Issue 3517: PATCH - Providing fullfsync on supported platforms (original) (raw)

Created on 2008-08-07 17:31 by icharnas, last changed 2022-04-11 14:56 by admin. This issue is now closed.

Messages (4)
msg70842 - (view)	Author: Ian Charnas (icharnas)	Date: 2008-08-07 17:31
Python currently provides os.fsync to call the POSIX 'fsync' on platforms that support it. While this function forces the operating system to force a file buffer to the storage device, data may still be waiting in the hardware write buffers on the storage device. Certain platforms (so far, only OS X) provide "fullfsync" [1] to request that storage devices flush their write buffers to the actual physical media. This functionality is especially useful to VCS and DB developers, and already appears in SQLite [2] and MySQL [3], amongst others. This patch includes code changes to Modules/posixmodule.c that exposes os.fullfsync on supported platforms, including the appropriate documentation added to Doc/library/os.rst -Ian Charnas [1] Discussion of fsync and fullfsync on darwin platform: http://lists.apple.com/archives/darwin-dev/2005/Feb/msg00072.html [2] SQLite uses fullfsync on all platforms that define it: http://www.sqlite.org/cvstrac/fileview?f=sqlite/src/os_unix.c [3] MySQL uses fullfsync only on the darwin platform and only when F_FULLFSYNC is defined as 51, which seems to be short-sighted in that this symbol may change value in future versions of OS X. To see this code, download a mysql 5.x source snapshot and open up mysql-/innobase/os/os0file.c
msg70847 - (view)	Author: Guido van Rossum (gvanrossum) *	Date: 2008-08-07 18:16
I'm sorry to have lead you this way, but since there is no fullfsync() system call, IMO you should just make the F_FULLFSYNC constant available. That should go into fcntlmodule.c.
msg70849 - (view)	Author: Ian Charnas (icharnas)	Date: 2008-08-07 18:42
Sounds fair enough. I was looking forward to the glitz and glamor of the os module, but I'll settle for a good seat in fcntl. Here's a patch implementing just that. -ian
msg70851 - (view)	Author: Guido van Rossum (gvanrossum) *	Date: 2008-08-07 18:52
Thanks, checked into the trunk as r65581.