modutimeq: Add peektime() function (provisional).

jpochyla · pfalcon · commit e9d7c3ea0ef7 · 2017-03-29T18:18:35.000+03:00
Allows to get event time for a head item in the queue. The usecase
if waiting for the next event *OR* I/O completion. I/O completion may
happen before event triggers, and then wait should continue for the
remaining event time (or I/O completion may schedule another earlier
event altogether).

The new function has a strongly provisional status - it may be converted
to e.g. peek() function returning all of the event fields, not just time.
diff --git a/extmod/modutimeq.c b/extmod/modutimeq.c
@@ -166,6 +166,17 @@ STATIC mp_obj_t mod_utimeq_heappop(mp_obj_t heap_in, mp_obj_t list_ref) {
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_utimeq_heappop_obj, mod_utimeq_heappop);
 
+STATIC mp_obj_t mod_utimeq_peektime(mp_obj_t heap_in) {
+    mp_obj_utimeq_t *heap = get_heap(heap_in);
+    if (heap->len == 0) {
+        nlr_raise(mp_obj_new_exception_msg(&mp_type_IndexError, "empty heap"));
+    }
+
+    struct qentry *item = &heap->items[0];
+    return MP_OBJ_NEW_SMALL_INT(item->time);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_utimeq_peektime_obj, mod_utimeq_peektime);
+
 #if DEBUG
 STATIC mp_obj_t mod_utimeq_dump(mp_obj_t heap_in) {
     mp_obj_utimeq_t *heap = get_heap(heap_in);
@@ -190,6 +201,7 @@ STATIC mp_obj_t utimeq_unary_op(mp_uint_t op, mp_obj_t self_in) {
 STATIC const mp_rom_map_elem_t utimeq_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_push), MP_ROM_PTR(&mod_utimeq_heappush_obj) },
     { MP_ROM_QSTR(MP_QSTR_pop), MP_ROM_PTR(&mod_utimeq_heappop_obj) },
+    { MP_ROM_QSTR(MP_QSTR_peektime), MP_ROM_PTR(&mod_utimeq_peektime_obj) },
     #if DEBUG
     { MP_ROM_QSTR(MP_QSTR_dump), MP_ROM_PTR(&mod_utimeq_dump_obj) },
     #endif
