Re: [libvirt] [PATCH 1/2] Java bindings for domain events

On Tue, 2008-11-18 at 16:51 +0000, Daniel P. Berrange wrote: > On Tue, Nov 18, 2008 at 11:06:10AM -0500, David Lively wrote: > > The attached patch (against libvirt-java) implements Java bindings for > > libvirt domain events. This version provides a libvirt EventImpl > > running in its own Java Thread, and provides per-Connect synchronization > > that makes using the bindings thread-safe. (Note the Domain, Network, > > StoragePool, and StorageVol methods also synchronize on their Connect > > object, as required by libvirt. I have similar changes for > > NodeDevice.java that need to be made when that code is checked in.) > > I don't particularly like the event loop code because it is adding a huge > pile of non-portable JNI code that won't work on Windows, which lacks > pipe() and poll(). Java already provides a portable pure Java API for > building a poll() like event loop in form of NIO. > > http://www.xhaus.com/alan/python/jynio/select.html Yeah, Daniel V and I had briefly considered this, and rejected it on the basis of "it's complicated" and (more importantly) some negative feedback I hear from our Java folks on the java.nio Select mechanism. But I agree the java.nio Select mechanism should greatly decrease the amount of JNI code in the Java EventImpl. I need to look over the docs again, but I think it's "just" a matter of implementing a SelectableChannel on top of a fd. (That JNI code will presumably be very different in Win32 and Unix, but it should be a relatively small amount of JNI code in comparison to my current impl.) So I'll look over the java.nio Select documentation and start thinking about a more portable approach ... (and also talk more with our Java folks about their Select gripes).