Session exposes a python log

Expose python logger via Session singleton, Session is now inherits singleton metaclass tests to prevent doubling sessions during various testing operations

Closes #4 (closed)

model_server/extensions/ilastik/router.py

@@ -25,9 +25,11 @@ def load_ilastik_model(model_class: ilm.IlastikModel, project_file: str, duplica
     if not duplicate:
         existing_model_id = session.find_param_in_loaded_models('project_file', project_file, is_path=True)
         if existing_model_id is not None:
+            session.log_info(f'An ilastik model from {project_file} already existing exists; did not load a duplicate')
             return {'model_id': existing_model_id}
     try:
         result = session.load_model(model_class, {'project_file': project_file})
+        session.log_info(f'Loaded ilastik model {result} from {project_file}')
     except (FileNotFoundError, ParameterExpectedError):
         raise HTTPException(
             status_code=404,
@@ -60,6 +62,7 @@ def infer_px_then_ob_maps(px_model_id: str, ob_model_id: str, input_filename: st
             channel=channel,
             mip=mip,
         )
+        session.log_info(f'Completed pixel and object classification of {input_filename}')
     except AssertionError:
         raise HTTPException(f'Incompatible models {px_model_id} and/or {ob_model_id}')
     return record
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