Improve file oprations coroutines

app/src/main/java/sushi/hardcore/droidfs/MainActivity.kt

@@ -24,6 +24,7 @@ import sushi.hardcore.droidfs.databinding.ActivityMainBinding
 import sushi.hardcore.droidfs.databinding.DialogDeleteVolumeBinding
 import sushi.hardcore.droidfs.explorers.ExplorerRouter
 import sushi.hardcore.droidfs.file_operations.FileOperationService
+import sushi.hardcore.droidfs.file_operations.TaskResult
 import sushi.hardcore.droidfs.util.IntentUtils
 import sushi.hardcore.droidfs.util.PathUtils
 import sushi.hardcore.droidfs.widgets.CustomAlertDialogBuilder
@@ -418,11 +419,11 @@ class MainActivity : BaseActivity(), VolumeAdapter.Listener {
     private fun copyVolume(srcDocumentFile: DocumentFile, dstDocumentFile: DocumentFile, getResultVolume: (DocumentFile) -> VolumeData?) {
         lifecycleScope.launch {
             val result = fileOperationService.copyVolume(srcDocumentFile, dstDocumentFile)
-            when {
+            when (result.taskResult.state) {
-                result.taskResult.cancelled -> {
+                TaskResult.State.CANCELLED -> {
                     result.dstRootDirectory?.delete()
                 }
-                result.taskResult.failedItem == null -> {
+                TaskResult.State.SUCCESS -> {
                     result.dstRootDirectory?.let {
                         getResultVolume(it)?.let { volume ->
                             volumeDatabase.saveVolume(volume)
@@ -435,13 +436,14 @@ class MainActivity : BaseActivity(), VolumeAdapter.Listener {
                         }
                     }
                 }
-                else -> {
+                TaskResult.State.FAILED -> {
                     CustomAlertDialogBuilder(this@MainActivity, theme)
                         .setTitle(R.string.error)
-                        .setMessage(getString(R.string.copy_failed, result.taskResult.failedItem.name))
+                        .setMessage(getString(R.string.copy_failed, result.taskResult.failedItem!!.name))
                         .setPositiveButton(R.string.ok, null)
                         .show()
                 }
+                TaskResult.State.ERROR -> result.taskResult.showErrorAlertDialog(this@MainActivity, theme)
             }
         }
     }

app/src/main/java/sushi/hardcore/droidfs/VolumeManager.kt

@@ -1,11 +1,16 @@
 package sushi.hardcore.droidfs
 
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.SupervisorJob
+import kotlinx.coroutines.cancel
 import sushi.hardcore.droidfs.filesystems.EncryptedVolume
 
 class VolumeManager {
     private var id = 0
     private val volumes = HashMap<Int, EncryptedVolume>()
     private val volumesData = HashMap<VolumeData, Int>()
+    private val scopes = HashMap<Int, CoroutineScope>()
 
     fun insert(volume: EncryptedVolume, data: VolumeData): Int {
         volumes[id] = volume
@@ -25,8 +30,13 @@ class VolumeManager {
         return volumes[id]
     }
 
+    fun getCoroutineScope(volumeId: Int): CoroutineScope {
+        return scopes[volumeId] ?: CoroutineScope(SupervisorJob() + Dispatchers.IO).also { scopes[volumeId] = it }
+    }
+
     fun closeVolume(id: Int) {
         volumes.remove(id)?.let { volume ->
+            scopes[id]?.cancel()
             volume.close()
             volumesData.filter { it.value == id }.forEach {
                 volumesData.remove(it.key)
@@ -35,7 +45,10 @@ class VolumeManager {
     }
 
     fun closeAll() {
-        volumes.forEach { it.value.close() }
+        volumes.forEach {
+            scopes[it.key]?.cancel()
+            it.value.close()
+        }
         volumes.clear()
         volumesData.clear()
     }

app/src/main/java/sushi/hardcore/droidfs/explorers/BaseExplorerActivity.kt

@@ -29,6 +29,7 @@ import sushi.hardcore.droidfs.adapters.OpenAsDialogAdapter
 import sushi.hardcore.droidfs.content_providers.ExternalProvider
 import sushi.hardcore.droidfs.file_operations.FileOperationService
 import sushi.hardcore.droidfs.file_operations.OperationFile
+import sushi.hardcore.droidfs.file_operations.TaskResult
 import sushi.hardcore.droidfs.file_viewers.*
 import sushi.hardcore.droidfs.filesystems.EncryptedVolume
 import sushi.hardcore.droidfs.filesystems.Stat
@@ -42,7 +43,7 @@ open class BaseExplorerActivity : BaseActivity(), ExplorerElementAdapter.Listene
     private var foldersFirst = true
     private var mapFolders = true
     private var currentSortOrderIndex = 0
-    private var volumeId = -1
+    protected var volumeId = -1
     protected lateinit var encryptedVolume: EncryptedVolume
     private lateinit var volumeName: String
     private lateinit var explorerViewModel: ExplorerViewModel
@@ -52,7 +53,7 @@ open class BaseExplorerActivity : BaseActivity(), ExplorerElementAdapter.Listene
             explorerViewModel.currentDirectoryPath = value
         }
     protected lateinit var fileOperationService: FileOperationService
-    protected val taskScope = CoroutineScope(SupervisorJob() + Dispatchers.Main.immediate)
+    protected val activityScope = MainScope()
     protected lateinit var explorerElements: MutableList<ExplorerElement>
     protected lateinit var explorerAdapter: ExplorerElementAdapter
     protected lateinit var app: VolumeManagerApp
@@ -171,11 +172,8 @@ open class BaseExplorerActivity : BaseActivity(), ExplorerElementAdapter.Listene
                 override fun onServiceConnected(className: ComponentName, service: IBinder) {
                     val binder = service as FileOperationService.LocalBinder
                     fileOperationService = binder.getService()
-                    binder.setEncryptedVolume(encryptedVolume)
-                }
-                override fun onServiceDisconnected(arg0: ComponentName) {
-
                 }
+                override fun onServiceDisconnected(arg0: ComponentName) {}
             }, Context.BIND_AUTO_CREATE)
         }
     }
@@ -439,7 +437,33 @@ open class BaseExplorerActivity : BaseActivity(), ExplorerElementAdapter.Listene
         }
     }
 
