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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.jdisc.handler;

import com.yahoo.jdisc.Request;
import com.yahoo.jdisc.ResourceReference;
import com.yahoo.jdisc.Response;

import java.util.Objects;
import java.util.concurrent.Executor;
import java.util.concurrent.TimeUnit;

/**
 * 

This class implements a {@link RequestHandler} with a synchronous {@link #handleRequest(Request, * BufferedContentChannel, ResponseHandler)} API for handling {@link Request}s. An Executor is provided at construction * time, and all Requests are automatically scheduled for processing on that Executor.

* *

A very simple echo handler could be implemented like this:

*
 * class MyRequestHandler extends ThreadedRequestHandler {
 *
 *     @Inject
 *     MyRequestHandler(Executor executor) {
 *         super(executor);
 *     }
 *
 *     @Override
 *     protected void handleRequest(Request request, ReadableContentChannel requestContent, ResponseHandler handler) {
 *         ContentWriter responseContent = ResponseDispatch.newInstance(Response.Status.OK).connectWriter(handler);
 *         try {
 *             for (ByteBuffer buf : requestContent) {
 *                 responseContent.write(buf);
 *             }
 *         } catch (RuntimeException e) {
 *             requestContent.failed(e);
 *             throw e;
 *         } finally {
 *             responseContent.close();
 *         }
 *     }
 * }
 * 
* * @author Simon Thoresen Hult */ public abstract class ThreadedRequestHandler extends AbstractRequestHandler { private final Executor executor; private volatile long timeout = 0; protected ThreadedRequestHandler(Executor executor) { Objects.requireNonNull(executor, "executor"); this.executor = executor; } /** *

Sets the timeout that this ThreadedRequestHandler sets on all handled {@link Request}s. If the * timeout value is less than or equal to zero, no timeout will be applied.

* * @param timeout The allocated amount of time. * @param unit The time unit of the timeout argument. */ public final void setTimeout(long timeout, TimeUnit unit) { this.timeout = unit.toMillis(timeout); } /** *

Returns the timeout that this ThreadedRequestHandler sets on all handled {@link Request}s.

* * @param unit The unit to use for the return value. * @return The timeout in the appropriate unit. */ public final long getTimeout(TimeUnit unit) { return unit.convert(timeout, TimeUnit.MILLISECONDS); } @Override public final ContentChannel handleRequest(Request request, ResponseHandler responseHandler) { if (timeout > 0) { request.setTimeout(timeout, TimeUnit.MILLISECONDS); } BufferedContentChannel content = new BufferedContentChannel(); executor.execute(new RequestTask(request, content, responseHandler)); return content; } /** *

Override this method if you want to access the {@link Request}'s content using a {@link * BufferedContentChannel}. If you do not override this method, it will call {@link #handleRequest(Request, * ReadableContentChannel, ResponseHandler)}.

* * @param request The Request to handle. * @param responseHandler The handler to pass the corresponding {@link Response} to. * @param requestContent The content of the Request. */ protected void handleRequest(Request request, BufferedContentChannel requestContent, ResponseHandler responseHandler) { ReadableContentChannel readable = requestContent.toReadable(); try { handleRequest(request, readable, responseHandler); } finally { while (readable.read() != null) {} // consume all ignored content } } /** *

Implement this method if you want to access the {@link Request}'s content using a {@link * ReadableContentChannel}. If you do not override this method, it will call {@link #handleRequest(Request, * ContentInputStream, ResponseHandler)}.

* * @param request The Request to handle. * @param responseHandler The handler to pass the corresponding {@link Response} to. * @param requestContent The content of the Request. */ protected void handleRequest(Request request, ReadableContentChannel requestContent, ResponseHandler responseHandler) { ContentInputStream inputStream = requestContent.toStream(); try { handleRequest(request, inputStream, responseHandler); } finally { while (inputStream.read() >= 0) {} // consume all ignored content } } /** *

Implement this method if you want to access the {@link Request}'s content using a {@link ContentInputStream}. * If you do not override this method, it will dispatch a {@link Response} to the {@link ResponseHandler} with a * Response.Status.NOT_IMPLEMENTED status.

* * @param request The Request to handle. * @param responseHandler The handler to pass the corresponding {@link Response} to. * @param requestContent The content of the Request. */ @SuppressWarnings("UnusedParameters") protected void handleRequest(Request request, ContentInputStream requestContent, ResponseHandler responseHandler) { ResponseDispatch.newInstance(Response.Status.NOT_IMPLEMENTED).dispatch(responseHandler); } private class RequestTask implements Runnable { final Request request; final BufferedContentChannel content; final ResponseHandler responseHandler; private final ResourceReference requestReference; RequestTask(Request request, BufferedContentChannel content, ResponseHandler responseHandler) { this.request = request; this.content = content; this.responseHandler = responseHandler; this.requestReference = request.refer(this); } @Override public void run() { try (final ResourceReference ref = requestReference) { ThreadedRequestHandler.this.handleRequest(request, content, responseHandler); consumeRequestContent(); } } private void consumeRequestContent() { if (content.isConnected()) return; try { ReadableContentChannel requestContent = content.toReadable(); while (requestContent.read() != null) { // consume all ignored content } } catch (IllegalStateException ignored) {} } } }




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