Hi!
Let me give you some context. context.Context in Go serves two main
purposes:
1. Cancellation and timeout support.
2. A carrier of values, as a de-facto replacement for thread-local
variables.
I have a problem with the first item. Cancellation and timeouts
automatically propagate to child contexts, which is usually a good thing.
However, sometimes it would be nice to be able to create child contexts
that share only values but not the timeout/cancellation.
Typically it's needed if the code wants to start a background goroutine to
do some work. E.g. in pseudocode:
func StartConnection(ctx context.Context, addr string) (err error) {
conn, err = net.DialWithContext(ctx, addr)
if err != nil { return err; }
go heartbeatFunc(ctx, conn);
...
}
Right now it's not possible to do that cleanly. The only way is to create a
brand new context and copy all the needed values. Which requires the code
to know which values might be needed.
Is there an interest in proposal to add this functionality? It can look
like another method: `context.Detached(ctx context.Context)` that simply
does not add it to the parent cancellation tree.
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