add stop() api to BackupManager for clean shutdown (#3553)

src/crypto/backup.ts

@@ -118,12 +118,21 @@ export class BackupManager {
     public checkedForBackup: boolean; // Have we checked the server for a backup we can use?
     private sendingBackups: boolean; // Are we currently sending backups?
     private sessionLastCheckAttemptedTime: Record<string, number> = {}; // When did we last try to check the server for a given session id?
+    // The backup manager will schedule backup of keys when active (`scheduleKeyBackupSend`), this allows cancel when client is stopped
+    private clientRunning = true;
 
     public constructor(private readonly baseApis: MatrixClient, public readonly getKey: GetKey) {
         this.checkedForBackup = false;
         this.sendingBackups = false;
     }
 
+    /**
+     * Stop the backup manager from backing up keys and allow a clean shutdown.
+     */
+    public stop(): void {
+        this.clientRunning = false;
+    }
+
     public get version(): string | undefined {
         return this.backupInfo && this.backupInfo.version;
     }
@@ -439,6 +448,10 @@ export class BackupManager {
             // the same time when a new key is sent
             const delay = Math.random() * maxDelay;
             await sleep(delay);
+            if (!this.clientRunning) {
+                logger.debug("Key backup send aborted, client stopped");
+                return;
+            }
             let numFailures = 0; // number of consecutive failures
             for (;;) {
                 if (!this.algorithm) {
@@ -473,6 +486,11 @@ export class BackupManager {
                     // exponential backoff if we have failures
                     await sleep(1000 * Math.pow(2, Math.min(numFailures - 1, 4)));
                 }
+
+                if (!this.clientRunning) {
+                    logger.debug("Key backup send loop aborted, client stopped");
+                    return;
+                }
             }
         } finally {
             this.sendingBackups = false;

src/crypto/index.ts

@@ -1832,6 +1832,7 @@ export class Crypto extends TypedEventEmitter<CryptoEvent, CryptoEventHandlerMap
         this.outgoingRoomKeyRequestManager.stop();
         this.deviceList.stop();
         this.dehydrationManager.stop();
+        this.backupManager.stop();
     }
 
     /**