/*
* ====================================================================
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
*/
package org.apache.http.nio.protocol;
import java.io.IOException;
import java.util.concurrent.atomic.AtomicBoolean;
import org.apache.http.HttpEntity;
import org.apache.http.HttpEntityEnclosingRequest;
import org.apache.http.HttpException;
import org.apache.http.HttpRequest;
import org.apache.http.entity.ContentType;
import org.apache.http.nio.ContentDecoder;
import org.apache.http.nio.IOControl;
import org.apache.http.protocol.HttpContext;
/**
* Abstract {@link HttpAsyncRequestConsumer} implementation that relieves its
* subclasses from having to manage internal state and provides a number of protected
* event methods that they need to implement.
*
* @since 4.2
*/
public abstract class AbstractAsyncRequestConsumer<T> implements HttpAsyncRequestConsumer<T> {
private final AtomicBoolean completed;
private volatile T result;
private volatile Exception ex;
public AbstractAsyncRequestConsumer() {
super();
this.completed = new AtomicBoolean(false);
}
/**
* Invoked when a HTTP request message is received. Please note
* that the {@link #onContentReceived(ContentDecoder, IOControl)} method
* will be invoked only for if the request message implements
* {@link HttpEntityEnclosingRequest} interface and has a content
* entity enclosed.
*
* @param request HTTP request message.
* @throws HttpException in case of HTTP protocol violation
* @throws IOException in case of an I/O error
*/
protected abstract void onRequestReceived(
HttpRequest request) throws HttpException, IOException;
/**
* Invoked if the request message encloses a content entity.
*
* @param entity HTTP entity
* @param contentType expected content type.
* @throws IOException in case of an I/O error
*/
protected abstract void onEntityEnclosed(
HttpEntity entity, ContentType contentType) throws IOException;
/**
* Invoked to process a chunk of content from the {@link ContentDecoder}.
* The {@link IOControl} interface can be used to suspend input events
* if the consumer is temporarily unable to consume more content.
* <p>
* The consumer can use the {@link ContentDecoder#isCompleted()} method
* to find out whether or not the message content has been fully consumed.
*
* @param decoder content decoder.
* @param ioctrl I/O control of the underlying connection.
* @throws IOException in case of an I/O error
*/
protected abstract void onContentReceived(
ContentDecoder decoder, IOControl ioctrl) throws IOException;
/**
* Invoked to generate a result object from the received HTTP request
* message.
*
* @param context HTTP context.
* @return result of the request processing.
* @throws Exception in case of an abnormal termination.
*/
protected abstract T buildResult(HttpContext context) throws Exception;
/**
* Invoked to release all system resources currently allocated.
*/
protected abstract void releaseResources();
/**
* Invoked when the consumer is being closed.
* @throws IOException may be thrown by subclassses
*
* @since 4.3
*/
protected void onClose() throws IOException {
}
/**
* Use {@link #onRequestReceived(HttpRequest)} instead.
*/
@Override
public final void requestReceived(
final HttpRequest request) throws HttpException, IOException {
onRequestReceived(request);
if (request instanceof HttpEntityEnclosingRequest) {
final HttpEntity entity = ((HttpEntityEnclosingRequest) request).getEntity();
if (entity != null) {
final ContentType contentType = ContentType.getOrDefault(entity);
onEntityEnclosed(entity, contentType);
}
}
}
/**
* Use {@link #onContentReceived(ContentDecoder, IOControl)} instead.
*/
@Override
public final void consumeContent(
final ContentDecoder decoder, final IOControl ioctrl) throws IOException {
onContentReceived(decoder, ioctrl);
}
/**
* Use {@link #buildResult(HttpContext)} instead.
*/
@Override
public final void requestCompleted(final HttpContext context) {
if (this.completed.compareAndSet(false, true)) {
try {
this.result = buildResult(context);
} catch (final Exception ex) {
this.ex = ex;
} finally {
releaseResources();
}
}
}
@Override
public final void failed(final Exception ex) {
if (this.completed.compareAndSet(false, true)) {
this.ex = ex;
releaseResources();
}
}
@Override
public final void close() throws IOException {
if (this.completed.compareAndSet(false, true)) {
releaseResources();
onClose();
}
}
@Override
public Exception getException() {
return this.ex;
}
@Override
public T getResult() {
return this.result;
}
@Override
public boolean isDone() {
return this.completed.get();
}
}