[PATCH v3 00/16] python: add mypy support to python/qemu

[PATCH v3 00/16] python: add mypy support to python/qemu

[John Snow]

Based-on: 20200604195252.20739-1-jsnow@redhat.com

This series is extracted from my larger series that attempted to bundle
our python module as an installable module. These fixes don't require that,
so they are being sent first as I think there's less up for debate in here.

This requires my "refactor shutdown" patch as a pre-requisite.

v3:
001/16:[----] [--] 'python/qmp.py: Define common types'
002/16:[----] [--] 'iotests.py: use qemu.qmp type aliases'
003/16:[----] [--] 'python/qmp.py: re-absorb MonitorResponseError'
004/16:[----] [--] 'python/qmp.py: Do not return None from cmd_obj'
005/16:[0002] [FC] 'python/qmp.py: add casts to JSON deserialization'
006/16:[----] [--] 'python/qmp.py: add QMPProtocolError'
007/16:[----] [-C] 'python/machine.py: Fix monitor address typing'
008/16:[----] [--] 'python/machine.py: reorder __init__'
009/16:[----] [-C] 'python/machine.py: Don't modify state in _base_args()'
010/16:[down] 'python/machine.py: Handle None events in events_wait'
011/16:[----] [--] 'python/machine.py: use qmp.command'
012/16:[----] [--] 'python/machine.py: Add _qmp access shim'
013/16:[----] [--] 'python/machine.py: fix _popen access'
014/16:[----] [--] 'python/qemu: make 'args' style arguments immutable'
015/16:[----] [--] 'iotests.py: Adjust HMP kwargs typing'
016/16:[0007] [FC] 'python/qemu: Add mypy type annotations'

005: Removed a cast, per Kevin Wolf's tip
010: Renamed with correct function name;
     Rewrote docstring and added comments
016: Use SocketAddrT instead of Union[Tuple[str,str],str]

"v2":
- This version supports iotests 297
- Many patches merged by Phil are removed
- Replaces iotests.py type aliases with centralized ones
  (See patch 2)
- Imports etc are reworked to use the non-installable
  package layout instead. (Mostly important for patch 3)

Testing this out:
- You'll need Python3.6+
- I encourage you to use a virtual environment!
- You don't necessarily need these exact versions, but I didn't test the
  lower bounds, use older versions at your peril:
  - pylint==2.5.0
  - mypy=0.770
  - flake8=3.7.8

> cd ~/src/qemu/python/
> flake8 qemu
> mypy --strict qemu
> cd qemu
> pylint *.py

These should all 100% pass.

---

Open RFC: What's the right way to hook this into make check to prevent
regressions?

John Snow (16):
  python/qmp.py: Define common types
  iotests.py: use qemu.qmp type aliases
  python/qmp.py: re-absorb MonitorResponseError
  python/qmp.py: Do not return None from cmd_obj
  python/qmp.py: add casts to JSON deserialization
  python/qmp.py: add QMPProtocolError
  python/machine.py: Fix monitor address typing
  python/machine.py: reorder __init__
  python/machine.py: Don't modify state in _base_args()
  python/machine.py: Handle None events in events_wait
  python/machine.py: use qmp.command
  python/machine.py: Add _qmp access shim
  python/machine.py: fix _popen access
  python/qemu: make 'args' style arguments immutable
  iotests.py: Adjust HMP kwargs typing
  python/qemu: Add mypy type annotations

 python/qemu/accel.py          |   8 +-
 python/qemu/machine.py        | 286 ++++++++++++++++++++--------------
 python/qemu/qmp.py            | 111 +++++++++----
 python/qemu/qtest.py          |  53 ++++---
 scripts/render_block_graph.py |   7 +-
 tests/qemu-iotests/iotests.py |  11 +-
 6 files changed, 298 insertions(+), 178 deletions(-)

-- 
2.21.3

[PATCH v3 01/16] python/qmp.py: Define common types

[John Snow]

Define some common types that we'll need to annotate a lot of other
functions going forward.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 python/qemu/qmp.py | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/python/qemu/qmp.py b/python/qemu/qmp.py
index e64b6b5faa7..8388c7b6030 100644
--- a/python/qemu/qmp.py
+++ b/python/qemu/qmp.py
@@ -12,13 +12,31 @@
 import socket
 import logging
 from typing import (
+    Any,
+    Dict,
     Optional,
     TextIO,
     Type,
+    Tuple,
+    Union,
 )
 from types import TracebackType
 
