[libvirt] [PATCH 0/3] Domain events - overview

Ben Guthro bguthro at virtualiron.com
Thu Oct 9 15:21:20 UTC 2008

The following patch series implements the Events API discussed here previously in this thread:

This is a rather large patch, and touches quite a few files, but in the end, accomplishes the goal of event delivery of notificaton of domain events.

It does so in a manner that is able to co-exist with older clients, or older libvirtd implementations. 
  In the former case, events will never be delivered to a client that does not request them.
  In the latter case, we will fail registration, and so events will not be available.

I have broken this up into 3 patches in the following manner:
1/3 - events.patch
    This is the bulk of the work. It emits, and delivers events to clients that are supported, and have registered to recieve the events.

2/3 - events-xen.patch
    These changes are currently untested (as I did my development with KVM), but are the changes that will be necessary to monitor xenstore for changes in domain states

3/3 - events-test.patch
    This is a test harness implemented to receive (and print) when domain events occur. I was unsure where this should live in the tree - so it currently is an independant patch (.c and Makefile in its own dir)

Please note that I have not yet made any effort to generate any Python, or Java bindings, but wanted to get this out on the list first.

Thread safeness:
We know that there are 2 data structures that need protection against concurrent access
_virDriver.conns and 

However, we have not addressed these issues at this juncture. 
We are considering recursive mutexes (specifically making conn->lock one) to avoid deadlocks in a vir* call from within a callback. We plan on addressing this with the next version of this code, after addressing any other issues the list may come up with, as well.

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