trivial patch to reduce allocations in nio open* methods

[Michael Skells]

Hi Remi,
the code in FileSystemProvider does not add to the immutable set, if we are
talking about the same method - the add of the WRITE only occurs in the
case where options are specified, and is pre-populated in the default case.

public OutputStream newOutputStream(Path path, OpenOption... options)
    throws IOException
{
    int len = options.length;
    Set<OpenOption> opts ;
    if (len == 0) {
        opts = DEFAULT_OPEN_OPTIONS;
    } else {
        opts = new HashSet<>(len + 1);
        for (OpenOption opt: options) {
            if (opt == StandardOpenOption.READ)
                throw new IllegalArgumentException("READ not allowed");
            opts.add(opt);
        }
        opts.add(StandardOpenOption.WRITE);
    }
    return Channels.newOutputStream(newByteChannel(path, opts));
}

 Files.createFile() - The usage that I was interested in is the new
input or output streams - I just looked through the other methods that
had similar patterns

What is the next step - are you looking for me to do any rework?

I dont have the ability to validate performance in the different
platforms, other than allocation (which is where I came in)

Regards

Mike



On Tue, 6 Mar 2018 at 19:05 Alan Bateman <Alan.Bateman at oracle.com> wrote:

> On 06/03/2018 18:34, Chris Hegarty wrote:
> >
> > It seems crummy, but using Set.of will require some care when
> > handling duplicate options. The code currently silently ignores
> > duplicates, if I'm not mistaken.
> I just read Rémi's mail now. So yes, it could only use Set.of for
> options.length < 2.
>
> -Alan
>
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