/*
* Copyright (c) 2010-2011 Sonatype, Inc. All rights reserved.
*
* This program is licensed to you under the Apache License Version 2.0,
* and you may not use this file except in compliance with the Apache License Version 2.0.
* You may obtain a copy of the Apache License Version 2.0 at http://www.apache.org/licenses/LICENSE-2.0.
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the Apache License Version 2.0 is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the Apache License Version 2.0 for the specific language governing permissions and limitations there under.
*/
package com.ning.http.client.extra;
import com.ning.http.client.AsyncHandler;
import com.ning.http.client.HttpResponseBodyPart;
import com.ning.http.client.HttpResponseHeaders;
import com.ning.http.client.HttpResponseStatus;
import com.ning.http.client.filter.FilterContext;
import com.ning.http.client.filter.FilterException;
import com.ning.http.client.filter.RequestFilter;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;
/**
* A {@link com.ning.http.client.filter.RequestFilter} throttles requests and block when the number of permits is reached, waiting for
* the response to arrives before executing the next request.
*/
public class ThrottleRequestFilter implements RequestFilter {
private final static Logger logger = LoggerFactory.getLogger(ThrottleRequestFilter.class);
private final int maxConnections;
private final Semaphore available;
private final int maxWait;
public ThrottleRequestFilter(int maxConnections) {
this.maxConnections = maxConnections;
this.maxWait = Integer.MAX_VALUE;
available = new Semaphore(maxConnections, true);
}
public ThrottleRequestFilter(int maxConnections, int maxWait) {
this.maxConnections = maxConnections;
this.maxWait = maxWait;
available = new Semaphore(maxConnections, true);
}
public FilterContext filter(FilterContext ctx) throws FilterException {
try {
if (logger.isDebugEnabled()) {
logger.debug("Current Throttling Status {}", available.availablePermits());
}
if (!available.tryAcquire(maxWait, TimeUnit.MILLISECONDS)) {
throw new FilterException(
String.format("No slot available for processing Request %s with AsyncHandler %s",
ctx.getRequest(), ctx.getAsyncHandler()));
}
;
} catch (InterruptedException e) {
throw new FilterException(
String.format("Interrupted Request %s with AsyncHandler %s", ctx.getRequest(), ctx.getAsyncHandler()));
}
return new FilterContext.FilterContextBuilder(ctx).asyncHandler(new AsyncHandlerWrapper(ctx.getAsyncHandler())).build();
}
private class AsyncHandlerWrapper<T> implements AsyncHandler {
private final AsyncHandler<T> asyncHandler;
public AsyncHandlerWrapper(AsyncHandler<T> asyncHandler) {
this.asyncHandler = asyncHandler;
}
public void onThrowable(Throwable t) {
try {
asyncHandler.onThrowable(t);
} finally {
available.release();
if (logger.isDebugEnabled()) {
logger.debug("Current Throttling Status after onThrowable {}", available.availablePermits());
}
}
}
public STATE onBodyPartReceived(HttpResponseBodyPart bodyPart) throws Exception {
return asyncHandler.onBodyPartReceived(bodyPart);
}
public STATE onStatusReceived(HttpResponseStatus responseStatus) throws Exception {
return asyncHandler.onStatusReceived(responseStatus);
}
public STATE onHeadersReceived(HttpResponseHeaders headers) throws Exception {
return asyncHandler.onHeadersReceived(headers);
}
public T onCompleted() throws Exception {
available.release();
if (logger.isDebugEnabled()) {
logger.debug("Current Throttling Status {}", available.availablePermits());
}
return asyncHandler.onCompleted();
}
}
}