From <sys/fnctl.h>:
#define F_FULLFSYNC 51 /* fsync + ask the drive to flush to the media */
This fcntl() will basically perform an fsync() on the file, then flush the write cache of the disk.
I'll attempt to work up the patch. It should be trivial. Might need some help on the configure tests though (it should #include <sys/fcntl.h> and make sure F_FULLFSYNC is defined).
What's an appropriate name? It seems equivalent to "fsync_writethrough". I suggest "fsync_full", "fsync_flushdisk", or something. Is there a reason we're not indicating the supported platform in the name of the method? Would "fsync_darwinfull" be better? Let users know that it's only available for Darwin? Should we do the same thing with win32-specific methods?
I think both fsync() and F_FULLFSYNC should both be available as options on Darwin. Currently in the code, "fsync" and "fsync_writethrough" set sync_method to SYNC_METHOD_FSYNC, so there's no way to distinguish between them.
Unsure which one would be the best default. fsync() matches the semantics on other platforms. And conscientious users could specify the F_FULLFSYNC fcntl() method if they want to make sure it goes through the write cache.
Comments?
Thanks!
- Chris
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