 
+# QMPMessage is a QMP Message of any kind.
+# e.g. {'yee': 'haw'}
+#
+# QMPReturnValue is the inner value of return values only.
+# {'return': {}} is the QMPMessage,
+# {} is the QMPReturnValue.
+QMPMessage = Dict[str, Any]
+QMPReturnValue = Dict[str, Any]
+
+InternetAddrT = Tuple[str, str]
+UnixAddrT = str
+SocketAddrT = Union[InternetAddrT, UnixAddrT]
+
+
 class QMPError(Exception):
     """
     QMP base exception
-- 
2.21.3

[PATCH v3 02/16] iotests.py: use qemu.qmp type aliases

[John Snow]

iotests.py should use the type definitions from qmp.py instead of its
own.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 tests/qemu-iotests/iotests.py | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/tests/qemu-iotests/iotests.py b/tests/qemu-iotests/iotests.py
index f20d90f9698..7c1773bba37 100644
--- a/tests/qemu-iotests/iotests.py
+++ b/tests/qemu-iotests/iotests.py
@@ -35,13 +35,10 @@
 # pylint: disable=import-error, wrong-import-position
 sys.path.append(os.path.join(os.path.dirname(__file__), '..', '..', 'python'))
 from qemu import qtest
+from qemu.qmp import QMPMessage
 
 assert sys.version_info >= (3, 6)
 
-# Type Aliases
-QMPResponse = Dict[str, Any]
-
-
 # Use this logger for logging messages directly from the iotests module
 logger = logging.getLogger('qemu.iotests')
 logger.addHandler(logging.NullHandler())
@@ -554,7 +551,7 @@ def add_incoming(self, addr):
         self._args.append(addr)
         return self
 
-    def hmp(self, command_line: str, use_log: bool = False) -> QMPResponse:
+    def hmp(self, command_line: str, use_log: bool = False) -> QMPMessage:
         cmd = 'human-monitor-command'
         kwargs = {'command-line': command_line}
         if use_log:
@@ -575,7 +572,7 @@ def resume_drive(self, drive: str) -> None:
         self.hmp(f'qemu-io {drive} "remove_break bp_{drive}"')
 
     def hmp_qemu_io(self, drive: str, cmd: str,
-                    use_log: bool = False) -> QMPResponse:
+                    use_log: bool = False) -> QMPMessage:
         """Write to a given drive using an HMP command"""
         return self.hmp(f'qemu-io {drive} "{cmd}"', use_log=use_log)
 
-- 
2.21.3

[PATCH v3 03/16] python/qmp.py: re-absorb MonitorResponseError

[John Snow]

When I initially split this out, I considered this more of a machine
error than a QMP protocol error, but I think that's misguided.

Move this back to qmp.py and name it QMPResponseError. Convert
qmp.command() to use this exception type.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 python/qemu/machine.py        | 15 +--------------
 python/qemu/qmp.py            | 17 +++++++++++++++--
 scripts/render_block_graph.py |  7 +++++--
 3 files changed, 21 insertions(+), 18 deletions(-)

diff --git a/python/qemu/machine.py b/python/qemu/machine.py
index 99bcb499878..8ea027566e4 100644
--- a/python/qemu/machine.py
+++ b/python/qemu/machine.py
@@ -49,19 +49,6 @@ class QEMUMachineAddDeviceError(QEMUMachineError):
     """
 
 
-class MonitorResponseError(qmp.QMPError):
-    """
-    Represents erroneous QMP monitor reply
-    """
-    def __init__(self, reply):
-        try:
-            desc = reply["error"]["desc"]
-        except KeyError:
-            desc = reply
-        super().__init__(desc)
-        self.reply = reply
-
-
 class QEMUMachine:
     """
     A QEMU VM
@@ -469,7 +456,7 @@ def command(self, cmd, conv_keys=True, **args):
         if reply is None:
             raise qmp.QMPError("Monitor is closed")
         if "error" in reply:
-            raise MonitorResponseError(reply)
+            raise qmp.QMPResponseError(reply)
         return reply["return"]
 
     def get_qmp_event(self, wait=False):
diff --git a/python/qemu/qmp.py b/python/qemu/qmp.py
index 8388c7b6030..aa8a666b8ab 100644
--- a/python/qemu/qmp.py
+++ b/python/qemu/qmp.py
@@ -61,6 +61,19 @@ class QMPTimeoutError(QMPError):
     """
 
