Re-use PanLogger instances if the parameters haven't changed. (#192)

* Re-use PanLogger instances if the parameters haven't changed.
* Remove global _logger and references to it, replace with calls to
get_root_logger.

pocs/__init__.py

@@ -72,7 +72,6 @@ def _check_config(temp_config):
 
 # Global vars
 _config = None
-_logger = None
 
 
 class PanBase(object):
@@ -96,12 +95,9 @@ def __init__(self, *args, **kwargs):
         _check_config(_config)
         self.config = _config
 
-        global _logger
-        if _logger is None:
-            _logger = get_root_logger()
-            _logger.info('{:*^80}'.format(' Starting POCS '))
-
-        self.logger = kwargs.get('logger', _logger)
+        self.logger = kwargs.get('logger')
+        if not self.logger:
+            self.logger = get_root_logger()
 
         self.__version__ = __version__
 

pocs/utils/google/storage.py

@@ -3,7 +3,7 @@
 
 from gcloud import storage
 
-from pocs import _logger
+import pocs.utils.logger
 
 
 class PanStorage(object):
@@ -14,7 +14,7 @@ def __init__(self, project_id='panoptes-survey', bucket_name=None, prefix=None):
             "A valid bucket name is required.")
         super(PanStorage, self).__init__()
 
-        self.logger = _logger
+        self.logger = pocs.utils.logger.get_root_logger()
         self.project_id = project_id
         self.prefix = prefix
 

pocs/utils/logger.py

@@ -1,3 +1,4 @@
+import json
 import os
 import sys
 import time
@@ -42,6 +43,12 @@ def error(self, fmt, *args, **kwargs):
         self.logger.error(self._process_str(fmt, *args, **kwargs))
 
 
+# We don't want to create multiple root loggers that are "identical",
+# so track the loggers in a dict keyed by a tuple of:
+#    (profile, json_serialized_logger_config).
+all_loggers = {}
+
+
 def get_root_logger(profile='panoptes', log_config=None):
     """ Creates a root logger for PANOPTES used by the PanBase object
     Returns:
@@ -51,11 +58,16 @@ def get_root_logger(profile='panoptes', log_config=None):
     # Get log info from config
     log_config = log_config if log_config else load_config('log').get('logger', {})
 
+    # If we already created a logger for this profile and log_config, return that.
+    logger_key = (profile, json.dumps(log_config, sort_keys=True))
+    logger_for_config = all_loggers.get(logger_key, None)
+    if logger_for_config:
+        return logger_for_config
+
     # Alter the log_config to use UTC times
     if log_config.get('use_utc', True):
         for name, formatter in log_config['formatters'].items():
             log_config['formatters'][name].setdefault('()', _UTCFormatter)
-
         log_fname_datetime = datetime.datetime.utcnow().strftime('%Y%m%dT%H%M%SZ')
     else:
         log_fname_datetime = datetime.datetime.now().strftime('%Y%m%dT%H%M%SZ')
@@ -100,7 +112,9 @@ def get_root_logger(profile='panoptes', log_config=None):
     except Exception:  # pragma: no cover
         pass
 
-    return PanLogger(logger)
+    logger = PanLogger(logger)
+    all_loggers[logger_key] = logger
+    return logger
 
 
 class _UTCFormatter(logging.Formatter):