Does the operating system dispatch events on write to disk?

Question

I was wondering if there is some way to determine when a file finishes writing to a directory on both Windows and Linux (obviously, they will probably be two different commands).

This is mostly so that, instead of constantly polling a directory for new non-temp files, I can set up a program to simply listen for the completion of a write-to-disk (it seems better to do things that way).

Answer 1

1. Files don't "write to directories". Data are written to files, and files may be (hard) linked into directories. But the data writing process to the file has nothing to do with the directory; and the hard linking process is atomic and has no "finish" to wait for.
2. On Windows, the function that you are looking for is FindFirstChangeNotification().
3. This is a StackOverflow topic, not a SuperUser one.

Answer 2

For linux, you can take a look at this question, the discussion was in c++ but the idea (from the answers, not jsut the choosen one) are still good. Basically, in linux you can use some flags, or watch the /proc/pid/fd process.

Answer 3

Windows at least since Vista there is an I/O scheduling system:

I/O Prioritization in Windows Vista.

Additionally also modern SATA disks in AHCI mode have their own integrated scheduler - called Native Command Queuing (NCQ).