 
+class QMPResponseError(QMPError):
+    """
+    Represents erroneous QMP monitor reply
+    """
+    def __init__(self, reply: QMPMessage):
+        try:
+            desc = reply['error']['desc']
+        except KeyError:
+            desc = reply
+        super().__init__(desc)
+        self.reply = reply
+
+
 class QEMUMonitorProtocol:
     """
     Provide an API to connect to QEMU via QEMU Monitor Protocol (QMP) and then
@@ -251,8 +264,8 @@ def command(self, cmd, **kwds):
         Build and send a QMP command to the monitor, report errors if any
         """
         ret = self.cmd(cmd, kwds)
-        if "error" in ret:
-            raise Exception(ret['error']['desc'])
+        if 'error' in ret:
+            raise QMPResponseError(ret)
         return ret['return']
 
     def pull_event(self, wait=False):
diff --git a/scripts/render_block_graph.py b/scripts/render_block_graph.py
index 409b4321f2e..da6acf050d1 100755
--- a/scripts/render_block_graph.py
+++ b/scripts/render_block_graph.py
@@ -25,7 +25,10 @@
 from graphviz import Digraph
 
 sys.path.append(os.path.join(os.path.dirname(__file__), '..', 'python'))
-from qemu.machine import MonitorResponseError
+from qemu.qmp import (
+    QEMUMonitorProtocol,
+    QMPResponseError,
+)
 
 
 def perm(arr):
@@ -102,7 +105,7 @@ def command(self, cmd):
         reply = json.loads(subprocess.check_output(ar))
 
         if 'error' in reply:
-            raise MonitorResponseError(reply)
+            raise QMPResponseError(reply)
 
         return reply['return']
 
-- 
2.21.3

[PATCH v3 04/16] python/qmp.py: Do not return None from cmd_obj

[John Snow]

This makes typing the qmp library difficult, as it necessitates wrapping
Optional[] around the type for every return type up the stack. At some
point, it becomes difficult to discern or remember why it's None instead
of the expected object.

Use the python exception system to tell us exactly why we didn't get an
object. Remove this special-cased return.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 python/qemu/qmp.py | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/python/qemu/qmp.py b/python/qemu/qmp.py
index aa8a666b8ab..ef3c919b76c 100644
--- a/python/qemu/qmp.py
+++ b/python/qemu/qmp.py
@@ -225,22 +225,18 @@ def accept(self, timeout=15.0):
         self.__sockfile = self.__sock.makefile(mode='r')
         return self.__negotiate_capabilities()
 
-    def cmd_obj(self, qmp_cmd):
+    def cmd_obj(self, qmp_cmd: QMPMessage) -> QMPMessage:
         """
         Send a QMP command to the QMP Monitor.
 
         @param qmp_cmd: QMP command to be sent as a Python dict
-        @return QMP response as a Python dict or None if the connection has
-                been closed
+        @return QMP response as a Python dict
         """
         self.logger.debug(">>> %s", qmp_cmd)
-        try:
-            self.__sock.sendall(json.dumps(qmp_cmd).encode('utf-8'))
-        except OSError as err:
-            if err.errno == errno.EPIPE:
-                return None
-            raise err
+        self.__sock.sendall(json.dumps(qmp_cmd).encode('utf-8'))
         resp = self.__json_read()
+        if resp is None:
+            raise QMPConnectError("Unexpected empty reply from server")
         self.logger.debug("<<< %s", resp)
         return resp
 
-- 
2.21.3

[PATCH v3 05/16] python/qmp.py: add casts to JSON deserialization

[John Snow]

mypy and python type hints are not powerful enough to properly describe
JSON messages in Python 3.6. The best we can do, generally, is describe
them as Dict[str, Any].

Add casts to coerce this type for static analysis; but do NOT enforce
this type at runtime in any way.

