Dart:io feature request: Fsync and Fdatasync

[DartBot]

This issue was originally filed by [email protected]

---

Hi,

I would like to have knowledge and control about whether file data and file metadata is sent to disk or not.

Like fsync and fdatasync on Linux.

This seems quite important to me for server systems.
If an operating system or filesystem does not support that control, than Dart should just ignore the fsync and fdatasync option.

Java NIO offers such control in the form of SYNC and DSYNC.
http://docs.oracle.com/javase/tutorial/essential/io/file.html
http://docs.oracle.com/javase/7/docs/api/java/nio/file/StandardOpenOption.html

And .net offers a similar control as well:
http://msdn.microsoft.com/en-us/library/2bw4h516%28v=VS.90%29.aspx

Best regards

[whesse]

Added Area-IO, Triaged labels.

[sgjesse]

Windows have the system call FlushFileBuffers which is equivalent to fsync. There does not seem to be something that distinguishes fsync and fsyncdata on Windows.

It would be possible to add methods sync() and syncSync() to RandomAccessFile.

File.openWrite returns an IOSink so in that case IOSink should have a flush method returning a future.

Finally the methods writeAsBytes, writeAsBytesSync, writeAsString, writeAsStringSync this would require an additional flag unless we always flush (they all use File.openWrite internally).

[sgjesse]

Set owner to @sgjesse.
Added this to the M6 milestone.

[sgjesse]

For RandomAccessFile fsync was already available through the methods flush() and flushSync().

Proposed change for IOSink and related methods in https://codereview.chromium.org/20745006/.

There will not be support for fdatasync.

---

Added Started label.

[larsbak]

Removed this from the M6 milestone.
Added this to the M7 milestone.

[sgjesse]

Removed this from the M7 milestone.
Added this to the M8 milestone.

[sgjesse]

See also: http://stackoverflow.com/questions/19464471/stdout-write-in-dart-has-apparently-been-altered-from-sync-to-async-but-how-c

[DartBot]

This comment was originally written by [email protected]

---

Thanks for your continuing attention on this subject :)

[sgjesse]

IOSink.flush added in https://code.google.com/p/dart/source/detail?r=29550

Added optional flush argument to some File methods in https://code.google.com/p/dart/source/detail?r=29880

---

Added Fixed label.

[kevmoo]

Removed Area-IO label.
Added Area-Library, Library-IO labels.