yjs-mergeUpdates-example.ts

import fs from 'fs';
import * as yjs from "yjs";
import process from 'process';

const comparisons = [
	{
		update1: fs.readFileSync('/home/terrance/Downloads/1651186108083 hotter-otter e8b59b6ae4', null),
		update2: fs.readFileSync('/home/terrance/Downloads/1651186088891 hotter-otter b94ca284fa', null),
	},
	{
		update1: fs.readFileSync('/home/terrance/Downloads/1651186951260 hotter-otter 8b576f85d3', null),
		update2: fs.readFileSync('/home/terrance/Downloads/1651186765027 hotter-otter 07269a0010', null),
	}
];

const typedKeys = <T extends {}>(x: T): (keyof T)[] => Object.keys(x) as any;
const logMemoryDiff = (before: NodeJS.MemoryUsage, after: NodeJS.MemoryUsage) => {
	console.log(typedKeys(after).reduce((acc, k) => ({
		...acc,
		[k]: Math.round(100 * (after[k] - before[k]) / 1024 / 1024) / 100,
	}), {} as {[key: string]: number}));
}

const mergeUpdatesTest = async () => {
	for (let updatePair of comparisons) {
		const { update1, update2 } = updatePair;

		console.log('');

		[update1, update2].forEach(update => {
			const { structs } = yjs.decodeUpdate(update);
			console.log(`${structs.length} structs`);
		});

		console.log('----------------');

		// For some reason one gc() doesn't clean up 'structs' above, but two does
		global!.gc!();
		global!.gc!();

		const memoryBefore = process.memoryUsage();
		const beforeTime = Date.now();

		const resultingUpdate = yjs.mergeUpdates([update1, update2]);

		const afterTime = Date.now();
		const memoryAfter = process.memoryUsage();

		console.log(`${afterTime-beforeTime} milliseconds`)
		console.log('update1.byteLength', update1.byteLength);
		console.log('update2.byteLength', update2.byteLength);
		console.log('resultingUpdate.byteLength', resultingUpdate.byteLength);
		logMemoryDiff(memoryBefore, memoryAfter);
	}
};

mergeUpdatesTest();

/*
626707 structs
609449 structs
----------------
613 milliseconds
update1.byteLength 11359087
update2.byteLength 11076124
resultingUpdate.byteLength 22435192
{
  rss: 84.63,
  heapTotal: 0,
  heapUsed: 0.61,
  external: 129.3,
  arrayBuffers: 129.3
}

1316911 structs
1155241 structs
----------------
1304 milliseconds
update1.byteLength 23811663
update2.byteLength 21135588
resultingUpdate.byteLength 44947233
{
  rss: 124.18,
  heapTotal: 0.25,
  heapUsed: 0.61,
  external: 253.21,
  arrayBuffers: 253.21
}
*/