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max_requests.go
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/
max_requests.go
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// Copyright 2018 xgfone
//
// 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 middleware
import (
"net/http"
"sync/atomic"
"github.com/xgfone/ship/v2"
)
// MaxRequests returns a Middleware to allow the maximum number of the requests
// to max at a time.
//
// If the number of the requests exceeds the maximum, it will call the handler,
// which return the status code 429. But you can appoint yourself handler.
func MaxRequests(max uint32, handler ...ship.Handler) Middleware {
h := func(c *ship.Context) error { return c.NoContent(http.StatusTooManyRequests) }
if len(handler) > 0 && handler[0] != nil {
h = handler[0]
}
var maxNum = int32(max)
var current int32
return func(next ship.Handler) ship.Handler {
return func(ctx *ship.Context) error {
atomic.AddInt32(¤t, 1)
defer atomic.AddInt32(¤t, -1)
if atomic.LoadInt32(¤t) > maxNum {
return h(ctx)
}
return next(ctx)
}
}
}