This module is intended to wait for the same promise result in different parallels executions.
As an example it could be used to wait for a token renew inside an axios interceptor.
Be aware that if your promise returns a non primitive value all the awaiters will get the same reference so clone it if you need to modify it.
Quick example:
async function meassureExecution(op: () => Promise<any>) {
var hrstart = process.hrtime()
var start = new Date()
await op();
var end = new Date().getTime() - start.getTime();
const hrend = process.hrtime(hrstart);
console.info('Execution time: %dms', end)
console.log('Execution time (hr): %dms', (hrend[0] * 1000) + (hrend[1] / 1000000))
}
export async function testMultiplex() {
let executionsCount = 0;
const longTask = () => {
return new Promise<number>(resolve => {
setTimeout(() => {
for (let a = 0; a < 100000000; a++) { }
executionsCount++;
resolve(1);
}, 100);
});
}
const longTaskMultiplexed = new MultiplexPromise(longTask);
let promises: Promise<any>[] = [];
let resultCounter = 0;
for (let i = 0; i < 10; i++) {
promises.push(longTask().then(() => resultCounter++));
}
console.log('No Multiplex')
await meassureExecution(() => Promise.all(promises));
console.log('Executions: ' + executionsCount);
console.log('Results count: ' + resultCounter);
resultCounter = 0;
executionsCount = 0;
promises = [];
for (let i = 0; i < 10; i++) {
promises.push(longTaskMultiplexed.run().then(() => resultCounter++));
}
console.log('Multiplex')
await meassureExecution(() => Promise.all(promises));
console.log('Executions: ' + executionsCount);
console.log('Results count: ' + resultCounter);
}Fn testMultiplex outputs:
No Multiplex
Execution time: 747ms
Execution time (hr): 746.136796ms
Executions: 10
Results count: 10
Multiplex
Execution time: 165ms
Execution time (hr): 165.597155ms
Executions: 1
Results count: 10