feat: add bandwidth limit example

middleware/bandwidth/README.md

@@ -0,0 +1,7 @@
+## How to run
+* start basicauth middleware server  
+`go run middleware/bandwidth/main.go`
+* use your browser to access "http://127.0.0.1:8080/rateLimit"
+## How to test
+* start unit_test
+`go test ./middleware/bandwidth`

middleware/bandwidth/bandwidth_test.go

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2022 CloudWeGo Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package main
+
+import (
+	"context"
+	"io/ioutil"
+	"net/http"
+	"testing"
+	"time"
+
+	"github.com/cloudwego/hertz/pkg/app"
+	"github.com/cloudwego/hertz/pkg/app/server"
+	"github.com/cloudwego/hertz/pkg/protocol/consts"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestRateLimitMiddleware(t *testing.T) {
+	h := server.Default(server.WithHostPorts("127.0.0.1:8888"))
+	h.Use(rateLimitMiddleware(100)) // set rate limit to 100KB/s
+
+	h.GET("/rateLimit", func(ctx context.Context, c *app.RequestContext) {
+		// Simulate a large response
+		data := make([]byte, 200*1024) // 200KB of data
+		c.Data(consts.StatusOK, "application/octet-stream", data)
+	})
+
+	go h.Spin()
+
+	time.Sleep(1 * time.Second) // Wait for the server to start
+
+	startTime := time.Now()
+	resp, err := http.Get("http://127.0.0.1:8888/rateLimit")
+	assert.NoError(t, err)
+	defer resp.Body.Close()
+
+	_, err = ioutil.ReadAll(resp.Body)
+	assert.NoError(t, err)
+
+	elapsedTime := time.Since(startTime)
+	expectedTime := 2 * time.Second // 200KB at 100KB/s should take 2 seconds
+
+	assert.GreaterOrEqual(t, elapsedTime, expectedTime, "Response time should be at least 2 seconds")
+}

middleware/bandwidth/main.go

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2022 CloudWeGo Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package main
+
+import (
+	"context"
+	"time"
+
+	"github.com/cloudwego/hertz/pkg/app"
+	"github.com/cloudwego/hertz/pkg/app/server"
+	"github.com/cloudwego/hertz/pkg/protocol/consts"
+)
+
+func rateLimitMiddleware(rateLimitKBps int) app.HandlerFunc {
+	bytesPerSecond := rateLimitKBps * 1024
+	return func(ctx context.Context, c *app.RequestContext) {
+		startTime := time.Now()
+		c.Next(ctx)
+		elapsedTime := time.Since(startTime)
+		expectedTime := time.Duration(len(c.Response.Body()) * int(time.Second) / bytesPerSecond)
+		if elapsedTime < expectedTime {
+			time.Sleep(expectedTime - elapsedTime)
+		}
+	}
+}
+
+func main() {
+	h := server.Default(server.WithHostPorts("127.0.0.1:8888"))
+	h.Use(rateLimitMiddleware(100)) // set rate limit to 100KB/s
+
+	h.GET("/rateLimit", func(ctx context.Context, c *app.RequestContext) {
+		c.String(consts.StatusOK, "hello hertz")
+	})
+
+	h.Spin()
+}