def start_backend(config):
"""
Start the backend by checking the currently running backend. Basically 2 cases/scenarios:
1. If no running backend => run the requested one.
2. If there is running backend =>
a. If the running backend is same as requested one => do nothing
b. If the running backend is different from the requested one => stop the running, and run the requested one.
In case the backend fails to start a IOError will be raised.
config (str): path to the microscope config file.
"""
# check if a backend is running
if driver.get_backend_status() in (driver.BACKEND_RUNNING,
driver.BACKEND_STARTING):
current_model = model.getMicroscope().model
try:
req_model = modelgen.Instantiator(open(config)).ast
except Exception as exp:
raise ValueError(exp)
if current_model == req_model:
logging.info("Backend for %s already running", config)
return
else:
logging.info(
"There is a backend running already, it will be turned off, and the backend \
%s will be run instead.", config)
stop_backend()
run_backend(config)
# check if no backend is running
else:
run_backend(config)
def __init__(self,
model_file,
settings_file,
create_sub_containers=False,
dry_run=False,
name=model.BACKEND_NAME):
"""
inst_file (file): opened file that contains the yaml
settings_file (file): opened file that contains the persistent data
container (Container): container in which to instantiate the components
create_sub_containers (bool): whether the leave components (components which
have no children created separately) are running in isolated containers
dry_run (bool): if True, it will check the semantic and try to instantiate the
model without actually any driver contacting the hardware.
"""
model.Container.__init__(self, name)
self._model = model_file
self._settings = settings_file
self._mdupdater = None
self._inst_thread = None # thread running the component instantiation
self._must_stop = threading.Event()
self._dry_run = dry_run
# TODO: have an argument to ask for disabling parallel start? same as create_sub_containers?
# parse the instantiation file
logging.debug("model instantiation file is: %s", self._model.name)
try:
self._instantiator = modelgen.Instantiator(model_file,
settings_file, self,
create_sub_containers,
dry_run)
# save the model
logging.info("model has been successfully parsed")
except modelgen.ParseError as exp:
raise ValueError("Error while parsing file %s:\n%s" %
(self._model.name, exp))
except modelgen.SemanticError as exp:
raise ValueError("When instantiating file %s:\n%s" %
(self._model.name, exp))
except Exception:
logging.exception("When instantiating file %s", self._model.name)
raise IOError("Unexpected error at instantiation")
# Initialize persistent data, will be updated and written to the settings_file in the
# end and every time a va is changed.
self._persistent_listeners = [
] # keep reference to persistent va listeners
self._persistent_data = self._instantiator.read_yaml(settings_file)