-    protected fun importFilesFromUris(uris: List<Uri>, callback: (String?) -> Unit) {
+    protected fun onTaskResult(
+        result: TaskResult<out String?>,
+        failedErrorMessage: Int,
+        successMessage: Int = -1,
+        onSuccess: (() -> Unit)? = null,
+    ) {
+        when (result.state) {
+            TaskResult.State.SUCCESS -> {
+                if (onSuccess == null) {
+                    Toast.makeText(this, successMessage, Toast.LENGTH_SHORT).show()
+                } else {
+                    onSuccess()
+                }
+            }
+            TaskResult.State.FAILED -> {
+                CustomAlertDialogBuilder(this, theme)
+                    .setTitle(R.string.error)
+                    .setMessage(getString(failedErrorMessage, result.failedItem))
+                    .setPositiveButton(R.string.ok, null)
+                    .show()
+            }
+            TaskResult.State.ERROR -> result.showErrorAlertDialog(this, theme)
+            TaskResult.State.CANCELLED -> {}
+        }
+    }
+
+    protected fun importFilesFromUris(uris: List<Uri>, callback: () -> Unit) {
         val items = ArrayList<OperationFile>()
         for (uri in uris) {
             val fileName = PathUtils.getFilenameFromURI(this, uri)
@@ -458,13 +482,10 @@ open class BaseExplorerActivity : BaseActivity(), ExplorerElementAdapter.Listene
         if (items.size > 0) {
             checkPathOverwrite(items, currentDirectoryPath) { checkedItems ->
                 checkedItems?.let {
-                    taskScope.launch {
+                    activityScope.launch {
-                        val taskResult = fileOperationService.importFilesFromUris(checkedItems.map { it.dstPath!! }, uris)
+                        val result = fileOperationService.importFilesFromUris(volumeId, checkedItems.map { it.dstPath!! }, uris)
-                        if (taskResult.cancelled) {
+                        onTaskResult(result, R.string.import_failed, onSuccess = callback)
                         setCurrentPath(currentDirectoryPath)
-                        } else {
-                            callback(taskResult.failedItem)
-                        }
                     }
                 }
             }
@@ -589,7 +610,7 @@ open class BaseExplorerActivity : BaseActivity(), ExplorerElementAdapter.Listene
     override fun onDestroy() {
         super.onDestroy()
         if (!isChangingConfigurations) { //activity won't be recreated
-            taskScope.cancel()
+            activityScope.cancel()
         }
     }
 

