From 63d85ad1b52146d520211d18b9d9e5c7420903c6 Mon Sep 17 00:00:00 2001
From: Hauke Petersen <hauke.petersen@fu-berlin.de>
Date: Thu, 25 Apr 2019 13:45:15 +0200
Subject: [PATCH] sys/event: add event_wait_timeout()

---
 sys/event/event.c   | 28 ++++++++++++++++++++++++++++
 sys/include/event.h | 15 ++++++++++++++-
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/sys/event/event.c b/sys/event/event.c
index 8acd98a062..96579d0a7d 100644
--- a/sys/event/event.c
+++ b/sys/event/event.c
@@ -29,6 +29,10 @@
 #include "clist.h"
 #include "thread.h"
 
+#ifdef MODULE_XTIMER
+#include "xtimer.h"
+#endif
+
 void event_queue_init_detached(event_queue_t *queue)
 {
     assert(queue);
@@ -110,6 +114,30 @@ event_t *event_wait(event_queue_t *queue)
     return result;
 }
 
+#ifdef MODULE_XTIMER
+event_t *event_wait_timeout(event_queue_t *queue, uint32_t timeout)
+{
+    assert(queue);
+    event_t *result;
+    xtimer_t timer;
+    thread_flags_t flags = 0;
+
+    xtimer_set_timeout_flag(&timer, timeout);
+    do {
+        result = event_get(queue);
+        if (result == NULL) {
+            flags = thread_flags_wait_any(THREAD_FLAG_EVENT | THREAD_FLAG_TIMEOUT);
+        }
+    } while ((result == NULL) && (flags & THREAD_FLAG_EVENT));
+
+    if (result) {
+        xtimer_remove(&timer);
+    }
+
+    return result;
+}
+#endif
+
 void event_loop(event_queue_t *queue)
 {
     event_t *event;
diff --git a/sys/include/event.h b/sys/include/event.h
index 096c3870bc..dcea3c23a9 100644
--- a/sys/include/event.h
+++ b/sys/include/event.h
@@ -1,7 +1,7 @@
 /*
  * Copyright (C) 2017 Inria
  *               2017 Kaspar Schleiser <kaspar@schleiser.de>
- *               2018 Freie Universität Berlin
+ *               2018-2019 Freie Universität Berlin
  *
  * This file is subject to the terms and conditions of the GNU Lesser
  * General Public License v2.1. See the file LICENSE in the top level
@@ -231,6 +231,19 @@ event_t *event_get(event_queue_t *queue);
  */
 event_t *event_wait(event_queue_t *queue);
 
+#if defined(MODULE_XTIMER) || defined(DOXYGEN)
+/**
+ * @brief   Get next event from event queue, blocking until timeout expires
+ *
+ * @param[in]   queue    queue to query for an event
+ * @param[in]   timeout  maximum time to wait for an event to be posted in us
+ *
+ * @return      pointer to next event if event was taken from the queue
+ * @return      NULL if timeout expired before an event was posted
+ */
+event_t *event_wait_timeout(event_queue_t *queue, uint32_t timeout);
+#endif
+
 /**
  * @brief   Simple event loop
  *