How to create a new context from the old one ignoring context break in go?

Question

go

There is a context with kenzel. I need to create (inherit) a new context from it without a kenzel and not lose information (not Background() in general).

Answer 1

Wrap the context in an irrevocable one.

// WithoutCancel returns a context that is never canceled.
func WithoutCancel(ctx context.Context) context.Context {
  return noCancel{ctx: ctx}
}

type noCancel struct {
  ctx context.Context
}

func (c noCancel) Deadline() (time.Time, bool)       { return time.Time{}, false }
func (c noCancel) Done() <-chan struct{}             { return nil }
func (c noCancel) Err() error                        { return nil }
func (c noCancel) Value(key interface{}) interface{} { return c.ctx.Value(key) }

Call something like this:

package main

import (
  "context"
  "time"
)

func main() {
  ctx := context.Background()
  ctx, c := context.WithTimeout(ctx, 100*time.Millisecond)
  defer c()

  ctxNo := WithoutCancel(ctx)
  ...
}

If a new timeout is set after WithoutCancel, then the new timeout will work and will not be canceled by the timeout that could have been before WithoutCancel.