threadCalcDraft.c

//Killian Mills 11368701
//Mark McCluskey 12514857

#include <pthread.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <signal.h>

#define ONE_SECOND 1000000
#define RANGE 10
#define PERIOD 2

typedef struct {
    int firstNum; //first sigHoldber to be added
    int secondNum; //second sigHoldber to be added
    char *fileName; //a string containing the filename

    pthread_t mainRef; //our reference to the main thread

}shared;


//reader thread reads from file and prints what is has read
static void * reader(void *shared_in){

    shared *structOb = (shared *)shared_in;

    sigset_t readBlock;
    sigemptyset(&readBlock);
    sigaddset(&readBlock, SIGUSR1);
    pthread_sigmask(SIG_BLOCK, &readBlock, NULL);

    int sigHold;

    FILE *fr;
    fr = fopen(structOb->fileName, "r");

    fscanf(fr, "%d", &structOb->firstNum);
    fscanf(fr, "%d", &structOb->secondNum);
    sigwait(&readBlock,&sigHold);

    while(!feof(fr)){

        printf("Read in first number %d\n", structOb->firstNum);
        printf("Read in second number %d\n", structOb->secondNum);
        int randomSleep = rand() % 10000;
        usleep( randomSleep );

        pthread_kill(structOb->mainRef, SIGUSR1); // thread version

        sigwait(&readBlock,&sigHold);
        fscanf(fr, "%d", &structOb->firstNum);
        fscanf(fr, "%d", &structOb->secondNum);

    }

    fclose(fr); // close the file
    pthread_kill(structOb->mainRef, SIGINT); // signal to main that reader has finished

    return ((void *)NULL);
}


//calculator thread adds two sigHoldbers together and prints result
static void * calculator(void *shared_in){

    shared *structOb = (shared *)shared_in;

    sigset_t calcBlock;
    sigemptyset(&calcBlock);
    sigaddset(&calcBlock, SIGUSR2);
    pthread_sigmask(SIG_BLOCK, &calcBlock, NULL);

    int sigHold;

    while(1){

        sigwait(&calcBlock,&sigHold); // wait for main to tell me to work

        int result = (structOb->firstNum + structOb->secondNum);
        printf("Result: %d + %d = %d\n\n", structOb->firstNum, structOb->secondNum, result);

        pthread_kill(structOb->mainRef,SIGUSR2); // thread version

    }

    printf("Goodbye from calculator\n");
    return ((void *)NULL);
}


int  main(int argc, char *argv[]){
    pthread_t readThread, calcThread; // make reader and calculator threads

    shared structOb; // declares the shared struct
    structOb.mainRef = pthread_self(); // makes t the reference to the main
    structOb.fileName = argv[1]; //

    // adds the three signals we are using to the main thread's signal blocker
    sigset_t mainBlock;
    sigemptyset(&mainBlock);
    sigaddset(&mainBlock, SIGUSR1);
    sigaddset(&mainBlock, SIGUSR2);
    sigaddset(&mainBlock, SIGINT);
    pthread_sigmask(SIG_BLOCK, &mainBlock, NULL);

     //Create our threads
    pthread_create(&readThread, NULL, reader, (void *)&structOb);
    pthread_create(&calcThread, NULL, calculator, (void *)&structOb);

    int sigHold; // hold the value of the current signal

    while(1){ // loop forver for the moment

        pthread_kill(readThread, SIGUSR1); // send reader to work
        sigwait(&mainBlock,&sigHold); // wait for reader to be done

        // if a sigint is sent, close the threads
        if (sigHold == SIGINT){
            pthread_cancel(readThread);
            pthread_cancel(calcThread);
            printf("goodbye from reader\n");
            printf("goodbye from calculator\n");
            break;
        }

        pthread_kill(calcThread, SIGUSR2); // send calculator to work
        sigwait(&mainBlock,&sigHold); // wait for calculator to be done

    }

    //Wait for our threads
    pthread_join(readThread, NULL);
    pthread_join(calcThread, NULL);

    return (0);

}