The first programming project is meant to introduce you to some programming tools you'll be using for the rest of the course, particularly the Unix software development environment (g++, autoconf, etc.) and the C++ asynchronous I/O library. You'll start with source to the C++ multifinger program described in Using TCP through sockets. You will modify multifinger to add a timeout, so that it does not sit waiting forever when a finger server hangs. Finally, you should turn in a software distribution of the modified multifinger program.
You will need to obtain an account on the class machines to complete this lab. See the lab information page for more information.
This lab is due at the start of class on Thursday, September 13th.
/home/to2/labs/multifinger.tar.gz on
the class machines. On these machines, you can get started with the
following commands:
benb@blood [~] > tar xzf /home/to2/labs/multifinger.tar.gz benb@blood [~] > cd multifinger benb@blood [~] > sh ./setup automake: configure.in: installing `./install-sh' automake: configure.in: installing `./mkinstalldirs' automake: configure.in: installing `./missing' configure.in: 22: required file `./ltconfig' not found automake: Makefile.am: installing `./INSTALL' automake: Makefile.am: installing `./COPYING' + autoconf + set +x benb@blood [~] >Next, you must configure the software and generate a Makefile--a set of instructions for how to compile the software. For this class, we will use the GNU autoconf and automake tools to generate Makefiles. You will also be linking against the libasync library; you can find the source in
/home/to2/sfs/async
or on the SFS web site. On the
class machines, generate the Makefile with the following commands:
benb@blood [~] > ./configure --with-sfs=/home/to2/sfs-debug
creating cache ./config.cache
checking for a BSD compatible install... /usr/bin/install -c
checking whether build environment is sane... yes
checking whether make sets ${MAKE}... yes
checking for working aclocal... found
checking for working autoconf... found
checking for working automake... found
checking for working autoheader... found
checking for working makeinfo... found
checking host system type... i386-unknown-openbsd2.8
...
updating cache ./config.cache
creating ./config.status
creating Makefile
creating config.h
benb@blood [~] >
It is very important that you supply the argument
--with-sfs=/home/to2/sfs-debug to
./configure. If you don't, things will appear to
work, but you will get a version of libasync without built-in
debugging sanity checks (including the dmalloc library). Your assignment will be
linked against debugging libraries for grading, so you want to make
sure you get the benefit of the sanity checking while testing the
software yourself.
Once the software is configured, you can build multifinger by running
gmake. (Note that this is gmake with
a g, and not make. At the end of the assignment
you will make a software distribution that compiles with any make, but
for development you must use gmake which is GNU make.)
benb@blood [~] > gmake c++ -DHAVE_CONFIG_H -I. -I. -I. -I/home/c/class/lib/debug ... /bin/sh ./libtool --mode=link c++ -g -ansi -Wall -Wsign-compare ... mkdir .libs c++ -g -ansi -Wall -Wsign-compare -Wchar-subscripts -Werror -Wno-unused ... benb@blood [~] >That's it! You've now built
multifinger. To test it,
type:
benb@blood [~] > ./multifinger fdabek@mit.edu rtm@mit.eduYou should get finger information for Frank Dabek and Robert Morris, though not necessarily in that order.
benb@blood [~] > ./multifinger rtm@frenulum.lcs.mit.edu ^C benb@blood [~] >The problem is that while the machine
frenulum accepts
finger requests, it never produces any responses.
Your assignment is to modify multifinger.C to terminate connections that don't finish producing a response within 10 seconds of the connection setup. That is, after finger::connected is called, your multifinger should spend no more than 10 seconds waiting for the write()s and read()s to complete. If 10 seconds pass without a complete answer from the server, close the file descriptor and move on to another command-line argument. For example, when your multifinger is run thus:
benb@blood [~] > ./multifinger rtm@frenulum.lcs.mit.edu fdabek@mit.eduit should quickly print the information for Frank Dabek, then wait 10 seconds, then exit.
You'll want to use the delaycb function mentioned in Section 6.6 of Using TCP Through Sockets.
/home/to2/labs. Copy it to your home directory and run
the tests as follows:
benb@blood [~] > cp /home/to2/labs/test-mf . benb@blood [~] > limit -h descriptors 64 benb@blood [~] > ./test-mf Finger one user: passed Finger two users: passed Time out a stuck host in 10 seconds: passed Combination of good and stuck hosts: passed More than 64 hosts: passed Lots of good and stuck hosts: passed benb@blood [~] >(If the limit command doesn't work, try limit -h openfiles 64 or ulimit -n 64 instead.) If all goes well, test-mf should finish in about 40 seconds and print out messages as above. Your program program will be graded with test-mf, and perhaps other tests.
benb@blood [~] > gmake dist rm -rf multifinger-0.0 mkdir multifinger-0.0 chmod 777 multifinger-0.0 ... ================================================ multifinger-0.0.tar.gz is ready for distribution ================================================ benb@blood [~] >To turn in your distribution, copy it to the directory
~/handin/lab1/ in your home directory. It will be copied
from this directory by the staff.
benb@blood [~] > mkdir -p ~/handin/lab1/ benb@blood [~] > cp multifinger-0.0.tar.gz ~/handin/lab1/ benb@blood [~] >If you have any problems about submission, please contact your TA (fdabek@mit.edu).