Ring buffer for allocator

alloc/ring.go

@@ -0,0 +1,51 @@
+package alloc
+
+import (
+	"github.com/pkg/errors"
+)
+
+func newRing[T any](capacity uint64) (*ring[T], []T) {
+	addresses := make([]T, capacity)
+	return &ring[T]{
+		addresses: addresses,
+		capacity:  capacity,
+		commitPtr: capacity,
+	}, addresses
+}
+
+type ring[T any] struct {
+	addresses []T
+
+	capacity                        uint64
+	allocPtr, commitPtr, deallocPtr uint64
+}
+
+func (r *ring[T]) Allocate() (T, error) {
+	if r.allocPtr == r.commitPtr {
+		var t T
+		return t, errors.New("no free address to allocate")
+	}
+	if r.allocPtr == r.capacity {
+		r.allocPtr = 0
+	}
+	a := r.addresses[r.allocPtr]
+	r.allocPtr++
+	return a, nil
+}
+
+func (r *ring[T]) Deallocate(item T) {
+	if r.deallocPtr == r.capacity {
+		r.deallocPtr = 0
+	}
+	if r.deallocPtr == r.allocPtr {
+		// This is really critical because it means that we deallocated more than allocated.
+		panic("no space left in the ring for deallocation")
+	}
+
+	r.addresses[r.deallocPtr] = item
+	r.deallocPtr++
+}
+
+func (r *ring[T]) Commit() {
+	r.commitPtr = r.deallocPtr - 1
+}