concurrency - Correct use of go context.Context -

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i read article: build own web framework in go , sharing values among handlers picked context.context , i'm using in following way share values across handlers , middlewares:

type appcontext struct {     db     *sql.db     ctx    context.context     cancel context.cancelfunc  }   func (c *appcontext)authhandler(next http.handler) http.handler {     fn := func(w http.responsewriter, r *http.request {         defer c.cancel() //this feels weird         authtoken := r.header.get("authorization") // fakes form         c.ctx = getuser(c.ctx, c.db, authtoken) // feels weird         next.servehttp(w, r)     }      return http.handlerfunc(fn) }  func (c *appcontext)adminhandler(w http.responsewriter, r *http.request) {     defer c.cancel()     user := c.ctx.value(0).(user)     json.newencoder(w).encode(user) }  func getuser(ctx context.context, db *sql.db, token string) context.context{     //this function mimics database access     return context.withvalue(ctx, 0, user{nome:"default user"}) }  func main() {     db, err := sql.open("my-driver", "my.db")     if err != nil {         panic(err)     }     ctx, cancel := context.withcancel(context.background())     appc := appcontext{db, ctx, cancel}     //.... }

everything working , handlers loading faster using gorilla/context questions are:

  1. is approach safe?
  2. is necessary defer c.cancel() function way i'm doing it?
  3. can use implement custom web framework using controllers struct share values models?

you have problem code because storing user app context. multiple users @ same time, doesn't work. context must related request not overwrote other requests. user must stored in request context. in articles use following gorilla function: context.set(r, "user", user). r request.

if want use context.context in app, should use gorilla wrapper (you can find @ end of article: https://blog.golang.org/context).

also, don't need context cancel. context.background() okay root context.


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