Monday, 28 October 2013

Few Clarifications

Following in from the design issue discussed earlier, as we realized we could not completely replace select with epoll, there had to be macros involved.
Fallback options : select - to make sure in the absence of epoll, boa could work with the original configuration.
And hence we considered the option of checking the type of the system, which was just a check on the predefined macros __linux and __APPLE__.

But was this check enough?
Linux has inbuilt epoll support from kernel version 2.5.44.
Is it enough to check the kind of system that is and assume that the feature is supported?
I was not sure. Hence, the double check. Found a piece of code which claimed to check for epoll support across systems [1]. Considered to use it in the epoll implementation to make a choice.

Another realization that came our way was that we needn't change the request structure itself, instead build the code around it. The request structure could remain the same way and function as it always did.

Also, as mentioned in the comment and the previous blog post [2] we do not have to consider altering the setting of the max connections as it is set to RLIMIT_NOFILE. Even though epoll may not have a limit on the maximum number of clients connected, but system limits have to be always accounted for. Also, setting the value to RLIMIT_INFINITY could cause some system dependent issues.


1 comment:

  1. But this code, the macro mentioned above [1] does the work of just checking the Linux version. Currently, at the time of this writing, having the 12.04 LTS release, we could definitely assume that once it were to be confirmed that the underlying system is Linux, the initial check was enough.
    And hence we determined to go against the additional checks.