Function AsyncReadRequest.this

The file must have the overlapped flag enabled on Windows and the nonblock flag set on Posix.

this(
  AsyncFile file,
  ubyte[] buffer,
  long offset
);

The buffer MUST NOT be touched by you - not used by another request, modified, read, or freed, including letting a static array going out of scope - until this request's isComplete returns true.

The offset is where to start reading a disk file. For all other types of files, pass 0.