77 lines
2.1 KiB
JavaScript
77 lines
2.1 KiB
JavaScript
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Test the situation in which two cases of a select can
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// both end up running. See http://codereview.appspot.com/180068.
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"use strict";
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const Channel = require(`../../lib`);
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it(`doubleselect`, async function() {
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this.timeout(10 * 1000);
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const iterations = 100000; // number of iterations
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// sender sends a counter to one of four different channels. If two cases both
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// end up running in the same iteration, the same value will be sent to two
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// different channels.
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const sender = async (n, c1, c2, c3, c4) => {
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for (let i = 0; i < n; i++) {
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await Channel.select([c1.push(i), c2.push(i), c3.push(i), c4.push(i)]);
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}
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c1.close();
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c2.close();
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c3.close();
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c4.close();
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};
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// mux receives the values from sender and forwards them onto another channel.
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// It would be simpler to just have sender's four cases all be the same
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// channel, but this doesn't actually trigger the bug.
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const mux = async (output, input, done) => {
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await input.forEach(async value => {
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await output.push(value);
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});
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await done.push(true);
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};
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// recver gets a steam of values from the four mux's and checks for
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// duplicates.
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const recver = input => {
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const seen = new Map();
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input.forEach(v => {
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if (seen.has(v)) {
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throw new Error(`got duplicate value: ${v}`);
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}
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seen.set(v, true);
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});
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};
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const c1 = Channel();
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const c2 = Channel();
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const c3 = Channel();
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const c4 = Channel();
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const done = Channel();
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const cmux = Channel();
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sender(iterations, c1, c2, c3, c4);
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mux(cmux, c1, done);
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mux(cmux, c2, done);
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mux(cmux, c3, done);
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mux(cmux, c4, done);
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// We keep the recver because it might catch more bugs in the future.
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// However, the result of the bug linked to at the top is that we'll
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// end up panicking with: "throw: bad g->status in ready".
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recver(cmux);
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await done.shift();
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await done.shift();
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await done.shift();
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await done.shift();
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cmux.close();
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});
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