Add a Resource plugin API for cancelling actions

Allow a resource type plugin to provide a handle_*_cancel() method to
handle cancelling an in-progress action.

Change-Id: I20d243328daf1ffa1a40d55c5fcf889c70a8a59c
Related-Bug: #1585815
Related-Bug: #1591337

heat/engine/resource.py

@@ -775,16 +775,34 @@ class Resource(object):
             handler_data = handler(*args)
             yield
             if callable(check):
-                while True:
-                    try:
-                        done = check(handler_data)
-                    except PollDelay as delay:
-                        yield delay.period
-                    else:
-                        if done:
-                            break
+                try:
+                    while True:
+                        try:
+                            done = check(handler_data)
+                        except PollDelay as delay:
+                            yield delay.period
                         else:
-                            yield
+                            if done:
+                                break
+                            else:
+                                yield
+                except Exception:
+                    raise
+                except:  # noqa
+                    with excutils.save_and_reraise_exception():
+                        canceller = getattr(
+                            self,
+                            'handle_%s_cancel' % handler_action,
+                            None
+                        )
+                        if callable(canceller):
+                            try:
+                                canceller(handler_data)
+                            except Exception:
+                                LOG.exception(
+                                    _LE('Error cancelling resource %s'),
+                                    action
+                                )
 
     @scheduler.wrappertask
     def _do_action(self, action, pre_func=None, resource_data=None):

heat/tests/generic_resource.py

@@ -62,6 +62,22 @@ class GenericResource(resource.Resource):
                     self.type())
 
 
+class CancellableResource(GenericResource):
+    def check_create_complete(self, cookie):
+        return True
+
+    def handle_create_cancel(self, cookie):
+        LOG.warning(_LW('Cancelling create generic resource (Type "%s")'),
+                    self.type())
+
+    def check_update_complete(self, cookie):
+        return True
+
+    def handle_update_cancel(self, cookie):
+        LOG.warning(_LW('Cancelling update generic resource (Type "%s")'),
+                    self.type())
+
+
 class ResWithShowAttr(GenericResource):
     def _show_resource(self):
         return {'foo': self.name,

heat/tests/test_resource.py

@@ -914,6 +914,52 @@ class ResourceTest(common.HeatTestCase):
         self.assertEqual((res.CREATE, res.COMPLETE), res.state)
         self.m.VerifyAll()
 
+    def test_create_cancel(self):
+        tmpl = rsrc_defn.ResourceDefinition('test_resource', 'Foo')
+        res = generic_rsrc.CancellableResource('test_resource', tmpl,
+                                               self.stack)
+
+        self.m.StubOutWithMock(res, 'handle_create')
+        self.m.StubOutWithMock(res, 'check_create_complete')
+        self.m.StubOutWithMock(res, 'handle_create_cancel')
+
+        cookie = object()
+        res.handle_create().AndReturn(cookie)
+        res.check_create_complete(cookie).AndReturn(False)
+        res.handle_create_cancel(cookie).AndReturn(None)
+
+        self.m.ReplayAll()
+
+        runner = scheduler.TaskRunner(res.create)
+        runner.start()
+        runner.step()
+        runner.cancel()
+
+        self.m.VerifyAll()
+
+    def test_create_cancel_exception(self):
+        tmpl = rsrc_defn.ResourceDefinition('test_resource', 'Foo')
+        res = generic_rsrc.CancellableResource('test_resource', tmpl,
+                                               self.stack)
+
+        self.m.StubOutWithMock(res, 'handle_create')
+        self.m.StubOutWithMock(res, 'check_create_complete')
+        self.m.StubOutWithMock(res, 'handle_create_cancel')
+
+        cookie = object()
+        res.handle_create().AndReturn(cookie)
+        res.check_create_complete(cookie).AndReturn(False)
+        res.handle_create_cancel(cookie).AndRaise(Exception)
+
+        self.m.ReplayAll()
+
+        runner = scheduler.TaskRunner(res.create)
+        runner.start()
+        runner.step()
+        runner.cancel()
+
+        self.m.VerifyAll()
+
     def test_preview(self):
         tmpl = rsrc_defn.ResourceDefinition('test_resource',
                                             'GenericResourceType')
@@ -1089,6 +1135,35 @@ class ResourceTest(common.HeatTestCase):
         self.assertEqual((res.UPDATE, res.FAILED), res.state)
         self.m.VerifyAll()
 
+    def test_update_cancel(self):
+        tmpl = rsrc_defn.ResourceDefinition('test_resource', 'Foo')
+        res = generic_rsrc.CancellableResource('test_resource', tmpl,
+                                               self.stack)
+
+        self.m.StubOutWithMock(res, '_needs_update')
+        self.m.StubOutWithMock(res, 'handle_update')
+        self.m.StubOutWithMock(res, 'check_update_complete')
+        self.m.StubOutWithMock(res, 'handle_update_cancel')
+
+        res._needs_update(mock.ANY, mock.ANY,
+                          mock.ANY, mock.ANY,
+                          None).AndReturn(True)
+        cookie = object()
+        res.handle_update(mock.ANY, mock.ANY, mock.ANY).AndReturn(cookie)
+        res.check_update_complete(cookie).AndReturn(False)
+        res.handle_update_cancel(cookie).AndReturn(None)
+
+        self.m.ReplayAll()
+
+        scheduler.TaskRunner(res.create)()
+
+        runner = scheduler.TaskRunner(res.update, tmpl)
+        runner.start()
+        runner.step()
+        runner.cancel()
+
+        self.m.VerifyAll()
+
     def test_check_supported(self):
         tmpl = rsrc_defn.ResourceDefinition('test_res', 'GenericResourceType')
         res = generic_rsrc.ResourceWithProps('test_res', tmpl, self.stack)