some system call and signal will interrupt poll,
making event loop stops and fails to react events and keepalive message
from libvirt.
adding handling EINTR to poll to make it more robust
Signed-off-by: NRoyce Lv <lvroyce@linux.vnet.ibm.com>

When the guest changes its memory balloon applications may want
to know what the new value is, without having to periodically
poll on XML / domain info. Introduce a "balloon change" event
to let apps see this

* include/libvirt/libvirt.h.in: Define the
  virConnectDomainEventBalloonChangeCallback callback
  and VIR_DOMAIN_EVENT_ID_BALLOON_CHANGE constant
* python/libvirt-override-virConnect.py,
  python/libvirt-override.c: Wire up helpers for new event
* daemon/remote.c: Helper for serializing balloon event
* examples/domain-events/events-c/event-test.c,
  examples/domain-events/events-python/event-test.py: Add
  example of balloon event usage
* src/conf/domain_event.c, src/conf/domain_event.h: Handling
  of balloon events
* src/remote/remote_driver.c: Add handler of balloon events
* src/remote/remote_protocol.x: Define wire protocol for
  balloon events
* src/remote_protocol-structs: Likewise.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

This patch introduces a new event type for the QMP event
SUSPEND:

    VIR_DOMAIN_EVENT_ID_PMSUSPEND

The event doesn't take any data, but considering there might
be reason for wakeup in future, the callback definition is:

typedef void
(*virConnectDomainEventSuspendCallback)(virConnectPtr conn,
                                        virDomainPtr dom,
                                        int reason,
                                        void *opaque);

"reason" is unused currently, always passes "0".

This patch introduces a new event type for the QMP event
WAKEUP:

    VIR_DOMAIN_EVENT_ID_PMWAKEUP

The event doesn't take any data, but considering there might
be reason for wakeup in future, the callback definition is:

typedef void
(*virConnectDomainEventWakeupCallback)(virConnectPtr conn,
                                       virDomainPtr dom,
                                       int reason,
                                       void *opaque);

"reason" is unused currently, always passes "0".

This patch introduces a new event type for the QMP event
DEVICE_TRAY_MOVED, which occurs when the tray of a removable
disk is moved (i.e opened or closed):

    VIR_DOMAIN_EVENT_ID_TRAY_CHANGE

The event's data includes the device alias and the reason
for tray status' changing, which indicates why the tray
status was changed. Thus the callback definition for the event
is:

enum {
    VIR_DOMAIN_EVENT_TRAY_CHANGE_OPEN = 0,
    VIR_DOMAIN_EVENT_TRAY_CHANGE_CLOSE,

\#ifdef VIR_ENUM_SENTINELS
    VIR_DOMAIN_EVENT_TRAY_CHANGE_LAST
\#endif
} virDomainEventTrayChangeReason;

typedef void
(*virConnectDomainEventTrayChangeCallback)(virConnectPtr conn,
                                           virDomainPtr dom,
                                           const char *devAlias,
                                           int reason,
                                           void *opaque);

If a disk source gets dropped because it is not accessible,
mgmt application might want to be informed about this. Therefore
we need to emit an event. The event presented in this patch
is however a bit superset of what written above. The reason is simple:
an intention to be easily expanded, e.g. on 'user ejected disk
in guest' events. Therefore, callback gets source string and disk alias
(which should be unique among a domain) and reason (an integer);

Add support for enabling debug output via command line option.
Allow to toggle the loop implementation between pure-Python and
native-C.
Signed-off-by: NPhilipp Hahn <hahn@univention.de>

When --help is requested, print usage() to stdout.
When an illegal option is passed, print usage to stderr.
Signed-off-by: NPhilipp Hahn <hahn@univention.de>

sys.argv contains the original command line arguments, while args only
contains the arguments not handled by getopt(). Currently this is no
problem since --help is the only command line option passable, which
terminates the process, so the code is never reached. Any option added
in the future will reveal the bug.
Signed-off-by: NPhilipp Hahn <hahn@univention.de>

If registering our own event loop implementation written in python,
any handles or timeouts callbacks registered by libvirt C code must
be wrapped in a python function. There is some argument trickery that
makes this all work, by wrapping the user passed opaque value in
a tuple, along with the callback function.

Problem is, the current setup requires the user's event loop to know
about this trickery, rather than just treating the opaque value
as truly opaque.

Fix this in a backwards compatible manner, and adjust the example
python event loop to do things the proper way.

The example C event loop code is a nasty hack and not compliant
with the require API semantics. Delete this, so that developers
don't mistakenly copy it. Instead call the new public event loop
APIs.

Update the python event loop example, so that it can optionally
use the public event APIs, as an alternative to the pure python
code. The pure python event code is a good working example, so
don't delete it.

Also make the python example use a read only connection to avoid
authentication prompts

* examples/domain-events/events-c/event-test.c: Replace event
  loop code with use of public APIs
* examples/domain-events/events-python/event-test.py: Allow
  optional use of new public event APIs

If the event loop takes a very long time todo something, it is
possible for the 'self pipe' buffer to become full at which
point the entire event loop + remote driver deadlock. Use a
boolean flag to ensure we have strict one-in, one-out behaviour
on writes/reads of the 'self pipe'

Make it easy to change debugging if being used by a client program.

The events demo program is slightly misleading printing

  myDomainEventCallback1 EVENT: Domain f14i686(-1) Added

which is not distinguishing Add vs Update events. It should have
been doing

  myDomainEventCallback1 EVENT: Domain f14i686(-1) Defined Updated

* examples/domain-events/events-python/event-test.py: Fully print
  event detail info string

The generator was disabled for the new event callbacks, since they
need to be hand written. This patch  adds the C and python glue to
expose the new APIs in the python binding. The python example
program is extended to demonstrate of the code

* python/libvirt-override.c: Registration and dispatch of events
   at the C layer
* python/libvirt-override-virConnect.py: Python glue for events
* examples/domain-events/events-python/event-test.py: Demo use
  of new event callbacks

The conversion from seconds to milliseconds should only be done for
actual delays >= 0, not for the magic -1 value used for infinite
timeouts.
Signed-off-by: NPhilipp Hahn <hahn@univention.de>

The existing python demo for domain events does not fully
implement the event loop contract. This makes the code useless
for real world applications. This change re-writes the demo so
that it has a full event loop implementation which is suitable
for application usage & better demonstrates integration

* examples/domain-events/events-python/event-test.py: Rewrite
  to include a real world usable event loop implementation

by running this command:
git ls-files -z | xargs -0 perl -pi -0777 -e 's/\n\n+$/\n/'
This is in preparation for a more strict make syntax-check
rule that will detect trailing blank lines.

  python/libvir.py python/libvirt_wrap.h python/types.c:
  adds support for events from the python bindings, also
  improves the generator allowing to embbed per function
  definition files, patch by Ben Guthro
* examples/domain-events/events-python/event-test.py: also
  adds a programming example
Daniel