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Re: [libvirt] [PATCH] Fix up the python bindings for snapshotting.



On 05/20/2010 12:34 PM, Cole Robinson wrote:
> On 05/20/2010 11:14 AM, Chris Lalancette wrote:
>> This involved a few fixes.  To start with,
>> an virDomainSnapshot object is really tied to a
>> domain, not a connection, so we have to generate
>> a slightly different object so that we can get
>> at self._dom for the object.
>>
>> Next, we had to "dummy" up an override piece of
>> XML with a bogus argument that the function doesn't
>> actually take.  That's so that the generator places
>> virDomainRevertToSnapshot underneath the correct
>> class (namely, the virDomain class).
>>
>> Finally, we had to hand-implement the
>> virDomainRevertToSnapshot implementation, ignoring the
>> bogus pointer we are being passed.
>>
>> With all of this in place, I was able to successfully
>> take a snapshot and revert to it using only the
>> Python bindings.
>>
>> Signed-off-by: Chris Lalancette <clalance redhat com>
>> ---
>>  python/generator.py             |   26 +++++++++++++++++++++++---
>>  python/libvirt-override-api.xml |    7 +++++++
>>  python/libvirt-override.c       |   23 +++++++++++++++++++++++
>>  3 files changed, 53 insertions(+), 3 deletions(-)
>>
>> diff --git a/python/generator.py b/python/generator.py
>> index a243c82..d876df6 100755
>> --- a/python/generator.py
>> +++ b/python/generator.py
>> @@ -331,7 +331,7 @@ skip_impl = (
>>      'virNodeListDevices',
>>      'virNodeDeviceListCaps',
>>      'virConnectBaselineCPU',
>> -    'virDomainSnapshotListNames',
>> +    'virDomainRevertToSnapshot',
>>  )
>>  
>>  
>> @@ -385,6 +385,10 @@ skip_function = (
>>      "virStorageVolGetConnect",
>>  )
>>  
>> +function_skip_index_one = (
>> +    "virDomainRevertToSnapshot",
>> +)
>> +
>>  
>>  def print_function_wrapper(name, output, export, include):
>>      global py_types
>> @@ -688,9 +692,13 @@ classes_destructors = {
>>  }
>>  
>>  class_skip_connect_impl = {
>> -    "virConnect" : True
>> +    "virConnect" : True,
>> +    "virDomainSnapshot": True,
>>  }
>>  
>> +class_domain_impl = {
>> +    "virDomainSnapshot": True,
>> +}
>>  
>>  functions_noexcept = {
>>      'virDomainGetID': True,
>> @@ -986,7 +994,7 @@ def buildWrappers():
>>  		info = (0, func, name, ret, args, file)
>>  		function_classes[classe].append(info)
>>  	    elif name[0:3] == "vir" and len(args) >= 2 and args[1][1] == type \
>> -	        and file != "python_accessor":
>> +	        and file != "python_accessor" and not name in function_skip_index_one:
>>  		found = 1
>>  		func = nameFixup(name, classe, type, file)
>>  		info = (1, func, name, ret, args, file)
>> @@ -1128,6 +1136,8 @@ def buildWrappers():
>>                                    "virStorageVol", "virNodeDevice", "virSecret","virStream",
>>                                    "virNWFilter" ]:
>>                      classes.write("    def __init__(self, conn, _obj=None):\n")
>> +                elif classname in [ 'virDomainSnapshot' ]:
>> +                    classes.write("    def __init__(self, dom, _obj=None):\n")
>>                  else:
>>                      classes.write("    def __init__(self, _obj=None):\n")
>>  		if reference_keepers.has_key(classname):
>> @@ -1142,6 +1152,8 @@ def buildWrappers():
>>                      classes.write("        self._conn = conn\n" + \
>>                                    "        if not isinstance(conn, virConnect):\n" + \
>>                                    "            self._conn = conn._conn\n")
>> +                elif classname in [ "virDomainSnapshot" ]:
>> +                    classes.write("        self._dom = dom\n")
>>  		classes.write("        if _obj != None:self._o = _obj;return\n")
>>  		classes.write("        self._o = None\n\n");
>>  	    destruct=None
>> @@ -1158,6 +1170,10 @@ def buildWrappers():
>>                  classes.write("    def connect(self):\n")
>>                  classes.write("        return self._conn\n\n")
