Example_contextHierarchy.go

package main

import (
	"context"
	"fmt"
	"regexp"
	"time"
)

func Example_contextHierarchy() {
	ctxV1 := context.WithValue(context.Background(), "foo", "bar")
	ctxV2 := context.WithValue(ctxV1, "foo", "baz")

	addrRe := regexp.MustCompile("0x[0-9a-f]+")

	vCtx := fmt.Sprintf("%#v", ctxV2)
	vCtx = addrRe.ReplaceAllString(vCtx, "0x0000000000")
	fmt.Println(vCtx)

	ctxCancel, cancel := context.WithCancel(ctxV2)
	defer cancel()
	cCtx := fmt.Sprintf("%#v", ctxCancel)
	cCtx = addrRe.ReplaceAllString(cCtx, "0x0000000000")
	fmt.Println(cCtx)

	ctxDeadline, cancelDeadline := context.WithDeadline(ctxV2, time.Now().Add(1*time.Hour))
	defer cancelDeadline()
	dCtx := fmt.Sprintf("%#v", ctxDeadline)
	dCtx = addrRe.ReplaceAllString(dCtx, "0x0000000000")
	dCtx = regexp.MustCompile("ext:[0-9]+").ReplaceAllString(dCtx, "ext:0000000000000")
	fmt.Println(dCtx)

	// Output:
	// &context.valueCtx{Context:(*context.valueCtx)(0x0000000000), key:"foo", val:"baz"}
	// &context.cancelCtx{Context:(*context.valueCtx)(0x0000000000), mu:sync.Mutex{state:0, sema:0x0000000000}, done:atomic.Value{v:interface {}(nil)}, children:map[context.canceler]struct {}(nil), err:error(nil), cause:error(nil)}
	// &context.timerCtx{cancelCtx:(*context.cancelCtx)(0x0000000000), timer:(*time.Timer)(0x0000000000), deadline:time.Time{wall:0x0000000000, ext:0000000000000, loc:(*time.Location)(0x0000000000)}}
}