[Python-Dev] [Python-checkins] cpython (3.2): logging: Added locking in flush() and close() handler methods. Thanks to Fayaz

[Gregory P. Smith]

On Thu, Feb 23, 2012 at 12:04 PM, vinay.sajip
<python-checkins at python.org> wrote:
> http://hg.python.org/cpython/rev/b2adcd90e656
> changeset:   75211:b2adcd90e656
> branch:      3.2
> parent:      75200:85d08a1ba74e
> user:        Vinay Sajip <vinay_sajip at yahoo.co.uk>
> date:        Thu Feb 23 19:45:52 2012 +0000
> summary:
>  logging: Added locking in flush() and close() handler methods. Thanks to Fayaz Yusuf Khan for the suggestion.
>
> files:
>  Lib/logging/__init__.py |  24 +++++++++-------
>  Lib/logging/handlers.py |  40 +++++++++++++++-------------
>  2 files changed, 35 insertions(+), 29 deletions(-)
>
>
> diff --git a/Lib/logging/__init__.py b/Lib/logging/__init__.py
> --- a/Lib/logging/__init__.py
> +++ b/Lib/logging/__init__.py
> @@ -1,4 +1,4 @@
> -# Copyright 2001-2010 by Vinay Sajip. All Rights Reserved.
> +# Copyright 2001-2012 by Vinay Sajip. All Rights Reserved.
>  #
>  # Permission to use, copy, modify, and distribute this software and its
>  # documentation for any purpose and without fee is hereby granted,
> @@ -16,9 +16,9 @@
>
>  """
>  Logging package for Python. Based on PEP 282 and comments thereto in
> -comp.lang.python, and influenced by Apache's log4j system.
> +comp.lang.python.
>
> -Copyright (C) 2001-2011 Vinay Sajip. All Rights Reserved.
> +Copyright (C) 2001-2012 Vinay Sajip. All Rights Reserved.
>
>  To use, simply 'import logging' and log away!
>  """
> @@ -917,8 +917,9 @@
>         """
>         Flushes the stream.
>         """
> -        if self.stream and hasattr(self.stream, "flush"):
> -            self.stream.flush()
> +        with self.lock:
> +            if self.stream and hasattr(self.stream, "flush"):
> +                self.stream.flush()

I don't know if anyone actually builds Python without thread support
anymore, but if so, self.lock will be set to None and these "with
self.lock"s will fail.

Perhaps change lock = None to self.lock = some dummy duck typed lock
that supports use as a context manager and acquire/release calls?

>
>     def emit(self, record):
>         """
> @@ -969,12 +970,13 @@
>         """
>         Closes the stream.
>         """
> -        if self.stream:
> -            self.flush()
> -            if hasattr(self.stream, "close"):
> -                self.stream.close()
> -            StreamHandler.close(self)
> -            self.stream = None
> +        with self.lock:
> +            if self.stream:
> +                self.flush()
> +                if hasattr(self.stream, "close"):
> +                    self.stream.close()
> +                StreamHandler.close(self)
> +                self.stream = None
>
>     def _open(self):
>         """
> diff --git a/Lib/logging/handlers.py b/Lib/logging/handlers.py
> --- a/Lib/logging/handlers.py
> +++ b/Lib/logging/handlers.py
> @@ -1,4 +1,4 @@
> -# Copyright 2001-2010 by Vinay Sajip. All Rights Reserved.
> +# Copyright 2001-2012 by Vinay Sajip. All Rights Reserved.
>  #
>  # Permission to use, copy, modify, and distribute this software and its
>  # documentation for any purpose and without fee is hereby granted,
> @@ -16,10 +16,9 @@
>
>  """
>  Additional handlers for the logging package for Python. The core package is
> -based on PEP 282 and comments thereto in comp.lang.python, and influenced by
> -Apache's log4j system.
> +based on PEP 282 and comments thereto in comp.lang.python.
>
> -Copyright (C) 2001-2010 Vinay Sajip. All Rights Reserved.
> +Copyright (C) 2001-2012 Vinay Sajip. All Rights Reserved.
>
>  To use, simply 'import logging.handlers' and log away!
>  """
> @@ -554,10 +553,11 @@
>         """
>         Closes the socket.
>         """
> -        if self.sock:
> -            self.sock.close()
> -            self.sock = None
> -        logging.Handler.close(self)
> +        with self.lock:
> +            if self.sock:
> +                self.sock.close()
> +                self.sock = None
> +            logging.Handler.close(self)
>
>  class DatagramHandler(SocketHandler):
>     """
> @@ -752,9 +752,10 @@
>         """
>         Closes the socket.
>         """
> -        if self.unixsocket:
> -            self.socket.close()
> -        logging.Handler.close(self)
> +        with self.lock:
> +            if self.unixsocket:
> +                self.socket.close()
> +            logging.Handler.close(self)
>
>     def mapPriority(self, levelName):
>         """
> @@ -1095,7 +1096,8 @@
>
>         This version just zaps the buffer to empty.
>         """
> -        self.buffer = []
> +        with self.lock:
> +            self.buffer = []
>
>     def close(self):
>         """
> @@ -1145,18 +1147,20 @@
>
>         The record buffer is also cleared by this operation.
>         """
> -        if self.target:
> -            for record in self.buffer:
> -                self.target.handle(record)
> -            self.buffer = []
> +        with self.lock:
> +            if self.target:
> +                for record in self.buffer:
> +                    self.target.handle(record)
> +                self.buffer = []
>
>     def close(self):
>         """
>         Flush, set the target to None and lose the buffer.
>         """
>         self.flush()
> -        self.target = None
> -        BufferingHandler.close(self)
> +        with self.lock:
> +            self.target = None
> +            BufferingHandler.close(self)
>
>
>  class QueueHandler(logging.Handler):
>
> --
> Repository URL: http://hg.python.org/cpython
>
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