Sync

Entry point for initializing background data synchronization using WorkManager.

This object provides a simple API to start the background sync process that keeps local data synchronized with remote Firebase Firestore. The sync runs automatically when the app starts and can be triggered on-demand through SyncManager.

Sync Architecture

• WorkManager: Handles background execution with constraints (network connectivity)

• SyncWorker: Performs the actual sync logic (pull from Firestore, push to Firestore)

• Foreground Service: Shows sync progress notification to the user

• Exponential Backoff: Retries failed syncs up to 3 times with increasing delays

Initialization

Call initialize once from your Application's onCreate():

class MyApplication : Application() {
    override fun onCreate() {
        super.onCreate()
        Sync.initialize(this)
    }
}

Sync Triggers

1. App Startup: Automatically when initialize is called

2. On-Demand: Via SyncManager.requestSync

3. Periodic: Can be configured with WorkManager's PeriodicWorkRequest (not implemented by default)

Work Policy

Uses ExistingWorkPolicy.KEEP which means:

• If sync is already running, new requests are ignored

• If sync is pending, it won't be replaced

• Only one sync runs at a time to prevent conflicts

Constraints

The sync worker only runs when:

• Network is available (CONNECTED)

• Battery is not critically low (handled by WorkManager)

Observing Sync State

Use SyncManager to observe when sync is running:

@HiltViewModel
class HomeViewModel @Inject constructor(
    private val syncManager: SyncManager
) : ViewModel() {
    val isSyncing: StateFlow<Boolean> = syncManager.isSyncing
        .stateIn(viewModelScope, SharingStarted.WhileSubscribed(5000), false)
}

See also