context2

Three context shapes the standard library does not provide.

context gives you cancellation that propagates down and a Done you cannot explain. These three cover the cases where that is not what you want: work that must outlive the request that started it, a deadline that has to be extended after the fact, and a cancellation that says why.

import "gitlab.internal/tuan.quang.tran/aioz-common/context2"

Usage

Work that must not die with its request

// The cleanup still needs the request's values (trace ids, auth), but it must
// not be killed when the client hangs up.
go cleanup(context2.WithoutCancellation(ctx))

The returned context keeps the parent's values and drops its Done and its deadline. That is exactly why it is dangerous: nothing will ever cancel it, so give the work its own timeout or it leaks.

A deadline decided after the context was made

ctx, cancel := context2.WithRetimeout(ctx, 30*time.Second)
defer cancel()

WithRetimeout gives a fresh timeout to a context that may already be canceled, which context.WithTimeout cannot do: it inherits the parent's cancellation, so a canceled parent yields an already-dead child.

A cancellation that carries a reason

sub, cancel := context2.WithCustomCancel(ctx)
...
cancel(io.ErrUnexpectedEOF)
<-sub.Done()
sub.Err() // io.ErrUnexpectedEOF, not context.Canceled

context.Canceled tells a caller that something gave up, and nothing else. The place that decides to cancel usually knows why, and WithCustomCancel is how that reason reaches the place that reports the failure. Cancelling with the parent still surfaces the parent's error.

API

func WithoutCancellation(ctx context.Context) context.Context
func WithRetimeout(ctx context.Context, timeout time.Duration) (context.Context, context.CancelFunc)
func WithCustomCancel(ctx context.Context) (context.Context, func(error))