Initial commit.

battle_srv/models/ringbuf.go

@@ -0,0 +1,73 @@
+package models
+
+type RingBuffer struct {
+	Ed        int32 // write index
+	St        int32 // read index
+	EdFrameId int32
+	StFrameId int32
+	N         int32
+	Cnt       int32 // the count of valid elements in the buffer, used mainly to distinguish what "st == ed" means for "Pop" and "Get" methods
+	Eles      []interface{}
+}
+
+func NewRingBuffer(n int32) *RingBuffer {
+	return &RingBuffer{
+		Ed:   0,
+		St:   0,
+		N:    n,
+		Cnt:  0,
+		Eles: make([]interface{}, n),
+	}
+}
+
+func (rb *RingBuffer) Put(pItem interface{}) {
+	rb.Eles[rb.Ed] = pItem
+	rb.EdFrameId++
+	rb.Cnt++
+	rb.Ed++
+	if rb.Ed >= rb.N {
+		rb.Ed -= rb.N // Deliberately not using "%" operator for performance concern
+	}
+}
+
+func (rb *RingBuffer) Pop() interface{} {
+	if 0 == rb.Cnt {
+		return nil
+	}
+	pItem := rb.Eles[rb.St]
+	rb.StFrameId++
+	rb.Cnt--
+	rb.St++
+	if rb.St >= rb.N {
+		rb.St -= rb.N
+	}
+	return pItem
+}
+
+func (rb *RingBuffer) GetByOffset(offsetFromSt int32) interface{} {
+	if 0 == rb.Cnt {
+		return nil
+	}
+	arrIdx := rb.St + offsetFromSt
+	if rb.St < rb.Ed {
+		// case#1: 0...st...ed...N-1
+		if rb.St <= arrIdx && arrIdx < rb.Ed {
+			return rb.Eles[arrIdx]
+		}
+	} else {
+		// if rb.St >= rb.Ed
+		// case#2: 0...ed...st...N-1
+		if arrIdx >= rb.N {
+			arrIdx -= rb.N
+		}
+		if arrIdx >= rb.St || arrIdx < rb.Ed {
+			return rb.Eles[arrIdx]
+		}
+	}
+
+	return nil
+}
+
+func (rb *RingBuffer) GetByFrameId(frameId int32) interface{} {
+	return rb.GetByOffset(frameId - rb.StFrameId)
+}