Java tutorial
// Copyright 2016 The Bazel Authors. All rights reserved. // // 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.google.devtools.build.lib.runtime; import com.google.common.annotations.VisibleForTesting; import com.google.common.collect.HashMultimap; import com.google.common.collect.ImmutableSet; import com.google.common.collect.Multimap; import com.google.common.collect.Sets; import com.google.common.eventbus.Subscribe; import com.google.devtools.build.lib.actions.ActionExecutedEvent; import com.google.devtools.build.lib.analysis.NoBuildEvent; import com.google.devtools.build.lib.buildeventstream.AbortedEvent; import com.google.devtools.build.lib.buildeventstream.BuildEvent; import com.google.devtools.build.lib.buildeventstream.BuildEventId; import com.google.devtools.build.lib.buildeventstream.BuildEventStreamProtos.Aborted.AbortReason; import com.google.devtools.build.lib.buildeventstream.BuildEventTransport; import com.google.devtools.build.lib.buildeventstream.BuildEventWithOrderConstraint; import com.google.devtools.build.lib.buildeventstream.ProgressEvent; import com.google.devtools.build.lib.buildtool.buildevent.BuildCompleteEvent; import com.google.devtools.build.lib.buildtool.buildevent.BuildInterruptedEvent; import com.google.devtools.build.lib.events.Event; import com.google.devtools.build.lib.events.EventHandler; import java.io.IOException; import java.util.Collection; import java.util.HashSet; import java.util.Set; import java.util.logging.Logger; /** Listen for {@link BuildEvent} and stream them to the provided {@link BuildEventTransport}. */ public class BuildEventStreamer implements EventHandler { private final Collection<BuildEventTransport> transports; private Set<BuildEventId> announcedEvents; private Set<BuildEventId> postedEvents; private final Multimap<BuildEventId, BuildEvent> pendingEvents; private int progressCount; private AbortReason abortReason = AbortReason.UNKNOWN; private static final Logger LOG = Logger.getLogger(BuildEventStreamer.class.getName()); public BuildEventStreamer(Collection<BuildEventTransport> transports) { this.transports = transports; this.announcedEvents = null; this.postedEvents = null; this.progressCount = 0; this.pendingEvents = HashMultimap.create(); } /** * Post a new event to all transports; simultaneously keep track of the events we announce to * still come. * * <p>Moreover, link unannounced events to the progress stream; we only expect failure events to * come before their parents. */ private void post(BuildEvent event) { BuildEvent linkEvent = null; BuildEventId id = event.getEventId(); synchronized (this) { if (announcedEvents == null) { announcedEvents = new HashSet<>(); postedEvents = new HashSet<>(); if (!event.getChildrenEvents().contains(ProgressEvent.INITIAL_PROGRESS_UPDATE)) { linkEvent = ProgressEvent.progressChainIn(progressCount, event.getEventId()); progressCount++; announcedEvents.addAll(linkEvent.getChildrenEvents()); postedEvents.add(linkEvent.getEventId()); } } else { if (!announcedEvents.contains(id)) { linkEvent = ProgressEvent.progressChainIn(progressCount, id); progressCount++; announcedEvents.addAll(linkEvent.getChildrenEvents()); postedEvents.add(linkEvent.getEventId()); } postedEvents.add(id); } announcedEvents.addAll(event.getChildrenEvents()); } for (BuildEventTransport transport : transports) { try { if (linkEvent != null) { transport.sendBuildEvent(linkEvent); } transport.sendBuildEvent(event); } catch (IOException e) { // TODO(aehlig): signal that the build ought to be aborted LOG.severe("Failed to write to build event transport: " + e); } } } /** Clear pending events by generating aborted events for all their requisits. */ private void clearPendingEvents() { while (!pendingEvents.isEmpty()) { BuildEventId id = pendingEvents.keySet().iterator().next(); buildEvent(new AbortedEvent(id, abortReason, "")); } } /** * Clear all events that are still announced; events not naturally closed by the expected event * normally only occur if the build is aborted. */ private void clearAnnouncedEvents() { if (announcedEvents != null) { // create a copy of the identifiers to clear, as the post method // will change the set of already announced events. Set<BuildEventId> ids; synchronized (this) { ids = Sets.difference(announcedEvents, postedEvents); } for (BuildEventId id : ids) { post(new AbortedEvent(id, abortReason, "")); } } } private void close() { for (BuildEventTransport transport : transports) { try { transport.close(); } catch (IOException e) { // TODO(aehlig): signal that the build ought to be aborted LOG.warning("Failure while closing build event transport: " + e); } } } @Override public void handle(Event event) { } @Subscribe public void noBuild(NoBuildEvent event) { close(); } @Subscribe public void buildInterrupted(BuildInterruptedEvent event) { abortReason = AbortReason.USER_INTERRUPTED; }; @Subscribe public void buildComplete(BuildCompleteEvent event) { clearPendingEvents(); post(ProgressEvent.finalProgressUpdate(progressCount)); clearAnnouncedEvents(); close(); } @Subscribe public void buildEvent(BuildEvent event) { if (event instanceof ActionExecutedEvent) { // We ignore events about action executions if the execution succeeded. if (((ActionExecutedEvent) event).getException() == null) { return; } } if (event instanceof BuildEventWithOrderConstraint) { // Check if all prerequisit events are posted already. for (BuildEventId prerequisiteId : ((BuildEventWithOrderConstraint) event).postedAfter()) { if (!postedEvents.contains(prerequisiteId)) { pendingEvents.put(prerequisiteId, event); return; } } } post(event); // Reconsider all events blocked by the event just posted. Collection<BuildEvent> toReconsider = pendingEvents.removeAll(event.getEventId()); for (BuildEvent freedEvent : toReconsider) { buildEvent(freedEvent); } } @VisibleForTesting ImmutableSet<BuildEventTransport> getTransports() { return ImmutableSet.copyOf(transports); } }