event: generic event refactoring

[bertos.git] / bertos / mware / event.c

diff --git a/bertos/mware/event.c b/bertos/mware/event.c
index 72663037497b1d2106b14065af8e2fbe23d9b8c3..9dcb71a077018ae77e3de5a78330b5550b1c43aa 100644 (file)
--- a/bertos/mware/event.c
+++ b/bertos/mware/event.c
@@ -47,7 +47,18 @@ void event_hook_ignore(UNUSED_ARG(Event *, e))
 {
 }
 
-#if CONFIG_KERN_SIGNALS
+void event_hook_softint(Event *e)
+{
+       e->Ev.Int.func(e->Ev.Int.user_data);
+}
+
+void event_hook_generic(Event *e)
+{
+       e->Ev.Gen.completed = true;
+       MEMORY_BARRIER;
+}
+
+#if CONFIG_KERN && CONFIG_KERN_SIGNALS
 void event_hook_signal(Event *e)
 {
        sig_post((e)->Ev.Sig.sig_proc, (e)->Ev.Sig.sig_bit);
@@ -55,50 +66,130 @@ void event_hook_signal(Event *e)
 
 void event_hook_generic_signal(Event *e)
 {
-       sig_postSignal(&e->Ev.SigGen.sig,
-                               e->Ev.SigGen.sig_proc,
-                               EVENT_GENERIC_SIGNAL);
+       sig_postSignal(&e->Ev.Sig.sig, e->Ev.Sig.sig_proc, e->Ev.Sig.sig_bit);
 }
-#endif
 
-void event_hook_softint(Event *e)
+/*
+ * Custom event hook to notify the completion of a event monitored via
+ * event_select().
+ */
+static void event_hook_generic_multiple_signal(Event *e)
 {
-       e->Ev.Int.func(e->Ev.Int.user_data);
+       sig_post(e->Ev.Sig.sig_proc, e->Ev.Sig.sig_bit);
 }
 
-void event_hook_generic(Event *e)
+/*
+ * Custom timer hook to notify the timeout of a event_waitTimeout().
+ */
+static void event_hook_generic_timeout_signal(void *arg)
 {
-       e->Ev.Gen.completed = true;
-       MEMORY_BARRIER;
+       Event *e = (Event *)arg;
+
+       sig_postSignal(&e->Ev.Sig.sig, e->Ev.Sig.sig_proc, SIG_TIMEOUT);
 }
 
-/**
- * Wait for multiple events
- *
- * On success return the offset in the \a evs vector of the Event that
- * happened, -1 if the timeout expires.
+/*
+ * event_waitTimeout() slow path: this function put the current process to
+ * sleep until the event is notified. The timeout is managed using the custom
+ * timer hook event_hook_generic_timeout_signal(): if the timeout expires the
+ * signal SIG_TIMEOUT is notified via sig_post() to the sigmask embedded in the
+ * event.
  *
- * NOTE: timeout == 0 means no timeout.
+ * The custom timer hook is required because the default timer's behaviour is
+ * to use the process's sigmask to notify the completion of an event, that is
+ * not suitable for this case, because we're sleeping on the event's sigmask
+ * instead.
  */
-#if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
-int event_select(Event **evs, int n, ticks_t timeout)
+static NOINLINE bool event_waitTimeoutSlowPath(Event *e, ticks_t timeout)
+{
+       bool ret;
+
+       e->Ev.Sig.sig_proc = proc_current();
+       ret = (sig_waitTimeoutSignal(&e->Ev.Sig.sig,
+                       EVENT_GENERIC_SIGNAL, timeout,
+                       event_hook_generic_timeout_signal, e) & SIG_TIMEOUT) ?
+                       false : true;
+       return ret;
+}
+
+bool event_waitTimeout(Event *e, ticks_t timeout)
+{
+       /*
+        * Fast path: check if the event already happened and return
+        * immediately in this case.
+        */
+       if (sig_checkSignal(&e->Ev.Sig.sig,
+                       EVENT_GENERIC_SIGNAL) == EVENT_GENERIC_SIGNAL)
+               return true;
+       return event_waitTimeoutSlowPath(e, timeout);
+}
+
+/*
+ * event_select() slow path: this function handles the case when any event was
+ * not yet notified, so it takes care of making the current process to sleep on
+ * the list of events, mapping them to a different signal bit and issuing a
+ * call to sig_waitTimeout() using the process's sigmask.
+ */
+static NOINLINE int event_selectSlowPath(Event **evs, int n, ticks_t timeout)
 {
        sigmask_t mask = (1 << n) - 1;
        int i;
 
-       ASSERT(n <= SIG_USER_MAX);
        for (i = 0; i < n; i++)
        {
                Event *e = evs[i];
+
                /* Map each event to a distinct signal bit */
-               event_initSignal(e, proc_current(), 1 << i);
+               e->Ev.Sig.sig_proc = proc_current();
+               e->Ev.Sig.sig_bit = 1 << i;
+               e->action = event_hook_generic_multiple_signal;
        }
+       IRQ_ENABLE;
+
        mask = timeout ? sig_waitTimeout(mask, timeout) : sig_wait(mask);
-       i = UINT8_LOG2(mask);
+       if (mask & SIG_TIMEOUT)
+               return -1;
+       return UINT8_LOG2(mask);
+}
+
+int event_select(Event **evs, int n, ticks_t timeout)
+{
+       int i;
 
-       return i < n ? i : -1;
+       ASSERT(n <= SIG_USER_MAX);
+
+       IRQ_DISABLE;
+       /* Fast path: check if one of the event already happened */
+       for (i = 0; i < n; i++)
+       {
+               Event *e = evs[i];
+
+               if (__sig_checkSignal(&e->Ev.Sig.sig,
+                               EVENT_GENERIC_SIGNAL) == EVENT_GENERIC_SIGNAL)
+               {
+                       IRQ_ENABLE;
+                       return i;
+               }
+       }
+       /* Otherwise, fallback to the slow path */
+       return event_selectSlowPath(evs, n, timeout);
 }
-#else
+#else /* !(CONFIG_KERN && CONFIG_KERN_SIGNALS) */
+bool event_waitTimeout(Event *e, ticks_t timeout)
+{
+       ticks_t end = timer_clock() + timeout;
+       bool ret;
+
+       while ((ACCESS_SAFE(e->Ev.Gen.completed) == false) ||
+                       TIMER_AFTER(timer_clock(), end))
+               cpu_relax();
+       ret = e->Ev.Gen.completed;
+       e->Ev.Gen.completed = false;
+       MEMORY_BARRIER;
+
+       return ret;
+}
+
 int event_select(Event **evs, int n, ticks_t timeout)
 {
        ticks_t end = timer_clock() + timeout;
@@ -122,4 +213,4 @@ int event_select(Event **evs, int n, ticks_t timeout)
        }
        return -1;
 }
-#endif
+#endif /* CONFIG_KERN && CONFIG_KERN_SIGNALS */