app/src/main/java/sushi/hardcore/droidfs/explorers/ExplorerActivity.kt

@@ -17,9 +17,7 @@ import sushi.hardcore.droidfs.R
 import sushi.hardcore.droidfs.adapters.IconTextDialogAdapter
 import sushi.hardcore.droidfs.content_providers.ExternalProvider
 import sushi.hardcore.droidfs.file_operations.OperationFile
-import sushi.hardcore.droidfs.filesystems.EncryptedVolume
 import sushi.hardcore.droidfs.filesystems.Stat
-import sushi.hardcore.droidfs.util.IntentUtils
 import sushi.hardcore.droidfs.util.PathUtils
 import sushi.hardcore.droidfs.widgets.CustomAlertDialogBuilder
 import sushi.hardcore.droidfs.widgets.EditTextDialog
@@ -36,7 +34,8 @@ class ExplorerActivity : BaseExplorerActivity() {
     private val pickFromOtherVolumes = registerForActivityResult(ActivityResultContracts.StartActivityForResult()) { result ->
         if (result.resultCode == Activity.RESULT_OK) {
             result.data?.let { resultIntent ->
-                val remoteEncryptedVolume = IntentUtils.getParcelableExtra<EncryptedVolume>(resultIntent, "volume")!!
+                val srcVolumeId = resultIntent.getIntExtra("volumeId", -1)
+                val srcEncryptedVolume = app.volumeManager.getVolume(srcVolumeId)!!
                 val path = resultIntent.getStringExtra("path")
                 val operationFiles = ArrayList<OperationFile>()
                 if (path == null){ //multiples elements
@@ -48,7 +47,7 @@ class ExplorerActivity : BaseExplorerActivity() {
                                 OperationFile(paths[i], types[i])
                             )
                             if (types[i] == Stat.S_IFDIR) {
-                                remoteEncryptedVolume.recursiveMapFiles(paths[i])?.forEach {
+                                srcEncryptedVolume.recursiveMapFiles(paths[i])?.forEach {
                                     operationFiles.add(OperationFile.fromExplorerElement(it))
                                 }
                             }
@@ -64,17 +63,14 @@ class ExplorerActivity : BaseExplorerActivity() {
                         if (items != null) {
                             // stop loading thumbnails while writing files
                             explorerAdapter.loadThumbnails = false
-                            taskScope.launch {
+                            activityScope.launch {
-                                val failedItem = fileOperationService.copyElements(items, remoteEncryptedVolume)
+                                onTaskResult(
-                                if (failedItem == null) {
+                                    fileOperationService.copyElements(
-                                    Toast.makeText(this@ExplorerActivity, R.string.success_import, Toast.LENGTH_SHORT).show()
+                                        volumeId,
-                                } else {
+                                        items,
-                                    CustomAlertDialogBuilder(this@ExplorerActivity, theme)
+                                        srcVolumeId
-                                        .setTitle(R.string.error)
+                                    ), R.string.import_failed, R.string.success_import
-                                        .setMessage(getString(R.string.import_failed, failedItem))
+                                )
-                                        .setPositiveButton(R.string.ok, null)
-                                        .show()
-                                }
                                 explorerAdapter.loadThumbnails = true
                                 setCurrentPath(currentDirectoryPath)
                             }
@@ -86,51 +82,45 @@ class ExplorerActivity : BaseExplorerActivity() {
     }
     private val pickFiles = registerForActivityResult(ActivityResultContracts.OpenMultipleDocuments()) { uris ->
         if (uris != null) {
-            importFilesFromUris(uris){ failedItem ->
+            for (uri in uris) {
-                onImportComplete(failedItem, uris)
+                contentResolver.takePersistableUriPermission(uri, Intent.FLAG_GRANT_WRITE_URI_PERMISSION)
+            }
+            importFilesFromUris(uris) {
+                onImportComplete(uris)
             }
         }
     }
     private val pickExportDirectory = registerForActivityResult(ActivityResultContracts.OpenDocumentTree()) { uri ->
         if (uri != null) {
-            taskScope.launch {
+            contentResolver.takePersistableUriPermission(uri, Intent.FLAG_GRANT_WRITE_URI_PERMISSION)
-                val result = fileOperationService.exportFiles(uri, explorerAdapter.selectedItems.map { i -> explorerElements[i] })
+            val items = explorerAdapter.selectedItems.map { i -> explorerElements[i] }
-                if (!result.cancelled) {
+            activityScope.launch {
-                    if (result.failedItem == null) {
+                val result = fileOperationService.exportFiles(volumeId, items, uri)
-                        Toast.makeText(this@ExplorerActivity, R.string.success_export, Toast.LENGTH_SHORT).show()
+                onTaskResult(result, R.string.export_failed, R.string.success_export)
-                    } else {
-                        CustomAlertDialogBuilder(this@ExplorerActivity, theme)
-                            .setTitle(R.string.error)
-                            .setMessage(getString(R.string.export_failed, result.failedItem))
-                            .setPositiveButton(R.string.ok, null)
-                            .show()
-                    }
-                }
             }
         }
         unselectAll()
     }
     private val pickImportDirectory = registerForActivityResult(ActivityResultContracts.OpenDocumentTree()) { rootUri ->
         rootUri?.let {
+            contentResolver.takePersistableUriPermission(it, Intent.FLAG_GRANT_READ_URI_PERMISSION)
             val tree = DocumentFile.fromTreeUri(this, it)!! //non-null after Lollipop
             val operation = OperationFile(PathUtils.pathJoin(currentDirectoryPath, tree.name!!), Stat.S_IFDIR)
             checkPathOverwrite(arrayListOf(operation), currentDirectoryPath) { checkedOperation ->
                 checkedOperation?.let {
-                    taskScope.launch {
+                    activityScope.launch {
-                        val result = fileOperationService.importDirectory(checkedOperation[0].dstPath!!, tree)
+                        val result = fileOperationService.importDirectory(volumeId, checkedOperation[0].dstPath!!, tree)
-                        if (result.taskResult.cancelled) {
+                        onTaskResult(result.taskResult, R.string.import_failed) {
-                            setCurrentPath(currentDirectoryPath)
+                            onImportComplete(result.uris, tree)
-                        } else {
-                            onImportComplete(result.taskResult.failedItem, result.uris, tree)
                         }
+                        setCurrentPath(currentDirectoryPath)
                     }
                 }
             }
         }
     }
 
-    private fun onImportComplete(failedItem: String?, urisToWipe: List<Uri>, rootFile: DocumentFile? = null) {
+    private fun onImportComplete(urisToWipe: List<Uri>, rootFile: DocumentFile? = null) {
-        if (failedItem == null){
         CustomAlertDialogBuilder(this, theme)
             .setTitle(R.string.success_import)
             .setMessage("""
@@ -138,29 +128,16 @@ class ExplorerActivity : BaseExplorerActivity() {
                             ${getString(R.string.ask_for_wipe)}
                             """.trimIndent())
             .setPositiveButton(R.string.yes) { _, _ ->
-                    taskScope.launch {
+                activityScope.launch {
-                        val errorMsg = fileOperationService.wipeUris(urisToWipe, rootFile)
+                    onTaskResult(
-                        if (errorMsg == null) {
+                        fileOperationService.wipeUris(urisToWipe, rootFile),
-                            Toast.makeText(this@ExplorerActivity, R.string.wipe_successful, Toast.LENGTH_SHORT).show()
+                        R.string.wipe_failed,
-                        } else {
+                        R.string.wipe_successful,
-                            CustomAlertDialogBuilder(this@ExplorerActivity, theme)
+                    )
-                                .setTitle(R.string.error)
-                                .setMessage(getString(R.string.wipe_failed, errorMsg))
-                                .setPositiveButton(R.string.ok, null)
-                                .show()
-                        }
                 }
             }
             .setNegativeButton(R.string.no, null)
             .show()
-        } else {
-            CustomAlertDialogBuilder(this, theme)
-                .setTitle(R.string.error)
-                .setMessage(getString(R.string.import_failed, failedItem))
-                .setPositiveButton(R.string.ok, null)
-                .show()
-        }
-        setCurrentPath(currentDirectoryPath)
     }
 
