[kupfer: 1/2] virtualbox: lazy loading and unloading supporting modules

[Ulrik Sverdrup <usverdrup src gnome org>]

commit 23ef5ab4e2a44a846917e2a40fbb88eb43d1b106
Author: Karol BÄ?dkowski <karol bedkowski gmail com>
Date:   Sun Mar 6 22:26:39 2011 +0100

    virtualbox: lazy loading and unloading supporting modules
    
    Supporting modules are loading when necessary (at first use).
    After change configuration ("force cli" setting) current module is removed
    from sys.modules.

 kupfer/plugin/virtualbox/__init__.py         |   69 ++++++++++++++++++++------
 kupfer/plugin/virtualbox/ose_support.py      |    4 ++
 kupfer/plugin/virtualbox/vboxapi4_support.py |   13 +++--
 kupfer/plugin/virtualbox/vboxapi_support.py  |   14 ++++--
 4 files changed, 76 insertions(+), 24 deletions(-)
---
diff --git a/kupfer/plugin/virtualbox/__init__.py b/kupfer/plugin/virtualbox/__init__.py
index 16c1e2f..a2c695c 100644
--- a/kupfer/plugin/virtualbox/__init__.py
+++ b/kupfer/plugin/virtualbox/__init__.py
@@ -7,22 +7,13 @@ __description__ = _("Control VirtualBox Virtual Machines. "
 __version__ = "0.3"
 __author__ = "Karol BÄ?dkowski <karol bedkowski gmail com>"
 
+import sys
+
 from kupfer.objects import Leaf, Action, Source
 from kupfer import pretty
 from kupfer import plugin_support
 from kupfer.obj.apps import ApplicationSource
 
-try:
-	try:
-		from kupfer.plugin.virtualbox import vboxapi4_support as vboxapi_support
-		pretty.print_info(__name__, 'Using vboxapi4...')
-	except ImportError, err:
-		from kupfer.plugin.virtualbox import vboxapi_support
-		pretty.print_info(__name__, 'Using vboxapi...')
-except ImportError, err:
-	pretty.print_info(__name__, 'vboxapi not available...', err)
-	vboxapi_support = None
-
 from kupfer.plugin.virtualbox import ose_support
 from kupfer.plugin.virtualbox import constants as vbox_const
 
@@ -37,12 +28,49 @@ __kupfer_settings__ = plugin_support.PluginSettings(
 )
 
 
+def _get_vbox():
+	if __kupfer_settings__['force_cli']:
+		pretty.print_info(__name__, 'Using cli...')
+		return ose_support
+	try:
+		from kupfer.plugin.virtualbox import vboxapi4_support
+		pretty.print_info(__name__, 'Using vboxapi4...')
+		return vboxapi4_support
+	except ImportError:
+		pass
+	try:
+		from kupfer.plugin.virtualbox import vboxapi_support
+		pretty.print_info(__name__, 'Using vboxapi...')
+		return vboxapi_support
+	except ImportError:
+		pass
+	pretty.print_info(__name__, 'Using cli...')
+	return ose_support
+
+
 class _VBoxSupportProxy:
+	VBOX = None
+
 	def __getattr__(self, attr):
-		vbox = ose_support
-		if vboxapi_support and not __kupfer_settings__['force_cli']:
-			vbox = vboxapi_support
-		return getattr(vbox, attr)
+		if not self.VBOX:
+			self.reload_settings()
+		return getattr(self.VBOX, attr)
+
+	def reload_settings(self):
+		pretty.print_debug(__name__, '_VBoxSupportProxy.reloading...')
+		self.unload_module()
+		self.VBOX = _get_vbox()
+
+	def unload_module(self):
+		if not self.VBOX:
+			return
+		# remove module
+		self.VBOX.unload()
+		for module_name, module in sys.modules.iteritems():
+			if module == self.VBOX:
+				sys.modules.pop(module_name)
+				break
+		self.VBOX = None
 
 
 vbox_support = _VBoxSupportProxy()
@@ -105,7 +133,7 @@ class VMAction(Action):
 
 
 class VBoxMachinesSource(ApplicationSource):
-	appleaf_content_id = vbox_support.APP_ID
+	appleaf_content_id = ("virtualbox-ose", "virtualbox")
 
