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qemu/python-aqmp-add-start_server-and-accept-.patch
2022-05-27 12:52:53 +00:00

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From: John Snow <jsnow@redhat.com>
Date: Fri, 25 Feb 2022 15:59:46 -0500
Subject: python/aqmp: add start_server() and accept() methods
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Git-commit: 481607c7d35de2bc4d9bec7f4734036fc467f330
Add start_server() and accept() methods that can be used instead of
start_server_and_accept() to allow more fine-grained control over the
incoming connection process.
(Eagle-eyed reviewers will surely notice that it's a bit weird that
"CONNECTING" is a state that's shared between both the start_server()
and connect() states. That's absolutely true, and it's very true that
checking on the presence of _accepted as an indicator of state is a
hack. That's also very certainly true. But ... this keeps client code an
awful lot simpler, as it doesn't have to care exactly *how* the
connection is being made, just that it *is*. Is it worth disrupting that
simplicity in order to provide a better state guard on `accept()`? Hm.)
Signed-off-by: John Snow <jsnow@redhat.com>
Acked-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-id: 20220225205948.3693480-9-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
Signed-off-by: Li Zhang <lizhang@suse.de>
---
python/qemu/aqmp/protocol.py | 67 +++++++++++++++++++++++++++++++++---
python/tests/protocol.py | 7 ++++
2 files changed, 69 insertions(+), 5 deletions(-)
diff --git a/python/qemu/aqmp/protocol.py b/python/qemu/aqmp/protocol.py
index cdbc9cba0d15dea19cc1c60ca3c3..2ecba1455571a35e0e6c565e3641 100644
--- a/python/qemu/aqmp/protocol.py
+++ b/python/qemu/aqmp/protocol.py
@@ -280,6 +280,8 @@ class AsyncProtocol(Generic[T]):
Accept a connection and begin processing message queues.
If this call fails, `runstate` is guaranteed to be set back to `IDLE`.
+ This method is precisely equivalent to calling `start_server()`
+ followed by `accept()`.
:param address:
Address to listen on; UNIX socket path or TCP address/port.
@@ -294,9 +296,62 @@ class AsyncProtocol(Generic[T]):
protocol-level failure occurs while establishing a new
session, the wrapped error may also be an `QMPError`.
"""
+ await self.start_server(address, ssl)
+ await self.accept()
+ assert self.runstate == Runstate.RUNNING
+
+ @upper_half
+ @require(Runstate.IDLE)
+ async def start_server(self, address: SocketAddrT,
+ ssl: Optional[SSLContext] = None) -> None:
+ """
+ Start listening for an incoming connection, but do not wait for a peer.
+
+ This method starts listening for an incoming connection, but
+ does not block waiting for a peer. This call will return
+ immediately after binding and listening on a socket. A later
+ call to `accept()` must be made in order to finalize the
+ incoming connection.
+
+ :param address:
+ Address to listen on; UNIX socket path or TCP address/port.
+ :param ssl: SSL context to use, if any.
+
+ :raise StateError: When the `Runstate` is not `IDLE`.
+ :raise ConnectError:
+ When the server could not start listening on this address.
+
+ This exception will wrap a more concrete one. In most cases,
+ the wrapped exception will be `OSError`.
+ """
await self._session_guard(
self._do_start_server(address, ssl),
'Failed to establish connection')
+ assert self.runstate == Runstate.CONNECTING
+
+ @upper_half
+ @require(Runstate.CONNECTING)
+ async def accept(self) -> None:
+ """
+ Accept an incoming connection and begin processing message queues.
+
+ If this call fails, `runstate` is guaranteed to be set back to `IDLE`.
+
+ :raise StateError: When the `Runstate` is not `CONNECTING`.
+ :raise QMPError: When `start_server()` was not called yet.
+ :raise ConnectError:
+ When a connection or session cannot be established.
+
+ This exception will wrap a more concrete one. In most cases,
+ the wrapped exception will be `OSError` or `EOFError`. If a
+ protocol-level failure occurs while establishing a new
+ session, the wrapped error may also be an `QMPError`.
+ """
+ if self._accepted is None:
+ raise QMPError("Cannot call accept() before start_server().")
+ await self._session_guard(
+ self._do_accept(),
+ 'Failed to establish connection')
await self._session_guard(
self._establish_session(),
'Failed to establish session')
@@ -512,7 +567,12 @@ class AsyncProtocol(Generic[T]):
async def _do_start_server(self, address: SocketAddrT,
ssl: Optional[SSLContext] = None) -> None:
"""
- Acting as the transport server, accept a single connection.
+ Start listening for an incoming connection, but do not wait for a peer.
+
+ This method starts listening for an incoming connection, but does not
+ block waiting for a peer. This call will return immediately after
+ binding and listening to a socket. A later call to accept() must be
+ made in order to finalize the incoming connection.
:param address:
Address to listen on; UNIX socket path or TCP address/port.
@@ -554,10 +614,7 @@ class AsyncProtocol(Generic[T]):
# This will start the server (bind(2), listen(2)). It will also
# call accept(2) if we yield, but we don't block on that here.
self._server = await coro
-
- # Just for this one commit, wait for a peer.
- # This gets split out in the next patch.
- await self._do_accept()
+ self.logger.debug("Server listening on %s", address)
@upper_half
async def _do_accept(self) -> None:
diff --git a/python/tests/protocol.py b/python/tests/protocol.py
index 5e442e1efbd19bf95a95de371060..d6849ad3062081c62b29bf89dd2a 100644
--- a/python/tests/protocol.py
+++ b/python/tests/protocol.py
@@ -43,11 +43,18 @@ class NullProtocol(AsyncProtocol[None]):
async def _do_start_server(self, address, ssl=None):
if self.fake_session:
+ self._accepted = asyncio.Event()
self._set_state(Runstate.CONNECTING)
await asyncio.sleep(0)
else:
await super()._do_start_server(address, ssl)
+ async def _do_accept(self):
+ if self.fake_session:
+ self._accepted = None
+ else:
+ await super()._do_accept()
+
async def _do_connect(self, address, ssl=None):
if self.fake_session:
self._set_state(Runstate.CONNECTING)