Fix for upload progress monitoring in Android.

RestrictedSocketFactory.java

package com.wistla.wistla.util;

import android.util.Log;

import java.io.IOException;
import java.net.InetAddress;
import java.net.Socket;
import java.net.SocketException;
import java.net.UnknownHostException;

import javax.net.SocketFactory;


/**
 * <b>Restricted Socket Factory</b>
 * <p>
 * OkHttp buffers to the network interface but the network interface's default
 * buffer size is sometimes set very high e.g. 512Kb which makes tracking
 * upload progress impossible as the upload content is sitting in the network
 * interface buffer waiting to be transmitted.
 * Re: https://github.com/square/okhttp/issues/1078
 * <p>
 * So here, we create socket factory that forces all sockets to have a restricted
 * send buffer size. So that further down the chain in OkHttps' RequestBody we can
 * track the actual progress to the nearest [sendBufferSize] unit.
 * <p>
 * Example usage with OkHttpClient 2.x:
 * <pre>
 *     okHttpClient.setSocketFactory(new RestrictedSocketFactory(16 * 1024));
 * </pre>
 * <p>
 * Example usage with OkHttpClient 3.x:
 * <pre>
 *     okHttpClientBuilder.socketFactory(new RestrictedSocketFactory(16 * 1024))
 * </pre>
 * <p>
 * Created by Simon Lightfoot <[email protected]> on 04/04/2016.
 */
public class RestrictedSocketFactory extends SocketFactory
{
	private static final String TAG = RestrictedSocketFactory.class.getSimpleName();

	private int mSendBufferSize;


	public RestrictedSocketFactory(int sendBufferSize)
	{
		mSendBufferSize = sendBufferSize;
		try{
			Socket socket = new Socket();
			Log.w(TAG, String.format("Changing SO_SNDBUF on new sockets from %d to %d.",
				socket.getSendBufferSize(), sendBufferSize));
		}
		catch(SocketException e){
			//
		}
	}

	@Override
	public Socket createSocket()
		throws IOException
	{
		return updateSendBufferSize(new Socket());
	}

	@Override
	public Socket createSocket(String host, int port)
		throws IOException, UnknownHostException
	{
		return updateSendBufferSize(new Socket(host, port));
	}

	@Override
	public Socket createSocket(String host, int port, InetAddress localHost, int localPort)
		throws IOException, UnknownHostException
	{
		return updateSendBufferSize(new Socket(host, port, localHost, localPort));
	}

	@Override
	public Socket createSocket(InetAddress host, int port)
		throws IOException
	{
		return updateSendBufferSize(new Socket(host, port));
	}

	@Override
	public Socket createSocket(InetAddress address, int port, InetAddress localAddress, int localPort)
		throws IOException
	{
		return updateSendBufferSize(new Socket(address, port, localAddress, localPort));
	}

	private Socket updateSendBufferSize(Socket socket)
		throws IOException
	{
		socket.setSendBufferSize(mSendBufferSize);
		return socket;
	}
}