     override fun init() {
@@ -324,24 +301,18 @@ class ExplorerActivity : BaseExplorerActivity() {
             }
             R.id.validate -> {
                 if (currentItemAction == ItemsActions.COPY){
-                    checkPathOverwrite(itemsToProcess, currentDirectoryPath){ items ->
+                    checkPathOverwrite(itemsToProcess, currentDirectoryPath) {
-                        items?.let {
+                        // copying before being cleared
-                            taskScope.launch {
+                        it?.toMutableList()?.let { items ->
-                                val failedItem = fileOperationService.copyElements(it.toMutableList() as ArrayList<OperationFile>)
+                            activityScope.launch {
-                                if (!isFinishing) {
+                                onTaskResult(
-                                    if (failedItem == null) {
+                                    fileOperationService.copyElements(volumeId, items),
-                                        Toast.makeText(this@ExplorerActivity, R.string.copy_success, Toast.LENGTH_SHORT).show()
+                                    R.string.copy_failed,
-                                    } else {
+                                    R.string.copy_success,
-                                        CustomAlertDialogBuilder(this@ExplorerActivity, theme)
+                                )
-                                            .setTitle(R.string.error)
-                                            .setMessage(getString(R.string.copy_failed, failedItem))
-                                            .setPositiveButton(R.string.ok, null)
-                                            .show()
-                                    }
                                 setCurrentPath(currentDirectoryPath)
                             }
                         }
-                        }
                         cancelItemAction()
                         invalidateOptionsMenu()
                     }
@@ -357,17 +328,12 @@ class ExplorerActivity : BaseExplorerActivity() {
                         toMove,
                         toClean,
                     ) {
-                        taskScope.launch {
+                        activityScope.launch {
-                            val failedItem = fileOperationService.moveElements(toMove, toClean)
+                            onTaskResult(
-                            if (failedItem == null) {
+                                fileOperationService.moveElements(volumeId, toMove, toClean),
-                                Toast.makeText(this@ExplorerActivity, R.string.move_success, Toast.LENGTH_SHORT).show()
+                                R.string.move_success,
-                            } else {
+                                R.string.move_failed,
-                                CustomAlertDialogBuilder(this@ExplorerActivity, theme)
+                            )
-                                    .setTitle(R.string.error)
-                                    .setMessage(getString(R.string.move_failed, failedItem))
-                                    .setPositiveButton(R.string.ok, null)
-                                    .show()
-                            }
                             setCurrentPath(currentDirectoryPath)
                         }
                         cancelItemAction()
@@ -381,8 +347,9 @@ class ExplorerActivity : BaseExplorerActivity() {
                 val dialog = CustomAlertDialogBuilder(this, theme)
                 dialog.setTitle(R.string.warning)
                 dialog.setPositiveButton(R.string.ok) { _, _ ->
-                    taskScope.launch {
+                    val items = explorerAdapter.selectedItems.map { i -> explorerElements[i] }
-                        fileOperationService.removeElements(explorerAdapter.selectedItems.map { i -> explorerElements[i] })?.let { failedItem ->
+                    activityScope.launch {
+                        fileOperationService.removeElements(volumeId, items)?.let { failedItem ->
                             CustomAlertDialogBuilder(this@ExplorerActivity, theme)
                                 .setTitle(R.string.error)
                                 .setMessage(getString(R.string.remove_failed, failedItem))

app/src/main/java/sushi/hardcore/droidfs/explorers/ExplorerActivityDrop.kt

@@ -73,9 +73,8 @@ class ExplorerActivityDrop : BaseExplorerActivity() {
         }
     }
 
-    private fun onImported(failedItem: String?){
+    private fun onImported() {
         setCurrentPath(currentDirectoryPath)
-        if (failedItem == null) {
         CustomAlertDialogBuilder(this, theme)
             .setTitle(R.string.success_import)
             .setMessage(R.string.success_import_msg)
@@ -84,12 +83,5 @@ class ExplorerActivityDrop : BaseExplorerActivity() {
                 finish()
             }
             .show()
-        } else {
-            CustomAlertDialogBuilder(this, theme)
-                    .setTitle(R.string.error)
-                    .setMessage(getString(R.string.import_failed, failedItem))
-                    .setPositiveButton(R.string.ok, null)
-                    .show()
-        }
     }
 }

app/src/main/java/sushi/hardcore/droidfs/explorers/ExplorerActivityPick.kt

@@ -14,7 +14,7 @@ class ExplorerActivityPick : BaseExplorerActivity() {
     private var isFinishingIntentionally = false
     override fun init() {
         setContentView(R.layout.activity_explorer_pick)
-        resultIntent.putExtra("volume", encryptedVolume)
+        resultIntent.putExtra("volumeId", volumeId)
     }
 
     override fun bindFileOperationService() {

app/src/main/java/sushi/hardcore/droidfs/explorers/ExplorerRouter.kt

@@ -2,7 +2,6 @@ package sushi.hardcore.droidfs.explorers
 
 import android.content.Context
 import android.content.Intent
-import sushi.hardcore.droidfs.filesystems.EncryptedVolume
 import sushi.hardcore.droidfs.util.IntentUtils
 
 class ExplorerRouter(private val context: Context, private val intent: Intent) {
@@ -16,7 +15,6 @@ class ExplorerRouter(private val context: Context, private val intent: Intent) {
             IntentUtils.forwardIntent(intent, explorerIntent)
         } else if (pickMode) {
             explorerIntent = Intent(context, ExplorerActivityPick::class.java)
-            explorerIntent.putExtra("destinationVolume", IntentUtils.getParcelableExtra<EncryptedVolume>(intent, "volume")!!)
             explorerIntent.flags = Intent.FLAG_ACTIVITY_FORWARD_RESULT
         }
         if (explorerIntent == null) {

