Trying to implement the critical section of this program to actually swap between both threads correctly as stated later in the description.
I am trying to do a problem for my Operating Systems course. The problem is that I need to input two files, one of each are put into their separate threads, they will read through the file till they hit a line with the number "0". Then the other thread is supposed to run by the same rules.
This program is supposed to take two file input and figure out the message by concatenating both of the inputs from the files in a specific order and then printing out the output after it has deciphered it.
The inputs of these two files as shown below
Person1 Person2
--------- ----------
t 0
0 h
i 0
s 0
0 i
0 s
0 a
t 0
e 0
0 s
t 0
the above inputs should result in a string with this output
Example: “thisisatest”
Currently what is going wrong with the assignment is that it is not swapping correctly between the two threads and sitting in infinite loops.
Like I said above I am trying to solve this assignment by use of Mutexes and Pthreads
Below is the current implementation of my code
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
static char *charArray[1000];
void *threadPerson1(void *value){
FILE *fPTR;
char buffer[2];
char *fileName = "Person1.txt";
fPTR = fopen(fileName, "r");
if (fPTR == NULL){
printf("was unable to open: %s\n", fileName);
return NULL;
}
while(1){
//Entering the critical section
pthread_mutex_lock(&mutex);
fscanf(fPTR, "%s", buffer);
printf("This is Person1: %s\n", buffer);
if(buffer != "0"){
charArray[count] = buffer;
count++;
}
if(buffer == "0"){
pthread_mutex_unlock(&mutex);
}
//exiting the critical section
}
}
void *threadPerson2(void *value){
FILE *fPTR;
char buffer[2];
char *fileName = "Person2.txt";
fPTR = fopen(fileName, "r");
if (fPTR == NULL){
printf("was unable to open: %s\n", fileName);
return NULL;
}
while(1){
//entering the critical section
pthread_mutex_lock(&mutex);
fscanf(fPTR, "%s", buffer);
printf("This is Person2: %s\n", buffer);
if(buffer != "0"){
charArray[count] = buffer;
count++;
}
if(feof(fPTR)){
printf("read end of file of: Person2\n");
fclose(fPTR);
return NULL;
}
if(buffer == "0"){
pthread_mutex_unlock(&mutex);
}
//exiting the critical section
}
}
int main(int argc, char **argv){
pthread_t thread1;
pthread_t thread2;
pthread_create(&thread1, NULL, threadPerson1, NULL);
pthread_create(&thread2, NULL, threadPerson2, NULL);
pthread_join(thread1, NULL);
pthread_join(thread2, NULL);
for(int x = 0; x < 1000; x++){
if(charArray[x] == NULL){
printf("\n");
break;
}else{
printf("%s", charArray[x]);
}
}
return 0;
}
