init

comet/ring.go

@@ -0,0 +1,80 @@
+package comet
+
+import (
+	"gitlab.33.cn/chat/im/api/comet/grpc"
+	"gitlab.33.cn/chat/im/comet/errors"
+)
+
+// Ring ring proto buffer.
+type Ring struct {
+	// read
+	rp   uint64
+	num  uint64
+	mask uint64
+	// TODO split cacheline, many cpu cache line size is 64
+	// pad [40]byte
+	// write
+	wp   uint64
+	data []grpc.Proto
+}
+
+// NewRing new a ring buffer.
+func NewRing(num int) *Ring {
+	r := new(Ring)
+	r.init(uint64(num))
+	return r
+}
+
+// Init init ring.
+func (r *Ring) Init(num int) {
+	r.init(uint64(num))
+}
+
+func (r *Ring) init(num uint64) {
+	// 2^N
+	if num&(num-1) != 0 {
+		for num&(num-1) != 0 {
+			num &= (num - 1)
+		}
+		num = num << 1
+	}
+	r.data = make([]grpc.Proto, num)
+	r.num = num
+	r.mask = r.num - 1
+}
+
+// Get get a proto from ring.
+func (r *Ring) Get() (proto *grpc.Proto, err error) {
+	if r.rp == r.wp {
+		return nil, errors.ErrRingEmpty
+	}
+	proto = &r.data[r.rp&r.mask]
+	return
+}
+
+// GetAdv incr read index.
+func (r *Ring) GetAdv() {
+	r.rp++
+}
+
+// Set get a proto to write.
+func (r *Ring) Set() (proto *grpc.Proto, err error) {
+	if r.wp-r.rp >= r.num {
+		return nil, errors.ErrRingFull
+	}
+	proto = &r.data[r.wp&r.mask]
+	return
+}
+
+// SetAdv incr write index.
+func (r *Ring) SetAdv() {
+	r.wp++
+}
+
+// Reset reset ring.
+func (r *Ring) Reset() {
+	r.rp = 0
+	r.wp = 0
+	// prevent pad compiler optimization
+	// r.pad = [40]byte{}
+}