add WithOnHitCache examples

examples/options/main.go

@@ -0,0 +1,38 @@
+package main
+
+import (
+	"fmt"
+	cache "github.com/chenyahui/gin-cache"
+	"github.com/chenyahui/gin-cache/persist"
+	"github.com/gin-gonic/gin"
+	"sync/atomic"
+	"time"
+)
+
+func main() {
+	app := gin.New()
+
+	memoryStore := persist.NewMemoryStore(1 * time.Minute)
+
+	var cacheHitCount int32
+	app.GET("/hello",
+		cache.CacheByRequestURI(
+			memoryStore,
+			2*time.Second,
+			cache.WithOnHitCache(func(c *gin.Context) {
+				atomic.AddInt32(&cacheHitCount, 1)
+			}),
+		),
+		func(c *gin.Context) {
+			c.String(200, "hello world")
+		},
+	)
+
+	app.GET("/get_hit_count", func(c *gin.Context) {
+		c.String(200, fmt.Sprintf("total hit count: %d", cacheHitCount))
+	})
+
+	if err := app.Run(":8080"); err != nil {
+		panic(err)
+	}
+}