| 1 | | | import 'dart:async'; |
| 2 | | | |
| 3 | | | import '../../channel.dart'; |
| 4 | | | import '../../exceptions/squadron_error.dart'; |
| 5 | | | import '../../exceptions/squadron_exception.dart'; |
| 6 | | | import '../../worker/worker_message.dart'; |
| 7 | | | import '../../worker/worker_request.dart'; |
| 8 | | | import '../../worker/worker_response.dart'; |
| 9 | | | import '_forward_stream_controller.dart'; |
| 10 | | | |
| 11 | | | class ResultStream { |
| 12 | | 1 | ResultStream( |
| 13 | | | Channel channel, |
| 14 | | | WorkerRequest req, |
| 15 | | | Stream<WorkerResponse> Function() sendRequest, |
| 16 | | | bool streaming, |
| 17 | | | ) { |
| 18 | | 1 | final streamIdCompleter = streaming ? Completer<StreamId?>() : null; |
| 19 | | 2 | final command = req.command, token = req.cancelToken; |
| 20 | | | |
| 21 | | 1 | void $decodeStreamOfResponses(WorkerResponse res) { |
| 22 | | 1 | if (!res.unwrapInPlace(channel)) return; |
| 23 | | | |
| 24 | | 1 | final hasStreamId = streamIdCompleter!.isCompleted; |
| 25 | | 1 | if (res.endOfStream) { |
| 26 | | | // handle endofStream |
| 27 | | | if (!hasStreamId) { |
| 28 | | 0 | streamIdCompleter.complete(null); |
| 29 | | 0 | channel.logger |
| 30 | | 0 | ?.e('Invalid state: unexpected endOfStream for command $command'); |
| 31 | | 0 | _controller.safeAddError(SquadronErrorImpl.create( |
| 32 | | | 'Invalid state: unexpected endOfStream', |
| 33 | | | null, |
| 34 | | | command, |
| 35 | | | )); |
| 36 | | | } |
| 37 | | 2 | _controller.close(); |
| 38 | | | return; |
| 39 | | | } |
| 40 | | | |
| 41 | | 1 | final error = res.error; |
| 42 | | | if (error == null && !hasStreamId) { |
| 43 | | | // the first result from a streaming operation is the stream ID |
| 44 | | 3 | streamIdCompleter.complete(StreamId.from(res.result)); |
| 45 | | | } else if (error != null) { |
| 46 | | 2 | _controller.safeAddError(error); |
| 47 | | | if (!hasStreamId) { |
| 48 | | | // if any error comes before the stream ID, somethind bad happened |
| 49 | | 0 | streamIdCompleter.complete(null); |
| 50 | | 0 | _controller.close(); |
| 51 | | | return; |
| 52 | | | } |
| 53 | | | } else { |
| 54 | | | try { |
| 55 | | 3 | _controller.safeAdd(res.result); |
| 56 | | | } catch (ex, st) { |
| 57 | | 0 | _controller.safeAddError(SquadronException.from(ex, st, command)); |
| 58 | | | } |
| 59 | | | } |
| 60 | | | |
| 61 | | 1 | final canceled = token?.exception; |
| 62 | | | if (canceled != null) { |
| 63 | | 0 | _controller.safeAddError(canceled); |
| 64 | | 0 | _controller.close(); |
| 65 | | | } |
| 66 | | | } |
| 67 | | | |
| 68 | | 1 | void $decodeSingleResponse(WorkerResponse res) { |
| 69 | | 1 | if (!res.unwrapInPlace(channel)) return; |
| 70 | | | |
| 71 | | 1 | final error = res.error; |
| 72 | | | if (error != null) { |
| 73 | | 2 | _controller.safeAddError(error); |
| 74 | | | } else { |
| 75 | | | try { |
| 76 | | 3 | _controller.safeAdd(res.result); |
| 77 | | | } catch (ex, st) { |
| 78 | | 0 | _controller.safeAddError(SquadronException.from(ex, st, command)); |
| 79 | | | } |
| 80 | | | } |
| 81 | | | |
| 82 | | 2 | _controller.close(); |
| 83 | | | } |
| 84 | | | |
| 85 | | 1 | Future<StreamId?> $getStreamId(StreamSubscription sub) { |
| 86 | | | streamIdCompleter as Completer<StreamId?>; |
| 87 | | | var count = 0; |
| 88 | | 2 | if (sub.isPaused && !streamIdCompleter.isCompleted) { |
| 89 | | | // if the subscription was paused and the streamId is not available, |
| 90 | | | // resume to have the streamId eventually come through. |
| 91 | | 0 | while (sub.isPaused) { |
| 92 | | 0 | count++; |
| 93 | | 0 | sub.resume(); |
| 94 | | | } |
| 95 | | | } |
| 96 | | | // wait for the streamId... |
| 97 | | 3 | return streamIdCompleter.future.then((streamId) { |
| 98 | | 1 | while (count > 0) { |
| 99 | | 0 | count--; |
| 100 | | 0 | sub.pause(); |
| 101 | | | } |
| 102 | | | return streamId; |
| 103 | | | }); |
| 104 | | | // restore subscription pause |
| 105 | | | } |
| 106 | | | |
| 107 | | 1 | Future<void> $onCancel() async { |
| 108 | | 2 | final sub = _controller.subscription; |
| 109 | | | if (streamIdCompleter != null && sub != null) { |
| 110 | | | // this is a streaming operation and the subscription is active, so |
| 111 | | | // we need to inform the worker that the stream has been canceled |
| 112 | | 1 | final streamId = await $getStreamId(sub); |
| 113 | | | if (streamId != null) { |
| 114 | | 1 | channel.cancelStream(streamId); |
| 115 | | | } |
| 116 | | | } |
| 117 | | 1 | await sub?.cancel(); |
| 118 | | | } |
| 119 | | | |
| 120 | | 1 | void $closeWithError(Object error, [StackTrace? st]) { |
| 121 | | 3 | _controller.safeAddError(SquadronException.from(error, st, command)); |
| 122 | | 2 | _controller.close(); |
| 123 | | | } |
| 124 | | | |
| 125 | | 1 | void $onListen() { |
| 126 | | | try { |
| 127 | | | // do not send the request if the token is already canceled |
| 128 | | 1 | token?.throwIfCanceled(); |
| 129 | | | // send the request and start decoding responses |
| 130 | | 4 | _controller.attachSubscription(sendRequest().listen( |
| 131 | | | streaming ? $decodeStreamOfResponses : $decodeSingleResponse, |
| 132 | | | onError: $closeWithError, |
| 133 | | 2 | onDone: _controller.close, |
| 134 | | | cancelOnError: false, |
| 135 | | | )); |
| 136 | | | } catch (ex, st) { |
| 137 | | 0 | $closeWithError(ex, st); |
| 138 | | | } |
| 139 | | | } |
| 140 | | | |
| 141 | | 2 | _controller = ForwardStreamController<dynamic>( |
| 142 | | | onListen: $onListen, |
| 143 | | | onCancel: $onCancel, |
| 144 | | | ); |
| 145 | | | } |
| 146 | | | |
| 147 | | | late final ForwardStreamController<dynamic> _controller; |
| 148 | | | |
| 149 | | 3 | Stream<dynamic> get stream => _controller.stream; |
| 150 | | | |
| 151 | | 3 | Future<void> get done => _controller.done; |
| 152 | | | } |