69 lines
1.9 KiB
JavaScript
69 lines
1.9 KiB
JavaScript
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function SyncChannel() {
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this.writers = [];
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this.readers = [];
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this.syncing = false;
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}
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SyncChannel.prototype.tryRead = function () {
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if (this.writers.length > 0) {
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var writer = this.writers.shift();
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writer.continuation();
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return { value: writer.value };
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} else {
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return null;
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}
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};
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SyncChannel.prototype.tryWrite = function (value) {
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if (this.readers.length > 0) {
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var reader = this.readers.shift();
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reader.continuation(value);
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return true;
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} else {
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return false;
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}
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};
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SyncChannel.prototype.read = function (continuation) {
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var channel = this;
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var reader = { continuation: continuation };
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channel.readers.push(reader);
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if (!channel.syncing) channel.sync();
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return function cancel() {
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var index = channel.readers.indexOf(reader);
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channel.readers.splice(index, 1);
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}
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};
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SyncChannel.prototype.write = function (value, continuation) {
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continuation = continuation || function () { };
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var channel = this;
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var writer = { continuation: continuation, value: value };
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channel.writers.push(writer);
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if (!channel.syncing) channel.sync();
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return function cancel() {
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var index = channel.writers.indexOf(writer);
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channel.writers.splice(index, 1);
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}
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};
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SyncChannel.prototype.sync = function () {
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var channel = this;
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channel.syncing = true;
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(function loop() {
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setImmediate(function () {
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if (channel.readers.length > 0 && channel.writers.length > 0) {
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var reader = channel.readers.shift();
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var writer = channel.writers.shift();
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reader.continuation(writer.value);
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writer.continuation();
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loop();
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} else {
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channel.syncing = false;
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}
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});
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})();
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};
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module.exports = SyncChannel;
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