SyncOrchestrator: restore the initial sync step (#4242)

* SyncOrchestrator: restore the initial sync step

* Try having internal and public functions to be able to unit test the initial sync and the state changes separately, as well as the initial sync followed by a state change

* Only manually start sync if the `SyncService` was previously stopped, don't do it for `Offline` state

appnav/src/main/kotlin/io/element/android/appnav/di/SyncOrchestrator.kt

@@ -7,6 +7,7 @@
 
 package io.element.android.appnav.di
 
+import androidx.annotation.VisibleForTesting
 import dagger.assisted.Assisted
 import dagger.assisted.AssistedFactory
 import dagger.assisted.AssistedInject
@@ -21,9 +22,9 @@ import kotlinx.coroutines.FlowPreview
 import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.debounce
 import kotlinx.coroutines.flow.distinctUntilChanged
-import kotlinx.coroutines.flow.launchIn
+import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.flow.onCompletion
-import kotlinx.coroutines.flow.onEach
+import kotlinx.coroutines.launch
 import timber.log.Timber
 import java.util.concurrent.atomic.AtomicBoolean
 import kotlin.time.Duration.Companion.milliseconds
@@ -53,13 +54,28 @@ class SyncOrchestrator @AssistedInject constructor(
      *
      * Before observing the state, a first attempt at starting the sync service will happen if it's not already running.
      */
-    @OptIn(FlowPreview::class)
     fun start() {
         if (!started.compareAndSet(false, true)) {
             Timber.tag(tag).d("already started, exiting early")
             return
         }
 
+        coroutineScope.launch {
+            // Perform an initial sync if the sync service is not running, to check whether the homeserver is accessible
+            // Otherwise, if the device is offline the sync service will never start and the SyncState will be Idle, not Offline
+            Timber.tag(tag).d("performing initial sync attempt")
+            syncService.startSync()
+
+            // Wait until the sync service is not idle, either it will be running or in error/offline state
+            syncService.syncState.first { it != SyncState.Idle }
+
+            observeStates()
+        }
+    }
+
+    @OptIn(FlowPreview::class)
+    @VisibleForTesting(otherwise = VisibleForTesting.PRIVATE)
+    internal fun observeStates() = coroutineScope.launch {
         Timber.tag(tag).d("start observing the app and network state")
 
         combine(
@@ -76,7 +92,7 @@ class SyncOrchestrator @AssistedInject constructor(
             Timber.tag(tag).d("isAppActive=$isAppActive, isNetworkAvailable=$isNetworkAvailable")
             if (syncState == SyncState.Running && !isAppActive) {
                 SyncStateAction.StopSync
-            } else if (syncState != SyncState.Running && isAppActive && isNetworkAvailable) {
+            } else if (syncState == SyncState.Idle && isAppActive && isNetworkAvailable) {
                 SyncStateAction.StartSync
             } else {
                 SyncStateAction.NoOp
@@ -87,7 +103,10 @@ class SyncOrchestrator @AssistedInject constructor(
                 // Don't stop the sync immediately, wait a bit to avoid starting/stopping the sync too often
                 if (action == SyncStateAction.StopSync) 3.seconds else 0.seconds
             }
-            .onEach { action ->
+            .onCompletion {
+                Timber.tag(tag).d("has been stopped")
+            }
+            .collect { action ->
                 when (action) {
                     SyncStateAction.StartSync -> {
                         syncService.startSync()
@@ -98,10 +117,6 @@ class SyncOrchestrator @AssistedInject constructor(
                     SyncStateAction.NoOp -> Unit
                 }
             }
-            .onCompletion {
-                Timber.tag(tag).d("has been stopped")
-            }
-            .launchIn(coroutineScope)
     }
 }
 

appnav/src/test/kotlin/io/element/android/appnav/SyncOrchestratorTest.kt

@@ -31,6 +31,50 @@ class SyncOrchestratorTest {
     @get:Rule
     val warmUpRule = WarmUpRule()
 
