pbio/light/animation: Fix lockup on restarting animation.

If it was restarted just as a new frame was being loaded,
the animation would get stuck handling timer events forever.

Fixes pybricks/support#1295

CHANGELOG.md

@@ -24,7 +24,10 @@
   loops ([support#1668]).
 - Fixed program restarting if the stop button was held to end the program
   without an exception ([support#1863]).
+- Fixed program lockup when restarting a hub light or light matrix animation
+  at exact multiples of its animation interval ([support#1295]).
 
+[support#1295]: https://github.com/pybricks/support/issues/1295
 [support#1623]: https://github.com/pybricks/support/issues/1623
 [support#1661]: https://github.com/pybricks/support/issues/1661
 [support#1668]: https://github.com/pybricks/support/issues/1668

lib/pbio/src/light/animation.c

@@ -50,10 +50,10 @@ void pbio_light_animation_start(pbio_light_animation_t *animation) {
     pbio_light_animation_list_head = animation;
 
     process_start(&pbio_light_animation_process);
-    // HACK: init timer since we don't call etimer_set()
-    timer_set(&animation->timer.timer, 0);
-    // fake a timer event to load the first cell and start the timer
-    process_post_synch(&pbio_light_animation_process, PROCESS_EVENT_TIMER, &animation->timer);
+    // Fake a timer event to load the first cell.
+    PROCESS_CONTEXT_BEGIN(&pbio_light_animation_process);
+    etimer_set(&animation->timer, 0);
+    PROCESS_CONTEXT_END(&pbio_light_animation_process);
 
     assert(animation->next_animation != PBIO_LIGHT_ANIMATION_STOPPED);
 }
@@ -114,11 +114,11 @@ PROCESS_THREAD(pbio_light_animation_process, ev, data) {
     PROCESS_BEGIN();
 
     for (;;) {
-        PROCESS_WAIT_EVENT_UNTIL(ev == PROCESS_EVENT_TIMER);
+        PROCESS_WAIT_EVENT_UNTIL(ev == PROCESS_EVENT_TIMER && etimer_expired(data));
         struct etimer *timer = data;
         pbio_light_animation_t *animation = PBIO_CONTAINER_OF(timer, pbio_light_animation_t, timer);
-        clock_time_t interval = animation->next(animation);
         if (pbio_light_animation_is_started(animation)) {
+            clock_time_t interval = animation->next(animation);
             etimer_reset_with_new_interval(&animation->timer, interval);
         }
     }

lib/pbio/test/src/test_animation.c

@@ -33,10 +33,12 @@ static PT_THREAD(test_light_animation(struct pt *pt)) {
     tt_want(!process_is_running(&pbio_light_animation_process));
     tt_want(!pbio_light_animation_is_started(&test_animation));
 
-    // starting animation should start process and call next() once synchonously
+    // starting animation should start process and set a timer at 0ms to call
+    // next() after handling pending events
     pbio_light_animation_start(&test_animation);
     tt_want(pbio_light_animation_is_started(&test_animation));
     tt_want(process_is_running(&pbio_light_animation_process));
+    pbio_handle_pending_events();
     tt_want_uint_op(test_animation_set_hsv_call_count, ==, 1);
 
     // next() should not be called again until after a delay

lib/pbio/test/src/test_color_light.c

@@ -63,9 +63,10 @@ static PT_THREAD(test_color_light(struct pt *pt)) {
     // reset call count for next series of tests
     test_light_set_hsv_call_count = 0;
 
-    // starting animation should call set_hsv() synchonously
+    // starting animation should call set_hsv() after handling pending events
     static const pbio_color_hsv_t hsv = { .h = PBIO_COLOR_HUE_BLUE, .s = 100, .v = 100 };
     pbio_color_light_start_blink_animation(&test_light, &hsv, test_blink);
+    pbio_handle_pending_events();
     tt_want_uint_op(test_light_set_hsv_call_count, ==, 1);
     // even blink cells turns the light on
     tt_want_uint_op(test_light_set_hsv_last_hue, ==, PBIO_COLOR_HUE_BLUE);
@@ -92,8 +93,9 @@ static PT_THREAD(test_color_light(struct pt *pt)) {
     // reset call count for next series of tests
     test_light_set_hsv_call_count = 0;
 
-    // starting animation should call set_hsv() synchonously
+    // starting animation should call set_hsv() after handling pending events
     pbio_color_light_start_animation(&test_light, TEST_ANIMATION_TIME, test_animation);
+    pbio_handle_pending_events();
     tt_want_uint_op(test_light_set_hsv_call_count, ==, 1);
     tt_want_uint_op(test_light_set_hsv_last_hue, ==, PBIO_COLOR_HUE_CYAN);
 

lib/pbio/test/src/test_light_matrix.c

@@ -82,9 +82,11 @@ static PT_THREAD(test_light_matrix(struct pt *pt)) {
         IMAGE_DATA(1, 2, 3, 4, 5, 6, 7, 8, 9)), ==, PBIO_SUCCESS);
     tt_want_light_matrix_data(1, 2, 3, 4, 5, 6, 7, 8, 9);
 
-    // starting animation should call set_pixel() synchonously with the first cell data
+    // starting animation should schedule timer event at 0 ms to call
+    // set_pixel() after handling pending events.
     test_light_matrix_reset();
     pbio_light_matrix_start_animation(&test_light_matrix, test_animation, 2, INTERVAL);
+    pbio_handle_pending_events();
     tt_want_light_matrix_data(1, 2, 3, 4, 5, 6, 7, 8, 9);
 
     // set_pixel() should not be called again until after a delay and it should

lib/pbio/test/test-pbio.h

@@ -8,6 +8,7 @@
 
 #include <pbio/button.h>
 #include <pbio/int_math.h>
+#include <pbio/main.h>
 
 // Use this macro to define tests that _don't_ require a Contiki event loop
 #define PBIO_TEST(name) \
@@ -57,6 +58,11 @@ void pbio_test_counter_set_abs_angle(int32_t millidegrees);
         PT_YIELD(pt); \
     }
 
+static inline void pbio_handle_pending_events(void) {
+    while (pbio_do_one_event()) {
+    }
+}
+
 #define pbio_test_int_is_close(value, target, tolerance) (pbio_int_math_abs((value) - (target)) <= (tolerance))
 
 #endif // _TEST_PBIO_H_