[Kimchi-devel] [PATCH] Abstract vm element updater for common usage

[lvroyce0210 at gmail.com]

From: Royce Lv <lvroyce at linux.vnet.ibm.com>

Different kinds of vm elements will be added through different
libvirt apis, this patch abstract a framework for this update.
Wrap correspondent libvirt api in vm element class,
and format their own libvirt call parameters in each class.

Signed-off-by: Royce Lv <lvroyce at linux.vnet.ibm.com>
---
 src/kimchi/model.py | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 63 insertions(+), 2 deletions(-)

diff --git a/src/kimchi/model.py b/src/kimchi/model.py
index 2c6d3a1..0f82b61 100644
--- a/src/kimchi/model.py
+++ b/src/kimchi/model.py
@@ -78,7 +78,6 @@ ISO_POOL_NAME = u'kimchi_isos'
 GUESTS_STATS_INTERVAL = 5
 HOST_STATS_INTERVAL = 1
 VM_STATIC_UPDATE_PARAMS = {'name': './name'}
-VM_LIVE_UPDATE_PARAMS = {}
 STORAGE_SOURCES = {'netfs': {'addr': '/pool/source/host/@name',
                              'path': '/pool/source/dir/@path'}}
 
@@ -490,7 +489,13 @@ class Model(object):
         return dom
 
     def _live_vm_update(self, dom, params):
-        pass
+        try:
+            for key, val in params.items():
+                element = VMElementDef.create(key, val, dom)
+                element.add_to_vm()
+        except libvirt.libvirtError as e:
+            raise OperationFailed("Cannot apply change on vm: %s",
+                                  e.get_error_message())
 
     def vm_update(self, name, params):
         dom = self._get_vm(name)
@@ -1510,6 +1515,62 @@ class LibvirtVMScreenshot(VMScreenshot):
             os.close(fd)
 
 
+class VMElementDef(object):
+    @classmethod
+    def create(cls, elem_type, elemArgs, dom):
+        for klass in cls.__subclasses__():
+            if elem_type == klass.elemType:
+                return klass(elemArgs, dom)
+        raise OperationFailed('Unsupported vm element type: %s' % elemArgs['type'])
+
+    def __init__(self, elemArgs, dom):
+        self.dom = dom
+        self.elemArgs = elemArgs
+
+    def add_to_vm(self):
+        """Live update domain with correspondant libvirt API.
+        This should be paired with cancel() operation to cancel failed update."""
+        pass
+
+    def delete_from_vm(self):
+        """Revert operation of live update vm."""
+        pass
+
+    @property
+    def _update_param(self):
+        ''' Subclasses have to override this method to actually generate the
+        update param.'''
+        raise OperationFailed('Update param generater is not implemented: %s' % self)
+
+
+class VMDiskDef(VMElementDef):
+    elemType = 'disk'
+
+    def __init__(self, elemArgs, dom):
+        super(VMDiskDef, self).__init__(elemArgs, dom)
+
+    def add_to_vm(self):
+        self.dom.attachDeviceFlags(xml=self._update_param['xml'],
+            flags=libvirt.VIR_DOMAIN_AFFECT_CURRENT|libvirt.VIR_DOMAIN_AFFECT_CONFIG)
+
+    def delete_from_vm(self):
+        self.dom.detachDeviceFlags(xml=self._update_param['xml'],
+            flags=libvirt.VIR_DOMAIN_AFFECT_CURRENT|libvirt.VIR_DOMAIN_AFFECT_CONFIG)
+
+    @property
+    def _update_param(self):
+        self.elemArgs['readonly'] = "<readonly/>" \
+            if self.elemArgs['target']['type'] == 'cdrom' else None
+        xml = """
+            <disk type='{source[type]}' device='{target[type]}'>
+            <source file='{source[path]}'/>
+            <target dev='{target[name]}' bus='{target[bus]}'/>
+            {readonly}
+            </disk>
+        """.format(**self.elemArgs)
+        return dict(xml=xml)
+
+
 class StoragePoolDef(object):
     @classmethod
     def create(cls, poolArgs):
-- 
1.8.1.2