fix(GODT-2822): retry 429 for metadata and exponential cooldown GODT-2823.

internal/user/cooldown.go

@@ -0,0 +1,62 @@
+// Copyright (c) 2023 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+package user
+
+import (
+	"math/rand"
+	"time"
+)
+
+const SyncRetryCooldown = 20 * time.Second
+
+type cooldownProvider interface {
+	GetNextWaitTime() time.Duration
+}
+
+func jitter(max int) time.Duration {
+	return time.Duration(rand.Intn(max)) * time.Second //nolint:gosec
+}
+
+type expCooldown struct {
+	count int
+}
+
+func (c *expCooldown) GetNextWaitTime() time.Duration {
+	waitTimes := []time.Duration{
+		20 * time.Second,
+		40 * time.Second,
+		80 * time.Second,
+		160 * time.Second,
+		300 * time.Second,
+		600 * time.Second,
+	}
+
+	last := len(waitTimes) - 1
+
+	if c.count >= last {
+		return waitTimes[last] + jitter(10)
+	}
+
+	c.count++
+
+	return waitTimes[c.count-1] + jitter(10)
+}
+
+type noCooldown struct{}
+
+func (c *noCooldown) GetNextWaitTime() time.Duration { return time.Millisecond }