Re: [libvirt] [RFC PATCH] qemu: new API for tracking arbitrary monitor events

Several times in the past, qemu has implemented a new event, but libvirt has not yet caught up to reporting that event to the user applications. While it is possible to track libvirt logs to see that an unknown event was received and ignored, it would be nicer to copy what 'virsh qemu-monitor-command' does, and expose this information to the end developer as one of our unsupported qemu-specific commands. If you find yourself needing to use this API for more than just development purposes, please ask on the libvirt list for a supported counterpart event to be added in libvirt.so. While the supported virConnectDomainEventRegisterAny() API takes an id which determines the signature of the callback, this version takes a string filter and always uses the same signature. Furthermore, I chose to expose this as a new API instead of trying to add a new eventID at the top level, in part because the generic option lacks event name filtering, and in part because the normal domain event namespace should not be polluted by a qemu-only event. I also added a flags argument; unused for now, but we might decide to use it to allow a user to request event names by glob or regex instead of literal match. * include/libvirt/libvirt-qemu.h (virConnectDomainQemuMonitorEventCallback) (virConnectDomainQemuMonitorEventRegister) (virConnectDomainQemuMonitorEventDeregister): New prototypes. * src/libvirt-qemu.c (virConnectDomainQemuMonitorEventRegister) (virConnectDomainQemuMonitorEventDeregister): New functions. * src/libvirt_qemu.syms (LIBVIRT_QEMU_1.2.1): Export them. * src/driver.h (virDrvConnectDomainQemuMonitorEventRegister) (virDrvConnectDomainQemuMonitorEventDeregister): New callbacks. Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- Before I go and implement the guts of this new API, I first wanted to get approval from the list that I'm on the right track. include/libvirt/libvirt-qemu.h | 31 ++++++++++- src/driver.h | 15 +++++ src/libvirt-qemu.c | 123 +++++++++++++++++++++++++++++++++++++++++ src/libvirt_qemu.syms | 6 ++ 4 files changed, 174 insertions(+), 1 deletion(-) diff --git a/include/libvirt/libvirt-qemu.h b/include/libvirt/libvirt-qemu.h index 3e79a8c..5403093 100644 --- a/include/libvirt/libvirt-qemu.h +++ b/include/libvirt/libvirt-qemu.h @@ -4,7 +4,7 @@ * Description: Provides the interfaces of the libvirt library to handle * qemu specific methods * - * Copyright (C) 2010, 2012 Red Hat, Inc. + * Copyright (C) 2010, 2012-2013 Red Hat, Inc. * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public @@ -54,6 +54,35 @@ typedef enum { char *virDomainQemuAgentCommand(virDomainPtr domain, const char *cmd, int timeout, unsigned int flags); +/** + * virConnectDomainQemuMonitorEventCallback: + * @conn: the connection pointer + * @dom: the domain pointer + * @event: the name of the event + * @details: the JSON details of the event + * @opaque: application specified data + * + * The callback signature to use when registering for a qemu monitor + * event with virConnectDomainQemuMonitorEventRegister(). + */ +typedef void (*virConnectDomainQemuMonitorEventCallback)(virConnectPtr conn, + virDomainPtr dom, + const char *event, + const char *details, + void *opaque);