Reuse context.WithTimeout in delay functions

Reusing context.WithTimeout in a delay function is an effective way to provide better control and flexibility when handling timeout operations. By using the context.WithTimeout function provided by PHP editor Youzi, you can set a timeout during function execution. Once the set time is exceeded, the function will automatically exit and return an error message. This method can avoid long-term blocking of functions and improve the stability and responsiveness of the program. At the same time, by reusing context.WithTimeout in the delay function, timeout control of different functions can also be achieved, making the code more concise and easier to maintain.

Question content

The following code snippet (reduced for brevity) from the go quickstart blog post for mongodb creates context.withtimeout when connecting to the database, and Reusing the delayed disconnect function, which I think is problematic.

func main() {
    client, _ := mongo.newclient(options.client().applyuri("<atlas_uri_here>"))
    ctx, _ := context.withtimeout(context.background(), 10*time.second)

    _ = client.connect(ctx)
    defer client.disconnect(ctx)
}

My thoughts-

context.withtimeout Set the deadline in unix time on creation. So it makes sense to pass it to connect since we want to cancel the process of establishing the connection when the time limit (i.e. the derived unix time) is exceeded.

Now, passing the same ctx to a delayed disconnect (which will most likely be called later in the future) will cause ctx's time to become a thing of the past. Meaning, it has expired by the time the function starts executing. This is not the expected result and breaks the logic of referencing the disconnect documentation -

If the context expires via cancellation,
deadline, or timeout before the in use connections have returned, the in use
connections will be closed, resulting in the failure of any in flight read
or write operations.

Please tell me if and how something is wrong and/or missing.

Solution

Your understanding is correct.

That's enough in the example, as the example just connects to the database, performs some example operations (such as listing the database), and then main() ends, so the delayed disconnect is run using the same context Won't cause any trouble (the example will/should run fine in 10 seconds).

In "real world" applications this is certainly not the case. So you probably won't use the same context to connect and disconnect (unless that context doesn't timeout).

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