[BUG] Attempting to use `FMTCTileProvider` when bulk downloading throws Isolate message exception

[Zverik]

What is the bug?

I haven't yet investigated, and frankly don't know where to start. But I've got this error, and maybe it would say something to you:

I/flutter (21729): Async error: Invalid argument(s): Illegal argument in isolate message: object is unsendable - Library:'dart:async' Class: _AsyncCompleter@5048458 (see restrictions listed at `SendPort.send()` documentation for more information)
I/flutter (21729):  <- value in Instance of '_HashMapEntry' (from dart:collection)
I/flutter (21729):  <- _List len:64 (from dart:core)
I/flutter (21729):  <- _buckets in Instance of '_HashMap<TileCoordinates, Completer<void>>' (from dart:collection)
I/flutter (21729):  <- _wasClientAutomaticallyGenerated in Instance of 'FMTCTileProvider' (from package:flutter_map_tile_caching/flutter_map_tile_caching.dart)
I/flutter (21729):  <- panBuffer in Instance of 'TileLayer' (from package:flutter_map/src/layer/tile_layer/tile_layer.dart)
I/flutter (21729):  <- start in Instance of 'DownloadableRegion<MultiRegion>' (from package:flutter_map_tile_caching/flutter_map_tile_caching.dart)
I/flutter (21729):  <- Record (backend: Instance of '_ObjectBoxBackendThreadSafeImpl', maxBufferLength: 10, maxReportInterval: Instance of 'Duration', parallelThreads: 1, rateLimit: null, recoveryId: null, region: Instance of 'DownloadableRegion
I/flutter (21729): #0      Isolate._spawnFunction (dart:isolate-patch/isolate_patch.dart:431:4)
I/flutter (21729): #1      Isolate.spawn (dart:isolate-patch/isolate_patch.dart:400:7)
I/flutter (21729): #2      StoreDownload.startForeground.<anonymous closure> (package:flutter_map_tile_caching/src/store/download.dart:299:21)
I/flutter (21729): #3      StoreDownload.startForeground (package:flutter_map_tile_caching/src/store/download.dart:358:6)
I/flutter (21729): #4      TileDownloadNotifier._startRasterDownload (package:every_door/providers/downloaders.dart:160:10)

Feel free to close if this is not related to FMTC.

How can we reproduce it?

Frankly idk. I've been trying to download the default OpenStreetMap layer. It worked fine with another layer before.

Here's the code for calling the downloader: https://github.com/Zverik/every_door/blob/main/lib/providers/downloaders.dart#L151

Do you have a potential solution?

No response

Platforms

Android 14, Xperia 10 IV, Flutter 3.32

Severity

Erroneous: Prevents normal functioning and causes errors in the console

[Zverik]

Another version of the same:

I/flutter (30030): Async error: Invalid argument(s): Illegal argument in isolate message: object is unsendable - Library:'dart:async' Class: _Future@5048458 (see restrictions listed at `SendPort.send()` documentation for more information)
I/flutter (30030):  <- _streamFuture in Instance of '_HttpClientConnection' (from dart:_http)
I/flutter (30030):  <- hashCode in Instance of '_HashSetEntry<_HttpClientConnection>' (from dart:collection)
I/flutter (30030):  <- _List len:64 (from dart:core)
I/flutter (30030):  <- _buckets in Instance of '_HashSet<_HttpClientConnection>' (from dart:collection)
I/flutter (30030):  <- _idle in Instance of '_ConnectionTarget' (from dart:_http)
I/flutter (30030):  <- value in Instance of '_HashMapEntry' (from dart:collection)
I/flutter (30030):  <- _List len:8 (from dart:core)
I/flutter (30030):  <- _buckets in Instance of '_HashMap<String, _ConnectionTarget>' (from dart:collection)
I/flutter (30030):  <- _connectionTargets in Instance of '_HttpClient' (from dart:_http)
I/flutter (30030):  <- _inner in Instance of 'IOClient' (from package:http/src/io_client.dart)
I/flutter (30030):  <- fakeNetworkDisconnect in Instance of 'FMTCTileProvider' (from package:flutter_map_tile_caching/flutter_map_tile_caching.
I/flutter (30030): #0      Isolate._spawnFunction (dart:isolate-patch/isolate_patch.dart:431:4)
I/flutter (30030): #1      Isolate.spawn (dart:isolate-patch/isolate_patch.dart:400:7)
I/flutter (30030): #2      StoreDownload.startForeground.<anonymous closure> (package:flutter_map_tile_caching/src/store/download.dart:299:21)
I/flutter (30030): #3      StoreDownload.startForeground (package:flutter_map_tile_caching/src/store/download.dart:358:6)
I/flutter (30030): #4      TileDownloadNotifier._startRasterDownload (package:every_door/providers/downloaders.dart:161:10)
I/flutter (30030): <asynchronous suspension>

[JaffaKetchup]

Thought I squashed all of these. I'll need to have a look. Thanks for reporting!

[Zverik]

This definitely relates to the tile provider being an FMTCTileProvider. I have temporarely added a function to replace it with a regular NetworkTileProvider, and it works fine.

[JaffaKetchup]

@Zverik I see, I understand why this is happening, although I didn't anticipate it.

