GODT-1840: Safe map for mailboxID cache

internal/imap/map.go

@@ -0,0 +1,44 @@
+// Copyright (c) 2022 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 imap
+
+import "sync"
+
+type safeMapOfStrings struct {
+	data  map[string]string
+	mutex sync.RWMutex
+}
+
+func newSafeMapOfString() safeMapOfStrings {
+	return safeMapOfStrings{
+		data:  map[string]string{},
+		mutex: sync.RWMutex{},
+	}
+}
+
+func (m *safeMapOfStrings) get(key string) string {
+	m.mutex.RLock()
+	defer m.mutex.RUnlock()
+	return m.data[key]
+}
+
+func (m *safeMapOfStrings) set(key, value string) {
+	m.mutex.Lock()
+	defer m.mutex.Unlock()
+	m.data[key] = value
+}

internal/imap/updates.go

@@ -235,7 +235,7 @@ func (iu *imapUpdates) getIDs(address, mailboxName string) (addressID, mailboxID
 	}
 	addressID = user.addressID
 
-	if v := user.mailboxIDs[mailboxName]; v != "" {
+	if v := user.mailboxIDs.get(mailboxName); v != "" {
 		mailboxID = v
 	}
 

internal/imap/user.go

@@ -54,8 +54,8 @@ type imapUser struct {
 	// UNSELECT, CLOSE, or LOGOUT.
 	appendExpungeLock sync.Mutex
 
-	addressID  string            // cached value for logs to avoid lock
-	mailboxIDs map[string]string // cached values for logs to avoid lock
+	addressID  string           // cached value for logs to avoid lock
+	mailboxIDs safeMapOfStrings // cached values for logs to avoid lock
 }
 
 // newIMAPUser returns struct implementing go-imap/user interface.
@@ -88,7 +88,7 @@ func newIMAPUser(
 
 		currentAddressLowercase: strings.ToLower(address),
 		addressID:               addressID,
-		mailboxIDs:              map[string]string{},
+		mailboxIDs:              newSafeMapOfString(),
 	}, err
 }
 
@@ -133,7 +133,7 @@ func (iu *imapUser) ListMailboxes(showOnlySubcribed bool) ([]goIMAPBackend.Mailb
 
 	mailboxes := []goIMAPBackend.Mailbox{}
 	for _, storeMailbox := range iu.storeAddress.ListMailboxes() {
-		iu.mailboxIDs[storeMailbox.Name()] = storeMailbox.LabelID()
+		iu.mailboxIDs.set(storeMailbox.Name(), storeMailbox.LabelID())
 
 		if storeMailbox.LabelID() == pmapi.AllMailLabel && !iu.backend.bridge.IsAllMailVisible() {
 			continue