Re: [PATCH v2 11/24] python/aqmp: add _cb_inbound and _cb_inbound logging hooks

["Niteesh G. S." <niteesh.gs@gmail.com>]

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I think there's a typo in your commit message subject.

Thanks,
Niteesh.

On Sat, Jul 17, 2021 at 6:03 AM John Snow <jsnow@redhat.com> wrote:

> Add hooks designed to log/filter incoming/outgoing messages. The primary
> intent for these is to be able to support iotests which may want to log
> messages with specific filters for reproducible output.
>
> Another use is for plugging into Urwid frameworks; all messages in/out
> can be automatically added to a rendering list for the purposes of a
> qmp-shell like tool.
>
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  python/qemu/aqmp/protocol.py | 50 +++++++++++++++++++++++++++++++++---
>  1 file changed, 46 insertions(+), 4 deletions(-)
>
> diff --git a/python/qemu/aqmp/protocol.py b/python/qemu/aqmp/protocol.py
> index 86002a52654..6f83d3e3922 100644
> --- a/python/qemu/aqmp/protocol.py
> +++ b/python/qemu/aqmp/protocol.py
> @@ -176,6 +176,11 @@ class AsyncProtocol(Generic[T]):
>           can be written after the super() call.
>       - `_on_message`:
>           Actions to be performed when a message is received.
> +     - `_cb_outbound`:
> +         Logging/Filtering hook for all outbound messages.
> +     - `_cb_inbound`:
> +         Logging/Filtering hook for all inbound messages.
> +         This hook runs *before* `_on_message()`.
>
>      :param name:
>          Name used for logging messages, if any. By default, messages
> @@ -732,6 +737,43 @@ async def _bh_recv_message(self) -> None:
>      # Section: Message I/O
>      # --------------------
>
> +    @upper_half
> +    @bottom_half
> +    def _cb_outbound(self, msg: T) -> T:
> +        """
> +        Callback: outbound message hook.
> +
> +        This is intended for subclasses to be able to add arbitrary
> +        hooks to filter or manipulate outgoing messages. The base
> +        implementation does nothing but log the message without any
> +        manipulation of the message.
> +
> +        :param msg: raw outbound message
> +        :return: final outbound message
> +        """
> +        self.logger.debug("--> %s", str(msg))
> +        return msg
> +
> +    @upper_half
> +    @bottom_half
> +    def _cb_inbound(self, msg: T) -> T:
> +        """
> +        Callback: inbound message hook.
> +
> +        This is intended for subclasses to be able to add arbitrary
> +        hooks to filter or manipulate incoming messages. The base
> +        implementation does nothing but log the message without any
> +        manipulation of the message.
> +
> +        This method does not "handle" incoming messages; it is a filter.
> +        The actual "endpoint" for incoming messages is `_on_message()`.
> +
> +        :param msg: raw inbound message
> +        :return: processed inbound message
> +        """
> +        self.logger.debug("<-- %s", str(msg))
> +        return msg
> +
>      @upper_half
>      @bottom_half
>      async def _do_recv(self) -> T:
> @@ -760,8 +802,8 @@ async def _recv(self) -> T:
>
>          :return: A single (filtered, processed) protocol message.
>          """
> -        # A forthcoming commit makes this method less trivial.
> -        return await self._do_recv()
> +        message = await self._do_recv()
> +        return self._cb_inbound(message)
>
>      @upper_half
>      @bottom_half
> @@ -791,7 +833,7 @@ async def _send(self, msg: T) -> None:
>
>          :raise OSError: For problems with the underlying stream.
>          """
> -        # A forthcoming commit makes this method less trivial.
> +        msg = self._cb_outbound(msg)
>          self._do_send(msg)
>
>      @bottom_half
> @@ -806,6 +848,6 @@ async def _on_message(self, msg: T) -> None:
>              directly cause the loop to halt, so logic may be best-kept
>              to a minimum if at all possible.
>
> -        :param msg: The incoming message
> +        :param msg: The incoming message, already logged/filtered.
>          """
>          # Nothing to do in the abstract case.
> --
> 2.31.1
>
>

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