The provided TileLayer doesn't really need any tile provider - it's used only to get the URL & headers. Unfortunately, with the current FM infrastructure, that can only occur through the full TileLayer with a TileProvider. When the modern tile layer is ready, this problem will be avoided.

But for now, that's the correct workaround.

[themumy10]

Is there any simple solution for now? ObjectBox keeps pop up in debugging mode

[JaffaKetchup]

Is there any simple solution for now?

Yes, you should use a standard NetworkTileProvider (which is safe to send through Isolates).

ObjectBox keeps pop up in debugging mode

Not quite sure what you mean by this?

[Nicoeevee]

Got a similar error when countTiles and startForeground, but related to cronet_http, fix by add jni: ^0.14.2

  flutter_map_tile_caching: ^10.1.1
  
  cronet_http: ^1.6.0
  jni: ^0.14.2

I/flutter (31296): CaptureException Invalid argument(s): Illegal argument in isolate message: object is unsendable - Library:'dart:io' Class: _SecurityContext@15069316 (see restrictions listed at `SendPort.send()` documentation for more information)
I/flutter (31296):  <- _context in Instance of '_HttpClient' (from dart:_http)
I/flutter (31296):  <- _inner in Instance of 'IOClient' (from package:http/src/io_client.dart)
I/flutter (31296):  <- _inner in Instance of 'RetryClient' (from package:http/retry.dart)
I/flutter (31296):  <- _isInternallyCreatedClient in Instance of 'NetworkTileProvider' (from package:flutter_map/src/layer/tile_layer/tile_provider/network/tile_provider.dart)
I/flutter (31296):  <- panBuffer in Instance of 'TileLayer' (from package:flutter_map/src/layer/tile_layer/tile_layer.dart)
I/flutter (31296):  <- start in Instance of 'DownloadableRegion<CircleRegion>' (from package:flutter_map_tile_caching/flutter_map_tile_caching.dart)
I/flutter (31296):  <- Record (backend: Instance of '_ObjectBoxBackendThreadSafeImpl', maxBufferLength: 0, maxReportInterval: Instance of 'Duration', parallelThreads: 3, rateLimit: 200, recoveryId: 115246268, region: Instance of 'DownloadableRegion<CircleRegion>', retryFailedRequestTiles: true, sendPort: SendPort, skipExistingTiles: false, skipSeaTiles: true, storeName: mapStore, urlTransformer: Closure: (String) => String) (from dart:core)
I/flutter (31296):  #0      Isolate._spawnFunction (dart:isolate-patch/isolate_patch.dart:431:4)
isolate_patch.dart:431
I/flutter (31296): #1      Isolate.spawn (dart:isolate-patch/isolate_patch.dart:400:7)
isolate_patch.dart:400
I/flutter (31296): #2      StoreDownload.startForeground.<anonymous closure> (package:flutter_map_tile_caching/src/store/download.dart:299:21)
download.dart:299
I/flutter (31296): #3      StoreDownload.startForeground (package:flutter_map_tile_caching/src/store/download.dart:358:6)
download.dart:358
I/flutter (31296): #4      _MapDownloadButtonState.build.<anonymous closure> (package:myapp/features/map/presentation/widgets/map_download_button.dart:91:20)
map_download_button.dart:91
I/flutter (31296): <asynchronous suspension>

I/flutter (22642): CaptureException Invalid argument(s): Illegal argument in isolate message: object is unsendable - Library:'dart:io' Class: _SecurityContext@15069316 (see restrictions listed at `SendPort.send()` documentation for more information)
I/flutter (22642):  <- _context in Instance of '_HttpClient' (from dart:_http)
I/flutter (22642):  <- _inner in Instance of 'IOClient' (from package:http/src/io_client.dart)
I/flutter (22642):  <- _inner in Instance of 'RetryClient' (from package:http/retry.dart)
I/flutter (22642):  <- _isInternallyCreatedClient in Instance of 'NetworkTileProvider' (from package:flutter_map/src/layer/tile_layer/tile_provider/network/tile_provider.dart)
I/flutter (22642):  <- panBuffer in Instance of 'TileLayer' (from package:flutter_map/src/layer/tile_layer/tile_layer.dart)
I/flutter (22642):  <- start in Instance of 'DownloadableRegion<CircleRegion>' (from package:flutter_map_tile_caching/flutter_map_tile_caching.dart)
I/flutter (22642):  <- field message in compute.<anonymous closure> (from package:flutter/src/foundation/_isolates_io.dart)
I/flutter (22642):  <- resultPort in Instance of '_RemoteRunner<int>' (from dart:isolate)
I/flutter (22642):  #0      Isolate._spawnFunction (dart:isolate-patch/isolate_patch.dart:431:4)
I/flutter (22642): #1      Isolate.spawn (dart:isolate-patch/isolate_patch.dart:400:7)
I/flutter (22642): #2      Isolate.run (dart:isolate:288:15)
I/flutter (22642): #3      compute (package:flutter/src/foundation/_isolates_io.dart:22:18)
I/flutter (22642): #4      compute (package:flutter/src/foundation/isolates.dart:82:19)
I/flutter (22642): #5      StoreDownload.countTiles (package:flutter_map_tile_caching/src/store/download.dart:373:56)
I/flutter (22642): #6      MapDownloadButton.build.<anonymous closure> (package:myapp/features/map/presentation/widgets/map_download_button.dart:61:52)