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52 lines
1.5 KiB
JavaScript
52 lines
1.5 KiB
JavaScript
"use strict";
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const range = require("range").range;
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const pushBuffer = require("push-buffer");
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const derivedStream = require("@promistream/derived-stream");
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const { validateArguments } = require("@validatem/core");
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const required = require("@validatem/required");
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const isInteger = require("@validatem/is-integer");
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const isPositive = require("@validatem/is-positive");
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const isFunction = require("@validatem/is-function");
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module.exports = function createForkSelectForks(_streamCount, _selectionCallback) {
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let [ streamCount, selectionCallback ] = validateArguments(arguments, {
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streamCount: [ required, isInteger, isPositive ],
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selectionCallback: [ required, isFunction ]
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});
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return derivedStream((source) => {
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let buffer = pushBuffer({
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lanes: streamCount,
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select: selectionCallback,
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pull: async () => source.read()
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});
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return range(0, streamCount).map((streamIndex) => {
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return {
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_promistreamVersion: true,
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_promistreamIsSource: true,
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description: `fork-select stream (${streamIndex})`,
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abort: function (reason) {
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return source.abort(reason);
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},
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peek: async function () {
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// TODO: Improve the behaviour here somehow, maybe buffering up read values on every peek?
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return (buffer.countLanes(streamIndex).values > 0);
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},
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read: async function () {
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try {
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let value = await buffer.request(streamIndex);
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return value;
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} catch (error) {
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throw error;
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}
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}
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};
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});
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});
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};
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