org.eclipse.mylyn.commons.net/src/org/eclipse/mylyn/internal/commons/net/http/CommonHeadMethod3.java

/*******************************************************************************
 * Copyright (c) 2004, 2013 Composent, Inc., IBM All rights reserved. This
 * program and the accompanying materials are made available under the terms of
 * the Eclipse Public License v2.0 which accompanies this distribution, and is
 * available at http://www.eclipse.org/legal/epl-v20.html
 *
 * Contributors: 
 *  Composent, Inc. - initial API and implementation
 *  Maarten Meijer - bug 237936, added gzip encoded transfer default
 *  Henrich Kraemer - bug 263869, testHttpsReceiveFile fails using HTTP proxy
 *  Henrich Kraemer - bug 263613, [transport] Update site contacting / downloading is not cancelable
 *  Tasktop Technologies - cancellation support for streams
 ******************************************************************************/

package org.eclipse.mylyn.internal.commons.net.http;

import java.io.IOException;
import java.io.InputStream;

import org.apache.commons.httpclient.HttpConnection;
import org.apache.commons.httpclient.HttpException;
import org.apache.commons.httpclient.HttpState;
import org.apache.commons.httpclient.methods.HeadMethod;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.mylyn.commons.net.http.CommonHttpMethod3;

/**
 * Based on {@code org.eclipse.ecf.provider.filetransfer.httpclient.HttpClientRetrieveFileTransfer}.
 * 
 * @author Steffen Pingel
 */
public class CommonHeadMethod3 extends HeadMethod implements CommonHttpMethod3 {

	private boolean gzipAccepted;

	private final Object releaseLock = new Object();

	public CommonHeadMethod3() {
		init();
	}

	public CommonHeadMethod3(String requestPath) {
		super(requestPath);
		init();
	}

	@Override
	public int execute(HttpState state, HttpConnection conn) throws HttpException, IOException {
		if (gzipAccepted) {
			this.setRequestHeader("Accept-encoding", CONTENT_ENCODING_GZIP); //$NON-NLS-1$
		}
		return super.execute(state, conn);
	}

	public InputStream getResponseBodyAsStream(IProgressMonitor monitor) throws IOException {
		return null;
	}

	private void init() {
		gzipAccepted = true;
	}

	public final boolean isGzipAccepted() {
		return gzipAccepted;
	}

	// This override is a workaround for 
	// https://bugs.eclipse.org/bugs/show_bug.cgi?id=279457
	// This makes GetMethod.releaseConnection non-reentrant,
	// as with reentrancy under some circumstances a NPE can be 
	// thrown with multithreaded access
	@Override
	public void releaseConnection() {
		synchronized (releaseLock) {
			super.releaseConnection();
		}
	}

	public void releaseConnection(IProgressMonitor monitor) {
		if (monitor != null && monitor.isCanceled()) {
			// force a connection close on cancel to avoid blocking to do reading the remainder of the response 
			abort();
		}
		try {
			releaseConnection();
		} catch (NullPointerException e) {
			// ignore, see bug 255417
		}
	}

	public final void setGzipAccepted(boolean gzipAccepted) {
		this.gzipAccepted = gzipAccepted;
	}

}