Add prototype to support SkipList keys

limiter.go

@@ -22,9 +22,10 @@ type Context struct {
 
 // Limiter is the limiter instance.
 type Limiter struct {
-	Store   Store
-	Rate    Rate
-	Options Options
+	Store    Store
+	Rate     Rate
+	Options  Options
+	SkipList SkipList
 }
 
 // New returns an instance of Limiter.
@@ -37,15 +38,22 @@ func New(store Store, rate Rate, options ...Option) *Limiter {
 	for _, o := range options {
 		o(&opt)
 	}
+	whiteList := SkipList{
+		Keys: opt.SkipList,
+	}
 	return &Limiter{
-		Store:   store,
-		Rate:    rate,
-		Options: opt,
+		Store:    store,
+		Rate:     rate,
+		Options:  opt,
+		SkipList: whiteList,
 	}
 }
 
 // Get returns the limit for given identifier.
 func (limiter *Limiter) Get(ctx context.Context, key string) (Context, error) {
+	if limiter.SkipList.HasKey(key) {
+		return Context{}, nil
+	}
 	return limiter.Store.Get(ctx, key, limiter.Rate)
 }
 

options.go

@@ -24,6 +24,9 @@ type Options struct {
 	// proxy is not configured properly to forward a trustworthy client IP.
 	// Please read the section "Limiter behind a reverse proxy" in the README for further information.
 	ClientIPHeader string
+
+	// SkipList represents list of keys which will be skipped by limiter
+	SkipList []string
 }
 
 // WithIPv4Mask will configure the limiter to use given mask for IPv4 address.
@@ -59,3 +62,13 @@ func WithClientIPHeader(header string) Option {
 		o.ClientIPHeader = header
 	}
 }
+
+// WithSkipList will configure the limiter to use list of provided
+// exception keys (which may be IP addresses or custome header values).
+// This list will be consulted at every request and if key will be found in
+// SkipList the limiter functionality will be skipped for that key.
+func WithSkipList(wlist []string) Option {
+	return func(o *Options) {
+		o.SkipList = wlist
+	}
+}

whitelist.go

@@ -0,0 +1,16 @@
+package limiter
+
+// SkipList represent white list of keys
+type SkipList struct {
+	Keys []string
+}
+
+// HasKey implements basic look-up of given key in SkipList
+func (w *SkipList) HasKey(key string) bool {
+	for _, k := range w.Keys {
+		if k == key {
+			return true
+		}
+	}
+	return false
+}