Logging: added stack_info argument.

3 files changed, 113 insertions, 21 deletions

diff --git a/Doc/library/logging.rst b/Doc/library/logging.rst
index 98c6bbf..1850cbb 100644
--- a/Doc/library/logging.rst
+++ b/Doc/library/logging.rst
@@ -757,13 +757,31 @@ functions.
    *msg* using the string formatting operator. (Note that this means that you can
    use keywords in the format string, together with a single dictionary argument.)
 
-   There are two keyword arguments in *kwargs* which are inspected: *exc_info*
+   There are three keyword arguments in *kwargs* which are inspected: *exc_info*
    which, if it does not evaluate as false, causes exception information to be
    added to the logging message. If an exception tuple (in the format returned by
    :func:`sys.exc_info`) is provided, it is used; otherwise, :func:`sys.exc_info`
    is called to get the exception information.
 
-   The other optional keyword argument is *extra* which can be used to pass a
+   The second optional keyword argument is *stack_info*, which defaults to
+   False. If specified as True, stack information is added to the logging
+   message, including the actual logging call. Note that this is not the same
+   stack information as that displayed through specifying *exc_info*: The
+   former is stack frames from the bottom of the stack up to the logging call
+   in the current thread, whereas the latter is information about stack frames
+   which have been unwound, following an exception, while searching for
+   exception handlers.
+
+   You can specify *stack_info* independently of *exc_info*, e.g. to just show
+   how you got to a certain point in your code, even when no exceptions were
+   raised. The stack frames are printed following a header line which says::
+
+       Stack (most recent call last):
+
+   This mimics the `Traceback (most recent call last):` which is used when
+   displaying exception frames.
+
+   The third optional keyword argument is *extra* which can be used to pass a
    dictionary which is used to populate the __dict__ of the LogRecord created for
    the logging event with user-defined attributes. These custom attributes can then
    be used as you like. For example, they could be incorporated into logged
@@ -796,6 +814,8 @@ functions.
    above example). In such circumstances, it is likely that specialized
    :class:`Formatter`\ s would be used with particular :class:`Handler`\ s.
 
+   .. versionadded:: 3.2
+      The *stack_info* parameter was added.
 
 .. function:: info(msg, *args, **kwargs)
 
@@ -1038,13 +1058,31 @@ instantiated directly, but always through the module-level function
    *msg* using the string formatting operator. (Note that this means that you can
    use keywords in the format string, together with a single dictionary argument.)
 
-   There are two keyword arguments in *kwargs* which are inspected: *exc_info*
+   There are three keyword arguments in *kwargs* which are inspected: *exc_info*
    which, if it does not evaluate as false, causes exception information to be
    added to the logging message. If an exception tuple (in the format returned by
    :func:`sys.exc_info`) is provided, it is used; otherwise, :func:`sys.exc_info`
    is called to get the exception information.
 
-   The other optional keyword argument is *extra* which can be used to pass a
+   The second optional keyword argument is *stack_info*, which defaults to
+   False. If specified as True, stack information is added to the logging
+   message, including the actual logging call. Note that this is not the same
+   stack information as that displayed through specifying *exc_info*: The
+   former is stack frames from the bottom of the stack up to the logging call
+   in the current thread, whereas the latter is information about stack frames
+   which have been unwound, following an exception, while searching for
+   exception handlers.
+
+   You can specify *stack_info* independently of *exc_info*, e.g. to just show
+   how you got to a certain point in your code, even when no exceptions were
+   raised. The stack frames are printed following a header line which says::
+
+       Stack (most recent call last):
+
+   This mimics the `Traceback (most recent call last):` which is used when
+   displaying exception frames.
+
+   The third keyword argument is *extra* which can be used to pass a
    dictionary which is used to populate the __dict__ of the LogRecord created for
    the logging event with user-defined attributes. These custom attributes can then
    be used as you like. For example, they could be incorporated into logged
@@ -1078,6 +1116,9 @@ instantiated directly, but always through the module-level function
    above example). In such circumstances, it is likely that specialized
    :class:`Formatter`\ s would be used with particular :class:`Handler`\ s.
 
+   .. versionadded:: 3.2
+      The *stack_info* parameter was added.
+
 
 .. method:: Logger.info(msg, *args, **kwargs)
 
@@ -1142,10 +1183,11 @@ instantiated directly, but always through the module-level function
    Removes the specified handler *hdlr* from this logger.
 
