From beec74b01a19b7ccdf6a6f249fc680f4886ed3b2 Mon Sep 17 00:00:00 2001
From: Robert Schmidt <robert.schmidt@eurecom.fr>
Date: Tue, 29 Jan 2019 16:41:51 +0100
Subject: [PATCH] Correctly stop link_manager sender and receiver threads

This changes the destroy_link_manager() function to:
* call a new function message_get_unlock() to unlock the sending thread from
  its blocking message_get()
* calls pthread_cancel() on the receiving thread, because this unlocks any
  blocking read from a file descriptor

The same message_get_unlock() function has been added ringbuffer_queue to keep
the interfaces the same (it does nothing, because ringbuffer_queue is
non-blocking).
---
 openair2/UTIL/ASYNC_IF/link_manager.c     | 10 +++-------
 openair2/UTIL/ASYNC_IF/message_queue.c    | 19 ++++++++++++++++++-
 openair2/UTIL/ASYNC_IF/message_queue.h    |  2 ++
 openair2/UTIL/ASYNC_IF/ringbuffer_queue.c |  5 +++++
 openair2/UTIL/ASYNC_IF/ringbuffer_queue.h |  1 +
 5 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/openair2/UTIL/ASYNC_IF/link_manager.c b/openair2/UTIL/ASYNC_IF/link_manager.c
index 110b9edb7e..e9a8e98e07 100644
--- a/openair2/UTIL/ASYNC_IF/link_manager.c
+++ b/openair2/UTIL/ASYNC_IF/link_manager.c
@@ -50,11 +50,6 @@ static void *link_manager_sender_thread(void *_manager)
       link_send_packet(manager->socket_link, data, size, manager->peer_addr, manager->peer_port);
       free(data);
     }
-    //    if (message_get(manager->send_queue, &data, &size, &priority))
-    //  goto error;
-    //if (link_send_packet(manager->socket_link, data, size))
-    //  goto error;
-    //free(data);
   }
 
   LOG_D(MAC, "link manager sender thread quits\n");
@@ -148,10 +143,11 @@ error:
 
 void destroy_link_manager(link_manager_t *manager)
 {
-  LOG_D(MAC, "destroying link manager\n");
   manager->run = 0;
+  message_get_unlock(manager->send_queue);
   pthread_join(manager->sender, NULL);
-  pthread_join(manager->receiver, NULL);
+  /* cancel aborts the read performed in the receiver, then cancels the thread */
+  pthread_cancel(manager->receiver);
 }
 
 #ifdef SERVER_TEST
diff --git a/openair2/UTIL/ASYNC_IF/message_queue.c b/openair2/UTIL/ASYNC_IF/message_queue.c
index 42790bdaaa..460c58bcd1 100644
--- a/openair2/UTIL/ASYNC_IF/message_queue.c
+++ b/openair2/UTIL/ASYNC_IF/message_queue.c
@@ -56,6 +56,10 @@ message_queue_t *new_message_queue(void)
   if (pthread_cond_init(ret->cond, NULL))
     goto error;
 
+  ret->head = NULL;
+  ret->tail = NULL;
+  ret->exit = 0;
+
   return ret;
 
 error:
@@ -121,10 +125,15 @@ int message_get(message_queue_t *queue, void **data, int *priority)
     goto error;
 
   while (queue->count == 0) {
-    if (pthread_cond_wait(queue->cond, queue->mutex)) {
+    int rc = pthread_cond_wait(queue->cond, queue->mutex);
+    if (rc != 0) {
       pthread_mutex_unlock(queue->mutex);
       goto error;
     }
+    if (queue->exit) {
+      pthread_mutex_unlock(queue->mutex);
+      return 0;
+    }
   }
 
   m = queue->head;
@@ -148,6 +157,14 @@ error:
   return -1;
 }
 
+void message_get_unlock(message_queue_t *queue)
+{
+  pthread_mutex_lock(queue->mutex);
+  queue->exit = 1;
+  pthread_mutex_unlock(queue->mutex);
+  pthread_cond_signal(queue->cond);
+}
+
 /* when calling this function, the queue must not be used anymore (we don't lock it) */
 /* we suppose that the data pointer in messages was allocated by malloc/calloc/realloc */
 void destroy_message_queue(message_queue_t *queue)
diff --git a/openair2/UTIL/ASYNC_IF/message_queue.h b/openair2/UTIL/ASYNC_IF/message_queue.h
index 6d8d2a591a..656f3db28e 100644
--- a/openair2/UTIL/ASYNC_IF/message_queue.h
+++ b/openair2/UTIL/ASYNC_IF/message_queue.h
@@ -51,11 +51,13 @@ typedef struct {
   volatile int    count;
   pthread_mutex_t *mutex;
   pthread_cond_t  *cond;
+  int             exit;
 } message_queue_t;
 
 message_queue_t *new_message_queue(void);
 int message_put(message_queue_t *queue, void *data, int size, int priority);
 int message_get(message_queue_t *queue, void **data, int *priority);
+void message_get_unlock(message_queue_t *queue);
 void destroy_message_queue(message_queue_t *queue);
 
 #ifdef __cplusplus
diff --git a/openair2/UTIL/ASYNC_IF/ringbuffer_queue.c b/openair2/UTIL/ASYNC_IF/ringbuffer_queue.c
index f46ca41d78..7bcd3b5647 100644
--- a/openair2/UTIL/ASYNC_IF/ringbuffer_queue.c
+++ b/openair2/UTIL/ASYNC_IF/ringbuffer_queue.c
@@ -119,6 +119,11 @@ int message_get(message_queue_t *queue, void **data, int *priority) {
   return size;
 }
 
+void message_get_unlock(message_queue_t *queue) {
+  /* don't do anything, this function exists to unlock a message_queue but is
+   * not needed in the case of the ringbuffer_queue */
+}
+
 void destroy_message_queue(message_queue_t *queue) {
   struct lfds700_misc_prng_state ls;
 
diff --git a/openair2/UTIL/ASYNC_IF/ringbuffer_queue.h b/openair2/UTIL/ASYNC_IF/ringbuffer_queue.h
index 344187fe5c..bb65612e6b 100644
--- a/openair2/UTIL/ASYNC_IF/ringbuffer_queue.h
+++ b/openair2/UTIL/ASYNC_IF/ringbuffer_queue.h
@@ -48,6 +48,7 @@ typedef struct {
 message_queue_t * new_message_queue(int size);
 int message_put(message_queue_t *queue, void *data, int size, int priority);
 int message_get(message_queue_t *queue, void **data, int *priority);
+void message_get_unlock(message_queue_t *queue);
 void destroy_message_queue(message_queue_t *queue);
 
 #endif /* RINGBUFFER_QUEUE_H */