Erlang R12B-3 needs a patch for fsync problem

[jerry.jalava@…]

The following has been taken from the erlang-patches mailing list. (​http://www.erlang.org/pipermail/erlang-patches/2008-July/000258.html)

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Dear OTP Team,

traditionally, on UNIX systems the fsync() system call is used to flush any filesystem buffers to disk. The file::sync() function triggers a fsync() call in OTP R12B-3

On Darwin (and Mac OS X) systems, the fsync() system call exists, but does not guarantee the writing to disk. The fcntl(F_FULLFSYNC) function call exists to achieve this. See ​http://developer.apple.com/documentation/Darwin/Reference/ManPages/man2/fsync.2.html and ​http://developer.apple.com/documentation/Darwin/Reference/ManPages/man2/fcntl.2.html for reference.

The patch below adds some #ifdefs to figure out if it is compiled on a Darwin system and uses the fcntl() function instead of the fsync() function.

Please note my poor understanding of how your build system actually detects the target host. My way of detecting Darwin was shamelessly ripped from elsewhere in the source tree and might be wrong in this case (although testing was successful). Please feel free to make any necessary changes in case you choose to integrate the patch.

I'm working on the CouchDB project (yes, a database in Erlang), and we require a reliable file::sync()-behaviour for data consistency.

Adding this to OTP would be highly appreciated.

Cheers Jan & the CouchDB Team --

--- erts/emulator/drivers/unix/unix_efile.c.orig 2008-07-17 20:44:23.000000000 +0200 +++ erts/emulator/drivers/unix/unix_efile.c 2008-07-17 20:44:21.000000000 +0200 @@ -44,6 +44,14 @@

#endif #endif /* _OSE_ */

+#if defined(APPLE) && defined(MACH) && !defined(DARWIN) +#define DARWIN 1 +#endif + +#ifdef DARWIN +#include <fcntl.h> +#endif /* DARWIN */ +

#ifdef VXWORKS #include <ioLib.h> #include <dosFsLib.h>

@@ -818,7 +826,11 @@

undefined fsync

#endif /* VXWORKS */ #else

+#if defined(DARWIN) && defined(F_FULLFSYNC) + return check_error(fcntl(fd, F_FULLFSYNC), errInfo); +#else

return check_error(fsync(fd), errInfo);

+#endif /* DARWIN */

#endif /* NO_FSYNC */ }

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Until this hopefulle gets added to the OTP at some point it would be great to include it in Port.

Regards, Jerry