/*
 * Copyright (c) 2010, 2018 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package org.glassfish.jersey.server.spi;

import java.io.OutputStream;
import java.util.concurrent.TimeUnit;

import org.glassfish.jersey.server.ApplicationHandler;
import org.glassfish.jersey.server.ContainerException;
import org.glassfish.jersey.server.ContainerResponse;

A suspendable, request-scoped I/O container response writer. I/O container sends a new instance of the response writer with every request as part of the call to the Jersey application ApplicationHandler.apply(ContainerRequest) apply(...)} method. Each container response writer represents an open connection to the client (waiting for a response). 
 For each request the Jersey runtime will make sure to directly call either suspend(...) or commit() method on a response writer supplied to the JerseyApplication.apply(...) method before the method has finished. Therefore the I/O container implementations may assume that when the JerseyApplication.apply(...) method is finished, the container response writer is either commited, or suspended. 
Author:
Marek Potociar/**
 * A suspendable, request-scoped I/O container response writer.
 *
 * I/O container sends a new instance of the response writer with every request as part
 * of the call to the Jersey application
 * {@link ApplicationHandler#apply(org.glassfish.jersey.server.ContainerRequest)}  apply(...)}
 * method. Each container response writer represents an open connection to the client
 * (waiting for a response).
 * <p>
 * For each request the Jersey runtime will make sure to directly call either
 * {@link #suspend(long, TimeUnit, TimeoutHandler) suspend(...)}
 * or {@code commit()} method on a response writer supplied to the
 * {@code JerseyApplication.apply(...)} method before the method has finished. Therefore
 * the I/O container implementations may assume that when the {@code JerseyApplication.apply(...)}
 * method is finished, the container response writer is either {@link #commit() commited},
 * or {@link #suspend(long, TimeUnit, TimeoutHandler) suspended}.
 * </p>
 *
 * @author Marek Potociar
 */
public interface ContainerResponseWriter {

    
Time-out handler can be registered when the container response writer gets suspended. Should the suspend operation time out, the container is responsible for invoking the onTimeout(ContainerResponseWriter) callback method to get the response that should be returned to the client. /**
     * Time-out handler can be registered when the container response writer gets
     * suspended.
     *
     * Should the suspend operation time out, the container is responsible for
     * invoking the {@link TimeoutHandler#onTimeout(ContainerResponseWriter)}
     * callback method to get the response that should be returned to the client.
     */
    public interface TimeoutHandler {

        
Method is called, when ContainerResponseWriter.suspend(...) operation times out. The custom time-out handler implementation is responsible for making sure a (time-out) response is written to the context and that the container context is properly closed. 
Params:
responseWriter – suspended container response writer that timed out./**
         * Method is called, when {@link ContainerResponseWriter#suspend(long, TimeUnit,
         * ContainerResponseWriter.TimeoutHandler) ContainerResponseWriter.suspend(...)}
         * operation times out.
         *
         * The custom time-out handler implementation is responsible for making
         * sure a (time-out) response is written to the context and that the
         * container context is properly closed.
         *
         * @param responseWriter suspended container response writer that timed out.
         */
        public void onTimeout(ContainerResponseWriter responseWriter);
    }

    
Write the status and headers of the response and return an output stream
for the web application to write the entity of the response.
 If the response content length is declared to be greater or equal to 0, it means that the content length in bytes of the entity to be written is known, otherwise -1. I/O containers may use this value to determine whether the "Content-Length" header can be set or utilize chunked transfer encoding. 
Params:
contentLength – greater or equal to 0 if the content length in bytes of the entity to be written is known, otherwise -1. Containers may use this value to determine whether the "Content-Length" header can be set or utilize chunked transfer encoding.
responseContext – the JAX-RS response to be written. The status and headers
    are obtained from the response.
Throws:
ContainerException – if an error occurred when writing out the
                           status and headers or obtaining the output stream.
Returns:
the output stream to write the entity (if any)./**
     * Write the status and headers of the response and return an output stream
     * for the web application to write the entity of the response.
     * <p>
     * If the response content length is declared to be greater or equal to 0, it
     * means that the content length in bytes of the entity to be written is known,
     * otherwise -1. I/O containers may use this value to determine whether the
     * {@code "Content-Length"} header can be set or utilize chunked transfer encoding.
     * </p>
     *
     * @param contentLength greater or equal to 0 if the content length in bytes
     *     of the entity to be written is known, otherwise -1. Containers
     *     may use this value to determine whether the {@code "Content-Length"}
     *     header can be set or utilize chunked transfer encoding.
     * @param responseContext the JAX-RS response to be written. The status and headers
     *     are obtained from the response.
     * @return the output stream to write the entity (if any).
     * @throws ContainerException if an error occurred when writing out the
     *                            status and headers or obtaining the output stream.
     */
    public OutputStream writeResponseStatusAndHeaders(long contentLength, ContainerResponse responseContext)
            throws ContainerException;

