Any easy way to extract files to memory buffer?

[Patrick Schluter]

On Monday, 18 March 2019 at 23:40:02 UTC, Michelle Long wrote:
> On Monday, 18 March 2019 at 23:01:27 UTC, H. S. Teoh wrote:
>> On Mon, Mar 18, 2019 at 10:38:17PM +0000, Michelle Long via 
>> Digitalmars-d-learn wrote:
>>> On Monday, 18 March 2019 at 21:14:05 UTC, Vladimir Panteleev 
>>> wrote:
>>> > On Monday, 18 March 2019 at 21:09:55 UTC, Michelle Long 
>>> > wrote:
>>> > > Trying to speed up extracting some files that I first 
>>> > > have to extract using the command line to files then read 
>>> > > those in...
>>> > > 
>>> > > Not sure what is taking so long. I imagine windows caches 
>>> > > the extraction so maybe it is pointless?
>> [...]
>>
>> Why not just use std.mmfile to memory-map the file into memory 
>> directly? Let the OS take care of actually paging in the file 
>> data.
>>
>>
>> T
>
> The files are on disk and there is an external program that 
> read them and converts them and then writes the converted files 
> to disk then my program reads. Ideally the conversion program 
> would take memory instead of disk files but it doesn't.

the file that was written by the first program will be in the 
file cache. mmap() (and the Windows equivalent of that) syscalls 
are at the core only giving access to the OS file cache. This 
means that std.mmfile is the way to go. There will be no 
reloading from disk if the file sizes are within reason.