Mike: On Mon, Dec 29, 2014 at 10:23:00AM -0600, Mike wrote: > Can anyone point me in the direction of more thorough > documentation for the IO::Socket module? Seems like the > documentation on perl.org is pretty limited. At least, it > doesn't feel very thorough to me. > > http://perldoc.perl.org/IO/Socket.html > > For example, what exactly does "timeout" affect? > > This documentation also doesn't explain what values the methods > accept or how to use them.
I believe that IO::Socket is intended to be a Perl OO wrapper around the raw UNIX socket concept (and WinSock's concept of an Internet socket copied from Berkeley's implementation) and its raw Perl wrapper (e.g., Socket.pm). I guess the documentation relies on knowledge of this underlying API and/or reference to its documentation. There appears to be a "send timeout" and a "receive timeout" option for UNIX sockets, though the documentation says that not all implementations support it. Since Perl's OO wrapper only seems to have one I can only assume that the timeout applies to both read and write operations on the socket. At least shy of accessing the source code to see for myself. ...read read read... It appears that IO::Socket's timeout is unrelated to the afforementioned send and receive timeout options (though those could potentially still be accessed using the raw /(get|set)sockopt/ functions).. The IO::Socket source appears to construct an IO::Select object with the timeout value and then waits until you can either read or write, depending on what's applicable, or the timeout is elapsed. This appeared to only affect connect() and accept() methods. Though the documentation cited this by saying that it's horribly inefficient to do this since the IO::Select object is constructed just for this one purpose and that using select() or non-blocking IO is preferred. Truly understanding the implenetation details may require dipping into IO::Select's source too and following it all back to C. I can't be bothered. I think that to understand what's going on here you need experience programming raw sockets in C. While raw socket access is a useful skill (mostly for a C programmer), I think that older and wiser Perl hackers would encourage the use of higher-level, event-based wrappers for networking in Perl to save yourself the trouble of reinventing the square wheel. YMMV. Raw socket access or experience shouldn't really be necessary if using one of the higher-level wrappers so you can spare yourself the nightmares if all you need is networking. :) Regards, -- Brandon McCaig <bamcc...@gmail.com> <bamcc...@castopulence.org> Castopulence Software <https://www.castopulence.org/> Blog <http://www.bamccaig.com/> perl -E '$_=q{V zrna gur orfg jvgu jung V fnl. }. q{Vg qbrfa'\''g nyjnlf fbhaq gung jnl.}; tr/A-Ma-mN-Zn-z/N-Zn-zA-Ma-m/;say'
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