    
Suspend the request/response processing. The method returns true to indicate the response writer was suspended successfully. In case the provider has already been suspended earlier, the method returns false. 
 I/O container must not automatically commit the response writer when the processing on the I/O container thread is finished and the thread is released. Instead, the Jersey runtime will make sure to manually close the container response writer instance by explicitly calling the commit() or failure(Throwable) method at some later point in time. 
 Once suspended, the specified suspend timeout can be further updated using setSuspendTimeout(long, TimeUnit) method. 
Params:
timeOut –        time-out value. Value less or equal to 0, indicates that
                      the processing is suspended indefinitely.
timeUnit –       time-out time unit.
timeoutHandler – time-out handler to process a time-out event if it
                      occurs.
See Also:
setSuspendTimeout(long, TimeUnit)
commit()
Returns:
true if the suspend operation completed successfully, false otherwise./**
     * Suspend the request/response processing.
     *
     * The method returns {@code true} to indicate the response writer was suspended successfully.
     * In case the provider has already been suspended earlier, the method returns {@code false}.
     * <p>
     * I/O container must not automatically {@link #commit() commit} the response writer
     * when the processing on the I/O container thread is finished and the thread is
     * released. Instead, the Jersey runtime will make sure to manually close
     * the container response writer instance by explicitly calling the {@link #commit()}
     * or {@link #failure(Throwable)} method at some later point in time.
     * </p>
     * <p>
     * Once suspended, the specified suspend timeout can be further updated using
     * {@link #setSuspendTimeout(long, java.util.concurrent.TimeUnit) } method.
     * </p>
     *
     * @param timeOut        time-out value. Value less or equal to 0, indicates that
     *                       the processing is suspended indefinitely.
     * @param timeUnit       time-out time unit.
     * @param timeoutHandler time-out handler to process a time-out event if it
     *                       occurs.
     * @return {@code true} if the suspend operation completed successfully, {@code false} otherwise.
     *
     * @see #setSuspendTimeout(long, TimeUnit)
     * @see #commit()
     */
    public boolean suspend(long timeOut, TimeUnit timeUnit, TimeoutHandler timeoutHandler);

    
Set the suspend timeout.
Once the container response writer is suspended, the suspend timeout value
can be further updated by the method.
Params:
timeOut –  time-out value. Value less or equal to 0, indicates that
                the processing is suspended indefinitely.
timeUnit – time-out time unit.
Throws:
IllegalStateException – in case the response writer has not been suspended
                              yet./**
     * Set the suspend timeout.
     *
     * Once the container response writer is suspended, the suspend timeout value
     * can be further updated by the method.
     *
     * @param timeOut  time-out value. Value less or equal to 0, indicates that
     *                 the processing is suspended indefinitely.
     * @param timeUnit time-out time unit.
     * @throws IllegalStateException in case the response writer has not been suspended
     *                               yet.
     */
    public void setSuspendTimeout(long timeOut, TimeUnit timeUnit) throws IllegalStateException;

    
Commit the response & close the container response writer.
Indicates to the I/O container that request has been fully processed and response
has been fully written. This signals the I/O  container to finish the request/response
processing, clean up any state, flush any streams, release resources etc.
See Also:
suspend(long, TimeUnit, TimeoutHandler)
failure(Throwable)/**
     * Commit the response & close the container response writer.
     *
     * Indicates to the I/O container that request has been fully processed and response
     * has been fully written. This signals the I/O  container to finish the request/response
     * processing, clean up any state, flush any streams, release resources etc.
     *
     * @see #suspend(long, TimeUnit, TimeoutHandler)
     * @see #failure(Throwable)
     */
    public void commit();

    
Propagate an unhandled error to the I/O container.
Indicates to the I/O container that the request processing has finished with an error
that could not be processed by the Jersey runtime. The I/O container is expected to process
the exception in a container-specific way. This method also signals the I/O container to
finish the request/response processing, clean up any state, flush any streams, release
resources etc.
Params:
error – unhandled request processing error.
See Also:
suspend(long, TimeUnit, TimeoutHandler)
commit()/**
     * Propagate an unhandled error to the I/O container.
     *
     * Indicates to the I/O container that the request processing has finished with an error
     * that could not be processed by the Jersey runtime. The I/O container is expected to process
     * the exception in a container-specific way. This method also signals the I/O container to
     * finish the request/response processing, clean up any state, flush any streams, release
     * resources etc.
     *
     * @param error unhandled request processing error.
     *
     * @see #suspend(long, TimeUnit, TimeoutHandler)
     * @see #commit()
     */
    public void failure(Throwable error);

    
Return true if the entity buffering should be enabled in Jersey. If enabled, the outbound entity is buffered by Jersey runtime up to a configured amount of bytes prior to being written to the output stream to determine its size that may be used to set the value of HTTP "Content-Length" header.
 Containers that provide it's own solution for determining the message payload size may decide to return false to prevent Jersey from buffering message entities unnecessarily. 
Returns:
true to enable entity buffering to be done by Jersey runtime, false otherwise./**
     * Return {@code true} if the entity buffering should be enabled in Jersey.
     *
     * If enabled, the outbound entity is buffered by Jersey runtime up to a configured amount of bytes
     * prior to being written to the output stream to determine its size that may be used to set the value
     * of HTTP <tt>{@value javax.ws.rs.core.HttpHeaders#CONTENT_LENGTH}</tt> header.
     * <p>
     * Containers that provide it's own solution for determining the message payload size may decide to
     * return {@code false} to prevent Jersey from buffering message entities unnecessarily.
     * </p>
     *
     * @return {@code true} to enable entity buffering to be done by Jersey runtime, {@code false} otherwise.
     */
    public boolean enableResponseBuffering();
}