two questions (issues?) about phobos/std/mmfile.d

October 14, 2022

Posted by mw

Permalink

I'm checking file:

https://github.com/dlang/phobos/blob/master/std/mmfile.d

and found two questions (issues?) I don't understand, can someone explain?

This ctor:

https://github.com/dlang/phobos/blob/master/std/mmfile.d#L79

version (linux) this(File file, Mode mode = Mode.read, ulong size = 0,
void* address = null, size_t window = 0) scope

is not doc-ed: https://dlang.org/phobos/std_mmfile.html

and there is a version (Posix) implementation inside the doc-ed ctor:

https://github.com/dlang/phobos/blob/master/std/mmfile.d#L275

There is some code duplication of these two implementation, so is the version (linux) needed at all? or it's some dead legacy code that should be deleted together with this:

https://github.com/dlang/phobos/blob/master/std/mmfile.d#L87

in ensureMapped() why the requested mmap length are 3x window (2x is enough, since the start offset of the mmap must be multiples of pagesize):

https://github.com/dlang/phobos/blob/master/std/mmfile.d#L556

                    map(window*(block-1),3*window);
// should this be?:
                    map(window*(block),  2*window);

and
https://github.com/dlang/phobos/blob/master/std/mmfile.d#L582

                    map(window*(iblock-1),cast(size_t)(window*(jblock-iblock+3)));
// should this be?:
                    map(window*(iblock),  cast(size_t)(window*(jblock-iblock+2)));

So the mapped buffer size is consistent of 2x window?

Thanks.

Forums