rate_limit.go

/*
Copyright Medcl (m AT medcl.net)

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 filter

import (
	"fmt"
	"github.com/huminghe/infini-framework/core/api/router"
	"io"
	"net/http"
	"sync"
	"time"
)

type RateLimitFilter struct {
	Interval time.Duration
	MaxCount int
	Lock     sync.Mutex
	ReqCount int
}

func NewRequestLimitService(interval time.Duration, maxCnt int) *RateLimitFilter {
	reqLimit := &RateLimitFilter{
		Interval: interval,
		MaxCount: maxCnt,
	}

	go func() {
		ticker := time.NewTicker(interval)
		for {
			<-ticker.C
			reqLimit.Lock.Lock()
			reqLimit.ReqCount = 0
			reqLimit.Lock.Unlock()
		}
	}()

	return reqLimit
}

func (filter *RateLimitFilter) Increase() {
	filter.Lock.Lock()
	defer filter.Lock.Unlock()

	filter.ReqCount += 1
}

func (filter *RateLimitFilter) IsAvailable() bool {
	filter.Lock.Lock()
	defer filter.Lock.Unlock()

	return filter.ReqCount < filter.MaxCount
}

var RequestLimit = NewRequestLimitService(10*time.Second, 5)

func (filter RateLimitFilter) FilterHttpRouter(pattern string, h httprouter.Handle) httprouter.Handle {

	Counter.Increase()

	if RequestLimit.IsAvailable() {
		RequestLimit.Increase()
		return h

	} else {
		return func(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
			fmt.Println("Reach request limiting!")
			io.WriteString(w, "Reach request limit!\n")
		}
	}

}

func (filter RateLimitFilter) FilterHttpHandlerFunc(pattern string, handler func(http.ResponseWriter, *http.Request)) func(http.ResponseWriter, *http.Request) {

	Counter.Increase()

	return func(w http.ResponseWriter, r *http.Request) {
		if RequestLimit.IsAvailable() {
			RequestLimit.Increase()
			handler(w, r)
		} else {
			fmt.Println("Reach request limiting!")
			io.WriteString(w, "Reach request limit!\n")
		}
	}

}