It would be helpful to have a small example though, if you have on Galen,
to see how you're passing it around.
On Fri, Feb 18, 2022 at 11:10 AM Austin Cawley-Edwards <
austin.caw...@gmail.com> wrote:
> Looking through the statefun Context interface, it indeed doesn't give
> access to the underlying context.Context and the only implementation is
> package-private [1]. I don't think there would be a way to update the
> statfun.Context interface without introducing breaking changes, but if we
> were to make that implementation public, that might be a stopgap solution.
> e.g.,
>
> ```
> type StatefunContext struct {
> // expose embedded context
> context.Context
>
> // make the mutext private
> mu sync.Mutex
>
> // keep internals private
> self Address
> caller *Address
> storage *storage
> response *protocol.FromFunction_InvocationResponse
> }
> ```
>
> You could then do a type assertion in the handlers for this type of
> context, and modify the context on it directly. It would be a bit ugly, but
> may work.
>
> ```
> func (s aFunc) Invoke(ctx Context, message Message) error {
> if sCtx, ok := ctx.(*statefun.StatefunContext); ok {
> sCtx.Context = context.WithValue(sCtx.Context, "logger", aLogger)
> }
> // ...
> }
> ```
>
> Let me know what you all think,
> Austin
>
>
> [1]:
> https://github.com/apache/flink-statefun/blob/1dfe226d85fea05a46c8ffa688175b4c0f2d4900/statefun-sdk-go/v3/pkg/statefun/context.go#L66-L73
>
>
> On Fri, Feb 18, 2022 at 11:03 AM Galen Warren <ga...@cvillewarrens.com>
> wrote:
>
>> Sorry Austin, I didn't see your response before I replied. Yes, we're
>> saying the same thing.
>>
>> On Fri, Feb 18, 2022 at 10:56 AM Austin Cawley-Edwards <
>> austin.caw...@gmail.com> wrote:
>>
>> > Hey all, jumping in. This makes sense to me – for instance to attach a
>> > logger with some common metadata, e.g trace ID for the request? This is
>> > common in go to add arbitrary items without updating the method
>> signatures,
>> > similar to thread local storage in Java.
>> >
>> > On Fri, Feb 18, 2022 at 10:53 AM Till Rohrmann <trohrm...@apache.org>
>> > wrote:
>> >
>> > > Thanks for the clarification Galen. If you call the other Go
>> functions,
>> > > then you could also pass the other values as separate arguments to
>> these
>> > > functions, can't you?
>> > >
>> > > Cheers,
>> > > Till
>> > >
>> > > On Fri, Feb 18, 2022 at 3:31 PM Galen Warren <ga...@cvillewarrens.com
>> >
>> > > wrote:
>> > >
>> > > > The former.
>> > > >
>> > > > I think there's potential for confusion here because we're using the
>> > > > word *function
>> > > > *in a couple of senses. One sense is a *stateful function*; another
>> > sense
>> > > > is a *Go function*.
>> > > >
>> > > > What I'm looking to do is to put values in the Context so that
>> > downstream
>> > > > Go functions that receive the context can access those values. Those
>> > > > downstream Go functions would be called during one invocation of the
>> > > > stateful function.
>> > > >
>> > > > On Fri, Feb 18, 2022 at 6:48 AM Till Rohrmann <trohrm...@apache.org
>> >
>> > > > wrote:
>> > > >
>> > > > > Hi Galen,
>> > > > >
>> > > > > Am I understanding it correctly, that you would like to set some
>> > values
>> > > > in
>> > > > > the Context of function A that is then accessible in a downstream
>> > call
>> > > of
>> > > > > function B? Or would you like to set a value that is accessible
>> once
>> > > > > function A is called again (w/ or w/o the same id)?
>> > > > >
>> > > > > Cheers,
>> > > > > Till
>> > > > >
>> > > > > On Thu, Feb 17, 2022 at 10:59 PM Galen Warren <
>> > ga...@cvillewarrens.com
>> > > >
>> > > > > wrote:
>> > > > >
>> > > > > > Also, a potentially simpler way to support this would be to add
>> a
>> > > > > > SetContext method to the statefun.Context interface, and have it
>> > > assign
>> > > > > the
>> > > > > > wrapped context. This would not require changes to the function
>> > spec,
>> > > > or
>> > > > > > anything else, and would be more flexible.
>> > > > > >
>> > > > > > On Thu, Feb 17, 2022 at 1:05 PM Galen Warren <
>> > > ga...@cvillewarrens.com>
>> > > > > > wrote:
>> > > > > >
>> > > > > > > Thanks for the quick reply!
