I'm working on a program (using dmd 2.059 under windows) that automatically reloads the contents of a file if it has changed, by checking the last modified timestamp on the file every 0.2 seconds, then using the readText function in std.file to read in the file contents.

It works pretty well, but every once in a while I get a "The process cannot access the file because it is in use by another process" error message. I guess this happens when my D program tries to read the file before the text editor manages to close its handle on the file.

This would be fair enough if I was writing to the file in my D program, but I only want to read from it. Is this a bug or is there a better way to get file contents in D?

On Jul 13, 2012 4:40 PM, "OlaOst" <olaa81@gmail.com> wrote:
>
> I'm working on a program (using dmd 2.059 under windows) that
automatically reloads the contents of a file if it has changed, by checking the last modified timestamp on the file every 0.2 seconds, then using the readText function in std.file to read in the file contents.
>
> It works pretty well, but every once in a while I get a "The process
cannot access the file because it is in use by another process" error message. I guess this happens when my D program tries to read the file before the text editor manages to close its handle on the file.
>
> This would be fair enough if I was writing to the file in my D program,
but I only want to read from it. Is this a bug or is there a better way to get file contents in D?

While the text editor is writing the file reading it is a silly thing to do (no one knows what's there).  I'm not familiar with windows but locking under Linux works as so.  Any number or processes can have a read lock but if there is a write lock only the single process can access that file.

Also isn't there something like inotify on windows?  Polling sounds like the wrong solution.

On 13/07/2012 21:47, Kevin Cox wrote:
>
> On Jul 13, 2012 4:40 PM, "OlaOst" <olaa81@gmail.com
> <mailto:olaa81@gmail.com>> wrote:
>  >
>  > I'm working on a program (using dmd 2.059 under windows) that
> automatically reloads the contents of a file if it has changed, by
> checking the last modified timestamp on the file every 0.2 seconds, then
> using the readText function in std.file to read in the file contents.
>  >
>  > It works pretty well, but every once in a while I get a "The process
> cannot access the file because it is in use by another process" error
> message. I guess this happens when my D program tries to read the file
> before the text editor manages to close its handle on the file.
>  >
>  > This would be fair enough if I was writing to the file in my D
> program, but I only want to read from it. Is this a bug or is there a
> better way to get file contents in D?
>
> While the text editor is writing the file reading it is a silly thing to
> do (no one knows what's there).  I'm not familiar with windows but
> locking under Linux works as so.  Any number or processes can have a
> read lock but if there is a write lock only the single process can
> access that file.
>
> Also isn't there something like inotify on windows?  Polling sounds like
> the wrong solution.
>

Yes:

http://msdn.microsoft.com/en-us/library/windows/desktop/aa365261%28v=vs.85%29.aspx

It's not straight forward to use though and I doubt that the necessary function definitions are provided by the default dmd windows imports.

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