292 lines
8.0 KiB
Java
292 lines
8.0 KiB
Java
// Copyright (C) 2010 The Android Open Source Project
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package com.google.gerrit.sshd.commands;
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import static java.nio.charset.StandardCharsets.UTF_8;
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import com.google.common.base.Supplier;
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import com.google.gerrit.common.UserScopedEventListener;
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import com.google.gerrit.common.data.GlobalCapability;
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import com.google.gerrit.extensions.annotations.RequiresCapability;
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import com.google.gerrit.extensions.registration.DynamicSet;
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import com.google.gerrit.extensions.registration.RegistrationHandle;
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import com.google.gerrit.reviewdb.client.Project;
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import com.google.gerrit.server.CurrentUser;
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import com.google.gerrit.server.IdentifiedUser;
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import com.google.gerrit.server.events.Event;
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import com.google.gerrit.server.events.EventTypes;
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import com.google.gerrit.server.events.ProjectNameKeySerializer;
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import com.google.gerrit.server.events.SupplierSerializer;
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import com.google.gerrit.server.git.WorkQueue;
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import com.google.gerrit.server.git.WorkQueue.CancelableRunnable;
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import com.google.gerrit.sshd.BaseCommand;
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import com.google.gerrit.sshd.CommandMetaData;
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import com.google.gerrit.sshd.StreamCommandExecutor;
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import com.google.gson.Gson;
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import com.google.gson.GsonBuilder;
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import com.google.inject.Inject;
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import java.io.IOException;
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import java.io.PrintWriter;
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import java.util.ArrayList;
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import java.util.List;
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import java.util.concurrent.Future;
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import java.util.concurrent.LinkedBlockingQueue;
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import org.apache.sshd.server.Environment;
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import org.kohsuke.args4j.Option;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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@RequiresCapability(GlobalCapability.STREAM_EVENTS)
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@CommandMetaData(name = "stream-events", description = "Monitor events occurring in real time")
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final class StreamEvents extends BaseCommand {
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private static final Logger log = LoggerFactory.getLogger(StreamEvents.class);
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/** Maximum number of events that may be queued up for each connection. */
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private static final int MAX_EVENTS = 128;
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/** Number of events to write before yielding off the thread. */
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private static final int BATCH_SIZE = 32;
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@Option(
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name = "--subscribe",
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aliases = {"-s"},
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metaVar = "SUBSCRIBE",
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usage = "subscribe to specific stream-events"
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)
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private List<String> subscribedToEvents = new ArrayList<>();
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@Inject private IdentifiedUser currentUser;
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@Inject private DynamicSet<UserScopedEventListener> eventListeners;
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@Inject @StreamCommandExecutor private WorkQueue.Executor pool;
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/** Queue of events to stream to the connected user. */
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private final LinkedBlockingQueue<Event> queue = new LinkedBlockingQueue<>(MAX_EVENTS);
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private Gson gson;
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private RegistrationHandle eventListenerRegistration;
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/** Special event to notify clients they missed other events. */
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private static final class DroppedOutputEvent extends Event {
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private static final String TYPE = "dropped-output";
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DroppedOutputEvent() {
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super(TYPE);
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}
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}
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static {
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EventTypes.register(DroppedOutputEvent.TYPE, DroppedOutputEvent.class);
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}
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private final CancelableRunnable writer =
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new CancelableRunnable() {
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@Override
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public void run() {
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writeEvents();
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}
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@Override
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public void cancel() {
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onExit(0);
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}
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@Override
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public String toString() {
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return "Stream Events (" + currentUser.getAccount().getUserName() + ")";
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}
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};
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/** True if {@link DroppedOutputEvent} needs to be sent. */
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private volatile boolean dropped;
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/** Lock to protect {@link #queue}, {@link #task}, {@link #done}. */
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private final Object taskLock = new Object();
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/** True if no more messages should be sent to the output. */
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private boolean done;
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/**
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* Currently scheduled task to spin out {@link #queue}.
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*
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* <p>This field is usually {@code null}, unless there is at least one object present inside of
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* {@link #queue} ready for delivery. Tasks are only started when there are events to be sent.
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*/
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private Future<?> task;
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private PrintWriter stdout;
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@Override
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public void start(final Environment env) throws IOException {
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try {
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parseCommandLine();
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} catch (UnloggedFailure e) {
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String msg = e.getMessage();
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if (!msg.endsWith("\n")) {
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msg += "\n";
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}
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err.write(msg.getBytes(UTF_8));
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err.flush();
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onExit(1);
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return;
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}
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stdout = toPrintWriter(out);
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eventListenerRegistration =
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eventListeners.add(
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new UserScopedEventListener() {
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@Override
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public void onEvent(final Event event) {
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if (subscribedToEvents.isEmpty() || subscribedToEvents.contains(event.getType())) {
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offer(event);
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}
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}
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@Override
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public CurrentUser getUser() {
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return currentUser;
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}
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});
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gson =
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new GsonBuilder()
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.registerTypeAdapter(Supplier.class, new SupplierSerializer())
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.registerTypeAdapter(Project.NameKey.class, new ProjectNameKeySerializer())
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.create();
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}
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private void removeEventListenerRegistration() {
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if (eventListenerRegistration != null) {
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eventListenerRegistration.remove();
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}
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}
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@Override
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protected void onExit(final int rc) {
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removeEventListenerRegistration();
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synchronized (taskLock) {
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done = true;
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}
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super.onExit(rc);
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}
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@Override
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public void destroy() {
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removeEventListenerRegistration();
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final boolean exit;
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synchronized (taskLock) {
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if (task != null) {
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task.cancel(true);
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exit = false; // onExit will be invoked by the task cancellation.
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} else {
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exit = !done;
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}
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done = true;
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}
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if (exit) {
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onExit(0);
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}
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}
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private void offer(final Event event) {
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synchronized (taskLock) {
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if (!queue.offer(event)) {
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dropped = true;
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}
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if (task == null && !done) {
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task = pool.submit(writer);
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}
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}
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}
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private Event poll() {
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synchronized (taskLock) {
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Event event = queue.poll();
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if (event == null) {
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task = null;
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}
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return event;
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}
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}
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private void writeEvents() {
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int processed = 0;
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while (processed < BATCH_SIZE) {
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if (Thread.interrupted() || stdout.checkError()) {
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// The other side either requested a shutdown by calling our
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// destroy() above, or it closed the stream and is no longer
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// accepting output. Either way terminate this instance.
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//
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removeEventListenerRegistration();
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flush();
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onExit(0);
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return;
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}
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if (dropped) {
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write(new DroppedOutputEvent());
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dropped = false;
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}
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final Event event = poll();
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if (event == null) {
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break;
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}
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write(event);
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processed++;
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}
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flush();
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if (BATCH_SIZE <= processed) {
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// We processed the limit, but more might remain in the queue.
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// Schedule the write task again so we will come back here and
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// can process more events.
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//
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synchronized (taskLock) {
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task = pool.submit(writer);
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}
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}
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}
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private void write(final Object message) {
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String msg = null;
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try {
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msg = gson.toJson(message) + "\n";
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} catch (Exception e) {
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log.warn("Could not deserialize the msg: ", e);
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}
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if (msg != null) {
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synchronized (stdout) {
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stdout.print(msg);
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}
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}
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}
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private void flush() {
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synchronized (stdout) {
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stdout.flush();
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}
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}
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}
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