 	def __init__(self, name=_("VirtualBox Machines")):
 		Source.__init__(self, name)
@@ -114,6 +142,11 @@ class VBoxMachinesSource(ApplicationSource):
 		if vbox_support.MONITORED_DIRS:
 			self.monitor_token = self.monitor_directories(
 					*vbox_support.MONITORED_DIRS)
+		__kupfer_settings__.connect("plugin-setting-changed", self._setting_changed)
+
+	def finalize(self):
+		if vbox_support:
+			vbox_support.unload_module()
 
 	def is_dynamic(self):
 		return vbox_support.IS_DYNAMIC
@@ -130,3 +163,7 @@ class VBoxMachinesSource(ApplicationSource):
 
 	def provides(self):
 		yield VirtualMachine
+
+	def _setting_changed(self, _setting, _key, _value):
+		if vbox_support:
+			vbox_support.reload_settings()
diff --git a/kupfer/plugin/virtualbox/ose_support.py b/kupfer/plugin/virtualbox/ose_support.py
index cdaf696..b1f406b 100644
--- a/kupfer/plugin/virtualbox/ose_support.py
+++ b/kupfer/plugin/virtualbox/ose_support.py
@@ -126,3 +126,7 @@ def get_machines():
 			name, description = _get_machine_info(vm_uuid, config)
 			if name:
 				yield (vm_uuid, name, description)
+
+
+def unload():
+	pass
diff --git a/kupfer/plugin/virtualbox/vboxapi4_support.py b/kupfer/plugin/virtualbox/vboxapi4_support.py
index 85c4a92..29e4ce4 100644
--- a/kupfer/plugin/virtualbox/vboxapi4_support.py
+++ b/kupfer/plugin/virtualbox/vboxapi4_support.py
@@ -6,14 +6,15 @@ Control VirtualBox via Python interface (vboxapi).
 Only (?) Sun VirtualBox (no OSE).
 '''
 __author__ = "Karol BÄ?dkowski <karol bedkowski gmail com>"
-__version__ = "0.3"
+__version__ = "2011-03-06"
 
-from kupfer import pretty
-
-#raise ImportError()
+import sys
 
 import vboxapi
 
+from kupfer import pretty
+
+
 # check api
 try:
 	vboxapi.VirtualBoxReflectionInfo(None).SessionState_Locked
@@ -152,3 +153,7 @@ def get_machines():
 	for machine in machines:
 		description = machine.description or machine.OSTypeId
 		yield (machine.id, machine.name, description)
+
+
+def unload():
+	sys.modules.pop('vboxapi')
diff --git a/kupfer/plugin/virtualbox/vboxapi_support.py b/kupfer/plugin/virtualbox/vboxapi_support.py
index abea025..fce39f7 100644
--- a/kupfer/plugin/virtualbox/vboxapi_support.py
+++ b/kupfer/plugin/virtualbox/vboxapi_support.py
@@ -6,14 +6,16 @@ Control VirtualBox via Python interface (vboxapi).
 Only (?) Sun VirtualBox (no OSE).
 '''
 __author__ = "Karol BÄ?dkowski <karol bedkowski gmail com>"
-__version__ = "2011-01-20"
+__version__ = "2011-03-06"
 
-from kupfer import pretty
 
-#raise ImportError()
+import sys
+
+from kupfer import pretty
 
 import vboxapi
 
+
 from kupfer.plugin.virtualbox import constants as vbox_const
 
 MONITORED_DIRS = None
@@ -77,7 +79,7 @@ def get_machine_state(machine_id):
 			state = vbox_const.VM_STATE_POWEROFF
 		elif machine_state == vbox.constants.MachineState_Saved:
 			state = vbox_const.VM_STATE_SAVED
-	except Exception:  # exception == machine is off (xpcom.Exception)
+	except Exception, err:  # exception == machine is off (xpcom.Exception)
 		# silently set state to off
 		state = vbox_const.VM_STATE_POWEROFF
 		pretty.print_debug(__name__, 'get_machine_state error', err)
@@ -158,3 +160,7 @@ def get_machines():
 		description = machine.description or machine.OSTypeId
 		yield (machine.id, machine.name, description)
 	pretty.print_debug(__name__, 'get_machines finished')
+
+
+def unload():
+	sys.modules.pop('vboxapi')