Use singleton pattern to only initialize DB once (#122)

* Use singleton pattern to only initialize DB once

* Move `setup_logger` back

* MInor change

utilix/__init__.py

@@ -3,7 +3,7 @@
 from . import config
 
 # try loading config, if it doesn't work then set uconfig to None
-# this is needed so that strax(en) CI  tests will work even without a config file
+# this is needed so that strax(en) CI tests will work even without a config file
 uconfig = config.Config()
 
 if uconfig.is_configured:

utilix/batchq.py

@@ -8,7 +8,7 @@
 from typing import Any, Dict, List, Literal, Optional
 from pydantic import BaseModel, Field, validator
 from simple_slurm import Slurm  # type: ignore
-from utilix import logger
+from . import logger
 
 USER: Optional[str] = os.environ.get("USER")
 if USER is None:

utilix/config.py

@@ -5,6 +5,8 @@
 
 def setup_logger(logging_level="WARNING"):
     logger = logging.getLogger("utilix")
+    if logger.hasHandlers():
+        logger.handlers.clear()
     ch = logging.StreamHandler()
     ch.setLevel(logging_level)
     logger.setLevel(logging_level)

utilix/rundb.py

@@ -5,20 +5,17 @@
 import datetime
 import logging
 import pymongo
+from typing import Tuple, Dict
 from warnings import warn
 import time
 
-from . import uconfig, io
-from .config import setup_logger
+from . import uconfig, logger, io
 
 
 # Config the logger:
 if uconfig is not None:  # type: ignore
     PREFIX = uconfig.get("RunDB", "rundb_api_url", fallback=None)  # type: ignore
     BASE_HEADERS = {"Content-Type": "application/json", "Cache-Control": "no-cache"}
-    logger = setup_logger(uconfig.logging_level)  # type: ignore
-else:
-    logger = setup_logger()
 
 
 class NewTokenError(Exception):
@@ -181,8 +178,24 @@ def write(self):
 class DB:
     """Wrapper around the RunDB API."""
 
-    def __init__(self, token_path=None):
+    _instances: Dict[Tuple, "DB"] = {}
+    _initialized: Dict[Tuple, bool] = {}
 
+    def __new__(cls, *args, **kwargs):
+        key = (args, frozenset(kwargs.items()))
+        if key not in cls._instances:
+            cls._instances[key] = super(DB, cls).__new__(cls)
+            cls._initialized[key] = False
+        return cls._instances[key]
+
+    def __init__(self, *args, **kwargs):
+        key = (args, frozenset(kwargs.items()))
+        if not self._initialized[key]:
+            self._instances[key].initialize(*args, **kwargs)
+            self._initialized[key] = True
+        return
+
+    def initialize(self, token_path=None):
         if token_path is None:
             if "HOME" not in os.environ:
                 logger.error("$HOME is not defined in the environment")
@@ -505,10 +518,11 @@ class PyMongoCannotConnect(Exception):
 
 
 def test_collection(collection, url, raise_errors=False):
-    """Warn user if client can be troublesome if read preference is not specified :param collection:
+    """Warn user if client can be troublesome if read preference is not specified.
 
-    pymongo client :param url: the mongo url we are testing (for the error message) :param
-    raise_errors: if False (default) warn, otherwise raise an error.
+    :param collection: pymongo client
+    :param url: the mongo url we are testing (for the error message)
+    :param raise_errors: if False (default) warn, otherwise raise an error.
 
     """
     try: