Communicative workflow reader

Created by: stefanoborini

Makes the workflow reader more robust and more communicative of what went wrong during reading.

force_bdss/io/workflow_reader.py

@@ -9,20 +9,34 @@ from force_bdss.core.output_slot_info import OutputSlotInfo
 from force_bdss.core.workflow import Workflow
 from ..factory_registry_plugin import IFactoryRegistryPlugin
 
-log = logging.getLogger(__name__)
+logger = logging.getLogger(__name__)
 
 SUPPORTED_FILE_VERSIONS = ["1"]
 
 
-class InvalidFileException(Exception):
-    """Raised if the file is invalid for some reason"""
+class BaseWorkflowReaderException(Exception):
+    """Base exception for the reader errors."""
 
 
-class InvalidVersionException(InvalidFileException):
+class InvalidFileException(BaseWorkflowReaderException):
+    """Raised for a generic file being invalid for some
+    reason, e.g. incorrect format or missing keys.
+    """
+
+
+class InvalidVersionException(BaseWorkflowReaderException):
     """Raised if the version tag does not satisfy the currently
     supported list."""
 
 
+class MissingPluginException(BaseWorkflowReaderException):
+    """Raised if the file requires a plugin we cannot find."""
+
+
+class ModelInstantiationFailedException(BaseWorkflowReaderException):
+    """Raised if we can't instantiate the model from a plugin"""
+
+
 class WorkflowReader(HasStrictTraits):
     """
     Reads the workflow from a file.
@@ -67,18 +81,30 @@ class WorkflowReader(HasStrictTraits):
         ------
         InvalidFileException
             Raised if the file is corrupted or cannot be read by this reader.
+
+        InvalidVersionException
+            Raised if the version is not supported.
+
+        MissingPluginException
+            The file cannot be opened because it needs a plugin that is not
+            available.
+
+        ModelInstantiationFailedException
+            When instantiating the model for a given plugin, an exception
+            occurred. This is likely due to a coding error in the plugin.
+
         """
         json_data = json.load(file)
 
         try:
             version = json_data["version"]
         except KeyError:
-            log.error("File missing version information")
+            logger.error("File missing version information")
             raise InvalidFileException("Corrupted input file, no version"
                                        " specified")
 
         if version not in SUPPORTED_FILE_VERSIONS:
-            log.error(
+            logger.error(
                 "File contains version {} that is not in the "
                 "list of supported versions {}".format(
                     version, SUPPORTED_FILE_VERSIONS)
@@ -95,13 +121,13 @@ class WorkflowReader(HasStrictTraits):
             wf.notification_listeners[:] = \
                 self._extract_notification_listeners(wf_data)
         except KeyError as e:
-            log.error("Could not read file {}".format(file), exc_info=True)
-            raise InvalidFileException(
+            msg = (
                 "Could not read file {}. "
-                "Unable to find key {}."
-                "The plugin responsible for the missing "
-                "key may be missing or broken.".format(file, e)
-            )
+                "Unable to find key {}. "
+                "The file might be corrupted or unsupported.".format(file, e))
+            logger.exception(msg)
+            raise InvalidFileException(msg)
+
         return wf
 
     def _extract_mco(self, wf_data):
@@ -127,13 +153,30 @@ class WorkflowReader(HasStrictTraits):
             return None
 
         mco_id = mco_data["id"]
-        mco_factory = registry.mco_factory_by_id(mco_id)
+        try:
+            mco_factory = registry.mco_factory_by_id(mco_id)
+        except KeyError:
+            raise MissingPluginException(
+                "Could not read file. "
+                "The plugin responsible for the missing "
+                "key '{}' may be missing or broken.".format(mco_id)
+            )
         model_data = wf_data["mco"]["model_data"]
         model_data["parameters"] = self._extract_mco_parameters(
             mco_id,
             model_data["parameters"])
-        model = mco_factory.create_model(
-            wf_data["mco"]["model_data"])
+
+        try:
+            model = mco_factory.create_model(model_data)
+        except Exception as e:
+            msg = (
+                "Unable to create model for MCO {}: {}. "
+                "This is likely due to a coding error in the plugin. "
+                "Check the logs for more information.".format(
+                    mco_id, e))
+
+            logger.exception(msg)
+            raise ModelInstantiationFailedException(msg)
         return model
 
