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nombrepremier_parallelthread.c

+//
+#include <errno.h>
+#include <sys/types.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+#include <stdbool.h>
+#include <time.h>
+#include <pthread.h>
+
+/* STRUCTURES AND VARIABLES */
+
+/* "struct factorization"
+ * "prime_dividers" is an array containing max N dividers
+ * "cnt" is the number of calculated dividers
+ * "number" is number to calculate the prime dividers
+*/
+#define N 8  // Max number of dividers in the buffer
+
+typedef struct factorization {
+    unsigned long prime_dividers[N];
+    unsigned int cnt;
+    unsigned long number;
+} factor;
+
+/* struct file_descriptors
+ * "in" is the inputfile file descriptor
+ * "out" is the outputfile file descriptor
+ * "options" "v" (verbose) with debugging information, "q" without debugging information
+ */
+typedef struct file_descriptors {
+    FILE *in;
+    FILE *out;
+//    char options; // For internal command test
+} fd;
+// Declare f (type fd). Structure containing the file descriptors
+fd f;
+
+/* MUTEX  */
+pthread_mutex_t mutex_readwrite; // define mutex variable
+
+/*
+* FUNCTIONS used in the programme:
+* bool is_div(unsigned long, unsigned long);
+* bool is_prime(unsigned long);
+* factor *prime_divs(unsigned long);
+* void *read_write(fd);
+*/
+bool is_div(unsigned long numbr, unsigned long i){
+    if((numbr % i) == 0) {  // verify if i is the divider of numbr
+        return(true);       // i is a divider of numbr
+    } else {
+        return(false);      // i is not a divider of numbr
+    }
+}
+
+bool is_prime(unsigned long nbr) {
+    /*
+ * Optimised solution with less loop, see: https://fr.wikipedia.org/wiki/Nombre_premier
+ * "Crible d'Ératosthène:
+ * Les premiers algorithmes pour décider si un nombre est premier
+ * (appelés tests de primalité) consistent à essayer de le diviser par tous les nombres
+ *  qui n'excèdent pas sa racine carrée"
+ */
+// for(unsigned long j = 2; j <= nbr; j++) { // OLD SOLUTION LESS EFFICIENT
+    for (unsigned long j = 2; j <= sqrt(nbr); j++) {
+        if ((nbr % j) == 0) {       // verify if i is the divider of nbr
+            return (false);         // i is a divider of nbr
+        }
+    }
+    return (true); // i is a prime number
+}
+
+factor* prime_divs (unsigned long numbr) {
+    factor *dividers; // Structure storing dividers and their number
+    /* Allocation of memory for "struct factor" and
+     * initialization the "dividers" struture to zero */
+    dividers = (factor *) calloc(1, sizeof(factor));
+    unsigned int n = 0;
+    dividers->number = numbr;
+    unsigned long tmp_number = dividers->number;
+
+    //for(unsigned long i = 2; i < number; i++) { //Old python approach
+    //for(unsigned long i = 2; i <number; i++) {
+    for(unsigned long i = 2; i <= tmp_number ; i++) {
+        if(is_div(dividers->number,i) == true){
+            if(is_prime(i) == true){
+                dividers->prime_dividers[n] = i;
+                /* The max numbers of loops is reduced
+                 * from "number" to "tmp_number/i" */
+                tmp_number = tmp_number/i;
+                if(i != dividers->number) {
+                    n++;
+                }
+            }
+        }
+    }
+    dividers->cnt = n;
+    return(dividers);
+}
+
+void *read_write() {
+    factor *dividers;
+    unsigned long number;
+
+    // Read input file line by line till the end of file (eof)
+    while (!feof(f.in)) {
+        fscanf(f.in, "%lu\n", &number); // Read number to be factored
+
+        /* Verify if the number is prime or not, in this case the dividers are calculated */
+        dividers = prime_divs(number); // Core function of the app //
+
+        /* MUTEX LOCK - CONTROL OF CRITICAL ACCESS - START  */
+        if (pthread_mutex_lock(&mutex_readwrite) != 0) {
+            printf("\nmutex_lock-mutex_readwrite %s\n", strerror(errno));
