ember-source/dist/packages/@ember/instrumentation/index.js

A JavaScript framework for creating ambitious web applications

import { E as ENV } from '../../shared-chunks/env-CwR5CFCu.js';
import '../debug/index.js';
import { isDevelopingApp } from '@embroider/macros';
import { assert } from '../debug/lib/assert.js';

/* eslint no-console:off */
/* global console */

/**
@module @ember/instrumentation
@private
*/

/**
  The purpose of the Ember Instrumentation module is
  to provide efficient, general-purpose instrumentation
  for Ember.

  Subscribe to a listener by using `subscribe`:

  ```javascript
  import { subscribe } from '@ember/instrumentation';

  subscribe("render", {
    before(name, timestamp, payload) {

    },

    after(name, timestamp, payload) {

    }
  });
  ```

  If you return a value from the `before` callback, that same
  value will be passed as a fourth parameter to the `after`
  callback.

  Instrument a block of code by using `instrument`:

  ```javascript
  import { instrument } from '@ember/instrumentation';

  instrument("render.handlebars", payload, function() {
    // rendering logic
  }, binding);
  ```

  Event names passed to `instrument` are namespaced
  by periods, from more general to more specific. Subscribers
  can listen for events by whatever level of granularity they
  are interested in.

  In the above example, the event is `render.handlebars`,
  and the subscriber listened for all events beginning with
  `render`. It would receive callbacks for events named
  `render`, `render.handlebars`, `render.container`, or
  even `render.handlebars.layout`.

  @class Instrumentation
  @static
  @private
*/
let subscribers = [];
let cache = {};
function populateListeners(name) {
  let listeners = [];
  for (let subscriber of subscribers) {
    if (subscriber.regex.test(name)) {
      listeners.push(subscriber.object);
    }
  }
  cache[name] = listeners;
  return listeners;
}
const time = (() => {
  let perf = 'undefined' !== typeof window ? window.performance || {} : {};
  let fn = perf.now || perf.mozNow || perf.webkitNow || perf.msNow || perf.oNow;
  return fn ? fn.bind(perf) : Date.now;
})();
function isCallback(value) {
  return typeof value === 'function';
}

/**
  Notifies event's subscribers, calls `before` and `after` hooks.

  @method instrument
  @for @ember/instrumentation
  @static
  @param {String} [name] Namespaced event name.
  @param {Object} payload
  @param {Function} callback Function that you're instrumenting.
  @param {Object} binding Context that instrument function is called with.
  @private
*/

function instrument(name, p1, p2, p3) {
  let _payload;
  let callback;
  let binding;
  if (arguments.length <= 3 && isCallback(p1)) {
    callback = p1;
    binding = p2;
  } else {
    _payload = p1;
    callback = p2;
    binding = p3;
  }

  // fast path
  if (subscribers.length === 0) {
    return callback.call(binding);
  }

  // avoid allocating the payload in fast path
  let payload = _payload || {};
  let finalizer = _instrumentStart(name, () => payload);
  if (finalizer === NOOP) {
    return callback.call(binding);
  } else {
    return withFinalizer(callback, finalizer, payload, binding);
  }
}
function flaggedInstrument(_name, _payload, callback) {
  return callback();
}
function withFinalizer(callback, finalizer, payload, binding) {
  try {
    return callback.call(binding);
  } catch (e) {
    payload.exception = e;
    throw e;
  } finally {
    finalizer();
  }
}
function NOOP() {}

// private for now

function _instrumentStart(name, payloadFunc, payloadArg) {
  if (subscribers.length === 0) {
    return NOOP;
  }
  let listeners = cache[name];
  if (!listeners) {
    listeners = populateListeners(name);
  }
  if (listeners.length === 0) {
    return NOOP;
  }
  let payload = payloadFunc(payloadArg);
  let STRUCTURED_PROFILE = ENV.STRUCTURED_PROFILE;
  let timeName;
  if (STRUCTURED_PROFILE) {
    timeName = `${name}: ${payload.object}`;
    console.time(timeName);
  }
  let beforeValues = [];
  let timestamp = time();
  for (let listener of listeners) {
    beforeValues.push(listener.before(name, timestamp, payload));
  }
  const constListeners = listeners;
  return function _instrumentEnd() {
    let timestamp = time();
    for (let i = 0; i < constListeners.length; i++) {
      let listener = constListeners[i];
      (isDevelopingApp() && !(listener) && assert('has listener', listener)); // Iterating over values
      if (typeof listener.after === 'function') {
        listener.after(name, timestamp, payload, beforeValues[i]);
      }
    }
    if (STRUCTURED_PROFILE) {
      console.timeEnd(timeName);
    }
  };
}

/**
  Subscribes to a particular event or instrumented block of code.

  @method subscribe
  @for @ember/instrumentation
  @static

  @param {String} [pattern] Namespaced event name.
  @param {Object} [object] Before and After hooks.

  @return {Subscriber}
  @private
*/
function subscribe(pattern, object) {
  let paths = pattern.split('.');
  let regexes = [];
  for (let path of paths) {
    if (path === '*') {
      regexes.push('[^\\.]*');
    } else {
      regexes.push(path);
    }
  }
  let regex = regexes.join('\\.');
  regex = `${regex}(\\..*)?`;
  let subscriber = {
    pattern,
    regex: new RegExp(`^${regex}$`),
    object
  };
  subscribers.push(subscriber);
  cache = {};
  return subscriber;
}

/**
  Unsubscribes from a particular event or instrumented block of code.

  @method unsubscribe
  @for @ember/instrumentation
  @static

  @param {Object} [subscriber]
  @private
*/
function unsubscribe(subscriber) {
  let index = 0;
  for (let i = 0; i < subscribers.length; i++) {
    if (subscribers[i] === subscriber) {
      index = i;
    }
  }
  subscribers.splice(index, 1);
  cache = {};
}

/**
  Resets `Instrumentation` by flushing list of subscribers.

  @method reset
  @for @ember/instrumentation
  @static
  @private
*/
function reset() {
  subscribers.length = 0;
  cache = {};
}

export { _instrumentStart, flaggedInstrument, instrument, reset, subscribe, subscribers, unsubscribe };