This is a note from a Java ISV who would like to implement a simple,
transactional data store in Java. Currently this can't be done in Java.

A 'force data to disk' method needs to be added to both FileOutputStream and RandomAccessFile.


We are building a simple transaction facility in Java, based on files
in the underlying file system. We need a way to ensure that all
modifications to a file are recorded on disk, i.e. written from any
operating system buffers or caches to the actual disk, in order to
guarantee our ability to perform recovery operations after a system
crash.

We'd like a way to perform this operation from Java. be added by
having java.io.FileOutputStream override the "flush" method, or by
adding a new method to java.io.FileOutputStream, for example.

Solaris, and all modern Unix systems, provide an "fsync" system call,
which does just what we need. (All Unix systems at least provide a
"sync" system call, which is also fine although "fsync" is
preferable.) Windows NT provides "FlushFileBuffers", and OS/2
provides "DosResetBuffer". So there's no problem providing this
operation portably.

------------------------------------------------------

Ken Arnold says: I will need this for JavaSpaces, since I will need to implement
transactions. For me this is a serious requirement.