[PATCH 2/2] python/qemu/machine: accept QMP connection asynchronously

[marcandre . lureau]

From: Marc-André Lureau <marcandre.lureau@redhat.com>

QMP accept is currently synchronous. If qemu dies before the connection
is established, it will wait there. Instead turn the code to do
concurrently accept() and wait(). Returns when the first task is
completed to determine whether a connection was established.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 python/qemu/machine/machine.py | 11 ++++++++++-
 python/qemu/qmp/legacy.py      | 10 ++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/python/qemu/machine/machine.py b/python/qemu/machine/machine.py
index 55c45f4b1205..5e2df7dc5055 100644
--- a/python/qemu/machine/machine.py
+++ b/python/qemu/machine/machine.py
@@ -362,9 +362,18 @@ def _pre_launch(self) -> None:
             self._args
         ))
 
+    async def _async_accept(self) -> bool:
+        accept = asyncio.create_task(self._qmp.async_accept())
+        wait = asyncio.create_task(self._subproc.wait())
+        done, pending = await asyncio.wait([accept, wait],
+                                           return_when=asyncio.FIRST_COMPLETED)
+        return accept in done
+
     def _post_launch(self) -> None:
         if self._qmp_connection:
-            self._qmp.accept(self._qmp_timer)
+            accepted = self._sync(self._async_accept())
+            if not accepted:
+                raise QEMUMachineError('VM returned before QMP accept')
 
     def _close_qemu_log_file(self) -> None:
         if self._qemu_log_file is not None:
diff --git a/python/qemu/qmp/legacy.py b/python/qemu/qmp/legacy.py
index 03b5574618fa..88bdbfb6e350 100644
--- a/python/qemu/qmp/legacy.py
+++ b/python/qemu/qmp/legacy.py
@@ -167,6 +167,16 @@ def accept(self, timeout: Optional[float] = 15.0) -> 
QMPMessage:
         assert ret is not None
         return ret
 
+    async def async_accept(self) -> QMPMessage:
+        self._qmp.await_greeting = True
+        self._qmp.negotiate = True
+
+        await self._qmp.accept()
+
+        ret = self._get_greeting()
+        assert ret is not None
+        return ret
+
     def cmd_obj(self, qmp_cmd: QMPMessage) -> QMPMessage:
         """
         Send a QMP command to the QMP Monitor.
-- 
2.37.0.rc0