pull-drain-gently/test.js

Like pull.drain, but respects CPU load

var pull = require('pull-stream');
var test = require('tape');
var usage = require('cpu-percentage');
var fs = require('fs');
var drainGently = require('./index');

function delay() {
  return pull.asyncMap(function (e, cb) {
    setTimeout(function () {
      cb(null, e);
    });
  });
}

test('like pull.drain: abort on drain', function (t) {
  var c = 100;
  var drain = drainGently(
    function () {
      if (c < 0) throw new Error('stream should have aborted');
      if (!--c) return false; //drain.abort()
    },
    function () {
      t.end();
    },
  );

  pull(pull.infinite(), drain);
});

test('like pull.drain: abort on drain - async', function (t) {
  var c = 100;
  var drain = drainGently(
    function () {
      if (c < 0) throw new Error('stream should have aborted');
      if (!--c) return drain.abort();
    },
    function () {
      t.end();
    },
  );

  pull(pull.infinite(), delay(), drain);
});

test('like pull.drain: abort on drain - sync', function (t) {
  var c = 100;
  var drain = drainGently(
    function () {
      if (c < 0) throw new Error('stream should have aborted');
      if (!--c) return drain.abort();
    },
    function () {
      t.end();
    },
  );

  pull(pull.infinite(), drain);
});

test('like pull.drain: abort on drain - async, out of cb', function (t) {
  t.plan(2);
  var c = 0,
    ERR = new Error('test ABORT');
  var drain = drainGently(
    function () {
      --c;
    },
    function (err) {
      t.ok(c < 0);
      t.equal(err, ERR);
      t.end();
    },
  );

  pull(pull.infinite(), delay(), drain);

  setTimeout(function () {
    drain.abort(ERR);
  }, 100);
});

test('supports drainGently()', function (t) {
  pull(pull.count(7), drainGently());

  setTimeout(() => {
    t.end();
  }, 50);
});

test('supports drainGently(null, done)', function (t) {
  t.plan(1);
  pull(
    pull.count(7),
    drainGently(null, () => {
      t.pass('all good');
      t.end();
    }),
  );
});

test('supports drainGently(opts)', function (t) {
  pull(pull.count(7), drainGently({ceiling: 90, wait: 90}));

  setTimeout(() => {
    t.end();
  }, 50);
});

test('supports drainGently(opts, null)', function (t) {
  pull(pull.count(7), drainGently({ceiling: 90, wait: 90}, null));

  setTimeout(() => {
    t.end();
  }, 50);
});

test('respects `maxPause` opt', function (t) {
  t.plan(1);
  t.timeoutAfter(8000);

  const ceiling = 0.01; // super low threshold, most likely never met
  const maxPause = 50; // ms

  pull(
    pull.count(200),
    pull.asyncMap((x, cb) => fs.readFile('./package.json', cb)),
    pull.map((contents) =>
      Buffer.from(contents.toString('hex').toUpperCase())
        .toString('base64')
        .toLowerCase()
        .substr(0, 20),
    ),
    drainGently({ceiling, maxPause, wait: 16}, null, () => {
      t.pass('all data points processed');
      t.end();
    }),
  );
});

test('heavy processing is below the prescribed CPU 90% ceiling', function (t) {
  t.plan(1);

  const ceiling = 90;

  const start = usage();
  pull(
    pull.count(20000),
    pull.asyncMap((x, cb) => fs.readFile('./package.json', cb)),
    pull.map((contents) =>
      Buffer.from(contents.toString('hex').toUpperCase())
        .toString('base64')
        .toLowerCase()
        .substr(0, 20),
    ),
    drainGently(
      {ceiling, wait: 40},
      () => {},
      () => {
        const stats = usage(start);
        console.log(usage(start));
        t.true(stats.percent < ceiling + 3, 'CPU usage was approx. 90%');
        t.end();
      },
    ),
  );
});

test('heavy processing is below the prescribed CPU 50% ceiling', function (t) {
  t.plan(1);

  const ceiling = 50;

  const start = usage();
  pull(
    pull.count(8000),
    pull.asyncMap((x, cb) => fs.readFile('./package.json', cb)),
    pull.map((contents) =>
      Buffer.from(contents.toString('hex').toUpperCase())
        .toString('base64')
        .toLowerCase()
        .substr(0, 20),
    ),
    drainGently({ceiling, wait: 40}, null, () => {
      const stats = usage(start);
      console.log(usage(start));
      t.true(stats.percent < ceiling + 3, 'CPU usage was approx. 50%');
      t.end();
    }),
  );
});