Log unhandled exceptions in worker

RPC calls to the worker use 'cast', so nothing is listening to find out the
result. If an exception occurs we will never hear about it. This change
logs such unhandled exceptions as errors.

Change-Id: I51365a9dee8fd4eff85e77d3e42bf33be814a22c
Partial-Bug: #1703043
(cherry picked from commit 33a16aa7a8)

heat/engine/worker.py

@@ -14,9 +14,11 @@
 # limitations under the License.
 
 import eventlet.queue
+import functools
 
 from oslo_log import log as logging
 import oslo_messaging
+from oslo_utils import excutils
 from oslo_utils import uuidutils
 from osprofiler import profiler
 
@@ -38,6 +40,18 @@ LOG = logging.getLogger(__name__)
 CANCEL_RETRIES = 3
 
 
+def log_exceptions(func):
+    @functools.wraps(func)
+    def exception_wrapper(*args, **kwargs):
+        try:
+            return func(*args, **kwargs)
+        except Exception:
+            with excutils.save_and_reraise_exception():
+                LOG.exception('Unhandled exception in %s', func.__name__)
+
+    return exception_wrapper
+
+
 @profiler.trace_cls("rpc")
 class WorkerService(object):
     """Service that has 'worker' actor in convergence.
@@ -150,6 +164,7 @@ class WorkerService(object):
                                         stack)
 
     @context.request_context
+    @log_exceptions
     def check_resource(self, cnxt, resource_id, current_traversal, data,
                        is_update, adopt_stack_data):
         """Process a node in the dependency graph.
@@ -183,6 +198,7 @@ class WorkerService(object):
                                                    stack.id, msg_queue)
 
     @context.request_context
+    @log_exceptions
     def cancel_check_resource(self, cnxt, stack_id):
         """Cancel check_resource for given stack.