Writeup for P2 EXP2B

Christian F. Jung

Unfortunately, I was not able to completely finish the homework in time. I was struggling to wrap my head around some of the C syntax and was unable to get past Version 1 of the implementation plan. I believe that I was limited by my C skills and not my understanding of the core concepts. In this document, I will discuss what I did and what I would do to implement V2 and V3 in hopes of demonstrating my knowledge for partial credit.

What I did

When starting this homework, I began my designing a program architecture that would allow me the structure needed to accomplish the task.

I would start by initializing what I called a "Master Hash Table" which was really an array of N length. Each entry in this array would be a "slave hash table" which would contain it's appropriate entries. To determine how which slave table that a new entry would go to, I would do key % N. In my implementation, I kept all my key and values as strings and for fun, I made my tables a grocery list. (My family has a lot of big eaters so we need to have many threads for our list).

Below is an abbreviated version of the myhash.c function which allowed me to to instantiate the master and slave tables. One thing that I struggled with was being able to pass a GHashTable object as a parameter to a function so instead I have several repeated lines in main. (I've kept these attempts commented out in the myhash.c in tar file)

#include <glib.h>
#include <stdio.h>

int getI(int N, int  key){
return key % N; 
}



int main() {

  int N = 5;
  GHashTable * m[N]; 

    for (int i = 0; i < N ; ++i)
  {

    printf(" creating %dth slave \n", i);

    m[i]= g_hash_table_new(g_str_hash, g_str_equal);

  }




  char * key = "0";
  char * value = "apples";
  int k = getI(N, atoi(key) );
  g_hash_table_insert(m[k],key,value);


  key = "1"; 
  value = "pears";
  k = getI(N, atoi(key) );
  g_hash_table_insert(m[k],key,value);



  key = "20"; 
  value = "pizza";
  k = getI(N, atoi(key) );
  g_hash_table_insert(m[k],key,value);



   for (int i = 0; i < N ; ++i)
  {

    printf(" loading %dth slave:", i);
    printf("There are %d keys in the hash table\n",
        g_hash_table_size(m[i]));

  }



    return 0;
}

What I would do next

Following my architecture diagram (see above), I would implement a locking method on each of the tables. I'd likely implement this by having another array of N length and storing boolean values to indicate if a slave table is locked.

Then, I'd run this file multiple times with varying N and numbers of entries in the table. I'd then modify my makefile to time these results and save to a log file. In addition, I'd pass the results to the csv version of vtune.