Note: Python 3.8 adds a TypedDict construct which allows for the
description of more arbitrary Dictionary shapes. There is a third-party
module, "Pydantic", which is compatible with 3.6 that can be used
instead of the JSON library that parses JSON messages to fully-typed
Python objects, and may be preferable in some cases.

(That is well beyond the scope of this commit or series.)

Signed-off-by: John Snow <jsnow@redhat.com>
---
 python/qemu/qmp.py | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/python/qemu/qmp.py b/python/qemu/qmp.py
index ef3c919b76c..1ae36050a42 100644
--- a/python/qemu/qmp.py
+++ b/python/qemu/qmp.py
@@ -13,6 +13,7 @@
 import logging
 from typing import (
     Any,
+    cast,
     Dict,
     Optional,
     TextIO,
@@ -130,7 +131,10 @@ def __json_read(self, only_event=False):
             data = self.__sockfile.readline()
             if not data:
                 return None
-            resp = json.loads(data)
+            # By definition, any JSON received from QMP is a QMPMessage,
+            # and we are asserting only at static analysis time that it
+            # has a particular shape.
+            resp: QMPMessage = json.loads(data)
             if 'event' in resp:
                 self.logger.debug("<<< %s", resp)
                 self.__events.append(resp)
@@ -262,7 +266,7 @@ def command(self, cmd, **kwds):
         ret = self.cmd(cmd, kwds)
         if 'error' in ret:
             raise QMPResponseError(ret)
-        return ret['return']
+        return cast(QMPReturnValue, ret['return'])
 
     def pull_event(self, wait=False):
         """
-- 
2.21.3

[PATCH v3 06/16] python/qmp.py: add QMPProtocolError

[John Snow]

In the case that we receive a reply but are unable to understand it, use
this exception name to indicate that case.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 python/qemu/qmp.py | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/python/qemu/qmp.py b/python/qemu/qmp.py
index 1ae36050a42..7935dababbf 100644
--- a/python/qemu/qmp.py
+++ b/python/qemu/qmp.py
@@ -62,6 +62,12 @@ class QMPTimeoutError(QMPError):
     """
 
 
+class QMPProtocolError(QMPError):
+    """
+    QMP protocol error; unexpected response
+    """
+
+
 class QMPResponseError(QMPError):
     """
     Represents erroneous QMP monitor reply
@@ -266,6 +272,10 @@ def command(self, cmd, **kwds):
         ret = self.cmd(cmd, kwds)
         if 'error' in ret:
             raise QMPResponseError(ret)
+        if 'return' not in ret:
+            raise QMPProtocolError(
+                "'return' key not found in QMP response '{}'".format(str(ret))
+            )
         return cast(QMPReturnValue, ret['return'])
 
     def pull_event(self, wait=False):
-- 
2.21.3

[PATCH v3 07/16] python/machine.py: Fix monitor address typing

[John Snow]

Prior to this, it's difficult for mypy to intuit what the concrete type
of the monitor address is; it has difficulty inferring the type across
two variables.

Create _monitor_address as a property that always returns a valid
address to simply static type analysis.

To preserve our ability to clean up, use a simple boolean to indicate
whether or not we should try to clean up the sock file after execution.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 python/qemu/machine.py | 45 +++++++++++++++++++++++++++---------------
 1 file changed, 29 insertions(+), 16 deletions(-)

diff --git a/python/qemu/machine.py b/python/qemu/machine.py
index 8ea027566e4..34713ba9b15 100644
--- a/python/qemu/machine.py
+++ b/python/qemu/machine.py
@@ -25,10 +25,14 @@
 import signal
 import socket
 import tempfile
-from typing import Optional, Type
+from typing import (
+    Optional,
+    Type,
+)
 from types import TracebackType
 
 from . import qmp
+from .qmp import SocketAddrT
 
 LOG = logging.getLogger(__name__)
 
