Re: [Caml-list] [Async / Cohttp_async] Problem getting all of the data in a response body

["Nicolás Ojeda Bär" <nicolas.ojeda.bar@lexifi.com>]

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Hi Shayne,

I am not very familiar with Async, but did you remember to run the
scheduler (Scheduler.go () or similar) ?

Cheers,
Nicolas


On Thu, Jul 6, 2017 at 12:55 AM, Shayne Fletcher <
shayne.fletcher.50@gmail.com> wrote:

> Can anyone help me out with this?
>
> In short, I'm doing a HTTP POST with a handler along the lines of:
> ```
> fun ((resp : Cohttp_async.Response.t)
>     , (body : Cohttp_async.Body.t)) : unit Or_error.t ->
>      let r : string Async.Pipe.Reader.t = Cohttp_async.Body.to_pipe body in
>      let _ =
>       Async.Pipe.iter
>         r
>         ~continue_on_error:true
>         ~f:(fun s -> Async.return (printf "%s" s)) in
>       (Ok () : unit Or_error.t)
>
> ```
>
> Each time I invoke the program I get, more or less output (very
> occasionally none) but never all of it. The response header says it's
> "fixed  2700816" and indeed, if I replace the code above with
> ```
> fun ((resp : Cohttp_async.Response.t)
>     , (body : Cohttp_async.Body.t)) : unit Or_error.t ->
>   let r : string Async.Pipe.Reader.t = Cohttp_async.Body.to_pipe body in
>   let n : int Deferred.t =
>     Async.Pipe.fold
>       r
>       ~init:0
>       ~f:(fun acc s ->
>             printf "acc : %d\n" acc; Async.return (acc + String.length s)
>           ) in
>   let _ : unit Deferred.t = n  >>| fun n -> printf "Chars read : %d" n in
>   (Ok () : unit Or_error.t)
>
>  ```
> then (for example), on the first run I might see
> ```
> acc : 0
> acc : 1118
> acc : 7503
> acc : 8780
>
> ```
>
> and then on the second run I might see
> ```
> acc : 0
> acc : 1118
> acc : 4949
>
> ```
> but never have I seen "Chars read : 2700816".
>
> I've tried a bunch of different things:
>
>   - `Pipe.read_all`:
>      ```
>        let _ =
>          Async.Pipe.read_all r >>|
>          fun q -> Queue.iter q ~f:(fun s -> printf "%s" s) in
>        ...
>
>      ```
>      No output.
>
>   - `Pipe.drain_and_count`:
>     ```
>       let _ =
>         Async.Pipe.drain_and_count r >>|
>         fun n -> printf "Count %d\n" n in
>       ...
>
>     ```
>     No output.
>
>   - `Pipe.to_list`:
>      ```
>      let _ =
>        Async.Pipe.to_list r >>|
>        fun l -> printf "%s" (String.concat ~sep:"" l) in
>      ...
>
>      ```
>      No output.
>
> Also tried the obvious:
>
>   - `Cohttp_async.Body.to_string`:
>     ```
>       let s = Cohttp_async.Body.to_string body in
>       let _ = s >>| fun  s -> printf "%s" s in
>       ...
>
>     ```
>     No output.
>
> I'm new to this and obviously missing something fundamental :) Is there a
> kind soul out there who can give me a hint on how to proceed please?
>
> Thanks!
>
> --
> Shayne Fletcher
>

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