I have an endpoint on my server named "/order".
When it gets triggered, I need to send an order over to an API. Sometimes, because some data over ipfs takes too long to download, the order fails within the try-catch block, and I need to resend it.
Since a while loop that tries to resend the order until it is successful would be blocking other requests, I thought I could make one myself using recursion and a setTimeout, to try to send the same request, say, 3 times every 5 minutes and if the third time it fails then it won't try again.
I wanted to know if this was the right way to achieve the non-blocking functionality and if there are some vulnerabilities/things I'm not taking into account:
async function makeOrder(body, tries) {
if (tries > 0) {
let order;
try {
order = getOrderTemplate(body.shipping_address)
for (const index in body.line_items) {
order.items.push(await getItemTemplate(body.line_items[index]))
}
await sendOrderToAPI(order)
} catch (err) {
setTimeout(function(){
makeOrder(body, tries - 1)
}, 180000)
}
} else {
console.log("order n " + body.order_number + " failed")
//write failed order number to database to deal with it later on
}
}
One significant problem is that, if there's a problem, it'll return a Promise that resolves not when the final API call is finished, but when the initial (failed) API call is finished. This:
setTimeout(function(){
makeOrder(body, tries - 1)
}, 180000)
is not chained properly with the async function outside.
As a result, the following logic will fail:
makeOrder(body, 3)
.then(() => {
// All orders are made
})
Promisify it instead, so that the recursive call can be chained with the outer function easily.
const delay = ms => new Promise(resolve => setTimeout(resolve, ms));
async function makeOrder(body, tries) {
if (tries > 0) {
let order;
try {
order = getOrderTemplate(body.shipping_address)
for (const index in body.line_items) {
order.items.push(await getItemTemplate(body.line_items[index]))
}
await sendOrderToAPI(order)
} catch (err) {
await delay(180_000);
return makeOrder(body, tries - 1);
}
} else {
console.log("order n " + body.order_number + " failed")
//write failed order number to database to deal with it later on
}
}
Another possible improvement would be to, instead of awaiting inside a loop here:
for (const index in body.line_items) {
order.items.push(await getItemTemplate(body.line_items[index]))
}
to use Promise.all, or a different mechanism that allows for fetching multiple templates at once, instead of having to wait for each one-by-one in serial.
Another potential issue is that makeOrder does not reject when it exceeds the number of tries allowed. That is, the consumer wouldn't be able to do:
makeOrder(body, 3)
.catch((error) => {
// implement logic here to handle the error
})
If you wanted to permit the above, at the very end of makeOrder, throw at the same time you're logging:
} else {
console.log("order n " + body.order_number + " failed")
//write failed order number to database to deal with it later on
throw new Error('Failed');
}