>>  
>> +            if class_domain_impl.has_key(classname):
>> +                classes.write("    def domain(self):\n")
>> +                classes.write("        return self._dom\n\n")
>> +
>>  	    flist = function_classes[classname]
>>  	    flist.sort(functionCompare)
>>  	    oldfile = ""
>> @@ -1252,6 +1268,10 @@ def buildWrappers():
>>                                  classes.write(
>>  		     "        if ret is None:raise libvirtError('%s() failed', vol=self)\n" %
>>                                                (name))
>> +                            elif classname == "virDomainSnapshot":
>> +                                classes.write(
>> +                     "        if ret is None:raise libvirtError('%s() failed', dom=self._dom)\n" %
>> +                                              (name))
>>                              else:
>>                                  classes.write(
>>  		     "        if ret is None:raise libvirtError('%s() failed')\n" %
>> diff --git a/python/libvirt-override-api.xml b/python/libvirt-override-api.xml
>> index 9ba8e4e..be28b40 100644
>> --- a/python/libvirt-override-api.xml
>> +++ b/python/libvirt-override-api.xml
>> @@ -277,5 +277,12 @@
>>        <arg name='flags' type='unsigned int' info='flags, curently unused'/>
>>        <return type='str *' info='the list of Names of None in case of error'/>
>>      </function>
>> +    <function name='virDomainRevertToSnapshot' file='python'>
>> +      <info>revert the domain to the given snapshot</info>
>> +      <arg name='dom' type='virDomainPtr' info='dummy domain pointer'/>
>> +      <arg name='snap' type='virDomainSnapshotPtr' info='pointer to the snapshot'/>
>> +      <arg name='flags' type='unsigned int' info='flags, curently unused'/>
>> +      <return type='int' info="0 on success, -1 on error"/>
>> +    </function>
>>    </symbols>
>>  </api>
>> diff --git a/python/libvirt-override.c b/python/libvirt-override.c
>> index c9721f7..ad55940 100644
>> --- a/python/libvirt-override.c
>> +++ b/python/libvirt-override.c
>> @@ -988,6 +988,28 @@ libvirt_virDomainSnapshotListNames(PyObject *self ATTRIBUTE_UNUSED,
>>  }
>>  
>>  static PyObject *
>> +libvirt_virDomainRevertToSnapshot(PyObject *self ATTRIBUTE_UNUSED,
>> +                                  PyObject *args) {
>> +    int c_retval;
>> +    virDomainSnapshotPtr snap;
>> +    PyObject *pyobj_snap;
>> +    PyObject *pyobj_dom;
>> +    int flags;
>> +
>> +    if (!PyArg_ParseTuple(args, (char *)"OOi:virDomainRevertToSnapshot", &pyobj_dom, &pyobj_snap, &flags))
>> +        return(NULL);
>> +    snap = (virDomainSnapshotPtr) PyvirDomainSnapshot_Get(pyobj_snap);
>> +
>> +    LIBVIRT_BEGIN_ALLOW_THREADS;
>> +    c_retval = virDomainRevertToSnapshot(snap, flags);
>> +    LIBVIRT_END_ALLOW_THREADS;
>> +    if (c_retval < 0)
>> +        return VIR_PY_INT_FAIL;
>> +
>> +    return PyInt_FromLong(c_retval);
>> +}
>> +
>> +static PyObject *
>>  libvirt_virDomainGetInfo(PyObject *self ATTRIBUTE_UNUSED, PyObject *args) {
>>      PyObject *py_retval;
>>      int c_retval;
>> @@ -3527,6 +3549,7 @@ static PyMethodDef libvirtMethods[] = {
>>      {(char *) "virConnectBaselineCPU", libvirt_virConnectBaselineCPU, METH_VARARGS, NULL},
>>      {(char *) "virDomainGetJobInfo", libvirt_virDomainGetJobInfo, METH_VARARGS, NULL},
>>      {(char *) "virDomainSnapshotListNames", libvirt_virDomainSnapshotListNames, METH_VARARGS, NULL},
>> +    {(char *) "virDomainRevertToSnapshot", libvirt_virDomainRevertToSnapshot, METH_VARARGS, NULL},
>>      {NULL, NULL, 0, NULL}
>>  };
>>  
> 
> ACK, change looks fine. Might be worth checking the python bindings diff
> though, the generator is fragile and changes can sometimes muck up
> existing APIs.

Excellent thought.  I did that across libvirt.c, libvirt-export.c, libvirt.h
and libvirt.py, and the only changes were the ones I expected.  Thanks for
the heads up.  I've now pushed this patch.

-- 
Chris Lalancette


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