socket multiplexing

[Havoc Pennington]

Hi,

Jim Gettys suggests a possible solution to several issues that have come
up, which is to multiplex multiple message streams over a single file
descriptor. He's sending me a paper on a simple protocol for this.

We could potentially use this for:
 - separate DBusConnection for unrelated code, without a lot of extra
   overhead
 - a "byte stream" primitive
 - to avoid blocking all parts of a process on a huge message one 
   part is sending
 - to allow selecting nonblock/EAGAIN vs. blocking behavior on 
   a per-message-stream basis, or to just make blocking 
   relatively unlikely to create deadlocks by blocking only 
   one of the streams

I don't know if all of these are good ideas or will work, but it's a
line of thought others may be interested in.

Havoc