vendor

vendor/github.com/google/certificate-transparency-go/jsonclient/backoff.go

@@ -0,0 +1,72 @@
+// Copyright 2017 Google Inc. All Rights Reserved.
+//
+// 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 jsonclient
+
+import (
+	"sync"
+	"time"
+)
+
+type backoff struct {
+	mu         sync.RWMutex
+	multiplier uint
+	notBefore  time.Time
+}
+
+const (
+	// maximum backoff is 2^(maxMultiplier-1) = 128 seconds
+	maxMultiplier = 8
+)
+
+func (b *backoff) set(override *time.Duration) time.Duration {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	if b.notBefore.After(time.Now()) {
+		if override != nil {
+			// If existing backoff is set but override would be longer than
+			// it then set it to that.
+			notBefore := time.Now().Add(*override)
+			if notBefore.After(b.notBefore) {
+				b.notBefore = notBefore
+			}
+		}
+		return time.Until(b.notBefore)
+	}
+	var wait time.Duration
+	if override != nil {
+		wait = *override
+	} else {
+		if b.multiplier < maxMultiplier {
+			b.multiplier++
+		}
+		wait = time.Second * time.Duration(1<<(b.multiplier-1))
+	}
+	b.notBefore = time.Now().Add(wait)
+	return wait
+}
+
+func (b *backoff) decreaseMultiplier() {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	if b.multiplier > 0 {
+		b.multiplier--
+	}
+}
+
+func (b *backoff) until() time.Time {
+	b.mu.RLock()
+	defer b.mu.RUnlock()
+	return b.notBefore
+}