load balancer implementation, code refactoring

server/internal/pool.go

@@ -0,0 +1,16 @@
+package internal
+
+type Pool []*Worker
+
+func (h Pool) Len() int           { return len(h) }
+func (h Pool) Less(i, j int) bool { return h[i].index < h[j].index }
+func (h Pool) Swap(i, j int)      { h[i], h[j] = h[j], h[i] }
+func (h *Pool) Push(x any)        { *h = append(*h, x.(*Worker)) }
+
+func (h *Pool) Pop() any {
+	old := *h
+	n := len(old)
+	x := old[n-1]
+	*h = old[0 : n-1]
+	return x
+}