ztimer: add on_demand_strict

jue89 · jue89 · commit 04607ed616ae · 2022-02-04T15:47:26.000+01:00
Enforce ztimer_clock_t to be active (i.e. clock-&gt;users &gt; 0) before ztimer_now() can be called.
diff --git a/sys/include/ztimer.h b/sys/include/ztimer.h
@@ -576,12 +576,18 @@ ztimer_now_t _ztimer_now_extend(ztimer_clock_t *clock);
  * @warning don't compare ztimer_now() values from different clocks. The
  *          clocks are almost certainly not synchronized.
  *
+ * @warning Make sure to call @ref ztimer_acquire(@p clock) before fetching
+ *          the clock's current time.
+ *
  * @param[in]   clock          ztimer clock to operate on
  *
  * @return  Current count on @p clock
  */
 static inline ztimer_now_t ztimer_now(ztimer_clock_t *clock)
 {
+#if MODULE_ZTIMER_ONDEMAND_STRICT
+    assert(clock->users > 0);
+#endif
 #if MODULE_ZTIMER_NOW64
     if (1) {
 #elif MODULE_ZTIMER_EXTEND
@@ -610,6 +616,10 @@ static inline ztimer_now_t ztimer_now(ztimer_clock_t *clock)
  * If the time (@p last_wakeup + @p period) has already passed, the function
  * sets @p last_wakeup to @p last_wakeup + @p period and returns immediately.
  *
+ * @warning Make sure to call @ref ztimer_acquire(@p clock) before making use
+ *          of @ref ztimer_periodic_wakeup. After usage
+ *          @ref ztimer_release(@p clock) should be called.
+ *
  * @param[in]   clock           ztimer clock to operate on
  * @param[in]   last_wakeup     base time stamp for the wakeup
  * @param[in]   period          time in ticks that will be added to @p last_wakeup
diff --git a/sys/ztimer/Makefile.dep b/sys/ztimer/Makefile.dep
@@ -48,6 +48,10 @@ ifneq (,$(filter ztimer_%,$(USEMODULE)))
   USEMODULE += ztimer_extend
 endif
 
+ifneq (,$(filter ztimer_ondemand_strict,$(USEMODULE)))
+  USEMODULE += ztimer_ondemand
+endif
+
 ifneq (,$(filter ztimer_convert_%,$(USEMODULE)))
   USEMODULE += ztimer_convert
 endif
