[Qemu-devel] [PATCH 2/3] scripts/qemu: Catch QEMU exit while waiting for QMP client

[Eduardo Habkost <ehabkost@redhat.com>]

To avoid waiting for the full 15-second timeout for a connection, check
if QEMU exited once in a while.  Start with a very short timeout (15ms),
and double it on each try.

This will be helpful for scripts/device-crash-test, on cases where QEMU
crashes or exits before connecting to the QMP socket.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 scripts/qemu.py | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/scripts/qemu.py b/scripts/qemu.py
index 880e3e8219..5416bcfef9 100644
--- a/scripts/qemu.py
+++ b/scripts/qemu.py
@@ -17,6 +17,7 @@ import string
 import os
 import sys
 import subprocess
+import socket
 import qmp.qmp
 
 
@@ -118,7 +119,18 @@ class QEMUMachine(object):
                                                 debug=self._debug)
 
     def _post_launch(self):
-        self._qmp.accept()
+        # Wait for a connection while checking if QEMU is still running:
+        timeout = 0.015
+        tries = 10 # 0.015*2**10 = ~15 seconds
+        for i in range(tries):
+            try:
+                self._qmp.accept(timeout=timeout)
+                break
+            except socket.timeout:
+                if self._popen.poll():
+                    raise Exception("QEMU terminated before connecting to QMP")
+                # wait a little longer on the next try:
+                timeout *= 2
 
     def _post_shutdown(self):
         if not isinstance(self._monitor_address, tuple):
-- 
2.11.0.259.g40922b1