[libvirt] [PATCH 1/5 v2] Add public API to register a callback to be invoked on connection close
Eric Blake
eblake at redhat.com
Fri Jul 20 17:43:36 UTC 2012
On 07/20/2012 08:21 AM, Daniel P. Berrange wrote:
> From: "Daniel P. Berrange" <berrange at redhat.com>
>
> Define a new virConnectSetCloseCallback() public API which allows
> registering a callback to be invoked when the connection to a
> hypervisor is closed. The callback is provided with the reason for
> the close, which may be 'error', 'eof' or 'keepalive'.
>
> Signed-off-by: Daniel P. Berrange <berrange at redhat.com>
> ---
> include/libvirt/libvirt.h.in | 40 +++++++++++++++++++++-------
> src/datatypes.c | 4 +++
> src/datatypes.h | 5 ++++
> src/libvirt.c | 60 ++++++++++++++++++++++++++++++++++++++++++
> src/libvirt_public.syms | 6 +++++
> 5 files changed, 105 insertions(+), 10 deletions(-)
>
> diff --git a/include/libvirt/libvirt.h.in b/include/libvirt/libvirt.h.in
> index e34438c..85d8c8a 100644
> --- a/include/libvirt/libvirt.h.in
> +++ b/include/libvirt/libvirt.h.in
> @@ -49,6 +49,17 @@ extern "C" {
> * defines VIR_ENUM_SENTINELS. Enumerations for bit values do not
> * have a *_LAST value, but additional bits may be defined. */
>
> +/*
> + * virFreeCallback:
> + * @opaque: opaque user data provided at registration
> + *
> + * Type for a domain event callback when the event is deregistered and
> + * need to be freed, @opaque is provided along with the callback at
> + * registration time
> + */
> +typedef void (*virFreeCallback)(void *opaque);
We're now using this for more than just domain events; the comment needs
a slight update. Maybe:
Type for a callback cleanup function to be paired with a callback. This
function will be called as a final chance to clean up the @opaque
registered with the primary callback, at the time when the primary
callback is deregistered.
> +++ b/src/datatypes.c
> @@ -115,6 +115,10 @@ virReleaseConnect(virConnectPtr conn) {
>
> virMutexLock(&conn->lock);
>
> + if (conn->closeOpaque &&
> + conn->closeFreeCallback)
> + conn->closeFreeCallback(conn->closeOpaque);
I'm still not sure I like filtering on NULL opaque. Our other uses of a
virFreeCallback include src/fdstream.c:virFDStreamRemoveCallback, and
there we call fdst->ff without regards to whether fdst->opaque is null.
> +int virConnectSetCloseCallback(virConnectPtr conn,
> + virConnectCloseFunc cb,
> + void *opaque,
> + virFreeCallback freecb)
> +{
> + VIR_DEBUG("conn=%p", conn);
> +
> + virResetLastError();
> +
> + if (!VIR_IS_CONNECT(conn)) {
> + virLibConnError(VIR_ERR_INVALID_CONN, __FUNCTION__);
> + virDispatchError(NULL);
> + return -1;
> + }
> +
> + virMutexLock(&conn->lock);
> +
> + if (conn->closeCallback) {
> + virLibConnError(VIR_ERR_OPERATION_INVALID, "%s",
> + _("A close callback is already registered"));
> + goto error;
> + }
Do we want to allow deregistration of a close callback (we have
virConnectDomainEventDeregister, after all).
--
Eric Blake eblake at redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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