Does Protocol.registerProtocol for apache HttpClient cause a global static change?

Question

I've come across some code that's using

Protocol.registerProtocol

in an attempt to block some TLS ciphers for a request, and retry the request with it re-enabled at times, depending on other factors.

But is Protocol.registerProtocol causing a global change - ie will other threads be affected by this?

Here's the code in question:

protected static HostConfiguration buildTLSConfig(String uri, HostConfiguration config,
        boolean blockTLS1)
        throws MalformedURLException
{
        scheme = "https";
        if (baseHttps == null)
        {
            baseHttps = Protocol.getProtocol(scheme);
            baseFactory = baseHttps.getSocketFactory();
        }

        URL newUrl = new URL(uri);

        defaultPort = baseHttps.getDefaultPort();

        if (blockTLS1)
        {
            ProtocolSocketFactory customFactory =
                    new CustomHttpsSocketFactory(baseFactory, TLS_PREFERRED_PROTOCOLS);
            Protocol applyHttps = new Protocol(scheme, customFactory, defaultPort);
            Protocol.registerProtocol(scheme, applyHttps);
            config.setHost(newUrl.getHost(), defaultPort, applyHttps);
        }
        else
        {
            Protocol.registerProtocol(scheme, baseHttps);
            config.setHost(newUrl.getHost(), defaultPort, baseHttps);
        }

        return config;
}

Answer 1

Yes, all threads will be affected by the change.

If we look at org.apache.commons.httpclient.protocol.Protocol, we see a global protocol Map:

    /** The available protocols */
    private static final Map PROTOCOLS = Collections.synchronizedMap(new HashMap());

And registerProtocol() simply modifying it:

public static void registerProtocol(String id, Protocol protocol) {

    // . . .

    PROTOCOLS.put(id, protocol);
}

At least it's synchronized, so there won't be a race during modification.