utils/logging: reset handlers before initialization/reconfiguration

Also improve the comments.

2 files changed, 16 insertions, 3 deletions

diff --git a/fg21sim/configs/manager.py b/fg21sim/configs/manager.py
index f5465a9..a889259 100644
--- a/fg21sim/configs/manager.py
+++ b/fg21sim/configs/manager.py
@@ -84,7 +84,13 @@ class ConfigManager:
     @property
     def logging(self):
         """Get and prepare the logging configurations for
-        `logging.basicConfig()`
+        ``logging.basicConfig()`` to initialize the logging module.
+
+        NOTE
+        ----
+        ``basicConfig()`` will automatically create a ``Formatter`` with
+        the giving ``format`` and ``datefmt`` for each handlers if necessary,
+        and then adding the handlers to the "root" logger.
         """
         from logging import FileHandler, StreamHandler
         conf = self.get("logging")
diff --git a/fg21sim/utils/logging.py b/fg21sim/utils/logging.py
index 0abf4d3..2630a58 100644
--- a/fg21sim/utils/logging.py
+++ b/fg21sim/utils/logging.py
@@ -19,6 +19,7 @@ def setup_logging(dict_config=None, level=None, stream=None, logfile=None):
     ----------
     dict_config : dict
         Dict of logging configurations specified in the config file.
+        If this parameter specified, the logging will be reconfigured.
     level : string;
         Override the existing log level
     stream : string; "stderr", "stdout", or ""
@@ -37,16 +38,22 @@ def setup_logging(dict_config=None, level=None, stream=None, logfile=None):
     """
     # default file open mode for logging to file
     filemode = "a"
+    root_logger = logging.getLogger()
     #
     if dict_config:
         # XXX:
         # "basicConfig()" does NOT accept paramter "filemode" if the
         # corresponding parameter "filename" NOT specified.
         filemode = dict_config.pop("filemode", filemode)
+        # Clear existing handlers, otherwise further "basicConfig" calls
+        # will be ignored
+        for handler in root_logger.handlers:
+            root_logger.removeHandler(handler)
+        # Initialize/reconfigure the logging, which will automatically
+        # create a ``Formatter`` for handlers if necessary, and adding
+        # the handlers to the "root" logger.
         logging.basicConfig(**dict_config)
     #
-    root_logger = logging.getLogger()
-    #
     if level is not None:
         level_int = getattr(logging, level.upper(), None)
         if not isinstance(level_int, int):