+            exit(EXIT_FAILURE);
+        }
+        if (dividers->cnt != 0) {
+            fprintf(f.out, "%lu ", dividers->number);
+            for (int i = 0; i < dividers->cnt; i++) {
+                fprintf(f.out, " %lu", dividers->prime_dividers[i]);
+            }
+        } else { // For internal command test
+                fprintf(f.out, "%lu ", dividers->number);
+        }
+        /*  MUTEX UNLOCK - CONTROL OF CRITICAL ACCESS - END  */
+        if (pthread_mutex_unlock(&mutex_readwrite) != 0) {
+            printf("\nmutex_lock-mutex_readwrite %s\n", strerror(errno));
+            exit(EXIT_FAILURE);
+        }
+        fprintf(f.out, "\n");
+        free(dividers);
+    }
+    pthread_exit((void *) 0); // thread exit: normal termination => 0
+}
+
+#define DEFAULT_NO_THREADS 2
+#define MAX_NO_THREADS 20
+// MAIN PROGRAMME
+int main (int argc, char *argv[]) {
+
+    // Input arguments
+    char *inputfile;    // Input filemane (string)
+    char *outputfile;   // Output filemane (string)
+    char *thread_arg;   //
+    int NO_THREADS = DEFAULT_NO_THREADS; // Define default number of threads
+
+    if (argc == 3) { // Check if the number of argument is correct
+        inputfile = argv[1];
+        outputfile = argv[2];
+        printf("Thread Number not mentioned\n");
+        printf("The threads default number is %d\n", DEFAULT_NO_THREADS);
+    } else if(argc == 5) {
+        thread_arg = argv[1];
+        if(strcmp(thread_arg, "-N") != 0) {
+            printf("%s\n", "Wrong input of the option \"-N\"\n");
+            exit(EXIT_FAILURE);
+        }
+        NO_THREADS = atoi(argv[2]);
+        if(NO_THREADS > MAX_NO_THREADS) {
+            printf("Threads requested > %d\n", MAX_NO_THREADS);
+            exit(EXIT_FAILURE);
+        }
+        inputfile = argv[3];
+        outputfile = argv[4];
+    } else {
+        printf("%s\n", "Many or few arguments\n");
+        printf("Correct command syntax:\n");
+        printf("./programme [-N number_of_threads] inputfile.txt outputfile.txt");
+        exit(EXIT_FAILURE);
+    }
+    /*
+ * START CLOCK to measure CPU time
+ * calculate programme performance
+ */
+    clock_t start, end;
+    double cpu_time_used;
+    start = clock();
+/*  For internal control test
+        system("pwd"); // Current directory
+        printf("\n -- Programme start --\n");
+        printf(" nr arguments: %d\n", argc);
+        printf("Thread activated no. %d\n",NO_THREADS);
+        printf(" input file: %s\n", inputfile);
+        printf(" output file: %s\n", outputfile);
+        printf(" option: %c\n", f.options);
+*/
+    // Open input and output files
+    f.in = fopen(inputfile, "r");
+    f.out = fopen(outputfile, "a+");
+    if ((f.in == NULL) || (f.out == NULL)) {
+        printf("Incorrect inputfile or outputfile name\n");
+        exit(EXIT_FAILURE);
+    }
+
+    pthread_t thread[NO_THREADS]; // thread IDs
+    // INITIALIZE MUTEX "mutex_readwrite"
+    if (pthread_mutex_init(&mutex_readwrite , NULL) != 0){
+        printf("\n mutex init failed-mutex_readwrite\n");
+        exit(EXIT_FAILURE);
+    }
+    for (int i = 0; i < NO_THREADS; i++) {
+        pthread_create(&thread[i], NULL, (void*)read_write, NULL);
+    }
+    for (int i = 0; i < NO_THREADS; i++) {
+        pthread_join(thread[i], NULL);
+    }
+ /* END CLOCK to measure CPU time */
+    end = clock();
+    cpu_time_used = ((double) (end - start)) / CLOCKS_PER_SEC;
+    fprintf(f.out, "\nThe programme execution needed %.3f seconds\n\n", cpu_time_used);
+    printf("\nThe programme execution needed %.3f seconds", cpu_time_used);
+    printf("\n -- Programme end --\n");
+
+    // Eliminate mutex "mutex_readwrite"
+    if (pthread_mutex_destroy(&mutex_readwrite) != 0){
+        printf("\nmutex_destroy-mutex_readwrite %s\n", strerror(errno));
+        exit(EXIT_FAILURE);
+    }
+    fclose(f.in);
+    fclose(f.out);
+    return (EXIT_SUCCESS);
+}