@@ -62,7 +66,8 @@ class QEMUMachine:
     """
 
     def __init__(self, binary, args=None, wrapper=None, name=None,
-                 test_dir="/var/tmp", monitor_address=None,
+                 test_dir="/var/tmp",
+                 monitor_address: Optional[SocketAddrT] = None,
                  socket_scm_helper=None, sock_dir=None):
         '''
         Initialize a QEMUMachine
@@ -85,8 +90,14 @@ def __init__(self, binary, args=None, wrapper=None, name=None,
         if sock_dir is None:
             sock_dir = test_dir
         self._name = name
-        self._monitor_address = monitor_address
-        self._vm_monitor = None
+        if monitor_address is not None:
+            self._monitor_address = monitor_address
+            self._remove_monitor_sockfile = False
+        else:
+            self._monitor_address = os.path.join(
+                sock_dir, f"{name}-monitor.sock"
+            )
+            self._remove_monitor_sockfile = True
         self._qemu_log_path = None
         self._qemu_log_file = None
         self._popen = None
@@ -225,15 +236,17 @@ def _load_io_log(self):
 
     def _base_args(self):
         args = ['-display', 'none', '-vga', 'none']
+
         if self._qmp_set:
             if isinstance(self._monitor_address, tuple):
-                moncdev = "socket,id=mon,host=%s,port=%s" % (
-                    self._monitor_address[0],
-                    self._monitor_address[1])
+                moncdev = "socket,id=mon,host={},port={}".format(
+                    *self._monitor_address
+                )
             else:
-                moncdev = 'socket,id=mon,path=%s' % self._vm_monitor
+                moncdev = f"socket,id=mon,path={self._monitor_address}"
             args.extend(['-chardev', moncdev, '-mon',
                          'chardev=mon,mode=control'])
+
         if self._machine is not None:
             args.extend(['-machine', self._machine])
         for _ in range(self._console_index):
@@ -258,14 +271,14 @@ def _pre_launch(self):
         self._qemu_log_file = open(self._qemu_log_path, 'wb')
 
         if self._qmp_set:
-            if self._monitor_address is not None:
-                self._vm_monitor = self._monitor_address
-            else:
-                self._vm_monitor = os.path.join(self._sock_dir,
-                                                self._name + "-monitor.sock")
-                self._remove_files.append(self._vm_monitor)
-            self._qmp = qmp.QEMUMonitorProtocol(self._vm_monitor, server=True,
-                                                nickname=self._name)
+            if self._remove_monitor_sockfile:
+                assert isinstance(self._monitor_address, str)
+                self._remove_files.append(self._monitor_address)
+            self._qmp = qmp.QEMUMonitorProtocol(
+                self._monitor_address,
+                server=True,
+                nickname=self._name
+            )
 
     def _post_launch(self):
         if self._qmp:
-- 
2.21.3

[PATCH v3 08/16] python/machine.py: reorder __init__

[John Snow]

Put the init arg handling all at the top, and mostly in order (deviating
when one is dependent on another), and put what is effectively runtime
state declaration at the bottom.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 python/qemu/machine.py | 29 +++++++++++++++++------------
 1 file changed, 17 insertions(+), 12 deletions(-)

diff --git a/python/qemu/machine.py b/python/qemu/machine.py
index 34713ba9b15..aae78e3bc87 100644
--- a/python/qemu/machine.py
+++ b/python/qemu/machine.py
@@ -81,38 +81,43 @@ def __init__(self, binary, args=None, wrapper=None, name=None,
         @param socket_scm_helper: helper program, required for send_fd_scm()
         @note: Qemu process is not started until launch() is used.
         '''
+        # Direct user configuration
+
+        self._binary = binary
+
         if args is None:
             args = []
+        # Copy mutable input: we will be modifying our copy
+        self._args = list(args)
+
         if wrapper is None:
             wrapper = []
-        if name is None:
-            name = "qemu-%d" % os.getpid()
-        if sock_dir is None:
-            sock_dir = test_dir
-        self._name = name
+        self._wrapper = wrapper
+
+        self._name = name or "qemu-%d" % os.getpid()
+        self._test_dir = test_dir
+        self._sock_dir = sock_dir or self._test_dir
+        self._socket_scm_helper = socket_scm_helper
+
         if monitor_address is not None:
             self._monitor_address = monitor_address
             self._remove_monitor_sockfile = False
         else:
             self._monitor_address = os.path.join(
-                sock_dir, f"{name}-monitor.sock"
+                self._sock_dir, f"{self._name}-monitor.sock"
             )
             self._remove_monitor_sockfile = True
+
+        # Runstate
         self._qemu_log_path = None
         self._qemu_log_file = None
         self._popen = None
-        self._binary = binary
-        self._args = list(args)     # Force copy args in case we modify them
-        self._wrapper = wrapper
         self._events = []
         self._iolog = None
-        self._socket_scm_helper = socket_scm_helper
         self._qmp_set = True   # Enable QMP monitor by default.
         self._qmp = None
         self._qemu_full_args = None
-        self._test_dir = test_dir
         self._temp_dir = None
-        self._sock_dir = sock_dir
         self._launched = False
         self._machine = None
         self._console_index = 0
-- 
2.21.3

