Bug 1021943 - Add some additional features to mozlog.structured to help with informational level logging;r=jgraham

testing/mozbase/docs/mozlog_structured.rst

@@ -19,6 +19,10 @@ loggers with the same name share the same internal state (the "Borg"
 pattern). In particular the list of handler functions is the same for
 all loggers with the same name.
 
+Typically, you would only instantiate one logger object per
+program. Two convenience methods are provided to set and get the
+default logger in the program.
+
 Logging is threadsafe, with access to handlers protected by a
 ``threading.Lock``. However it is `not` process-safe. This means that
 applications using multiple processes, e.g. via the
@@ -192,6 +196,7 @@ StructuredLogger Objects
 ------------------------
 
 .. automodule:: mozlog.structured.structuredlog
+  :members: set_default_logger, get_default_logger
 
 .. autoclass:: StructuredLogger
    :members: add_handler, remove_handler, handlers, suite_start,

testing/mozbase/mozlog/mozlog/structured/__init__.py

@@ -4,3 +4,4 @@
 
 import commandline
 import structuredlog
+from structuredlog import get_default_logger, set_default_logger

testing/mozbase/mozlog/mozlog/structured/commandline.py

@@ -5,7 +5,7 @@
 import argparse
 import sys
 
-from structuredlog import StructuredLogger
+from structuredlog import StructuredLogger, set_default_logger
 import handlers
 import formatters
 
@@ -52,6 +52,9 @@ def setup_logging(suite, args, defaults):
     """
     Configure a structuredlogger based on command line arguments.
 
+    The created structuredlogger will also be set as the default logger, and
+    can be retrieved with :py:func:`get_default_logger`.
+
     :param suite: The name of the testsuite being run
     :param args: A dictionary of {argument_name:value} produced from
                  parsing the command line arguments for the application
@@ -90,4 +93,6 @@ def setup_logging(suite, args, defaults):
                 logger.add_handler(handlers.StreamHandler(stream=value,
                                                           formatter=formatter_cls()))
 
+    set_default_logger(logger)
+
     return logger

testing/mozbase/mozlog/mozlog/structured/formatters/machformatter.py

@@ -83,6 +83,9 @@ class BaseMachFormatter(base.BaseFormatter):
                                              data["command"])
 
     def log(self, data):
+        if data.get('component'):
+            return " ".join([data["component"], data["level"], data["message"]])
+
         return "%s %s" % (data["level"], data["message"])
 
     def _get_subtest_data(self, data):

testing/mozbase/mozlog/mozlog/structured/formatters/tbplformatter.py

@@ -17,6 +17,9 @@ class TbplFormatter(BaseMachFormatter):
         return getattr(self, data["action"])(data)
 
     def log(self, data):
+        if data.get('component'):
+            return "%s %s\n" % (data["component"], data["message"])
+
         return "%s\n" % (data["message"])
 
     def process_output(self, data):

testing/mozbase/mozlog/mozlog/structured/structuredlog.py

@@ -52,8 +52,34 @@ Subfields for all messages:
       thread - name for the thread emitting the message
       pid - id of the python process in which the logger is running
       source - name for the source emitting the message
+      component - name of the subcomponent emitting the message
 """
 
+_default_logger_name = None
+
+def get_default_logger(component=None):
+    """Gets the default logger if available, optionally tagged with component
+    name. Will return None if not yet set
+
+    :param component: The component name to tag log messages with
+    """
+    global _default_logger_name
+
+    if not _default_logger_name:
+        return None
+
+    return StructuredLogger(_default_logger_name, component=component)
+
+def set_default_logger(default_logger):
+    """Sets the default logger to logger.
+
+    It can then be retrieved with :py:func:`get_default_logger`
+
+    :param default_logger: The logger to set to default.
+    """
+    global _default_logger_name
+
+    _default_logger_name = default_logger.name
 
 log_levels = dict((k.upper(), v) for v, k in
                   enumerate(["critical", "error", "warning", "info", "debug"]))
@@ -67,8 +93,9 @@ class StructuredLogger(object):
     :param name: The name of the logger.
     """
 
-    def __init__(self, name):
+    def __init__(self, name, component=None):
         self.name = name
+        self.component = component
 
     def add_handler(self, handler):
         """Add a handler to the current logger"""
@@ -101,6 +128,8 @@ class StructuredLogger(object):
                     "thread": current_thread().name,
                     "pid": current_process().pid,
                     "source": self.name}
+        if self.component:
+            all_data['component'] = self.component
         all_data.update(data)
         return all_data