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To: cs551@merlot.usc.edu
Subject: Re: gethostbyname giving error
Date: Thu, 30 Oct 2008 11:53:42 -0700
From: Bill Cheng <william@bourbon.usc.edu>

Someone wrote:

  > In the c8-n07.ini file, there is only 1 beacon node which is
  > localhost:18007, so when gethostname is called and say it  returns
  > nunki,usc.edu, what should be done?

"c8-n07.ini" looks like:

    [init]
    Port=18007
    Location=30687
    HomeDir=/home/scf-22/csci551b/tmp/final1/n07
    AutoShutdown=90
    MsgLifetime=15
    KeepAliveTimeout=10

    [beacons]
    nunki.usc.edu:18007=

Let's say hostname_str contains "nunki.usc.edu" and port_str
contains "18007", which is what you have read from the [init]
section.  Then you can do:

    char buf[256];

    snprintf(buf, sizeof(buf), "%s:%s", hostname_str, port_str);

Then you can see if what's in buf can be found as a key in
the [beacons] section of the same startup configuration file.
If it can be found, this node is a beacon node.  Otherwise,
it's regular node.
--
Bill Cheng // bill.cheng@usc.edu <URL:http://merlot.usc.edu/william/usc/>




  On Thu, Oct 30, 2008 at 11:44 AM, Bill Cheng <william@bourbon.usc.edu> wrote:
  > Someone wrote:
  >
  >  > Does a beacon node get its hostname from the startup configuration fle
  >  > or by gethostname()?
  >
  > A node first calls gethostname() and then compare it with
  > what's in the startup configuration to determine if it is a
  > beacon node.
  > --
  > Bill Cheng // bill.cheng@usc.edu <URL:http://merlot.usc.edu/william/usc/>
  >
  >
  >
  >
  >  On Thu, Oct 30, 2008 at 8:53 AM, Bill Cheng <william@bourbon.usc.edu> wrote:
  >  > Someone wrote:
  >  >
  >  >  > gethostbyname is returning null, saying Too many open files. Please help.
  >  >
  >  > If you write a small program with just a call to gethostbyname()
  >  > in it, I assume that works.  Therefore, the problem is not
  >  > gethostbyname().  May be you have too many files/sockets opened.
  >  > Do you know how many files/sockets you have opened?
  >  >
  >  > In general, you need to know how much resources you are using.
  >  > --
  >  > Bill Cheng // bill.cheng@usc.edu <URL:http://merlot.usc.edu/william/usc/>