support concurrent consume

exmaple/main.go

@@ -0,0 +1,37 @@
+package main
+
+import (
+	"github.com/go-redis/redis/v8"
+	"github.com/hdt3213/delayqueue"
+	"strconv"
+	"time"
+)
+
+func main() {
+	redisCli := redis.NewClient(&redis.Options{
+		Addr: "127.0.0.1:6379",
+	})
+	queue := delayqueue.NewQueue("example", redisCli, func(payload string) bool {
+		// callback returns true to confirm successful consumption.
+		// If callback returns false or not return within maxConsumeDuration, DelayQueue will re-deliver this message
+		println(payload)
+		return true
+	}).WithConcurrent(4)
+	// send delay message
+	for i := 0; i < 10; i++ {
+		err := queue.SendDelayMsg(strconv.Itoa(i), time.Second, delayqueue.WithRetryCount(3))
+		if err != nil {
+			panic(err)
+		}
+	}
+	// send schedule message
+	for i := 0; i < 10; i++ {
+		err := queue.SendScheduleMsg(strconv.Itoa(i), time.Now().Add(time.Second))
+		if err != nil {
+			panic(err)
+		}
+	}
+	// start consume
+	done := queue.StartConsume()
+	<-done
+}