>> > > > > > >
>> > > > > > > What I'm trying to do is put some things into the context so
>> that
>> > > > > they're
>> > > > > > > available in downstream calls, perhaps in methods with pointer
>> > > > > receivers
>> > > > > > to
>> > > > > > > the function struct (MyFunc) but also perhaps in methods that
>> are
>> > > > > further
>> > > > > > > downstream that don't have access to MyFunc. If I'm
>> understanding
>> > > > > > > correctly, your proposal would work for the former but not the
>> > > > latter.
>> > > > > > >
>> > > > > > > An example would be to put a configured Logger into the
>> context
>> > > via a
>> > > > > > > WithLogger method (logging package - knative.dev/pkg/logging
>> -
>> > > > > > pkg.go.dev
>> > > > > > > <https://pkg.go.dev/knative.dev/pkg/logging#WithLogger>) and
>> > then
>> > > > pull
>> > > > > > it
>> > > > > > > out downstream via FromContext (logging package -
>> > > > > > knative.dev/pkg/logging
>> > > > > > > - pkg.go.dev <
>> > > https://pkg.go.dev/knative.dev/pkg/logging#FromContext
>> > > > > >).
>> > > > > > >
>> > > > > > >
>> > > > > > >
>> > > > > > >
>> > > > > > > On Wed, Feb 16, 2022 at 5:50 PM Seth Wiesman <
>> > sjwies...@gmail.com>
>> > > > > > wrote:
>> > > > > > >
>> > > > > > >> Hi Galen,
>> > > > > > >>
>> > > > > > >> No, that is not currently supported, the current idiomatic
>> way
>> > > would
>> > > > > be
>> > > > > > to
>> > > > > > >> pass those values to the struct implementing the Statefun
>> > > interface.
>> > > > > > >>
>> > > > > > >>
>> > > > > > >> type MyFunc struct { someRuntimeInfo string } func (m
>> *MyFunc)
>> > > > > > Invoke(ctx
>> > > > > > >> statefun.Context, message statefun.Message) error { } func
>> > main()
>> > > {
>> > > > > > >> builder
>> > > > > > >> := statefun.StatefulFunctionsBuilder()
>> > > > > > >> f := MyFunc { someRuntimeInfo: "runtime-provided" }
>> > > builder.WithSpec
>> > > > > > >> (statefun.StatefulFunctionSpec{ FunctionType:
>> > > statefun.TypeNameFrom(
>> > > > > > >> "example/my-func"), Function: f })
>> > > > > > >> http.Handle("/statefun", builder.AsHandler())
>> > > > > > >> _ = http.ListenAndServe(":8000", nil) }
>> > > > > > >>
>> > > > > > >> Would this work for you? Or what is the context (pun
>> intended)
>> > you
>> > > > are
>> > > > > > >> looking for?
>> > > > > > >>
>> > > > > > >> Seth
>> > > > > > >>
>> > > > > > >> On Wed, Feb 16, 2022 at 4:35 PM Galen Warren <
>> > > > ga...@cvillewarrens.com
>> > > > > >
>> > > > > > >> wrote:
>> > > > > > >>
>> > > > > > >> > When stateful functions are invoked, they are passed an
>> > instance
>> > > > of
>> > > > > > >> > statefun.Context, which wraps the context.Context received
>> by
>> > > the
>> > > > > HTTP
>> > > > > > >> > request. Is there any way to customize that context.Context
>> > to,
>> > > > say,
>> > > > > > >> hold
>> > > > > > >> > custom values, using ctx.WithValue()? I don't see a way
>> but I
>> > > > wanted
>> > > > > > to
>> > > > > > >> > ask.
>> > > > > > >> >
>> > > > > > >> > If not, would you be interested in a PR to add this
>> > > > functionality? A
>> > > > > > >> simple
>> > > > > > >> > way might be to add a property to StatefulFunctionSpec,
>> say:
>> > > > > > >> >
>> > > > > > >> > TransformContext func(ctx context.Context) context.Context
>> > > > > > >> >
>> > > > > > >> > ... that, if supplied, would be called to create a
>> customized
>> > > > > context
>> > > > > > >> that
>> > > > > > >> > would be used downstream?
>> > > > > > >> >
>> > > > > > >> > Thanks.
>> > > > > > >> >
>> > > > > > >>
>> > > > > > >
>> > > > > >
>> > > > >
>> > > >
>> > >
>> >
>>
>
