WIP Spike Test harden perf on XS

packages/xsnap/harden-perf-node/data.readme

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+turing-node-data.json was captured on my local linux box named 'turing',
+whose /proc/cpuinfo says:
+
+   model name    : Intel(R) Xeon(R) CPU E3-1230L v3 @ 1.80GHz
+
+by running './drive-node-perf.sh > data.json' and then lightly editing
+data.json to add [] and remove a trailing comma.
+
+ -Brian Warner, 18-may-2021

packages/xsnap/harden-perf-node/drive-node-perf.sh

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+#!/bin/bash
+
+for name in nothing list hardList listHard; do
+    for branding in BOTH POSITIVE NEGATIVE; do
+        # 'listHard' is the most time consuming, 10000 takes 90s
+        for count in 10 100 1000 10000; do
+            node -r esm ./t-node-perf.js $branding $name $count |grep -v "Removing"
+        done
+    done
+done

packages/xsnap/harden-perf-node/t-node-perf.js

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+import { branding, name, count } from './t-setup.js';
+import { performance } from 'perf_hooks';
+
+function f(count, body, post) {
+  const before = performance.now();
+  let list = {};
+  for (let i = 0; i < count; i++) {
+    if (body === '//nothing') {
+      //nothing
+    } else if (body === 'list = {next: list};') {
+      list = {next: list};
+    } else if (body === 'list = harden({next: list});') {
+      list = harden({next: list});
+    } else {
+      throw Error(`unknown body '${body}'`);
+    }
+  }
+  if (post === '//nothing') {
+    // nothing
+  } else if (post === 'harden(list);') {
+    harden(list);
+  } else {
+    throw Error(`unknown post '${post}'`);
+  }
+  const after = performance.now();
+  return(after - before);
+}
+
+const [body, post] = {
+  nothing: ['//nothing', '//nothing'],
+  list: ['list = {next: list};', '//nothing'],
+  listHard: ['list = harden({next: list});', '//nothing'],
+  hardList: ['list = {next: list};', 'harden(list);'],
+}[name];
+
+const title = `time, ${branding}, ${count}, ${name}`;
+try {
+  const innerTime = f(count, body, post);
+  const record = {
+    branding,
+    count,
+    name,
+    innerTime,
+  };
+  console.log(JSON.stringify(record, undefined, ' '), '\n,\n');
+} catch (e) {
+  console.log(`error`, e);
+  process.exit(1);
+}

packages/xsnap/harden-perf-node/t-setup.js

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+import 'ses';
+
+const argv = process.argv.splice(2);
+const [branding, name, count_s] = argv;
+const count = Number(count_s);
+globalThis.HARDEN_BRANDING = branding;
+lockdown({});
+
+export { branding, name, count };