1 files changed, 54 insertions, 0 deletions
diff --git a/modules/ratelimit/ratelimit.go b/modules/ratelimit/ratelimit.go
new file mode 100644
index 0000000..b02f5d5
--- /dev/null
+++ b/modules/ratelimit/ratelimit.go
@@ -0,0 +1,54 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package ratelimit
+
+import (
+	"time"
+
+	"github.com/philippta/flyscrape"
+)
+
+func init() {
+	flyscrape.RegisterModule(new(Module))
+}
+
+type Module struct {
+	Rate float64 `json:"rate"`
+
+	ticker    *time.Ticker
+	semaphore chan struct{}
+}
+
+func (m *Module) ID() string {
+	return "ratelimit"
+}
+
+func (m *Module) OnLoad(v flyscrape.Visitor) {
+	rate := time.Duration(float64(time.Second) / m.Rate)
+
+	m.ticker = time.NewTicker(rate)
+	m.semaphore = make(chan struct{}, 1)
+
+	go func() {
+		for range m.ticker.C {
+			m.semaphore <- struct{}{}
+		}
+	}()
+}
+
+func (m *Module) OnRequest(_ *flyscrape.Request) {
+	<-m.semaphore
+}
+
+func (m *Module) OnComplete() {
+	m.ticker.Stop()
+}
+
+var (
+	_ flyscrape.Module     = (*Module)(nil)
+	_ flyscrape.OnRequest  = (*Module)(nil)
+	_ flyscrape.OnLoad     = (*Module)(nil)
+	_ flyscrape.OnComplete = (*Module)(nil)
+)