Async read an output stream but how many bytes ?

[Adam D. Ruppe via Digitalmars-d-learn]

On Thursday, 31 March 2016 at 00:50:16 UTC, Basile B. wrote:
> There should be a way to know how many bytes are available ?

You are already using poll()... I'd just use read() directly on 
the file number too. It will read as much as is available up to 
the max size of the buffer, but if it can't fill it all, it just 
does what it can and returns.