app/src/main/java/sushi/hardcore/droidfs/file_operations/FileOperationService.kt

@@ -13,9 +13,18 @@ import android.os.IBinder
 import androidx.core.app.NotificationCompat
 import androidx.core.app.NotificationManagerCompat
 import androidx.documentfile.provider.DocumentFile
-import kotlinx.coroutines.*
+import kotlinx.coroutines.CancellationException
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Deferred
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.MainScope
+import kotlinx.coroutines.async
+import kotlinx.coroutines.yield
 import sushi.hardcore.droidfs.Constants
 import sushi.hardcore.droidfs.R
+import sushi.hardcore.droidfs.VolumeManager
+import sushi.hardcore.droidfs.VolumeManagerApp
 import sushi.hardcore.droidfs.explorers.ExplorerElement
 import sushi.hardcore.droidfs.filesystems.EncryptedVolume
 import sushi.hardcore.droidfs.util.ObjRef
@@ -31,19 +40,18 @@ class FileOperationService : Service() {
     }
 
     private val binder = LocalBinder()
-    private lateinit var encryptedVolume: EncryptedVolume
+    private lateinit var volumeManger: VolumeManager
+    private var serviceScope = MainScope()
     private lateinit var notificationManager: NotificationManagerCompat
     private val tasks = HashMap<Int, Job>()
     private var lastNotificationId = 0
 
     inner class LocalBinder : Binder() {
         fun getService(): FileOperationService = this@FileOperationService
-        fun setEncryptedVolume(volume: EncryptedVolume) {
-            encryptedVolume = volume
-        }
     }
 
     override fun onBind(p0: Intent?): IBinder {
+        volumeManger = (application as VolumeManagerApp).volumeManager
         return binder
     }
 
@@ -110,29 +118,55 @@ class FileOperationService : Service() {
         tasks[notificationId]?.cancel()
     }
 
-    class TaskResult<T>(val cancelled: Boolean, val failedItem: T?)
+    private fun getEncryptedVolume(volumeId: Int): EncryptedVolume {
+        return volumeManger.getVolume(volumeId) ?: throw IllegalArgumentException("Invalid volumeId: $volumeId")
+    }
 
-    private suspend fun <T> waitForTask(notification: FileOperationNotification, task: Deferred<T>): TaskResult<T> {
+    private suspend fun <T> waitForTask(notification: FileOperationNotification, task: Deferred<T>): TaskResult<out T> {
         tasks[notification.notificationId] = task
-        return try {
+        return serviceScope.async {
-            TaskResult(false, task.await())
+            try {
+                TaskResult.completed(task.await())
             } catch (e: CancellationException) {
-            TaskResult(true, null)
+                TaskResult.cancelled()
+            } catch (e: Throwable) {
+                e.printStackTrace()
+                TaskResult.error(e.localizedMessage)
             } finally {
                 cancelNotification(notification)
             }
+        }.await()
     }
 
-    private fun copyFile(srcPath: String, dstPath: String, remoteEncryptedVolume: EncryptedVolume = encryptedVolume): Boolean {
+    private suspend fun <T> volumeTask(
+        volumeId: Int,
+        notification: FileOperationNotification,
+        task: suspend (encryptedVolume: EncryptedVolume) -> T
+    ): TaskResult<out T> {
+        return waitForTask(
+            notification,
+            volumeManger.getCoroutineScope(volumeId).async {
+                task(getEncryptedVolume(volumeId))
+            }
+        )
+    }
+
+    private suspend fun copyFile(
+        encryptedVolume: EncryptedVolume,
+        srcPath: String,
+        dstPath: String,
+        srcEncryptedVolume: EncryptedVolume = encryptedVolume,
+    ): Boolean {
         var success = true
-        val srcFileHandle = remoteEncryptedVolume.openFileReadMode(srcPath)
+        val srcFileHandle = srcEncryptedVolume.openFileReadMode(srcPath)
         if (srcFileHandle != -1L) {
             val dstFileHandle = encryptedVolume.openFileWriteMode(dstPath)
             if (dstFileHandle != -1L) {
                 var offset: Long = 0
                 val ioBuffer = ByteArray(Constants.IO_BUFF_SIZE)
                 var length: Long
-                while (remoteEncryptedVolume.read(srcFileHandle, offset, ioBuffer, 0, ioBuffer.size.toLong()).also { length = it.toLong() } > 0) {
+                while (srcEncryptedVolume.read(srcFileHandle, offset, ioBuffer, 0, ioBuffer.size.toLong()).also { length = it.toLong() } > 0) {
+                    yield()
                     val written = encryptedVolume.write(dstFileHandle, offset, ioBuffer, 0, length).toLong()
                     if (written == length) {
                         offset += written
@@ -146,7 +180,7 @@ class FileOperationService : Service() {
             } else {
                 success = false
             }
-            remoteEncryptedVolume.closeFile(srcFileHandle)
+            srcEncryptedVolume.closeFile(srcFileHandle)
         } else {
             success = false
         }
@@ -154,26 +188,25 @@ class FileOperationService : Service() {
     }
 
     suspend fun copyElements(
-        items: ArrayList<OperationFile>,
+        volumeId: Int,
-        remoteEncryptedVolume: EncryptedVolume = encryptedVolume
+        items: List<OperationFile>,
-    ): String? = coroutineScope {
+        srcVolumeId: Int = volumeId,
+    ): TaskResult<out String?> {
         val notification = showNotification(R.string.file_op_copy_msg, items.size)
-        val task = async {
+        val srcEncryptedVolume = getEncryptedVolume(srcVolumeId)
+        return volumeTask(volumeId, notification) { encryptedVolume ->
             var failedItem: String? = null
-            for (i in 0 until items.size) {
+            for (i in items.indices) {
-                withContext(Dispatchers.IO) {
+                yield()
                 if (items[i].isDirectory) {
                     if (!encryptedVolume.pathExists(items[i].dstPath!!)) {
                         if (!encryptedVolume.mkdir(items[i].dstPath!!)) {
                             failedItem = items[i].srcPath
                         }
                     }
-                    } else {
+                } else if (!copyFile(encryptedVolume, items[i].srcPath, items[i].dstPath!!, srcEncryptedVolume)) {
-                        if (!copyFile(items[i].srcPath, items[i].dstPath!!, remoteEncryptedVolume)) {
                     failedItem = items[i].srcPath
                 }
-                    }
-                }
                 if (failedItem == null) {
                     updateNotificationProgress(notification, i+1, items.size)
                 } else {
@@ -182,13 +215,11 @@ class FileOperationService : Service() {
             }
             failedItem
         }
-        // treat cancellation as success
-        waitForTask(notification, task).failedItem
     }
 
