Delivery-Date: Thu Oct  9 06:59:39 2008
Message-Id: <200810091406.m99E6Afe022978@bourbon.usc.edu>
To: cs551@merlot.usc.edu
Subject: Re: Connection establishment
Date: Thu, 09 Oct 2008 07:06:10 -0700
From: Bill Cheng <william@bourbon.usc.edu>

Someone wrote:

  > I went through the sequence when 3 nodes - X, Y and Z are started. I am
  > implementing the following sequence:
  > 
  > Node X is started and it creates 2 child threads - say X1 and X2.
  > X1 is blocking on accept().
  > X2 is trying to connect to Y and Z, inside a for loop that runs twice (or
  > minNeighbors number of times), and it sleeps for 30 seconds if no connection
  > formed.

For a beacon node, it needs to connect to all other beacon
ndoes.  Remember, the beacon nodes form a fully connected
mesh.  The way you described it, it sounds like you just want
to connect to another beacon node.

By the way, MinNeighbors is only used by regular nodes.
(The description mentioned the init_neighbor_list file and
only a regular node uses the init_neighbor_list file.)

Also, in my posting, for this example, node X would create
one child thread to connect to Y and another child thread
to connect to Z.  Of course, you don't have to do it the
way I mentioned.  But I just want to make sure that there
is no misunderstanding.

  > Same case for nodes Y and Z.
  > 
  > I am getting a broken pipe error.
  > 
  > Could this be because my thread (X2 or Y2 or Z2) are handling or forming 2
  > separate connections with other 2 nodes using a for loop ?

Most likely it's just a bug.

  > If yes, then does this mean that we need a new thread to handle every new
  > connection , and no thread can handle multiple connections at the same time
  > ?

As I mentioned before, you can pretty much get anything
reasonable to work.  You can even use one thread to handle
*all* the connections if you code it correctly!  (But that
would not be efficient.  Also, threads are cheap, so you
should take advantage of that if it makes your code clean
and easier to debug.)  You need to understand exactly what
your code is doing.  When it's not doing what it suppose to
do, you need to debug, debug, and debug!
--
Bill Cheng // bill.cheng@usc.edu <URL:http://merlot.usc.edu/william/usc/>