lib: avoid quadratic shift() in startup snapshot callback · nodejs/node@97e32c7

'use strict';

// Benchmarks startup time when deserialize callbacks are registered in a

// startup snapshot, measuring real binary execution with --snapshot-blob.

const common = require('../common.js');

const { spawnSync } = require('child_process');

const { mkdtempSync, writeFileSync, rmSync } = require('fs');

const { tmpdir } = require('os');

const path = require('path');

const bench = common.createBenchmark(main, {

count: [10, 100, 1000, 10000],

n: [30],

});

function buildSnapshot(snapshotBlob, fixtureScript, count) {

writeFileSync(fixtureScript, `

'use strict';

const v8 = require('node:v8');

for (let i = 0; i < ${count}; i++) {

v8.startupSnapshot.addDeserializeCallback(() => {});

}

v8.startupSnapshot.setDeserializeMainFunction(() => {});

`);

const result = spawnSync(process.execPath, [

'--snapshot-blob', snapshotBlob,

'--build-snapshot', fixtureScript,

]);

if (result.status !== 0) {

throw new Error(`Failed to build snapshot:\n${result.stderr}`);

}

}

function main({ n, count }) {

const dir = mkdtempSync(path.join(tmpdir(), 'node-bench-snapshot-'));

const snapshotBlob = path.join(dir, 'snapshot.blob');

const fixtureScript = path.join(dir, 'build.js');

try {

buildSnapshot(snapshotBlob, fixtureScript, count);

const warmup = 3;

let finished = -warmup;

while (finished < n) {

const child = spawnSync(process.execPath, ['--snapshot-blob', snapshotBlob]);

if (child.status !== 0) {

throw new Error(`Snapshot run failed:\n${child.stderr}`);

}

finished++;

if (finished === 0) bench.start();

if (finished === n) bench.end(n);

}

} finally {

rmSync(dir, { recursive: true, force: true });

}

}