diff mbox series

[v3,12/25] python/aqmp: add AsyncProtocol._readline() method

Message ID 20210803182941.504537-13-jsnow@redhat.com (mailing list archive)
State New, archived
Headers show
Series python: introduce Asynchronous QMP package | expand

Commit Message

John Snow Aug. 3, 2021, 6:29 p.m. UTC
This is added as a courtesy: many protocols are line-based, including
QMP. Putting it in AsyncProtocol lets us keep the QMP class
implementation just a pinch more abstract.

(And, if we decide to add a QTEST implementation later, it will need
this, too. (Yes, I have a QTEST implementation.))

Signed-off-by: John Snow <jsnow@redhat.com>
---
 python/qemu/aqmp/protocol.py | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

Comments

Eric Blake Aug. 17, 2021, 7:36 p.m. UTC | #1
On Tue, Aug 03, 2021 at 02:29:28PM -0400, John Snow wrote:
> This is added as a courtesy: many protocols are line-based, including
> QMP. Putting it in AsyncProtocol lets us keep the QMP class
> implementation just a pinch more abstract.
> 
> (And, if we decide to add a QTEST implementation later, it will need
> this, too. (Yes, I have a QTEST implementation.))
> 
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  python/qemu/aqmp/protocol.py | 29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)

Reviewed-by: Eric Blake <eblake@redhat.com>
diff mbox series

Patch

diff --git a/python/qemu/aqmp/protocol.py b/python/qemu/aqmp/protocol.py
index 86aede5d7af..066d52dccf4 100644
--- a/python/qemu/aqmp/protocol.py
+++ b/python/qemu/aqmp/protocol.py
@@ -794,6 +794,35 @@  def _cb_inbound(self, msg: T) -> T:
         self.logger.debug("<-- %s", str(msg))
         return msg
 
+    @upper_half
+    @bottom_half
+    async def _readline(self) -> bytes:
+        """
+        Wait for a newline from the incoming reader.
+
+        This method is provided as a convenience for upper-layer
+        protocols, as many are line-based.
+
+        This method *may* return a sequence of bytes without a trailing
+        newline if EOF occurs, but *some* bytes were received. In this
+        case, the next call will raise `EOFError`. It is assumed that
+        the layer 5 protocol will decide if there is anything meaningful
+        to be done with a partial message.
+
+        :raise OSError: For stream-related errors.
+        :raise EOFError:
+            If the reader stream is at EOF and there are no bytes to return.
+        :return: bytes, including the newline.
+        """
+        assert self._reader is not None
+        msg_bytes = await self._reader.readline()
+
+        if not msg_bytes:
+            if self._reader.at_eof():
+                raise EOFError
+
+        return msg_bytes
+
     @upper_half
     @bottom_half
     async def _do_recv(self) -> T: