CSS 503 - Lab Work 1: Process Management

CSS 503
Lab Work 1: Process Management
Professor: Munehiro Fukuda
Lab work date: See the syllabus

1. Purpose

This laboratory work intends to familiarize you with Unix process management including process creation, process termination, and synchronization. You will code a program that creates a process tree.

2. System Calls

You will use the following four system calls. Check the specification of each function using man.

fork: creates a child process that starts right after fork().
exit: terminates the calling process.
wait: suspends the calling process until one of its children gets terminated.
getpid: returns the identifier of the calling process.

3. Statement of Work

The following code is a template for creating a process tree in a recursive manner:

   #include <iostream>    // cout, cerr
   #include <queue>       // stl queue
   #include <sys/types.h> // fork, wait
   #include <sys/wait.h>  // wait
   #include <unistd.h>    // fork

   using namespace std;

   queue<int> pids;      // stores a list of processses from the parent to a leaf process

   void recursive_creation( int leaves ) {
     if ( leaves > 1 ) {
       pids.push( getpid( ) );
       // fork a left child
       // fork a right child
   
       // wait for one of the children
       // wait for the other children
       exit ( 0 );
     }
     else { // I'm a leaf process
       while( pids.size( ) > 0 ) {  // print out a list of my ascendants
         cout << pids.front( ) << " ";
         pids.pop( );
       }
       cout << getpid( ) << endl;   // print out myself
       exit( 0 );
     }
   }

   int main( int argc, char* argv[] ) {
     // validate arguments
     if ( argc != 2 ) {
       cerr << "usage: lab1 #leaves" << endl;
       return -1;
     }
     int leaves = atoi( argv[1] );
     if ( leaves < 1 ) {
       cerr << "usage: lab1 #leaves" << endl;
       cerr << "where #leaves >= 1" << endl;
       return -1;
     }
     recursive_creation( leaves );
     return 0;
   }

The main program receives #leaves of a tree that it should create as follows:

   css503@uw1-320-18 lab1]$ ./lab1 1
   869
   [css503@uw1-320-18 lab1]$ ./lab1 2
   870 871
   870 872
   [css503@uw1-320-18 lab1]$ ./lab1 3
   873 874 875
   873 877
   873 874 876
   [css503@uw1-320-18 lab1]$ ./lab1 4
   878 879 880
   878 879 881
   878 882 883
   878 882 884
   [css503@uw1-320-18 lab1]$ ./lab1 5
   885 886 887 888
   885 886 887 890
   885 889 891
   885 886 893
   885 889 892
   [css503@uw1-320-18 lab1]$

Complete the recursive_creation() function so that the program runs as specified above.

4. What to Turn in

Turn in the following materials at the end of class:

Your lab1.cpp
Your execution output

If your time runs out, you may submit it together with programming assignment 1.