 
-.. method:: Logger.findCaller()
+.. method:: Logger.findCaller(stack_info=False)
 
    Finds the caller's source filename and line number. Returns the filename, line
-   number and function name as a 3-element tuple.
+   number, function name and stack information as a 4-element tuple. The stack
+   information is returned as *None* unless *stack_info* is *True*.
 
 
 .. method:: Logger.handle(record)
@@ -1156,7 +1198,7 @@ instantiated directly, but always through the module-level function
    Logger-level filtering is applied using :meth:`~Logger.filter`.
 
 
-.. method:: Logger.makeRecord(name, lvl, fn, lno, msg, args, exc_info, func=None, extra=None)
+.. method:: Logger.makeRecord(name, lvl, fn, lno, msg, args, exc_info, func=None, extra=None, sinfo=None)
 
    This is a factory method which can be overridden in subclasses to create
    specialized :class:`LogRecord` instances.
@@ -3043,6 +3085,9 @@ Currently, the useful mapping keys in a :class:`LogRecord` are:
       formatter to handle the event doesn't use the cached value but
       recalculates it afresh.
 
+      If stack information is available, it's appended after the exception
+      information, using :meth:`formatStack` to transform it if necessary.
+
 
    .. method:: formatTime(record, datefmt=None)
 
@@ -3062,6 +3107,12 @@ Currently, the useful mapping keys in a :class:`LogRecord` are:
       just uses :func:`traceback.print_exception`. The resulting string is
       returned.
 
+   .. method:: formatStack(stack_info)
+
+      Formats the specified stack information (a string as returned by
+      :func:`traceback.print_stack`, but with the last newline removed) as a
+      string. This default implementation just returns the input value.
+
 .. _filter:
 
 Filter Objects
@@ -3131,7 +3182,7 @@ every time something is logged, and can be created manually via
 wire).
 
 
-.. class:: LogRecord(name, lvl, pathname, lineno, msg, args, exc_info, func=None)
+.. class:: LogRecord(name, lvl, pathname, lineno, msg, args, exc_info, func=None, sinfo=None)
 
    Contains all the information pertinent to the event being logged.
 
@@ -3178,6 +3229,12 @@ wire).
 
       Absolute pathname of the source file of origin.
 
+   .. attribute:: stack_info
+
+      Stack frame information (where available) from the bottom of the stack
+      in the current thread, up to and including the stack frame of the
+      logging call which resulted in the creation of this record.
+
    .. method:: getMessage()
 
       Returns the message for this :class:`LogRecord` instance after merging any
diff --git a/Lib/logging/__init__.py b/Lib/logging/__init__.py
index f03d9f2..c4229e9 100644
--- a/Lib/logging/__init__.py
+++ b/Lib/logging/__init__.py
@@ -238,7 +238,7 @@ class LogRecord(object):
     information to be logged.
     """
     def __init__(self, name, level, pathname, lineno,
-                 msg, args, exc_info, func=None):
+                 msg, args, exc_info, func=None, sinfo=None):
         """
         Initialize a logging record with interesting information.
         """
@@ -272,6 +272,7 @@ class LogRecord(object):
             self.module = "Unknown module"
         self.exc_info = exc_info
         self.exc_text = None      # used to cache the traceback text
+        self.stack_info = sinfo
         self.lineno = lineno
         self.funcName = func
         self.created = ct
@@ -515,6 +516,19 @@ class Formatter(object):
     def formatMessage(self, record):
         return self._style.format(record)
 
+    def formatStack(self, stack_info):
+        """
+        This method is provided as an extension point for specialized
+        formatting of stack information.
+
+        The input data is a string as returned from a call to
+        :func:`traceback.print_stack`, but with the last trailing newline
+        removed.
+
+        The base implementation just returns the value passed in.
+        """
+        return stack_info
+
     def format(self, record):
         """
         Format the specified record as text.
@@ -541,6 +555,10 @@ class Formatter(object):
             if s[-1:] != "\n":
                 s = s + "\n"
             s = s + record.exc_text
+        if record.stack_info:
+            if s[-1:] != "\n":
+                s = s + "\n"
+            s = s + self.formatStack(record.stack_info)
         return s
 
 #
@@ -1213,11 +1231,12 @@ class Logger(Filterer):
         if self.isEnabledFor(ERROR):
             self._log(ERROR, msg, args, **kwargs)
 
