Files
react-native/Libraries/Interaction/JSEventLoopWatchdog.js
James Ide 0ee5f68929 Migrate "Libraries" from Haste to standard path-based requires (sans vendor & renderers) (#24749)
Summary:
This is the next step in moving RN towards standard path-based requires. All the requires in `Libraries` have been rewritten to use relative requires with a few exceptions, namely, `vendor` and `Renderer/oss` since those need to be changed upstream. This commit uses relative requires instead of `react-native/...` so that if Facebook were to stop syncing out certain folders and therefore remove code from the react-native package, internal code at Facebook would not need to change.

See the umbrella issue at https://github.com/facebook/react-native/issues/24316 for more detail.

[General] [Changed] - Migrate "Libraries" from Haste to standard path-based requires
Pull Request resolved: https://github.com/facebook/react-native/pull/24749

Differential Revision: D15258017

Pulled By: cpojer

fbshipit-source-id: a1f480ea36c05c659b6f37c8f02f6f9216d5a323
2019-05-08 08:48:59 -07:00

89 lines
2.6 KiB
JavaScript

/**
* Copyright (c) Facebook, Inc. and its affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*
* @format
* @flow
*/
'use strict';
const infoLog = require('../Utilities/infoLog');
const performanceNow = require('fbjs/lib/performanceNow');
type Handler = {
onIterate?: () => void,
onStall: (params: {lastInterval: number, busyTime: number}) => ?string,
};
/**
* A utility for tracking stalls in the JS event loop that prevent timers and
* other events from being processed in a timely manner.
*
* The "stall" time is defined as the amount of time in access of the acceptable
* threshold, which is typically around 100-200ms. So if the treshold is set to
* 100 and a timer fires 150 ms later than it was scheduled because the event
* loop was tied up, that would be considered a 50ms stall.
*
* By default, logs stall events to the console when installed. Can also be
* queried with `getStats`.
*/
const JSEventLoopWatchdog = {
getStats: function(): Object {
return {stallCount, totalStallTime, longestStall, acceptableBusyTime};
},
reset: function() {
infoLog('JSEventLoopWatchdog: reset');
totalStallTime = 0;
stallCount = 0;
longestStall = 0;
lastInterval = performanceNow();
},
addHandler: function(handler: Handler) {
handlers.push(handler);
},
install: function({thresholdMS}: {thresholdMS: number}) {
acceptableBusyTime = thresholdMS;
if (installed) {
return;
}
installed = true;
lastInterval = performanceNow();
function iteration() {
const now = performanceNow();
const busyTime = now - lastInterval;
if (busyTime >= thresholdMS) {
const stallTime = busyTime - thresholdMS;
stallCount++;
totalStallTime += stallTime;
longestStall = Math.max(longestStall, stallTime);
let msg =
`JSEventLoopWatchdog: JS thread busy for ${busyTime}ms. ` +
`${totalStallTime}ms in ${stallCount} stalls so far. `;
handlers.forEach(handler => {
msg += handler.onStall({lastInterval, busyTime}) || '';
});
infoLog(msg);
}
handlers.forEach(handler => {
handler.onIterate && handler.onIterate();
});
lastInterval = now;
setTimeout(iteration, thresholdMS / 5);
}
iteration();
},
};
let acceptableBusyTime = 0;
let installed = false;
let totalStallTime = 0;
let stallCount = 0;
let longestStall = 0;
let lastInterval = 0;
const handlers: Array<Handler> = [];
module.exports = JSEventLoopWatchdog;