: // It is a timer message, ACKing is disabled comms.get(from).commsChannel.publish(message); break; case USERSPACE: // It is a userspace message, ACKing is enabled PipelineMessage actionableMessage = message; ImmutableSet.Builder<EventSet> ackCandidatesBuilder = ImmutableSet.builder(); if (!message.getMessages().isAggregate()) { // Find out the oldest ancestor of this event set while (true) { if (null == actionableMessage.getParent()) { break; } actionableMessage = actionableMessage.getParent(); } if (!tracker.containsKey(actionableMessage.getMessages().getId())) { // Set up the tracker for this event set since it is sent from a source for the first time // Add this event set to the tracker with an empty bitset tracker.put(actionableMessage.getMessages().getId(), new SimpleBitSet(64)); } SimpleBitSet msgBitSet = tracker.get(actionableMessage.getMessages().getId()); try { // If the event set is being sent forward and the sender sends normal message, set bits // for each of the receivers based on the auto incremented id assigned to them if (forward && connections.containsKey(from) && ((comms.containsKey(from) && comms.get(from).pipelineStage.sendsNormalMessage()) || !comms.containsKey(from))) { connections.get(from).pipelineStages.stream().forEach(msgBitSet::set); } } catch (Exception e) { LOGGER.error("Error setting tracking bits for generator: {}", from, e); } // unset the bit corresponding to the sender msgBitSet.unset(from); // if all the bits are unset and if this event set is generated by a source, mark the // event set as a candidate for ACKing if (!msgBitSet.hasSetBits() && actionableMessage.getMessages().isSourceGenerated()) { ackCandidatesBuilder.add(actionableMessage.getMessages()); } } try { // publish the message to each of the receivers if (forward && connections.containsKey(from)) { connections.get(from).pipelineStages.stream() .forEach(pipeLineStage -> comms.get(pipeLineStage).commsChannel.publish(message)); } } catch (Throwable t) { LOGGER.error("Error sending event to children for {}", from, t); } // event sets which are eligible for ACKing ImmutableSet<EventSet> ackSet = ackCandidatesBuilder.build(); // ACK all the event sets ackSet.stream().forEach(eventSet -> sources.get(eventSet.getSourceId()).ackMessage(eventSet)); // No event set to ACK, hence we can remove the tracker entry for this event set if (!ackSet.isEmpty()) { tracker.remove(actionableMessage.getMessages().getId()); } break; default: break; } } public void start() { connections = ImmutableMap.copyOf(connections); comms.values().forEach(communicator -> communicator.commsChannel.start()); } public void stop() { comms.values().forEach(communicator -> communicator.commsChannel.stop()); } private static class Connection { private final Set<Integer> pipelineStages; Connection() { pipelineStages = Sets.newHashSet(); } Connection addConnection(int pipelineStage) { pipelineStages.add(pipelineStage); return this; } } /** * TODO javadoc. */ @Builder public static class Communicator { private MessageSource pipelineStage; private CommsChannel<PipelineMessage> commsChannel; } }