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-rw-r--r--src/queue.cpp24
1 files changed, 15 insertions, 9 deletions
diff --git a/src/queue.cpp b/src/queue.cpp
index d3fd69c52..5585b772f 100644
--- a/src/queue.cpp
+++ b/src/queue.cpp
@@ -10,11 +10,12 @@ struct MPSCNode {
//
template <typename T>
struct MPSCQueue {
+ gbAllocator allocator;
+ std::atomic<isize> count;
+
std::atomic<MPSCNode<T> *> head;
std::atomic<MPSCNode<T> *> tail;
- std::atomic<isize> count;
MPSCNode<T> sentinel;
- gbAllocator allocator;
};
template <typename T> gb_internal void mpsc_init (MPSCQueue<T> *q, gbAllocator const &allocator);
@@ -29,6 +30,7 @@ gb_internal void mpsc_init(MPSCQueue<T> *q, gbAllocator const &allocator) {
q->count.store(0, std::memory_order_relaxed);
q->head.store(&q->sentinel, std::memory_order_relaxed);
q->tail.store(&q->sentinel, std::memory_order_relaxed);
+
q->sentinel.next.store(nullptr, std::memory_order_relaxed);
}
@@ -36,14 +38,20 @@ template <typename T>
gb_internal void mpsc_destroy(MPSCQueue<T> *q) {
while (mpsc_dequeue(q, (T *)nullptr)) {}
// DO NOTHING for the time being
+ // free the nodes later
}
template <typename T>
gb_internal MPSCNode<T> *mpsc_alloc_node(MPSCQueue<T> *q, T const &value) {
- auto node = gb_alloc_item(q->allocator, MPSCNode<T>);
- node->value = value;
- return node;
+ auto new_node = gb_alloc_item(q->allocator, MPSCNode<T>);
+ new_node->value = value;
+ return new_node;
+}
+
+template <typename T>
+gb_internal void mpsc_free_node(MPSCQueue<T> *q, MPSCNode<T> *node) {
+ // TODO(bill): reuse the free nodes
}
template <typename T>
@@ -68,10 +76,8 @@ gb_internal bool mpsc_dequeue(MPSCQueue<T> *q, T *value_) {
auto next = tail->next.load(std::memory_order_relaxed);
if (next) {
q->tail.store(next, std::memory_order_relaxed);
- // `tail` is now "dead" and needs to be "freed"
- tail->value = next->value;
- T value = tail->value;
- if (value_) *value_ = value;
+ if (value_) *value_ = next->value;
+ mpsc_free_node(q, tail);
q->count.fetch_sub(1, std::memory_order_acq_rel);
return true;
}