[Aggregator] Better handling of threads

Fix thread headers, check the return value of pthread_create(), and wait
for the threads at the end of the program.

owlps-aggregator/owlps-aggregator.h

@@ -32,6 +32,7 @@
 #define ERR_BAD_USAGE 3 // Bad program call
 #define ERR_PARSING_CONFIG_FILE 4 // Error reading the configuration file
 #define ERR_SENDING_INFO 5 // Error sending a message on a socket
+#define ERR_CREATING_THREAD 6 // Error creating a thread
 
 
 /* Linked list storing data of each request */
@@ -89,14 +90,14 @@ void check_configuration(void) ;
 int read_loop(int sockfd) ;
 void got_request(owl_captured_request request) ;
 
-void* monitor_requests(void) ;
+void* monitor_requests(void *NULL_value) ;
 void free_request_list(void) ;
 #ifdef DEBUG
 void print_request_list(void) ;
 void print_request_info(request_info_list *info) ;
 #endif // DEBUG
 
-void listen_for_aps(void) ;
+void* listen_for_aps(void *NULL_value) ;
 void update_ap(uint8_t mac_addr_bytes[6], char ip_addr[16]) ;
 ap_list* find_ap(uint8_t mac_addr_bytes[6]) ;
 ap_list* add_ap_front(uint8_t mac_addr_bytes[6]) ;
@@ -104,7 +105,7 @@ void update_ap_ip_addr(ap_list *ap, char ip_addr[16]) ;
 void update_ap_seen(ap_list *ap) ;
 void push_ap(ap_list *ap) ;
 
-void monitor_aps(void) ;
+void* monitor_aps(void *NULL_value) ;
 void delete_old_aps(void) ;
 void delete_ap(ap_list *ap) ;
 void unlink_ap(ap_list *ap) ;

owlps-aggregator/owlps-aggregatord.c

@@ -51,19 +51,70 @@ int main(int argc, char **argv)
     }
 
   /* Set up threads */
-  pthread_create(&monitor_thread, NULL,
-                 (void *) &monitor_requests, NULL) ;
+  ret = pthread_create(&monitor_thread, NULL, &monitor_requests, NULL) ;
+  if (ret != 0)
+    {
+      perror("Cannot create monitor thread") ;
+      ret = ERR_CREATING_THREAD ;
+      goto exit ;
+    }
   if (cfg_getbool(cfg, "autocalibration"))
     {
-      pthread_create(&autocalibration_hello_thread, NULL,
-                     (void *) &listen_for_aps, NULL) ;
-      pthread_create(&monitor_aps_thread, NULL,
-                     (void *) &monitor_aps, NULL) ;
+      ret = pthread_create(&autocalibration_hello_thread, NULL,
+                           &listen_for_aps, NULL) ;
+      if (ret != 0)
+        {
+          perror("Cannot create autocalibration hello thread") ;
+          ret = ERR_CREATING_THREAD ;
+          goto exit ;
+        }
+      ret = pthread_create(&monitor_aps_thread, NULL,
+                           &monitor_aps, NULL) ;
+      if (ret != 0)
+        {
+          perror("Cannot create monitor APs thread") ;
+          ret = ERR_CREATING_THREAD ;
+          goto exit ;
+        }
     }
 
   run = TRUE ;
   ret = read_loop(sockfd) ;
 
+  /* Wait for the threads to terminate */
+
+  fprintf(stderr, "Waiting for the monitor thread... ") ;
+  if (pthread_join(monitor_thread, NULL) != 0)
+    perror("Cannot join monitor thread") ;
+  else
+    fprintf(stderr, "OK.\n") ;
+
+  if (cfg_getbool(cfg, "autocalibration"))
+    {
+      // We must cancel this thread because it can be blocked on the
+      // recvfrom() call:
+      fprintf(stderr,
+              "Cancelling the autocalibration hello thread... ") ;
+      if (pthread_cancel(autocalibration_hello_thread) != 0)
+        perror("Cannot cancel autocalibration hello thread") ;
+      else
+        fprintf(stderr, "OK.\n") ;
+
+      fprintf(stderr,
+              "Waiting for the autocalibration hello thread... ") ;
+      if (pthread_join(autocalibration_hello_thread, NULL) != 0)
+        perror("Cannot join autocalibration hello thread") ;
+      else
+        fprintf(stderr, "OK.\n") ;
+
+      fprintf(stderr, "Waiting for the monitor APs thread... ") ;
+      if (pthread_join(monitor_aps_thread, NULL) != 0)
+        perror("Cannot join monitor APs thread") ;
+      else
+        fprintf(stderr, "OK.\n") ;
+    }
+
+  /* Last cleaning tasks */
  exit:
   (void) close(sockfd) ; // Close socket
   free_request_list() ;
@@ -419,7 +470,7 @@ int read_loop(int sockfd)
  * Thread function. Monitors the list and sends information to the
  * localisation server when the timeout is reached.
  */
-void* monitor_requests()
+void* monitor_requests(void *NULL_value)
 {
   request_list *request_ptr, *request_prev ;
   request_info_list *request_info_ptr ;
@@ -605,7 +656,7 @@ void* monitor_requests()
     perror("Error closing output file") ;
   (void) close(sockfd) ;
 
-  return NULL ;
+  pthread_exit(NULL_value) ;
 }
 
 
@@ -757,7 +808,7 @@ void free_request_list()
 /*
  * Thread function. Listens for hello messages from APs.
  */
-void listen_for_aps(void)
+void* listen_for_aps(void *NULL_value)
 {
   int listen_sockfd ;
   int nread ; // recvfrom return value
@@ -803,6 +854,8 @@ void listen_for_aps(void)
     }
 
   (void) close(listen_sockfd) ;
+
+  pthread_exit(NULL_value) ;
 }
 
 
@@ -919,7 +972,7 @@ void push_ap(ap_list *ap)
  * Monitors the AP list: sends orders to APs following their order in
  * the list, and deletes old APs.
  */
-void monitor_aps()
+void* monitor_aps(void *NULL_value)
 {
 #ifdef DEBUG
   fprintf(stderr, "Monitor AP thread launched.\n") ;
@@ -937,6 +990,8 @@ void monitor_aps()
 
       usleep(cfg_getint(cfg, "ap_check_interval") * 1000) ;
     }
+
+  pthread_exit(NULL_value) ;
 }