Change buffer to a fixed size

Author: zielinsky

analyzer.c

@@ -1,7 +1,4 @@
 #include "analyzer.h"
-#include "cputracker.h"
-#include <stdio.h>
-int x = 0;
 
 void *analyzer() {
   while (1) {
@@ -19,6 +16,5 @@ void *analyzer() {
              stats[i].iowait, stats[i].irq, stats[i].softirq, stats[i].steal,
              stats[i].guest, stats[i].guest_nice);
     }
-    free(stats);
   }
 }

analyzer.h

@@ -1,5 +1,6 @@
 #ifndef ANALYZER_H
 #define ANALYZER_H
+#include "cputracker.h"
 
 void *analyzer();
 #endif

cputracker.c

@@ -23,13 +23,12 @@ int get_semaphore_value(sem_t *sem) {
   return sval;
 }
 
-int put_item(struct proc_stat *stats) {
+struct proc_stat *get_item() {
   int index = get_semaphore_value(&g_filledSpaceSemaphore);
   if (index > BUFFER_SIZE) {
-    return -1;
+    return NULL;
   }
-  g_buffer[index] = stats;
-  return 0;
+  return g_buffer[index];
 }
 
 struct proc_stat *remove_item() {
@@ -45,6 +44,12 @@ int main() {
   if (get_nproc(&g_nproc) == -1) {
     exit(EXIT_FAILURE);
   }
+  for(int i = 0 ; i < BUFFER_SIZE; i++){
+    g_buffer[i] = malloc(g_nproc * sizeof(struct proc_stat));
+    if(g_buffer[i] == NULL){
+      exit(EXIT_FAILURE);
+    }
+  }
 
   if (sem_init(&g_filledSpaceSemaphore, 0, 0) ||
       sem_init(&g_leftSpaceSemaphore, 0, BUFFER_SIZE)) {

cputracker.h

@@ -39,8 +39,8 @@ extern pthread_mutex_t g_bufferMutex;
 extern sem_t g_filledSpaceSemaphore;
 extern sem_t g_leftSpaceSemaphore;
 
-int get_nproc();
+int get_nproc(int *nproc);
 int get_semaphore_value(sem_t *sem);
-int put_item(struct proc_stat *stats);
+struct proc_stat *get_item();
 struct proc_stat *remove_item();
 #endif

reader.c

@@ -1,18 +1,14 @@
 #include "reader.h"
-#include "cputracker.h"
 
-struct proc_stat *get_proc_stats() {
+int get_proc_stats(struct proc_stat *stats) {
   FILE *file = fopen("/proc/stat", "r");
   char line[1024];
-  struct proc_stat *stats = malloc(g_nproc * sizeof(struct proc_stat));
   for (int thread = 0; thread < g_nproc; thread++) {
     fgets(line, sizeof(line), file);
-    // assert(strncmp(line, "cpu", 3) == 0);
     if (strncmp(line, "cpu", 3) != 0) {
       perror("Reading thread info failed");
       fclose(file);
-      free(stats);
-      return NULL;
+      return -1;
     }
 
     sscanf(line, "%s %lu %lu %lu %lu %lu %lu %lu %lu %lu %lu",
@@ -22,21 +18,23 @@ struct proc_stat *get_proc_stats() {
            &stats[thread].guest, &stats[thread].guest_nice);
   }
   fclose(file);
-  return stats;
+  return 0;
 }
 
 void *reader() {
-  struct proc_stat *stats = NULL;
   while (1) {
-    if ((stats = get_proc_stats()) == NULL) {
-      return NULL;
-    }
 
     sem_wait(&g_leftSpaceSemaphore);
 
     pthread_mutex_lock(&g_bufferMutex);
 
-    put_item(stats);
+    struct proc_stat *stats = get_item();
+    if(stats == NULL){
+      continue;
+    }
+    if (get_proc_stats(stats) == -1) {
+      continue;
+    }
 
     pthread_mutex_unlock(&g_bufferMutex);
 

reader.h

@@ -1,7 +1,8 @@
 #ifndef READER_H
 #define READER_H
+#include "cputracker.h"
 
+int get_proc_stats(struct proc_stat *stats);
 void *reader();
-struct proc_stat *get_proc_stats();
 
 #endif