``` feat(pet): 重构宠物繁殖系统，添加蛋孵化功能

common/utils/timer/README.md

@@ -0,0 +1,130 @@
+## timer
+[![Go](https://github.com/antlabs/timer/workflows/Go/badge.svg)](https://github.com/antlabs/timer/actions)
+[![codecov](https://codecov.io/gh/antlabs/timer/branch/master/graph/badge.svg)](https://codecov.io/gh/antlabs/timer)
+
+timer是高性能定时器库
+## feature
+* 支持一次性定时器
+* 支持周期性定时器
+* 支持多种数据结构后端，最小堆，5级时间轮
+
+## 一次性定时器
+```go
+import (
+    "github.com/antlabs/timer"
+    "log"
+)
+
+func main() {
+        tm := timer.NewTimer()
+
+        tm.AfterFunc(1*time.Second, func() {
+                log.Printf("after\n")
+        })
+
+        tm.AfterFunc(10*time.Second, func() {
+                log.Printf("after\n")
+        })
+        tm.Run()
+}
+```
+## 周期性定时器
+```go
+import (
+    "github.com/antlabs/timer"
+    "log"
+)
+
+func main() {
+        tm := timer.NewTimer()
+
+        tm.ScheduleFunc(1*time.Second, func() {
+                log.Printf("schedule\n")
+        })
+
+        tm.Run()
+}
+```
+## 自定义周期性定时器
+实现时间翻倍定时的例子
+```go
+type curstomTest struct {
+	count int
+}
+// 只要实现Next接口就行
+func (c *curstomTest) Next(now time.Time) (rv time.Time) {
+	rv = now.Add(time.Duration(c.count) * time.Millisecond * 10)
+	c.count++
+	return
+}
+
+func main() {
+        tm := timer.NewTimer(timer.WithMinHeap())
+        node := tm.CustomFunc(&curstomTest{count: 1}, func() {
+                log.Printf("%v\n", time.Now())
+        })
+        tm.Run()
+}
+```
+## 取消某一个定时器
+```go
+import (
+	"log"
+	"time"
+
+	"github.com/antlabs/timer"
+)
+
+func main() {
+
+	tm := timer.NewTimer()
+
+	// 只会打印2 time.Second
+	tm.AfterFunc(2*time.Second, func() {
+		log.Printf("2 time.Second")
+	})
+
+	// tk3 会被 tk3.Stop()函数调用取消掉
+	tk3 := tm.AfterFunc(3*time.Second, func() {
+		log.Printf("3 time.Second")
+	})
+
+	tk3.Stop() //取消tk3
+
+	tm.Run()
+}
+```
+## 选择不同的的数据结构
+```go
+import (
+    "github.com/antlabs/timer"
+    "log"
+)
+
+func main() {
+        tm := timer.NewTimer(timer.WithMinHeap())// 选择最小堆，默认时间轮
+}
+```
+## benchmark
+
+github.com/antlabs/timer 性能最高
+```
+goos: linux
+goarch: amd64
+pkg: benchmark
+Benchmark_antlabs_Timer_AddTimer/N-1m-16        	 9177537	       124 ns/op
+Benchmark_antlabs_Timer_AddTimer/N-5m-16        	10152950	       128 ns/op
+Benchmark_antlabs_Timer_AddTimer/N-10m-16       	 9955639	       127 ns/op
+Benchmark_RussellLuo_Timingwheel_AddTimer/N-1m-16         	 5316916	       222 ns/op
+Benchmark_RussellLuo_Timingwheel_AddTimer/N-5m-16         	 5848843	       218 ns/op
+Benchmark_RussellLuo_Timingwheel_AddTimer/N-10m-16        	 5872621	       231 ns/op
+Benchmark_ouqiang_Timewheel/N-1m-16                       	  720667	      1622 ns/op
+Benchmark_ouqiang_Timewheel/N-5m-16                       	  807018	      1573 ns/op
+Benchmark_ouqiang_Timewheel/N-10m-16                      	  666183	      1557 ns/op
+Benchmark_Stdlib_AddTimer/N-1m-16                         	 8031864	       144 ns/op
+Benchmark_Stdlib_AddTimer/N-5m-16                         	 8437442	       151 ns/op
+Benchmark_Stdlib_AddTimer/N-10m-16                        	 8080659	       167 ns/op
+
+```
+* 压测代码位于
+https://github.com/junelabs/timer-benchmark