diff --git a/runtime/src/priority_queue.c b/runtime/src/priority_queue.c index d050458..63beff7 100644 --- a/runtime/src/priority_queue.c +++ b/runtime/src/priority_queue.c @@ -12,6 +12,12 @@ * Private Helper Functions * ***************************/ +static inline void +priority_queue_update_highest_priority(struct priority_queue *self, const uint64_t priority) +{ + self->highest_priority = priority; +} + /** * Adds a value to the end of the binary heap * @param self the priority queue @@ -27,7 +33,7 @@ priority_queue_append(struct priority_queue *self, void *new_item) int rc; - /* Add one and prefix because we use 1-based indices in our backing array */ + if (unlikely(self->size + 1 > self->capacity)) panic("PQ overflow"); if (self->size + 1 == self->capacity) goto err_enospc; self->items[++self->size] = new_item; @@ -67,7 +73,7 @@ priority_queue_percolate_up(struct priority_queue *self) /* If there's only one element, set memoized lookup and early out */ if (self->size == 1) { - self->highest_priority = self->get_priority_fn(self->items[1]); + priority_queue_update_highest_priority(self, self->get_priority_fn(self->items[1])); return; } @@ -78,7 +84,7 @@ priority_queue_percolate_up(struct priority_queue *self) self->items[i / 2] = self->items[i]; self->items[i] = temp; /* If percolated to highest priority, update highest priority */ - if (i / 2 == 1) self->highest_priority = self->get_priority_fn(self->items[1]); + if (i / 2 == 1) priority_queue_update_highest_priority(self, self->get_priority_fn(self->items[1])); } } @@ -89,7 +95,7 @@ priority_queue_percolate_up(struct priority_queue *self) * @returns the index of the smallest child */ static inline int -priority_queue_find_smallest_child(struct priority_queue *self, int parent_index) +priority_queue_find_smallest_child(struct priority_queue *self, const int parent_index) { assert(self != NULL); assert(parent_index >= 1 && parent_index <= self->size); @@ -130,6 +136,8 @@ priority_queue_percolate_down(struct priority_queue *self, int parent_index) assert(runtime_is_worker()); assert(!software_interrupt_is_enabled()); + bool update_highest_value = parent_index == 1; + int left_child_index = 2 * parent_index; while (left_child_index >= 2 && left_child_index <= self->size) { int smallest_child_index = priority_queue_find_smallest_child(self, parent_index); @@ -147,11 +155,11 @@ priority_queue_percolate_down(struct priority_queue *self, int parent_index) } /* Update memoized value if we touched the head */ - if (parent_index == 1) { + if (update_highest_value) { if (!priority_queue_is_empty(self)) { - self->highest_priority = self->get_priority_fn(self->items[1]); + priority_queue_update_highest_priority(self, self->get_priority_fn(self->items[1])); } else { - self->highest_priority = ULONG_MAX; + priority_queue_update_highest_priority(self, ULONG_MAX); } } } @@ -174,15 +182,17 @@ priority_queue_initialize(size_t capacity, bool use_lock, priority_queue_get_pri assert(!runtime_is_worker() || !software_interrupt_is_enabled()); /* Add one to capacity because this data structure ignores the element at 0 */ - struct priority_queue *self = calloc(sizeof(struct priority_queue) + sizeof(void *) * (capacity + 1), 1); + size_t one_based_capacity = capacity + 1; + + struct priority_queue *self = calloc(sizeof(struct priority_queue) + sizeof(void *) * one_based_capacity, 1); /* We're assuming a min-heap implementation, so set to larget possible value */ - self->highest_priority = ULONG_MAX; - self->size = 0; - self->capacity = capacity; - self->get_priority_fn = get_priority_fn; - self->use_lock = use_lock; + priority_queue_update_highest_priority(self, ULONG_MAX); + self->size = 0; + self->capacity = one_based_capacity; // Add one because we skip element 0 + self->get_priority_fn = get_priority_fn; + self->use_lock = use_lock; if (use_lock) LOCK_INIT(&self->lock); @@ -368,9 +378,9 @@ priority_queue_dequeue_if_earlier_nolock(struct priority_queue *self, void **deq /* Update the highest priority */ if (!priority_queue_is_empty(self)) { - self->highest_priority = self->get_priority_fn(self->items[1]); + priority_queue_update_highest_priority(self, self->get_priority_fn(self->items[1])); } else { - self->highest_priority = ULONG_MAX; + priority_queue_update_highest_priority(self, ULONG_MAX); } return_code = 0;