[libvirt-users] Where actually is the callback triggered?

[kadir yüceer]

2011/4/14 Matthias Bolte <matthias.bolte at googlemail.com>

> 2011/4/14 kadir yüceer <kadiryuceer at gmail.com>:
> > Hi all,
> >
> > Quick question:
> > When the hypervisor triggers a callback which is registered for generic
> > events, (assuming I'm connected through qemu+tcp) where exactly is the
> > callback triggered? On the hypervisor host or on my host?
> >
> > Regards
> > Kadir
> >
>
> The event system is more complex.
>
> The hypervisor/connection driver add events to a queue. The events
> from this queue are transported to the client and can trigger you
> registered callbacks.
>
> In order to have your callbacks called you need to register an "event
> implementation" that is responsible for driving the event delivery.
> Recent libvirt exposed it's default "event implementation" via
> virEventRegisterDefaultImpl().
>
> In order to have events delivered to your callbacks you need to call
> virEventRegisterDefaultImpl() or virEventRegisterImpl() with your own
> "event implementation".
>
> I assume you're still talking about the Java bindings here then you
> hit the problem that the bindings are incomplete and don't export
> virEventRegisterImpl() nor virEventRegisterDefaultImpl() yet. This
> means that the event related part of the libvirt API can not be used
> from the Java bindings yet.
>
>
> A totally untested patch to add virEventRegisterDefaultImpl() looks like
> this:
>
>
> diff --git a/src/main/java/org/libvirt/jna/Libvirt.java
> b/src/main/java/org/libvirt/jna/Libvirt.java
> index 2c8c03d..5b73859 100644
> --- a/src/main/java/org/libvirt/jna/Libvirt.java
> +++ b/src/main/java/org/libvirt/jna/Libvirt.java
> @@ -373,4 +373,7 @@ public interface Libvirt extends Library {
>     public int virNWFilterGetUUID(NetworkFilterPointer
> virNWFilterPtr, byte[] uuidString);
>     public int virNWFilterGetUUIDString(NetworkFilterPointer
> virNWFilterPtr, byte[] uuidString);
>     public int virNWFilterUndefine(NetworkFilterPointer virNWFilterPtr);
> +
> +    // Event Methods
> +    public int virEventRegisterDefaultImpl(void);
>  }
>
>
> Then import org.libvirt.jna.Libvirt in your code and call:
>
> Libvirt.INSTANCE.virEventRegisterDefaultImpl()
>
> This _should_ register the default event implementation and make
> events work for you assuming the rest of your event related code is
> correct.
>
> Matthias
>

First of all, thanks for the answer Matthias, I've been looking for help for
some time.

I had already tried your suggestion, I added the function just as the same
way you did above, and I have this error:

Exception in thread "main"* java.lang.UnsatisfiedLinkError: Error looking up
function 'virEventRegisterDefaultImpl': /usr/local/lib/libvirt.so: undefined
symbol: virEventRegisterDefaultImpl*
        at com.sun.jna.Function.<init>(Function.java:179)
        at com.sun.jna.NativeLibrary.getFunction(NativeLibrary.java:345)
        at com.sun.jna.NativeLibrary.getFunction(NativeLibrary.java:325)
        at com.sun.jna.Library$Handler.invoke(Library.java:203)
        at $Proxy0.virEventRegisterDefaultImpl(Unknown Source)
        at novatest_v03.MainFrame.main(MainFrame.java:168)

I did not post not go too technical. I have the feeling that I need to
arrange one more step to satisfy the link to java bindings, because I've
tested event-driving in C and it works fine. Since I could not figure out if
I can do it on binding side or it should be done originally by the driver,
I've posted my question.

So, any comments about how can I complete the link to C API? Maybe how to
edit this "libvirt.so"?

Regards
Kadir

PS: Everything else works fine, libvirtd running, I can command to domains,
etc. I can even register my own callback and register it via
Connect.setErrorCallback(). I assume only missing thing is the link.
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