We build too many walls and not enough bridges

internal/store/store_structure_version.go

@@ -0,0 +1,68 @@
+// Copyright (c) 2020 Proton Technologies AG
+//
+// This file is part of ProtonMail Bridge.
+//
+// ProtonMail 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.
+//
+// ProtonMail 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 ProtonMail Bridge.  If not, see <https://www.gnu.org/licenses/>.
+
+package store
+
+import bolt "go.etcd.io/bbolt"
+
+const (
+	versionKey = "version"
+
+	// versionOffset makes it possible to force email client to reload all
+	// mailboxes. If increased during application update it will trigger
+	// the reload on client side without needing to sync DB or re-setup account.
+	versionOffset = uint32(3)
+)
+
+func (store *Store) getMailboxesVersion() uint32 {
+	localVersion := store.readMailboxesVersion()
+	// If a read error occurs it returns 0 which is an invalid version value.
+	if localVersion == 0 {
+		localVersion = 1
+		_ = store.writeMailboxesVersion(localVersion)
+	}
+
+	// versionOffset will make email clients reload if increased during bridge update.
+	return localVersion + versionOffset
+}
+
+func (store *Store) increaseMailboxesVersion() error {
+	ver := store.readMailboxesVersion()
+	// The version is zero if a read error occurred. Operation ++ will make it 1
+	// which is default starting value.
+	ver++
+	return store.writeMailboxesVersion(ver)
+}
+
+func (store *Store) readMailboxesVersion() (version uint32) {
+	_ = store.db.View(func(tx *bolt.Tx) (err error) {
+		b := tx.Bucket(mboxVersionBucket)
+		verRaw := b.Get([]byte(versionKey))
+		if verRaw != nil {
+			version = btoi(verRaw)
+		}
+		return nil
+	})
+	return
+}
+
+func (store *Store) writeMailboxesVersion(ver uint32) error {
+	return store.db.Update(func(tx *bolt.Tx) (err error) {
+		b := tx.Bucket(mboxVersionBucket)
+		return b.Put([]byte(versionKey), itob(ver))
+	})
+}