-    def exception(self, msg, *args):
+    def exception(self, msg, *args, **kwargs):
         """
         Convenience method for logging an ERROR with exception information.
         """
-        self.error(msg, exc_info=1, *args)
+        kwargs['exc_info'] = True
+        self.error(msg, *args, **kwargs)
 
     def critical(self, msg, *args, **kwargs):
         """
@@ -1250,7 +1269,7 @@ class Logger(Filterer):
         if self.isEnabledFor(level):
             self._log(level, msg, args, **kwargs)
 
-    def findCaller(self):
+    def findCaller(self, stack_info=False):
         """
         Find the stack frame of the caller so that we can note the source
         file name, line number and function name.
@@ -1260,23 +1279,34 @@ class Logger(Filterer):
         #IronPython isn't run with -X:Frames.
         if f is not None:
             f = f.f_back
-        rv = "(unknown file)", 0, "(unknown function)"
+        rv = "(unknown file)", 0, "(unknown function)", None
         while hasattr(f, "f_code"):
             co = f.f_code
             filename = os.path.normcase(co.co_filename)
             if filename == _srcfile:
                 f = f.f_back
                 continue
-            rv = (co.co_filename, f.f_lineno, co.co_name)
+            sinfo = None
+            if stack_info:
+                sio = io.StringIO()
+                sio.write('Stack (most recent call last):\n')
+                traceback.print_stack(f, file=sio)
+                sinfo = sio.getvalue()
+                if sinfo[-1] == '\n':
+                    sinfo = sinfo[:-1]
+                sio.close()
+            rv = (co.co_filename, f.f_lineno, co.co_name, sinfo)
             break
         return rv
 
-    def makeRecord(self, name, level, fn, lno, msg, args, exc_info, func=None, extra=None):
+    def makeRecord(self, name, level, fn, lno, msg, args, exc_info,
+                   func=None, extra=None, sinfo=None):
         """
         A factory method which can be overridden in subclasses to create
         specialized LogRecords.
         """
-        rv = _logRecordClass(name, level, fn, lno, msg, args, exc_info, func)
+        rv = _logRecordClass(name, level, fn, lno, msg, args, exc_info, func,
+                             sinfo)
         if extra is not None:
             for key in extra:
                 if (key in ["message", "asctime"]) or (key in rv.__dict__):
@@ -1284,17 +1314,18 @@ class Logger(Filterer):
                 rv.__dict__[key] = extra[key]
         return rv
 
-    def _log(self, level, msg, args, exc_info=None, extra=None):
+    def _log(self, level, msg, args, exc_info=None, extra=None, stack_info=False):
         """
         Low-level logging routine which creates a LogRecord and then calls
         all the handlers of this logger to handle the record.
         """
+        sinfo = None
         if _srcfile:
             #IronPython doesn't track Python frames, so findCaller throws an
             #exception on some versions of IronPython. We trap it here so that
             #IronPython can use logging.
             try:
-                fn, lno, func = self.findCaller()
+                fn, lno, func, sinfo = self.findCaller(stack_info)
             except ValueError:
                 fn, lno, func = "(unknown file)", 0, "(unknown function)"
         else:
@@ -1302,7 +1333,8 @@ class Logger(Filterer):
         if exc_info:
             if not isinstance(exc_info, tuple):
                 exc_info = sys.exc_info()
-        record = self.makeRecord(self.name, level, fn, lno, msg, args, exc_info, func, extra)
+        record = self.makeRecord(self.name, level, fn, lno, msg, args,
+                                 exc_info, func, extra, sinfo)
         self.handle(record)
 
     def handle(self, record):
@@ -1657,12 +1689,13 @@ def error(msg, *args, **kwargs):
         basicConfig()
     root.error(msg, *args, **kwargs)
 
-def exception(msg, *args):
+def exception(msg, *args, **kwargs):
     """
     Log a message with severity 'ERROR' on the root logger,
     with exception information.
     """
-    error(msg, exc_info=1, *args)
+    kwargs['exc_info'] = True
+    error(msg, *args, **kwargs)
 
 def warning(msg, *args, **kwargs):
     """
diff --git a/Misc/NEWS b/Misc/NEWS
index 09f02c2..f33aba0 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -63,6 +63,8 @@ Core and Builtins
 Library
 -------
 
+- Issue #1553375: logging: Added stack_info kwarg to display stack information.
+
 - Issue #5111: IPv6 Host in the Header is wrapped inside [ ]. Patch by Chandru.
 
 - Fix Fraction.__hash__ so that Fraction.__hash__(-1) is -2.  (See also issue