Merge "Fix MediaHTTPConnection.disconnect() blocking for a long time." into qt-dev

import java.net.UnknownServiceException;

import java.util.HashMap;

import java.util.Map;

import java.util.concurrent.atomic.AtomicInteger;

/** @hide */

public class MediaHTTPConnection extends IMediaHTTPConnection.Stub {

    private final static int HTTP_TEMP_REDIRECT = 307;

    private final static int MAX_REDIRECTS = 20;

    // The number of threads that are currently running disconnect() (possibly

    // not yet holding the synchronized lock).

    private final AtomicInteger mNumDisconnectingThreads = new AtomicInteger(0);

    @UnsupportedAppUsage

    public MediaHTTPConnection() {

        CookieHandler cookieHandler = CookieHandler.getDefault();

    @Override

    @UnsupportedAppUsage

    public void disconnect() {

        mNumDisconnectingThreads.incrementAndGet();

        try {

            HttpURLConnection connectionToDisconnect = mConnection;

            // Call disconnect() before blocking for the lock in order to ensure that any

            // other thread that is blocked in readAt() will return quickly.

                connectionToDisconnect.disconnect();

            }

            synchronized (this) {

            // It's unlikely but possible that while we were waiting to acquire the lock, another

            // thread concurrently started a new connection; if so, we're disconnecting that one

                // It's possible that while we were waiting to acquire the lock, another thread

                // concurrently started a new connection; if so, we're disconnecting that one

                // here, too.

                teardownConnection();

                mHeaders = null;

                mURL = null;

            }

        } finally {

            mNumDisconnectingThreads.decrementAndGet();

        }

    }

    private synchronized void teardownConnection() {

            boolean noProxy = isLocalHost(url);

            while (true) {

                // If another thread is concurrently disconnect()ing, there's a race

                // between them and us. Therefore, we check mNumDisconnectingThreads shortly

                // (not atomically) before & after writing mConnection. This guarantees that

                // we won't "lose" a disconnect by creating a new connection that might

                // miss the disconnect.

                //

                // Note that throwing an instanceof IOException is also what this thread

                // would have done if another thread disconnect()ed the connection while

                // this thread was blocked reading from that connection further down in this

                // loop.

                if (mNumDisconnectingThreads.get() > 0) {

                    throw new IOException("concurrently disconnecting");

                }

                if (noProxy) {

                    mConnection = (HttpURLConnection)url.openConnection(Proxy.NO_PROXY);

                } else {

                    mConnection = (HttpURLConnection)url.openConnection();

                }

                // If another thread is concurrently disconnecting, throwing IOException will

                // cause us to release the lock, giving the other thread a chance to acquire

                // it. It also ensures that the catch block will run, which will tear down

                // the connection even if the other thread happens to already be on its way

                // out of disconnect().

                if (mNumDisconnectingThreads.get() > 0) {

                    throw new IOException("concurrently disconnecting");

                }

                // If we get here without having thrown, we know that other threads

                // will see our write to mConnection. Any disconnect() on that mConnection

                // instance will cause our read from/write to that connection instance below

                // to encounter an instanceof IOException.

                mConnection.setConnectTimeout(CONNECT_TIMEOUT_MS);

                // handle redirects ourselves if we do not allow cross-domain redirect