     def _extract_execution_layers(self, wf_data):
@@ -157,7 +200,16 @@ class WorkflowReader(HasStrictTraits):
 
             for ds_entry in el_entry:
                 ds_id = ds_entry["id"]
-                ds_factory = registry.data_source_factory_by_id(ds_id)
+
+                try:
+                    ds_factory = registry.data_source_factory_by_id(ds_id)
+                except KeyError:
+                    raise MissingPluginException(
+                        "Could not read file. "
+                        "The plugin responsible for the missing data source "
+                        "key '{}' may be missing or broken.".format(ds_id)
+                    )
+
                 model_data = ds_entry["model_data"]
                 model_data["input_slot_info"] = self._extract_input_slot_info(
                     model_data["input_slot_info"]
@@ -166,8 +218,21 @@ class WorkflowReader(HasStrictTraits):
                     self._extract_output_slot_info(
                         model_data["output_slot_info"]
                     )
-                layer.data_sources.append(
-                    ds_factory.create_model(model_data))
+
+                try:
+                    ds_model = ds_factory.create_model(model_data)
+                except Exception as e:
+                    msg = (
+                        "Unable to create model for DataSource {} : {}. "
+                        "This is likely due to a coding "
+                        "error in the plugin. Check the logs for more "
+                        "information.".format(ds_id, e)
+                    )
+                    logger.exception(msg)
+                    raise ModelInstantiationFailedException(msg)
+
+                layer.data_sources.append(ds_model)
+
             layers.append(layer)
 
         return layers
@@ -189,9 +254,29 @@ class WorkflowReader(HasStrictTraits):
         parameters = []
 
         for p in parameters_data:
-            id = p["id"]
-            factory = registry.mco_parameter_factory_by_id(mco_id, id)
-            model = factory.create_model(p["model_data"])
+            parameter_id = p["id"]
+            try:
+                factory = registry.mco_parameter_factory_by_id(
+                    mco_id, parameter_id)
+            except KeyError:
+                raise MissingPluginException(
+                    "Could not read file. "
+                    "The plugin responsible for the missing MCO '{}' "
+                    "parameter key '{}' may be missing or broken.".format(
+                        mco_id, parameter_id)
+                )
+
+            try:
+                model = factory.create_model(p["model_data"])
+            except Exception as e:
+                msg = (
+                    "Unable to create model for MCO {} parameter {} : {}. "
+                    "This is likely due to an error in the plugin. "
+                    "Check the logs for more information.".format(
+                        mco_id, parameter_id, e))
+                logger.exception(msg)
+                raise ModelInstantiationFailedException(msg)
+
             parameters.append(model)
 
         return parameters
@@ -207,8 +292,29 @@ class WorkflowReader(HasStrictTraits):
         listeners = []
         for nl_entry in wf_data["notification_listeners"]:
             nl_id = nl_entry["id"]
-            nl_factory = registry.notification_listener_factory_by_id(nl_id)
+            try:
+                nl_factory = registry.notification_listener_factory_by_id(
+                    nl_id)
+            except KeyError:
+                raise MissingPluginException(
+                    "Could not read file. "
+                    "The plugin responsible for the missing "
+                    "notification listener key '{}' may be missing "
+                    "or broken.".format(nl_id)
+                )
+
             model_data = nl_entry["model_data"]
-            listeners.append(nl_factory.create_model(model_data))
+
+            try:
+                model = nl_factory.create_model(model_data)
+            except Exception as e:
+                msg = (
+                    "Unable to create model for Notification Listener "
+                    "{} : {}. This is likely due to an error in the plugin. "
+                    "Check the logs for more information.".format(nl_id, e))
+                logger.exception(msg)
+                raise ModelInstantiationFailedException(msg)
+
+            listeners.append(model)
 
         return listeners