Add rate limiter instead of connection limit for now

pkg/api/quota/conn_limit.go

@@ -16,74 +16,35 @@
 
 package quota
 
-import (
-	"net"
-	"net/http"
-	"sync"
-
-	"github.com/minio/minio/pkg/utils/log"
-)
+import "net/http"
 
 // requestLimitHandler
 type connLimit struct {
-	sync.RWMutex
-	handler     http.Handler
-	connections map[uint32]int
-	limit       int
+	handler         http.Handler
+	connectionQueue chan bool
 }
 
-func (c *connLimit) IsLimitExceeded(ip uint32) bool {
-	if c.connections[ip] >= c.limit {
-		return true
-	}
-	return false
-}
-
-func (c *connLimit) GetUsed(ip uint32) int {
-	return c.connections[ip]
-}
-
-func (c *connLimit) Add(ip uint32) {
-	c.Lock()
-	defer c.Unlock()
-	count := c.connections[ip]
-	count = count + 1
-	c.connections[ip] = count
+func (c *connLimit) Add() {
+	c.connectionQueue <- true
 	return
 }
 
-func (c *connLimit) Remove(ip uint32) {
-	c.Lock()
-	defer c.Unlock()
-	count, _ := c.connections[ip]
-	count = count - 1
-	if count <= 0 {
-		delete(c.connections, ip)
-		return
-	}
-	c.connections[ip] = count
+func (c *connLimit) Remove() {
+	<-c.connectionQueue
+	return
 }
 
 // ServeHTTP is an http.Handler ServeHTTP method
 func (c *connLimit) ServeHTTP(w http.ResponseWriter, req *http.Request) {
-	host, _, _ := net.SplitHostPort(req.RemoteAddr)
-	longIP := longIP{net.ParseIP(host)}.IptoUint32()
-	if c.IsLimitExceeded(longIP) {
-		hosts, _ := net.LookupAddr(uint32ToIP(longIP).String())
-		log.Debug.Printf("Connection limit reached - Host: %s, Total Connections: %d\n", hosts, c.GetUsed(longIP))
-		writeErrorResponse(w, req, ConnectionLimitExceeded, req.URL.Path)
-		return
-	}
-	c.Add(longIP)
-	defer c.Remove(longIP)
+	c.Add()
 	c.handler.ServeHTTP(w, req)
+	c.Remove()
 }
 
 // ConnectionLimit limits the number of concurrent connections
 func ConnectionLimit(h http.Handler, limit int) http.Handler {
 	return &connLimit{
-		handler:     h,
-		connections: make(map[uint32]int),
-		limit:       limit,
+		handler:         h,
+		connectionQueue: make(chan bool, limit),
 	}
 }

pkg/api/quota/rate_limiter.go

@@ -0,0 +1,50 @@
+/*
+ * Minimalist Object Storage, (C) 2015 Minio, Inc.
+ *
+ * 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 quota
+
+import "net/http"
+
+// rateLimit
+type rateLimit struct {
+	handler   http.Handler
+	rateQueue chan bool
+}
+
+func (c *rateLimit) Add() {
+	c.rateQueue <- true // fill in the queue
+	return
+}
+
+func (c *rateLimit) Remove() {
+	<-c.rateQueue // invalidate the queue, after the request is served
+	return
+}
+
+// ServeHTTP is an http.Handler ServeHTTP method
+func (c *rateLimit) ServeHTTP(w http.ResponseWriter, req *http.Request) {
+	c.Add()                     // add
+	c.handler.ServeHTTP(w, req) // serve
+	c.Remove()                  // remove
+}
+
+// RateLimit limits the number of concurrent http requests
+func RateLimit(handle http.Handler, limit int) http.Handler {
+	return &rateLimit{
+		handler:   handle,
+		rateQueue: make(chan bool, limit),
+	}
+}