Android BackupAgent never called

Question

I am trying to implement a custom backupAgentHelper to backup my app's database file. I've gone through the docs several times but whenever I try to force backup, the backupAgentHelper on Create/onBackup/onRestore are never called.

Manifest has the following under application:

android:allowBackup="true"
android:backupAgent="myBackupHelper"
android:restoreAnyVersion="true"

and metadata

    <meta-data 
        android:name="com.google.android.backup.api_key"
        android:value="<my-api-key>" />

myBackupHelper:

public class myBackupHelper extends BackupAgentHelper{

public static String DATABASE_NAME = "db.dat";

@Override
public void onCreate(){
    log.d("Backup oncreate called");
    FileBackupHelper hosts = new FileBackupHelper(this, this.getExternalFilesDir(DATABASE_NAME).getAbsolutePath());
    addHelper(DATABASE_NAME,hosts);
}

@Override
public void onBackup(ParcelFileDescriptor oldState, BackupDataOutput data, ParcelFileDescriptor newState) {
    log.d("backup onbackup called");
    try {
        //class is the lock since we are using static synchronized methods to read/write
        synchronized (DBManager.class) {
            super.onBackup(oldState, data, newState);
            log.d("Backedup");
        }
    } catch (IOException e) {
        log.d("Backup error, Unable to write to file: " + e);
    }
}

@Override
public void onRestore(BackupDataInput data, int appVersionCode, ParcelFileDescriptor newState){
    log.d("Backup onrestore called");
    try {
        //class is the lock since we are using static synchronized methods to read/write
        synchronized (DBManager.class) {
            super.onRestore(data, appVersionCode, newState);
        }
    } catch (IOException e) {
        log.d("Backup error, Unable to read from file: " + e);
    }
}

I initialize the BackupManager in the mainactivity as follows:

BackupManager bm = new BackupManager(getApplicationContext());

and call bm.dataChanged(); when the database changes.

In testing, I use adb to force backup:

./adb shell bmgr backup com.test.android.backuptest
./adb shell bmgr run

but the logs are never hit and when i reinstall, data is never restored.

Note: backup and restore settings are enabled and the device has over the required api 8 so I have no idea why its not being hit!

Answer 1

The reason why my backupAgentHelper functions were never called is because of the transport being used. Doing

./adb shell bmgr list transports

showed

android/com.android.internal.backup.LocalTransport
*com.google.android.gms/.backup.BackupTransportService

For some reason the goodle transportservice wasn't working but changing it to the internal localtransport with

./adb shell bmgr transport android/com.android.internal.backup.LocalTransport

fixed my problem and now logs are showing up.