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authorFilipe David Manana <[email protected]>2010-04-22 23:40:26 +0100
committerRaimo Niskanen <[email protected]>2010-05-20 15:48:17 +0200
commit3f53a96a8bd0cd4a18f819b6857e6a764706ede5 (patch)
tree04841cd714a6e23ac664a05ff9219dd8e5da474e /lib/kernel/src/file.erl
parent80b231a0874aa5cd68c3d9f0dc7e13b6736a5dd3 (diff)
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Add file:datasync/1 for syncing file contents only
file:datasync/1 invokes the POSIX system call "int fdatasync(int fd)". This system call is similar to "fsync" but, unlike fsync, it does not update the metadata associated with the file (like the access time for example). It's used by many DBMSs (MySQL and SQLite of example) to increase disk IO performance, as it avoids disk seeks and disk write operations compared to fsync. More details on it at: http://linux.die.net/man/2/fdatasync An example, from the MySQL source: http://bazaar.launchpad.net/~mysql/mysql-server/mysql-5.1-telco-6.1/annotate/head%3A/mysys/my_sync.c#L61 This new function just calls fsync on systems not implementing fdatasync.
Diffstat (limited to 'lib/kernel/src/file.erl')
-rw-r--r--lib/kernel/src/file.erl12
1 files changed, 11 insertions, 1 deletions
diff --git a/lib/kernel/src/file.erl b/lib/kernel/src/file.erl
index 46ffa9d708..5da359fdf1 100644
--- a/lib/kernel/src/file.erl
+++ b/lib/kernel/src/file.erl
@@ -40,7 +40,7 @@
read/2, write/2,
pread/2, pread/3, pwrite/2, pwrite/3,
read_line/1,
- position/2, truncate/1, sync/1,
+ position/2, truncate/1, datasync/1, sync/1,
copy/2, copy/3]).
%% High level operations
-export([consult/1, path_consult/2]).
@@ -472,6 +472,16 @@ pwrite(#file_descriptor{module = Module} = Handle, Offs, Bytes) ->
pwrite(_, _, _) ->
{error, badarg}.
+-spec datasync(File :: io_device()) -> 'ok' | {'error', posix()}.
+
+datasync(File) when is_pid(File) ->
+ R = file_request(File, datasync),
+ wait_file_reply(File, R);
+datasync(#file_descriptor{module = Module} = Handle) ->
+ Module:datasync(Handle);
+datasync(_) ->
+ {error, badarg}.
+
-spec sync(File :: io_device()) -> 'ok' | {'error', posix()}.
sync(File) when is_pid(File) ->