Add semaphore's

Author: zielinsky

cputracker.c

@@ -1,13 +1,49 @@
 #include "cputracker.h"
 #include "reader.h"
+#include <stdio.h>
 #include <stdlib.h>
 
 int nproc = 0;
+struct proc_stat *BUFFER[BUFFER_SIZE];
+pthread_mutex_t bufferMutex = PTHREAD_MUTEX_INITIALIZER;
+sem_t filledSpaceSemaphore;
+sem_t leftSpaceSemaphore;
+
+int get_nproc(int *nproc) {
+  *nproc = sysconf(_SC_NPROCESSORS_ONLN);
+  if (*nproc == -1) {
+    perror("Reading number of threads failed");
+    return -1;
+  }
+  return 0;
+}
+
+int get_semaphore_value(sem_t *sem) {
+  int sval;
+  sem_getvalue(sem, &sval);
+  return sval;
+}
+
+int put_item(struct proc_stat *stats) {
+  int index = get_semaphore_value(&filledSpaceSemaphore);
+  if (index > BUFFER_SIZE) {
+    return -1;
+  }
+  BUFFER[index] = stats;
+  return 0;
+}
 
 int main() {
-  if (get_nproc(&nproc) == -1)
+  if (get_nproc(&nproc) == -1) {
+    exit(EXIT_FAILURE);
+  }
+
+  if (sem_init(&filledSpaceSemaphore, 0, 0) ||
+      sem_init(&leftSpaceSemaphore, 0, BUFFER_SIZE)) {
     exit(EXIT_FAILURE);
+  }
+
   nproc++;
-  print_stats();
+  reader();
   return 0;
 }

cputracker.h

@@ -2,15 +2,18 @@
 #define CPUTRACKER_H
 
 #include <assert.h>
+#include <pthread.h>
+#include <semaphore.h>
+#include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
+#define BUFFER_SIZE 100
+
 #define EXIT_FAILURE 1
 #define EXIT_SUCCESS 0
 
-extern int nproc;
-
 struct proc_stat {
   char name[256];
   unsigned long user, // Time spent with normal processing in user mode.
@@ -29,4 +32,13 @@ struct proc_stat {
                   // operating systems under the control of the Linux kernel).
 };
 
+extern int nproc;
+extern struct proc_stat *BUFFER[];
+extern pthread_mutex_t bufferMutex;
+extern sem_t filledSpaceSemaphore;
+extern sem_t leftSpaceSemaphore;
+
+int get_nproc();
+int get_semaphore_value(sem_t *sem);
+int put_item(struct proc_stat *stats);
 #endif

reader.c

@@ -1,16 +1,9 @@
 #include "reader.h"
 #include "cputracker.h"
+#include <pthread.h>
+#include <semaphore.h>
 #include <stdio.h>
 
-int get_nproc(int *nproc) {
-  *nproc = sysconf(_SC_NPROCESSORS_ONLN);
-  if (*nproc == -1) {
-    perror("Reading number of threads failed");
-    return -1;
-  }
-  return 0;
-}
-
 struct proc_stat *get_proc_stats() {
   FILE *file = fopen("/proc/stat", "r");
   char line[1024];
@@ -20,6 +13,7 @@ struct proc_stat *get_proc_stats() {
     // assert(strncmp(line, "cpu", 3) == 0);
     if (strncmp(line, "cpu", 3) != 0) {
       perror("Reading thread info failed");
+      fclose(file);
       free(stats);
       return NULL;
     }
@@ -34,8 +28,23 @@ struct proc_stat *get_proc_stats() {
   return stats;
 }
 
-int print_stats() {
-  struct proc_stat *stats = get_proc_stats();
+void reader() {
+  struct proc_stat *stats = NULL;
+  while (1) {
+    if ((stats = get_proc_stats()) == NULL) {
+      return;
+    }
+
+    sem_wait(&leftSpaceSemaphore);
+
+    pthread_mutex_lock(&bufferMutex);
+
+    put_item(stats);
+
+    pthread_mutex_unlock(&bufferMutex);
+
+    sem_wait(&filledSpaceSemaphore);
+  }
 
   for (int i = 0; i < nproc; i++) {
     printf("%s %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu\n", stats[i].name,
@@ -44,6 +53,5 @@ int print_stats() {
            stats[i].guest, stats[i].guest_nice);
   }
 
-  free(stats);
-  return 0;
+  // free(stats);
 }

reader.h

@@ -2,8 +2,7 @@
 #define READER_H
 #include <unistd.h>
 
-int print_stats();
+void reader();
 struct proc_stat *get_proc_stats();
-int get_nproc();
 
 #endif