+    @Test
+    fun `when the sync wasn't running before, an initial sync will take place, even with no network`() = runTest {
+        val startSyncRecorder = lambdaRecorder<Result<Unit>> { Result.success(Unit) }
+        val syncService = FakeSyncService(initialSyncState = SyncState.Idle).apply {
+            startSyncLambda = startSyncRecorder
+        }
+        val networkMonitor = FakeNetworkMonitor(initialStatus = NetworkStatus.Disconnected)
+        val syncOrchestrator = createSyncOrchestrator(
+            syncService = syncService,
+            networkMonitor = networkMonitor,
+        )
+
+        // We start observing with an initial sync
+        syncOrchestrator.start()
+
+        // Advance the time just enough to make sure the initial sync has run
+        advanceTimeBy(1.milliseconds)
+        startSyncRecorder.assertions().isCalledOnce()
+    }
+
+    @Test
+    fun `when the sync wasn't running before, an initial sync will take place`() = runTest {
+        val startSyncRecorder = lambdaRecorder<Result<Unit>> { Result.success(Unit) }
+        val syncService = FakeSyncService(initialSyncState = SyncState.Idle).apply {
+            startSyncLambda = startSyncRecorder
+        }
+        val networkMonitor = FakeNetworkMonitor(initialStatus = NetworkStatus.Connected)
+        val syncOrchestrator = createSyncOrchestrator(
+            syncService = syncService,
+            networkMonitor = networkMonitor,
+        )
+
+        // We start observing with an initial sync
+        syncOrchestrator.start()
+
+        // Advance the time just enough to make sure the initial sync has run
+        advanceTimeBy(1.milliseconds)
+        startSyncRecorder.assertions().isCalledOnce()
+
+        // If we wait for a while, the sync will not be started again by the observer since it's already running
+        advanceTimeBy(10.seconds)
+        startSyncRecorder.assertions().isCalledOnce()
+    }
+
     @Test
     fun `when the app goes to background and the sync was running, it will be stopped after a delay`() = runTest {
         val stopSyncRecorder = lambdaRecorder<Result<Unit>> { Result.success(Unit) }
@@ -46,7 +90,7 @@ class SyncOrchestratorTest {
         )
 
         // We start observing
-        syncOrchestrator.start()
+        syncOrchestrator.observeStates()
 
         // Advance the time to make sure the orchestrator has had time to start processing the inputs
         advanceTimeBy(100.milliseconds)
@@ -78,7 +122,7 @@ class SyncOrchestratorTest {
         )
 
         // We start observing
-        syncOrchestrator.start()
+        syncOrchestrator.observeStates()
 
         // Advance the time to make sure the orchestrator has had time to start processing the inputs
         advanceTimeBy(100.milliseconds)
@@ -126,7 +170,7 @@ class SyncOrchestratorTest {
         )
 
         // We start observing
-        syncOrchestrator.start()
+        syncOrchestrator.observeStates()
 
         // Advance the time to make sure the orchestrator has had time to start processing the inputs
         advanceTimeBy(100.milliseconds)
@@ -169,7 +213,7 @@ class SyncOrchestratorTest {
         )
 
         // We start observing
-        syncOrchestrator.start()
+        syncOrchestrator.observeStates()
 
         // Advance the time to make sure the orchestrator has had time to start processing the inputs
         advanceTimeBy(100.milliseconds)
@@ -213,7 +257,7 @@ class SyncOrchestratorTest {
         )
 
         // We start observing
-        syncOrchestrator.start()
+        syncOrchestrator.observeStates()
 
         // Advance the time to make sure the orchestrator has had time to start processing the inputs
         advanceTimeBy(100.milliseconds)
@@ -256,7 +300,7 @@ class SyncOrchestratorTest {
         )
 
         // We start observing
-        syncOrchestrator.start()
+        syncOrchestrator.observeStates()
 
         // Advance the time to make sure the orchestrator has had time to start processing the inputs
         advanceTimeBy(100.milliseconds)
@@ -285,7 +329,7 @@ class SyncOrchestratorTest {
         )
 
         // We start observing
-        syncOrchestrator.start()
+        syncOrchestrator.observeStates()
 
         // This should still not trigger a sync, since there is no network
         advanceTimeBy(10.seconds)