Rate limiting for frontends

vendor/github.com/mailgun/minheap/minheap.go

@@ -0,0 +1,75 @@
+package minheap
+
+import (
+	"container/heap"
+)
+
+// An Element is something we manage in a priority queue.
+type Element struct {
+	Value    interface{}
+	Priority int // The priority of the item in the queue.
+	// The index is needed by update and is maintained by the heap.Interface methods.
+	index int // The index of the item in the heap.
+}
+
+// A PriorityQueue implements heap.Interface and holds Items.
+type MinHeap []*Element
+
+func NewMinHeap() *MinHeap {
+	mh := &MinHeap{}
+	heap.Init(mh)
+	return mh
+}
+
+func (mh MinHeap) Len() int { return len(mh) }
+
+func (mh MinHeap) Less(i, j int) bool {
+	return mh[i].Priority < mh[j].Priority
+}
+
+func (mh MinHeap) Swap(i, j int) {
+	mh[i], mh[j] = mh[j], mh[i]
+	mh[i].index = i
+	mh[j].index = j
+}
+
+func (mh *MinHeap) Push(x interface{}) {
+	n := len(*mh)
+	item := x.(*Element)
+	item.index = n
+	*mh = append(*mh, item)
+}
+
+func (mh *MinHeap) Pop() interface{} {
+	old := *mh
+	n := len(old)
+	item := old[n-1]
+	item.index = -1 // for safety
+	*mh = old[0 : n-1]
+	return item
+}
+
+func (mh *MinHeap) PushEl(el *Element) {
+	heap.Push(mh, el)
+}
+
+func (mh *MinHeap) PopEl() *Element {
+	el := heap.Pop(mh)
+	return el.(*Element)
+}
+
+func (mh *MinHeap) PeekEl() *Element {
+	items := *mh
+	return items[0]
+}
+
+// update modifies the priority and value of an Item in the queue.
+func (mh *MinHeap) UpdateEl(el *Element, priority int) {
+	heap.Remove(mh, el.index)
+	el.Priority = priority
+	heap.Push(mh, el)
+}
+
+func (mh *MinHeap) RemoveEl(el *Element) {
+	heap.Remove(mh, el.index)
+}