add queue package

core/queue/balancedqueuepusher.go

@@ -0,0 +1,44 @@
+package queue
+
+import (
+	"errors"
+	"sync/atomic"
+
+	"github.com/tal-tech/go-zero/core/logx"
+)
+
+var ErrNoAvailablePusher = errors.New("no available pusher")
+
+type BalancedQueuePusher struct {
+	name    string
+	pushers []Pusher
+	index   uint64
+}
+
+func NewBalancedQueuePusher(pushers []Pusher) Pusher {
+	return &BalancedQueuePusher{
+		name:    generateName(pushers),
+		pushers: pushers,
+	}
+}
+
+func (pusher *BalancedQueuePusher) Name() string {
+	return pusher.name
+}
+
+func (pusher *BalancedQueuePusher) Push(message string) error {
+	size := len(pusher.pushers)
+
+	for i := 0; i < size; i++ {
+		index := atomic.AddUint64(&pusher.index, 1) % uint64(size)
+		target := pusher.pushers[index]
+
+		if err := target.Push(message); err != nil {
+			logx.Error(err)
+		} else {
+			return nil
+		}
+	}
+
+	return ErrNoAvailablePusher
+}