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denoland-deno/cli/tests/node_compat/test/parallel/test-fs-read-stream-concurrent-reads.js

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// deno-fmt-ignore-file
// deno-lint-ignore-file
// Copyright Joyent and Node contributors. All rights reserved. MIT license.
// Taken from Node 18.12.1
// This file is automatically generated by "node/_tools/setup.ts". Do not modify this file manually
'use strict';
const common = require('../common');
const fixtures = require('../common/fixtures');
const assert = require('assert');
const fs = require('fs');
// Test that concurrent file read streams dont interfere with each others
// contents, and that the chunks generated by the reads only retain a
// 'reasonable' amount of memory.
// Refs: https://github.com/nodejs/node/issues/21967
const filename = fixtures.path('loop.js'); // Some small non-homogeneous file.
const content = fs.readFileSync(filename);
const N = 2000;
let started = 0;
let done = 0;
const arrayBuffers = new Set();
function startRead() {
++started;
const chunks = [];
fs.createReadStream(filename)
.on('data', (chunk) => {
chunks.push(chunk);
arrayBuffers.add(chunk.buffer);
})
.on('end', common.mustCall(() => {
if (started < N)
startRead();
assert.deepStrictEqual(Buffer.concat(chunks), content);
if (++done === N) {
const retainedMemory =
[...arrayBuffers].map((ab) => ab.byteLength).reduce((a, b) => a + b);
assert(retainedMemory / (N * content.length) <= 3,
`Retaining ${retainedMemory} bytes in ABs for ${N} ` +
`chunks of size ${content.length}`);
}
}));
}
// Dont start the reads all at once that way we would have to allocate
// a large amount of memory upfront.
for (let i = 0; i < 6; ++i)
startRead();