是否总是需要使用 await 调用异步函数？

Question

First some context, I have an async function which logs messages on a MongoDB database.

async function log_message(sender, conversationId, text) {
    try {
        const msg = new Message({
            sender: sender,
            conversationId: conversationId,
            text: text
        });
        await msg.save();
        console.log("Done");
    } catch (e) {
        console.log("An error happened while logging the message: " + e)
    }
}

Now, I have another async function that gets triggered when I receive a message and takes care of processing it and fetching some data. As soon as this function get triggered I call "log_message" to log the message on my database, but I do not want to call it with await, otherwise, I would wait until the "log_message" function returns before processing the message slowing down the message processing.

    async getReply(username, message) {
        log_message("user", username, message);
        console.log("HI");
        let reply = await this.rs.reply(username, message, this);
        return reply;
    }

Nevertheless, Jetbrains Webstorm gives me this warning "Missing await for an async function call". Now, I did some tests and if I call the function without await the system behaves as I expect, the message gets processed and my logging function writes the data on the db asynchronously without interrupting. If instead, I put the await keyword before calling the logging function the execution of the code in the main function gets suspended until the db has not been written.

Could someone tell me whether there are some flaws in the way I intended the usage of the async/await keywords?

Answer 1

It is not necessary if your logic doesn't require the result of the async call. Although not needed in your case, the documentation lists two benefits to having that warning enabled:

While this is generally not necessary, it gives two main benefits. The first one is that you won't forget to add 'await' when surrounding your code with try-catch. The second one is that having explicit 'await' helps V8 runtime to provide async stack traces

Answer 2

When you set async to a method, the method expects to use await inside its scope. Because the functionality of async keyword is like if you were telling to the method that inside its scope there's another process which must be completed before can proceed to the method process.

In other words, if you don't want to await to some other process to finish, then you should avoid async keyword in your method.

Here, makes sense the await keyword:

await msg.save();

Because it awaits till it's saved before log that is Done. But in the methods you want all run without waiting for other processes to end. Just don't use asyn keyword. If you don't want to await here:

await this.rs.reply(username, message, this);

Don't use async here:

async getReply(username, message)

If you need to await something in getReply then you should add async keyword, otherwise, is not necessary the keyword.

Answer 3

每当您想等待某个操作时，您都必须将 await 与其关联，但在将 await 与其关联之前，您需要使父函数异步。

Answer 4

Though I see you have answers here.

Let me tell you the thing now!

Async functions are not necessarily required to have an await call inside it, but the reason behind making a function async is that you need an asynchronous call for which you want to wait for the result before moving forward in the thread.

async getReply(username, message) {
        log_message("user", username, message);
        console.log("HI");
        let reply = await this.rs.reply(username, message, this);
        return reply;
    }

The above function will work, but why exactly would you make it async? Since you aren't using any asynchronous functionality. It works the same if used as following:-

getReply(username, message) {
        log_message("user", username, message);
        console.log("HI");
        let reply = await this.rs.reply(username, message, this);
        return reply;
    }