Working on ReadWriter problem

Author: Emmanuel Massaquoi

p1/Makefile

@@ -1,6 +1,6 @@
 
 ReadWrite: ReadWrite.c
-gcc -o ReadWrite ReadWrite.c -pthread
+gcc -std=c99 -o ReadWrite ReadWrite.c -pthread
 
 Clean:
 rm ReadWrite

p1/ReadWrite.c

@@ -1,13 +1,20 @@
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <pthread.h>
 
+#define NUM_THREADS 10
+
 //
 // Created by Emmanuel Massaquoi on 6/19/17.
 //
 
 int shared_var = 0;
-int resource_use = 0;
+int resource_use;
+int num_reader = 0;
+
+int reading = 0;
+int writing = 1;
 
 pthread_mutex_t m = PTHREAD_MUTEX_INITIALIZER;
 pthread_cond_t read_phase = PTHREAD_COND_INITIALIZER;
@@ -19,7 +26,29 @@ void *writer (void *param);
 
 int main(int argc, char *argv[]) {
 
- printf("Hello World/m");
+ pthread_t tid[NUM_THREADS];
+
+ for (int i = 0; i < 5; i++) {
+
+ printf("Create Reader\n");
+ if(pthread_create(&tid[i], NULL, reader, NULL) != 0) {
+ fprintf(stderr, "Unable to create reader thread");
+ exit(1);
+ }
+
+ printf("Create Writer\n");
+ if(pthread_create(&tid[i+5], NULL, writer, NULL) != 0) {
+ fprintf(stderr, "Unable to create writer thread");
+ exit(1);
+ }
+ }
+
+ for (int j = 0; j < NUM_THREADS; ++j) {
+ pthread_join(tid[j], NULL);
+ }
+
+ printf("Parent quiting\n");
+
  return 0;
 }
 
@@ -29,10 +58,39 @@ void *reader(void *param) {
 
  pthread_mutex_lock(&m);
 
- while (resource_use == 1) {
+ while (resource_use == writing) {
  pthread_cond_wait(&read_phase, &m);
  }
 
+ printf("Reader Value: %d\n", shared_var);
+ printf("Number of Readers Present: %d\n", num_reader);
+
+ resource_use = reading;
+ pthread_cond_broadcast(&write_phase);
+
+ pthread_mutex_unlock(&m);
+ }
+
+ return 0;
+}
+
+void *writer(void *param) {
+
+ for (int i = 1; i <= 20; ++i) {
+ pthread_mutex_lock(&m);
+
+ while (resource_use == reading || num_reader != 0) {
+ pthread_cond_wait(&write_phase, &m);
+ }
+
+ shared_var = i;
+ printf("Written Value: %d\n", shared_var);
+ printf("Number of Readers Present: %d\n", num_reader);
+
+ resource_use = writing;
+ pthread_cond_broadcast(&read_phase);
+
  pthread_mutex_unlock(&m);
  }
+
 }