Some Tips of Golang

Table of Contents

• Some Tips of Golang
  • Table of Contents
  • Context
  • time.After

Context

https://siadat.github.io/post/context

Context package was initially designed to implement:

1. Request cancellation
2. Deadline

Instead of forcing a function to stop, the caller should inform it that its work is no longer needed. Caller sends the information about cancellation and let the function decide how to deal with it. For example, a function could clean up and return early when it is informed that its work is no longer needed.

The caller prepares the context and passes it to the callee.

parentContext := context.Background()
ctx, cancel := context.WithDeadline(parentContext, time)
// or
ctx, cancel := context.WithTimeout(parentContext, duration)

The direction of the cancellation only goes down from parent to child.

The callee checks if the context is cancelled.

func Perform(ctx context.Context) error {
    for {
        SomeFunction()

        select {
        case <-ctx.Done():
            return ctx.Err()
        case <-time.After(time.Second):
            // wait for 1 second
        }
    }
    return nil
}

context.TODO() returns an empty context like context.Background(). TODO is used while refactoring functions to support context.

time.After

Use it in goroutine to wait for some time.

select {
case <-ctx.Done():
    return ctx.Err()
case <-time.After(time.Second):
    // wait for 1 second
}