-    suspend fun moveElements(toMove: List<OperationFile>, toClean: List<String>): String? = coroutineScope {
+    suspend fun moveElements(volumeId: Int, toMove: List<OperationFile>, toClean: List<String>): TaskResult<out String?> {
         val notification = showNotification(R.string.file_op_move_msg, toMove.size)
-        val task = async(Dispatchers.IO) {
+        return volumeTask(volumeId, notification) { encryptedVolume ->
             val total = toMove.size+toClean.size
             var failedItem: String? = null
             for ((i, item) in toMove.withIndex()) {
@@ -211,18 +242,17 @@ class FileOperationService : Service() {
             }
             failedItem
         }
-        // treat cancellation as success
-        waitForTask(notification, task).failedItem
     }
 
     private suspend fun importFilesFromUris(
+        encryptedVolume: EncryptedVolume,
         dstPaths: List<String>,
         uris: List<Uri>,
         notification: FileOperationNotification,
     ): String? {
         var failedIndex = -1
         for (i in dstPaths.indices) {
-            withContext(Dispatchers.IO) {
+            yield()
             try {
                 if (!encryptedVolume.importFile(this@FileOperationService, uris[i], dstPaths[i])) {
                     failedIndex = i
@@ -230,7 +260,6 @@ class FileOperationService : Service() {
             } catch (e: FileNotFoundException) {
                 failedIndex = i
             }
-            }
             if (failedIndex == -1) {
                 updateNotificationProgress(notification, i+1, dstPaths.size)
             } else {
@@ -240,12 +269,11 @@ class FileOperationService : Service() {
         return null
     }
 
-    suspend fun importFilesFromUris(dstPaths: List<String>, uris: List<Uri>): TaskResult<String?> = coroutineScope {
+    suspend fun importFilesFromUris(volumeId: Int, dstPaths: List<String>, uris: List<Uri>): TaskResult<out String?> {
         val notification = showNotification(R.string.file_op_import_msg, dstPaths.size)
-        val task = async {
+        return volumeTask(volumeId, notification) { encryptedVolume ->
-            importFilesFromUris(dstPaths, uris, notification)
+            importFilesFromUris(encryptedVolume, dstPaths, uris, notification)
         }
-        waitForTask(notification, task)
     }
 
     /**
@@ -255,53 +283,42 @@ class FileOperationService : Service() {
      *
      * @return false if cancelled early, true otherwise.
      */
-    private fun recursiveMapDirectoryForImport(
+    private suspend fun recursiveMapDirectoryForImport(
         rootSrcDir: DocumentFile,
         rootDstPath: String,
         dstFiles: ArrayList<String>,
         srcUris: ArrayList<Uri>,
         dstDirs: ArrayList<String>,
-        scope: CoroutineScope,
+    ) {
-    ): Boolean {
         dstDirs.add(rootDstPath)
         for (child in rootSrcDir.listFiles()) {
-            if (!scope.isActive) {
+            yield()
-                return false
-            }
             child.name?.let { name ->
                 val subPath = PathUtils.pathJoin(rootDstPath, name)
                 if (child.isDirectory) {
-                    if (!recursiveMapDirectoryForImport(child, subPath, dstFiles, srcUris, dstDirs, scope)) {
+                    recursiveMapDirectoryForImport(child, subPath, dstFiles, srcUris, dstDirs)
-                        return false
+                } else if (child.isFile) {
-                    }
-                }
-                else if (child.isFile) {
                     srcUris.add(child.uri)
                     dstFiles.add(subPath)
                 }
             }
         }
-        return true
     }
 
-    class ImportDirectoryResult(val taskResult: TaskResult<String?>, val uris: List<Uri>)
+    class ImportDirectoryResult(val taskResult: TaskResult<out String?>, val uris: List<Uri>)
 
     suspend fun importDirectory(
+        volumeId: Int,
         rootDstPath: String,
         rootSrcDir: DocumentFile,
-    ): ImportDirectoryResult = coroutineScope {
+    ): ImportDirectoryResult {
         val notification = showNotification(R.string.file_op_import_msg, null)
         val srcUris = arrayListOf<Uri>()
-        val task = async {
+        return ImportDirectoryResult(volumeTask(volumeId, notification) { encryptedVolume ->
             var failedItem: String? = null
             val dstFiles = arrayListOf<String>()
             val dstDirs = arrayListOf<String>()
-
+            recursiveMapDirectoryForImport(rootSrcDir, rootDstPath, dstFiles, srcUris, dstDirs)
-            withContext(Dispatchers.IO) {
-                if (!recursiveMapDirectoryForImport(rootSrcDir, rootDstPath, dstFiles, srcUris, dstDirs, this)) {
-                    return@withContext
-                }
-
             // create destination folders so the new files can use them
             for (dir in dstDirs) {
                 if (!encryptedVolume.mkdir(dir)) {
@@ -309,23 +326,20 @@ class FileOperationService : Service() {
                     break
                 }
             }
-            }
             if (failedItem == null) {
-                failedItem = importFilesFromUris(dstFiles, srcUris, notification)
+                failedItem = importFilesFromUris(encryptedVolume, dstFiles, srcUris, notification)
             }
             failedItem
-        }
+        }, srcUris)
-        ImportDirectoryResult(waitForTask(notification, task), srcUris)
     }
 
-    suspend fun wipeUris(uris: List<Uri>, rootFile: DocumentFile? = null): String? = coroutineScope {
+    suspend fun wipeUris(uris: List<Uri>, rootFile: DocumentFile? = null): TaskResult<out String?> {
         val notification = showNotification(R.string.file_op_wiping_msg, uris.size)
-        val task = async {
+        val task = serviceScope.async(Dispatchers.IO) {
             var errorMsg: String? = null
             for (i in uris.indices) {
-                withContext(Dispatchers.IO) {
+                yield()
                 errorMsg = Wiper.wipe(this@FileOperationService, uris[i])
-                }
                 if (errorMsg == null) {
                     updateNotificationProgress(notification, i+1, uris.size)
                 } else {
@@ -337,11 +351,10 @@ class FileOperationService : Service() {
             }
             errorMsg
         }
-        // treat cancellation as success
+        return waitForTask(notification, task)
-        waitForTask(notification, task).failedItem
     }
 
-    private fun exportFileInto(srcPath: String, treeDocumentFile: DocumentFile): Boolean {
+    private fun exportFileInto(encryptedVolume: EncryptedVolume, srcPath: String, treeDocumentFile: DocumentFile): Boolean {
         val outputStream = treeDocumentFile.createFile("*/*", File(srcPath).name)?.uri?.let {
             contentResolver.openOutputStream(it)
         }
@@ -352,44 +365,41 @@ class FileOperationService : Service() {
         }
     }
 
-    private fun recursiveExportDirectory(
+    private suspend fun recursiveExportDirectory(
+        encryptedVolume: EncryptedVolume,
         plain_directory_path: String,
         treeDocumentFile: DocumentFile,
-        scope: CoroutineScope
     ): String? {
         treeDocumentFile.createDirectory(File(plain_directory_path).name)?.let { childTree ->
             val explorerElements = encryptedVolume.readDir(plain_directory_path) ?: return null
             for (e in explorerElements) {
-                if (!scope.isActive) {
+                yield()
-                    return null
-                }
                 val fullPath = PathUtils.pathJoin(plain_directory_path, e.name)
                 if (e.isDirectory) {
-                    val failedItem = recursiveExportDirectory(fullPath, childTree, scope)
+                    recursiveExportDirectory(encryptedVolume, fullPath, childTree)?.let { return it }
-                    failedItem?.let { return it }
+                } else if (!exportFileInto(encryptedVolume, fullPath, childTree)) {
-                } else {
-                    if (!exportFileInto(fullPath, childTree)){
                     return fullPath
                 }
             }
-            }
             return null
         }
         return treeDocumentFile.name
     }
 
-    suspend fun exportFiles(uri: Uri, items: List<ExplorerElement>): TaskResult<String?> = coroutineScope {
+    suspend fun exportFiles(volumeId: Int, items: List<ExplorerElement>, uri: Uri): TaskResult<out String?> {
         val notification = showNotification(R.string.file_op_export_msg, items.size)
-        val task = async {
+        return volumeTask(volumeId, notification) { encryptedVolume ->
-            contentResolver.takePersistableUriPermission(uri, Intent.FLAG_GRANT_WRITE_URI_PERMISSION)
             val treeDocumentFile = DocumentFile.fromTreeUri(this@FileOperationService, uri)!!
             var failedItem: String? = null
             for (i in items.indices) {
-                withContext(Dispatchers.IO) {
+                yield()
                 failedItem = if (items[i].isDirectory) {
-                        recursiveExportDirectory(items[i].fullPath, treeDocumentFile, this)
+                    recursiveExportDirectory(encryptedVolume, items[i].fullPath, treeDocumentFile)
                 } else {
-                        if (exportFileInto(items[i].fullPath, treeDocumentFile)) null else items[i].fullPath
+                    if (exportFileInto(encryptedVolume, items[i].fullPath, treeDocumentFile)) {
+                        null
+                    } else {
+                        items[i].fullPath
                     }
                 }
                 if (failedItem == null) {
@@ -400,22 +410,38 @@ class FileOperationService : Service() {
             }
             failedItem
         }
-        waitForTask(notification, task)
     }
 
-    suspend fun removeElements(items: List<ExplorerElement>): String? = coroutineScope {
+    private suspend fun recursiveRemoveDirectory(encryptedVolume: EncryptedVolume, path: String): String? {
+        encryptedVolume.readDir(path)?.let { elements ->
+            for (e in elements) {
+                yield()
+                val fullPath = PathUtils.pathJoin(path, e.name)
+                if (e.isDirectory) {
+                    recursiveRemoveDirectory(encryptedVolume, fullPath)?.let { return it }
+                } else if (!encryptedVolume.deleteFile(fullPath)) {
+                    return fullPath
+                }
+            }
+        }
+        return if (!encryptedVolume.rmdir(path)) {
+            path
+        } else {
+            null
+        }
+    }
+
+    suspend fun removeElements(volumeId: Int, items: List<ExplorerElement>): String? {
         val notification = showNotification(R.string.file_op_delete_msg, items.size)
-        val task = async(Dispatchers.IO) {
+        return volumeTask(volumeId, notification) { encryptedVolume ->
             var failedItem: String? = null
             for ((i, element) in items.withIndex()) {
+                yield()
                 if (element.isDirectory) {
-                    val result = encryptedVolume.recursiveRemoveDirectory(element.fullPath)
+                    recursiveRemoveDirectory(encryptedVolume, element.fullPath)?.let { failedItem = it }
-                    result?.let { failedItem = it }
+                } else if (!encryptedVolume.deleteFile(element.fullPath)) {
-                } else {
-                    if (!encryptedVolume.deleteFile(element.fullPath)) {
                     failedItem = element.fullPath
                 }
-                }
                 if (failedItem == null) {
                     updateNotificationProgress(notification, i + 1, items.size)
                 } else {
@@ -423,14 +449,11 @@ class FileOperationService : Service() {
                 }
             }
             failedItem
-        }
+        }.failedItem // treat cancellation as success
-        waitForTask(notification, task).failedItem
     }
 
