On 8/12/05, Christopher Kohlhoff <chris@kohlhoff.com> wrote:
Hi Caleb,
--- Caleb Epstein <caleb.epstein@gmail.com> wrote:
Just to clarify one point: asio is portable. It runs on Windows (using I/O completion ports), Linux (via epoll or select), Solaris and *should* work on any other UNIX-like platform that supports select(2). I had to make a couple of very simple changes to get it to compile on OS/X (the gethostby*_r functions don't seem to be available on this platform).
In fact I have a patch for OS/X which should be in asio 0.3.3. However I believe the functions it uses are not guaranteed to be thread-safe until 10.4, so you would only be able to use asio in a single-threaded program for earlier OS/X releases.
Or you could implement a custom thread-safe implementation of the asio resolvers that holds a mutex while resolving names on OS/X < 10.4. Its a pain, and not 100% bulletproof (what if someone links with some other library that is using gethostby* in another thread?), but its just about the best you can do given a thread-unaware runtime. Another approach, which I've used from time to time, is to provide your own version of the unsafe C runtime functions that hold a mutex while calling the unsafe C library routine and copy the result into thread-specific storage and return that pointer. As long as your implementation gets linked in before the libc version, you've solved the problem in all cases.
Basically the approach I have been taking has been to make asio portable first (via select) and then to optimise for each platform. For example, it theoretically supports implementations that use /dev/poll on Solaris and kqueues on on *bsd (including OS/X AFAIK).
Its a very nice library. I commend you on the design and implementation. Personally, I think this should be proposed as a Boost. Networking library more or less as-is. -- Caleb Epstein caleb dot epstein at gmail dot com