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Tyler Goodlet 5eb9144921 First draft "payload receiver in a new `.msg._ops`
As per much tinkering, re-designs and preceding rubber-ducking via many
"commit msg novelas", **finally** this adds the (hopefully) final
missing layer for typed msg safety: `tractor.msg._ops.PldRx`

(or `PayloadReceiver`? haven't decided how verbose to go..)

Design justification summary:
      ------ - ------
- need a way to be as-close-as-possible to the `tractor`-application
  such that when `MsgType.pld: PayloadT` validation takes place, it is
  straightforward and obvious how user code can decide to handle any
  resulting `MsgTypeError`.
- there should be a common and optional-yet-modular way to modify
  **how** data delivered via IPC (possibly embedded as user defined,
  type-constrained `.pld: msgspec.Struct`s) can be handled and processed
  during fault conditions and/or IPC "msg attacks".
- support for nested type constraints within a `MsgType.pld` field
  should be simple to define, implement and understand at runtime.
- a layer between the app-level IPC primitive APIs
  (`Context`/`MsgStream`) and application-task code (consumer code of
  those APIs) should be easily customized and prove-to-be-as-such
  through demonstrably rigorous internal (sub-sys) use!
  -> eg. via seemless runtime RPC eps support like `Actor.cancel()`
  -> by correctly implementing our `.devx._debug.Lock` REPL TTY mgmt
    dialog prot, via a dead simple payload-as-ctl-msg-spec.

There are some fairly detailed doc strings included so I won't duplicate
that content, the majority of the work here is actually somewhat of
a factoring of many similar blocks that are doing more or less the same
`msg = await Context._rx_chan.receive()` with boilerplate for
`Error`/`Stop` handling via `_raise_from_no_key_in_msg()`. The new
`PldRx` basically provides a shim layer for this common "receive msg,
decode its payload, yield it up to the consuming app task" by pairing
the RPC feeder mem-chan with a msg-payload decoder and expecting IPC API
internals to use **one** API instead of re-implementing the same pattern
all over the place XD

`PldRx` breakdown
 ------ - ------
- for now only expects a `._msgdec: MsgDec` which allows for
  override-able `MsgType.pld` validation and most obviously used in
  the impl of `.dec_msg()`, the decode message method.
- provides multiple mem-chan receive options including:
 |_ `.recv_pld()` which does the e2e operation of receiving a payload
    item.
 |_ a sync `.recv_pld_nowait()` version.
 |_ a `.recv_msg_w_pld()` which optionally allows retreiving both the
    shuttling `MsgType` as well as it's `.pld` body for use cases where
    info on both is important (eg. draining a `MsgStream`).

Dirty internal changeover/implementation deatz:
             ------ - ------
- obvi move over all the IPC "primitives" that previously had the duplicate recv-n-yield
  logic:
 - `MsgStream.receive[_nowait]()` delegating instead to the equivalent
   `PldRx.recv_pld[_nowait]()`.
 - add `Context._pld_rx: PldRx`, created and passed in by
   `mk_context()`; use it for the `.started()` -> `first: Started`
   retrieval inside `open_context_from_portal()`.
 - all the relevant `Portal` invocation methods: `.result()`,
   `.run_from_ns()`, `.run()`; also allows for dropping `_unwrap_msg()`
   and `.Portal_return_once()` outright Bo
- rename `Context.ctx._recv_chan` -> `._rx_chan`.
- add detailed `Context._scope` info for logging whether or not it's
  cancelled inside `_maybe_cancel_and_set_remote_error()`.
- move `._context._drain_to_final_msg()` -> `._ops.drain_to_final_msg()`
  since it's really not necessarily ctx specific per say, and it does
  kinda fit with "msg operations" more abstractly ;)
2024-04-24 00:59:41 -04:00
..
__init__.py Add a `MsgDec` for receive-only decoding 2024-04-22 19:29:30 -04:00
_codec.py Add a `MsgDec` for receive-only decoding 2024-04-22 19:29:30 -04:00
_ops.py First draft "payload receiver in a new `.msg._ops` 2024-04-24 00:59:41 -04:00
pretty_struct.py Add msg-from-dict constructor helper 2024-04-11 20:23:55 -04:00
ptr.py `NamespacePath._mk_fqnp()` handle `__mod__` for methods 2024-04-18 15:10:27 -04:00
types.py Add a `MsgDec` for receive-only decoding 2024-04-22 19:29:30 -04:00