-    private fun recursiveCountChildElements(rootDirectory: DocumentFile, scope: CoroutineScope): Int {
+    private suspend fun recursiveCountChildElements(rootDirectory: DocumentFile, scope: CoroutineScope): Int {
-        if (!scope.isActive) {
+        yield()
-            return 0
-        }
         val children = rootDirectory.listFiles()
         var count = children.size
         for (child in children) {
@@ -441,7 +464,7 @@ class FileOperationService : Service() {
         return count
     }
 
-    private fun recursiveCopyVolume(
+    private suspend fun recursiveCopyVolume(
         src: DocumentFile,
         dst: DocumentFile,
         dstRootDirectory: ObjRef<DocumentFile?>?,
@@ -453,9 +476,7 @@ class FileOperationService : Service() {
         val dstDir = dst.createDirectory(src.name ?: return src) ?: return src
         dstRootDirectory?.let { it.value = dstDir }
         for (child in src.listFiles()) {
-            if (!scope.isActive) {
+            yield()
-                return null
-            }
             if (child.isFile) {
                 val dstFile = dstDir.createFile("", child.name ?: return child) ?: return child
                 val outputStream = contentResolver.openOutputStream(dstFile.uri)
@@ -474,21 +495,16 @@ class FileOperationService : Service() {
         return null
     }
 
-    class CopyVolumeResult(val taskResult: TaskResult<DocumentFile?>, val dstRootDirectory: DocumentFile?)
+    class CopyVolumeResult(val taskResult: TaskResult<out DocumentFile?>, val dstRootDirectory: DocumentFile?)
 
-    suspend fun copyVolume(src: DocumentFile, dst: DocumentFile): CopyVolumeResult = coroutineScope {
+    suspend fun copyVolume(src: DocumentFile, dst: DocumentFile): CopyVolumeResult {
         val notification = showNotification(R.string.copy_volume_notification, null)
         val dstRootDirectory = ObjRef<DocumentFile?>(null)
-        val task = async(Dispatchers.IO) {
+        val task = serviceScope.async(Dispatchers.IO) {
             val total = recursiveCountChildElements(src, this)
-            if (isActive) {
             updateNotificationProgress(notification, 0, total)
             recursiveCopyVolume(src, dst, dstRootDirectory, notification, total, this)
-            } else {
+        }
-                null
+        return CopyVolumeResult(waitForTask(notification, task), dstRootDirectory.value)
-            }
-        }
-        // treat cancellation as success
-        CopyVolumeResult(waitForTask(notification, task), dstRootDirectory.value)
     }
 }

app/src/main/java/sushi/hardcore/droidfs/file_operations/TaskResult.kt

@@ -0,0 +1,47 @@
+package sushi.hardcore.droidfs.file_operations
+
+import android.content.Context
+import sushi.hardcore.droidfs.R
+import sushi.hardcore.droidfs.Theme
+import sushi.hardcore.droidfs.widgets.CustomAlertDialogBuilder
+
+class TaskResult<T> private constructor(val state: State, val failedItem: T?, val errorMessage: String?) {
+    enum class State {
+        SUCCESS,
+        /**
+         * Task completed but failed
+         */
+        FAILED,
+        /**
+         * Task thrown an exception
+         */
+        ERROR,
+        CANCELLED,
+    }
+
+    fun showErrorAlertDialog(context: Context, theme: Theme) {
+        CustomAlertDialogBuilder(context, theme)
+            .setTitle(R.string.error)
+            .setMessage(context.getString(R.string.task_failed, errorMessage))
+            .setPositiveButton(R.string.ok, null)
+            .show()
+    }
+
+    companion object {
+        fun <T> completed(failedItem: T?): TaskResult<T> {
+            return if (failedItem == null) {
+                TaskResult(State.SUCCESS, null, null)
+            } else {
+                TaskResult(State.FAILED, failedItem, null)
+            }
+        }
+
+        fun <T> error(errorMessage: String?): TaskResult<T> {
+            return TaskResult(State.ERROR, null, errorMessage)
+        }
+
+        fun <T> cancelled(): TaskResult<T> {
+            return TaskResult(State.CANCELLED, null, null)
+        }
+    }
+}

app/src/main/java/sushi/hardcore/droidfs/filesystems/EncryptedVolume.kt

@@ -218,25 +218,4 @@ abstract class EncryptedVolume: Parcelable {
         }
         return result
     }
-
-    fun recursiveRemoveDirectory(path: String): String? {
-        readDir(path)?.let { elements ->
-            for (e in elements) {
-                val fullPath = PathUtils.pathJoin(path, e.name)
-                if (e.isDirectory) {
-                    val result = recursiveRemoveDirectory(fullPath)
-                    result?.let { return it }
-                } else {
-                    if (!deleteFile(fullPath)) {
-                        return fullPath
-                    }
-                }
-            }
-        }
-        return if (!rmdir(path)) {
-            path
-        } else {
-            null
-        }
-    }
 }

app/src/main/res/values/strings.xml

@@ -261,4 +261,5 @@
     <string name="config_load_error">The configuration file cannot be loaded. Make sure the volume is accessible.</string>
     <string name="wrong_password">The configuration file cannot be decrypted. Please check your password.</string>
     <string name="filesystem_id_changed">The filesystem id in the config file is different to the last time we opened this volume. This could mean an attacker replaced the filesystem with a different one.</string>
+    <string name="task_failed">The task failed: %s</string>
 </resources>