On Thu, Nov 30, 2017 at 11:12 PM, Andrew Schwartzmeyer < and...@schwartzmeyer.com> wrote:
> For Linux it is literally an `int`: > > using int_fd = int; >> > > https://github.com/apache/mesos/blob/bf4bc6380cb99132736fbbe > fc85f3a7ca60b032c/3rdparty/stout/include/stout/os/int_fd.hpp#L35 > > Yes I realize that :) > So it's a safe drop-in replacement on non-Windows platforms, with all the > same properties of an `int`. > > It's only on Windows where it is instead `os::WindowsFD`, and then you may > need to worry about its properties and semantics. Do you want these > documented in `stout/os/windows/fd.hpp`? Yes, we have code using int_fd within hashmaps, maps, etc, already across platforms so I assume it has the properties I listed on windows, but it would be good to document that as being something that int_fd is guaranteed to provide. > > > On 11/30/2017 3:05 pm, Benjamin Mahler wrote: > >> Is it possible to document in that header the properties of int_fd that we >> can rely on? >> >> For example, it has a hash defined for use in unordered map, set, etc. >> It's >> a POD type, etc. >> >> On Wed, Nov 29, 2017 at 10:17 PM, Andrew Schwartzmeyer < >> and...@schwartzmeyer.com> wrote: >> >> Hello everyone! >>> >>> I've realized that a lot of developers working in libprocess (and >>> elsewhere) may not know about how to handle file descriptors in a >>> cross-platform way for Mesos. >>> >>> IMPORTANT: You cannot just use `int`. File descriptors on Windows are >>> various types of handles, but not just an `int`. >>> >>> The abstraction we use in Mesos is `int_fd`, found here: >>> https://github.com/apache/mesos/blob/master/3rdparty/stout/ >>> include/stout/os/int_fd.hpp >>> >>> On non-Windows platforms, it's just an `int`. But on Windows, it's a >>> `WindowsFD` which can be an `int` (from the Windows CRT which we're >>> deprecating), a `HANDLE` (the Windows 32 API), and a `SOCKET` (from the >>> WinSock library). If you're curious, the implementation is here: >>> https://github.com/apache/mesos/blob/master/3rdparty/stout/ >>> include/stout/os/windows/fd.hpp >>> >>> I just want you to be aware that if you're writing code and need an `int` >>> file descriptor, please use `int_fd` (and include the appropriate header) >>> instead of `int`, as otherwise you break the Windows build. >>> >>> Thank you, >>> >>> Andy >>> >>>
