Hi Chris, --- Chris Cleeland <cleeland@ociweb.com> wrote: <snip>
- Implement the Socket_Option concept for the option.
Maybe you could show an example in the docs for this?
Yep, no problem. <snip>
I disagree. First, I stated that KNOWING the details is important, not that one need to manipulate the details all the way down the line. But even if I do need to manipulate details at different layers (all the way down to the wire), that need doesn't necessarily diminish the utility of a feature like asio. Why should I be prevented from using an otherwise-useful feature simply because I need to tweak things at a lower level?
If it's just knowing the details and having the ability to tweak the implementation, then what I'm planning is: - To document the implementation strategies for each supported platform. There's a little bit in the design docs already. - To provide compile-time (i.e. #define), and in the long term possibly runtime, ways to choose the implementation strategy. However these mechanisms will be outside the library's public interface, since they're tied to the implementation, and that can change between releases. <snip>
The issue here is that hostname resolution is a potentially lengthy operation. If resolution is only performed at program startup, then that might be ok. However, if a server needs to resolve hostnames on a regular basis, you would not want to block the flow of control and delay other clients.
Okay, I can understand the motivation, but are there not other ways to implement besides firing off a thread?
The alternatives that I'm aware of are: - To use a platform's native asynchronous host resolution functions, if available. - To implement DNS lookup using sockets. This might be a really good solution for some platforms, but unfortunately not for all. Using gethostbyname on Windows, for example, also resolves NetBIOS names, and asio should provide identical behaviour to the platform's own host resolution functions. <snip>
Can you expand on this a little more? I'm having a hard time understanding what it means to have tss hold a pointer to something on the stack. I'll try to check out the code itself, too.
The only place TSS is used in asio is to determine whether or not the current thread is inside a call to demuxer::run() for a specific demuxer object. It works as follows: - The TSS value holds a pointer to the top of a stack implemented as a linked list. - When a demuxer::run() call starts it creates a linked list node on the stack, and pushes it on to the top of the stack. - When a demuxer::run() call exits it pops the node from the stack. - To determine whether the current thread is inside demuxer::run(), the TSS pointer is access and the stack traversed to see if the demuxer object is present. See asio/detail/demuxer_run_call_stack.hpp for the implementation of this. Cheers, Chris