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| 1 | +// Copyright 2013 The Flutter Authors. All rights reserved. |
| 2 | +// Use of this source code is governed by a BSD-style license that can be |
| 3 | +// found in the LICENSE file. |
| 4 | + |
| 5 | +// @dart = 2.10 |
| 6 | + |
| 7 | +part of engine; |
| 8 | + |
| 9 | +class _ChannelCallbackRecord { |
| 10 | + _ChannelCallbackRecord(this.callback) : zone = Zone.current; |
| 11 | + final ui.ChannelCallback callback; |
| 12 | + final Zone zone; |
| 13 | + |
| 14 | + void invoke(ByteData? dataArg, ui.PlatformMessageResponseCallback callbackArg) { |
| 15 | + _invoke2<ByteData?, ui.PlatformMessageResponseCallback>(callback, zone, dataArg, callbackArg); |
| 16 | + } |
| 17 | +} |
| 18 | + |
| 19 | +class _StoredMessage { |
| 20 | + const _StoredMessage(this.data, this.callback); |
| 21 | + |
| 22 | + final ByteData? data; |
| 23 | + |
| 24 | + final ui.PlatformMessageResponseCallback callback; |
| 25 | +} |
| 26 | + |
| 27 | +class _Channel { |
| 28 | + _Channel(this._capacity) |
| 29 | + : _queue = ListQueue<_StoredMessage>(_capacity); |
| 30 | + |
| 31 | + final ListQueue<_StoredMessage> _queue; |
| 32 | + |
| 33 | + int get length => _queue.length; |
| 34 | + |
| 35 | + int _capacity; |
| 36 | + int get capacity => _capacity; |
| 37 | + |
| 38 | + int resize(int newSize) { |
| 39 | + _capacity = newSize; |
| 40 | + return _dropOverflowMessages(newSize); |
| 41 | + } |
| 42 | + |
| 43 | + bool _draining = false; |
| 44 | + |
| 45 | + bool push(_StoredMessage message) { |
| 46 | + if (!_draining && _channelCallbackRecord != null) { |
| 47 | + assert(_queue.isEmpty); |
| 48 | + _channelCallbackRecord!.invoke(message.data, message.callback); |
| 49 | + return false; |
| 50 | + } |
| 51 | + if (_capacity <= 0) { |
| 52 | + return true; |
| 53 | + } |
| 54 | + final int overflowCount = _dropOverflowMessages(_capacity - 1); |
| 55 | + _queue.addLast(message); |
| 56 | + return overflowCount > 0; |
| 57 | + } |
| 58 | + |
| 59 | + _StoredMessage pop() => _queue.removeFirst(); |
| 60 | + |
| 61 | + int _dropOverflowMessages(int lengthLimit) { |
| 62 | + int result = 0; |
| 63 | + while (_queue.length > lengthLimit) { |
| 64 | + final _StoredMessage message = _queue.removeFirst(); |
| 65 | + message.callback(null); // send empty reply to the plugin side |
| 66 | + result += 1; |
| 67 | + } |
| 68 | + return result; |
| 69 | + } |
| 70 | + |
| 71 | + _ChannelCallbackRecord? _channelCallbackRecord; |
| 72 | + |
| 73 | + void setListener(ui.ChannelCallback callback) { |
| 74 | + final bool needDrain = _channelCallbackRecord == null; |
| 75 | + _channelCallbackRecord = _ChannelCallbackRecord(callback); |
| 76 | + if (needDrain && !_draining) |
| 77 | + _drain(); |
| 78 | + } |
| 79 | + |
| 80 | + void clearListener() { |
| 81 | + _channelCallbackRecord = null; |
| 82 | + } |
| 83 | + |
| 84 | + void _drain() { |
| 85 | + assert(!_draining); |
| 86 | + _draining = true; |
| 87 | + scheduleMicrotask(_drainStep); |
| 88 | + } |
| 89 | + |
| 90 | + void _drainStep() { |
| 91 | + assert(_draining); |
| 92 | + if (_queue.isNotEmpty && _channelCallbackRecord != null) { |
| 93 | + final _StoredMessage message = pop(); |
| 94 | + _channelCallbackRecord!.invoke(message.data, message.callback); |
| 95 | + scheduleMicrotask(_drainStep); |
| 96 | + } else { |
| 97 | + _draining = false; |
| 98 | + } |
| 99 | + } |
| 100 | +} |
| 101 | + |
| 102 | +class EngineChannelBuffers extends ui.ChannelBuffers { |
| 103 | + final Map<String, _Channel> _channels = <String, _Channel>{}; |
| 104 | + |
| 105 | + @override |
| 106 | + bool push(String name, ByteData? data, ui.PlatformMessageResponseCallback callback) { |
| 107 | + final _Channel channel = _channels.putIfAbsent(name, () => _Channel(ui.ChannelBuffers.kDefaultBufferSize)); |
| 108 | + return channel.push(_StoredMessage(data, callback)); |
| 109 | + } |
| 110 | + |
| 111 | + @override |
| 112 | + void setListener(String name, ui.ChannelCallback callback) { |
| 113 | + final _Channel channel = _channels.putIfAbsent(name, () => _Channel(ui.ChannelBuffers.kDefaultBufferSize)); |
| 114 | + channel.setListener(callback); |
| 115 | + } |
| 116 | + |
| 117 | + @override |
| 118 | + void clearListener(String name) { |
| 119 | + final _Channel? channel = _channels[name]; |
| 120 | + if (channel != null) |
| 121 | + channel.clearListener(); |
| 122 | + } |
| 123 | + |
| 124 | + @override |
| 125 | + Future<void> drain(String name, ui.DrainChannelCallback callback) async { |
| 126 | + final _Channel? channel = _channels[name]; |
| 127 | + while (channel != null && !channel._queue.isEmpty) { |
| 128 | + final _StoredMessage message = channel.pop(); |
| 129 | + await callback(message.data, message.callback); |
| 130 | + } |
| 131 | + } |
| 132 | + |
| 133 | + String _getString(ByteData data) { |
| 134 | + final ByteBuffer buffer = data.buffer; |
| 135 | + final Uint8List list = buffer.asUint8List(data.offsetInBytes, data.lengthInBytes); |
| 136 | + return utf8.decode(list); |
| 137 | + } |
| 138 | + |
| 139 | + @override |
| 140 | + void handleMessage(ByteData data) { |
| 141 | + final List<String> command = _getString(data).split('\r'); |
| 142 | + if (command.length == 1 + /*arity=*/2 && command[0] == 'resize') { |
| 143 | + _resize(command[1], int.parse(command[2])); |
| 144 | + } else { |
| 145 | + throw Exception('Unrecognized command $command sent to ${ui.ChannelBuffers.kControlChannelName}.'); |
| 146 | + } |
| 147 | + } |
| 148 | + |
| 149 | + void _resize(String name, int newSize) { |
| 150 | + _Channel? channel = _channels[name]; |
| 151 | + if (channel == null) { |
| 152 | + channel = _Channel(newSize); |
| 153 | + _channels[name] = channel; |
| 154 | + } else { |
| 155 | + channel.resize(newSize); |
| 156 | + } |
| 157 | + } |
| 158 | +} |
| 159 | + |
| 160 | +final ui.ChannelBuffers channelBuffers = EngineChannelBuffers(); |
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