config: Add api requests max & deadline configs (#9273)

Add two new configuration entries, api.requests-max and
api.requests-deadline which have the same role of
MINIO_API_REQUESTS_MAX and MINIO_API_REQUESTS_DEADLINE.

cmd/handler-utils.go

@@ -28,7 +28,6 @@ import (
 	"net/url"
 	"regexp"
 	"strings"
-	"time"
 
 	xhttp "github.com/minio/minio/cmd/http"
 	"github.com/minio/minio/cmd/logger"
@@ -359,31 +358,6 @@ func httpTraceHdrs(f http.HandlerFunc) http.HandlerFunc {
 	}
 }
 
-// maxClients throttles the S3 API calls
-func maxClients(f http.HandlerFunc, enabled bool, requestsMaxCh chan struct{}, requestsDeadline time.Duration) http.HandlerFunc {
-	return func(w http.ResponseWriter, r *http.Request) {
-		if !enabled {
-			f.ServeHTTP(w, r)
-			return
-		}
-
-		select {
-		case requestsMaxCh <- struct{}{}:
-			defer func() { <-requestsMaxCh }()
-			f.ServeHTTP(w, r)
-		case <-time.NewTimer(requestsDeadline).C:
-
-			// Send a http timeout message
-			writeErrorResponse(r.Context(), w,
-				errorCodes.ToAPIErr(ErrOperationMaxedOut),
-				r.URL, guessIsBrowserReq(r))
-			return
-		case <-r.Context().Done():
-			return
-		}
-	}
-}
-
 func collectAPIStats(api string, f http.HandlerFunc) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {