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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.messagebus.jdisc;
import com.yahoo.component.annotation.Inject;
import com.yahoo.jdisc.AbstractResource;
import com.yahoo.jdisc.Request;
import com.yahoo.jdisc.ResourceReference;
import com.yahoo.jdisc.handler.ContentChannel;
import com.yahoo.jdisc.handler.RequestDeniedException;
import com.yahoo.jdisc.handler.ResponseHandler;
import com.yahoo.jdisc.service.ClientProvider;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.logging.Level;
import com.yahoo.messagebus.EmptyReply;
import com.yahoo.messagebus.Error;
import com.yahoo.messagebus.ErrorCode;
import com.yahoo.messagebus.Message;
import com.yahoo.messagebus.Reply;
import com.yahoo.messagebus.ReplyHandler;
import com.yahoo.messagebus.shared.ClientSession;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;
import java.util.logging.Logger;
/**
* @author Simon Thoresen Hult
*/
public final class MbusClient extends AbstractResource implements ClientProvider, ReplyHandler {
private static final Logger log = Logger.getLogger(MbusClient.class.getName());
private static final AtomicInteger threadId = new AtomicInteger(0);
private final BlockingQueue<MbusRequest> queue = new LinkedBlockingQueue<>();
private final ClientSession session;
private final Thread thread;
private volatile boolean done = false;
private final ResourceReference sessionReference;
@Inject
public MbusClient(ClientSession session) {
this.session = session;
this.sessionReference = session.refer(this);
thread = new Thread(new SenderTask(), "mbus-client-" + threadId.getAndIncrement());
thread.setDaemon(true);
}
@Override
public void start() {
thread.start();
}
@Override
public ContentChannel handleRequest(Request request, ResponseHandler handler) {
if (!(request instanceof MbusRequest)) {
throw new RequestDeniedException(request);
}
final Message msg = ((MbusRequest)request).getMessage();
msg.getTrace().trace(6, "Request received by MbusClient.");
msg.pushHandler(null); // save user context
final Long timeout = request.timeRemaining(TimeUnit.MILLISECONDS);
if (timeout != null) {
msg.setTimeReceivedNow();
msg.setTimeRemaining(Math.max(1, timeout)); // negative or zero timeout has semantics
}
msg.setContext(handler);
msg.pushHandler(this);
sendBlocking((MbusRequest)request);
return null;
}
@Override
public void handleTimeout(Request request, final ResponseHandler handler) {
// ignore, mbus has guaranteed reply
}
@Override
protected void destroy() {
log.log(Level.FINE, "Destroying message bus client.");
sessionReference.close();
done = true;
try {
thread.join();
} catch (InterruptedException e) {
log.log(Level.WARNING, "Interrupted while joining thread on destroy.", e);
}
}
@Override
public void handleReply(final Reply reply) {
reply.getTrace().trace(6, "Reply received by MbusClient.");
final ResponseHandler handler = (ResponseHandler)reply.getContext();
reply.popHandler(); // restore user context
try {
handler.handleResponse(new MbusResponse(StatusCodes.fromMbusReply(reply), reply))
.close(IgnoredCompletionHandler.INSTANCE);
} catch (final Exception e) {
log.log(Level.WARNING, "Ignoring exception thrown by ResponseHandler.", e);
}
}
private void sendBlocking(MbusRequest request) {
while (!sendMessage(request)) {
try {
Thread.sleep(5);
} catch (final InterruptedException e) {
// ignore
}
}
}
private boolean sendMessage(MbusRequest request) {
Error error;
final Long millis = request.timeRemaining(TimeUnit.MILLISECONDS);
if (millis != null && millis <= 0) {
error = new Error(ErrorCode.TIMEOUT, request.getTimeout(TimeUnit.MILLISECONDS) + " millis");
} else if (request.isCancelled()) {
error = new Error(ErrorCode.APP_FATAL_ERROR, "request cancelled");
} else {
try {
error = session.sendMessage(request.getMessage()).getError();
} catch (final Exception e) {
error = new Error(ErrorCode.FATAL_ERROR, e.toString());
}
}
if (error == null) {
return true;
}
if (error.isFatal() || done) {
final Reply reply = new EmptyReply();
reply.swapState(request.getMessage());
reply.addError(error);
reply.popHandler().handleReply(reply);
return true;
}
return false;
}
private class SenderTask implements Runnable {
@Override
public void run() {
while (!done) {
try {
final MbusRequest request = queue.poll(100, TimeUnit.MILLISECONDS);
if (request == null) {
continue;
}
sendBlocking(request);
} catch (final Exception e) {
log.log(Level.WARNING, "Ignoring exception thrown by MbusClient.", e);
}
}
}
}
}
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