[PATCH v3 09/16] python/machine.py: Don't modify state in _base_args()

[John Snow]

Don't append to the _remove_files list during _base_args; instead do so
during _launch. Rework _base_args as a @property to help facilitate
this impression.

This has the additional benefit of making the type of _console_address
easier to analyze statically.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 python/qemu/machine.py | 16 ++++++++++------
 python/qemu/qtest.py   | 11 ++++++++---
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/python/qemu/machine.py b/python/qemu/machine.py
index aae78e3bc87..92528a44097 100644
--- a/python/qemu/machine.py
+++ b/python/qemu/machine.py
@@ -26,6 +26,7 @@
 import socket
 import tempfile
 from typing import (
+    List,
     Optional,
     Type,
 )
@@ -123,7 +124,9 @@ def __init__(self, binary, args=None, wrapper=None, name=None,
         self._console_index = 0
         self._console_set = False
         self._console_device_type = None
-        self._console_address = None
+        self._console_address = os.path.join(
+            self._sock_dir, f"{self._name}-console.sock"
+        )
         self._console_socket = None
         self._remove_files = []
         self._killed = False
@@ -239,7 +242,8 @@ def _load_io_log(self):
             with open(self._qemu_log_path, "r") as iolog:
                 self._iolog = iolog.read()
 
-    def _base_args(self):
+    @property
+    def _base_args(self) -> List[str]:
         args = ['-display', 'none', '-vga', 'none']
 
         if self._qmp_set:
@@ -257,9 +261,6 @@ def _base_args(self):
         for _ in range(self._console_index):
             args.extend(['-serial', 'null'])
         if self._console_set:
-            self._console_address = os.path.join(self._sock_dir,
-                                                 self._name + "-console.sock")
-            self._remove_files.append(self._console_address)
             chardev = ('socket,id=console,path=%s,server,nowait' %
                        self._console_address)
             args.extend(['-chardev', chardev])
@@ -275,6 +276,9 @@ def _pre_launch(self):
         self._qemu_log_path = os.path.join(self._temp_dir, self._name + ".log")
         self._qemu_log_file = open(self._qemu_log_path, 'wb')
 
+        if self._console_set:
+            self._remove_files.append(self._console_address)
+
         if self._qmp_set:
             if self._remove_monitor_sockfile:
                 assert isinstance(self._monitor_address, str)
@@ -349,7 +353,7 @@ def _launch(self):
         devnull = open(os.path.devnull, 'rb')
         self._pre_launch()
         self._qemu_full_args = (self._wrapper + [self._binary] +
-                                self._base_args() + self._args)
+                                self._base_args + self._args)
         LOG.debug('VM launch command: %r', ' '.join(self._qemu_full_args))
         self._popen = subprocess.Popen(self._qemu_full_args,
                                        stdin=devnull,
diff --git a/python/qemu/qtest.py b/python/qemu/qtest.py
index 888c8bd2f60..05c63a1d583 100644
--- a/python/qemu/qtest.py
+++ b/python/qemu/qtest.py
@@ -19,7 +19,11 @@
 
 import socket
 import os
-from typing import Optional, TextIO
+from typing import (
+    List,
+    Optional,
+    TextIO,
+)
 
 from .machine import QEMUMachine
 
@@ -111,8 +115,9 @@ def __init__(self, binary, args=None, name=None, test_dir="/var/tmp",
         self._qtest = None
         self._qtest_path = os.path.join(sock_dir, name + "-qtest.sock")
 
-    def _base_args(self):
-        args = super()._base_args()
+    @property
+    def _base_args(self) -> List[str]:
+        args = super()._base_args
         args.extend(['-qtest', 'unix:path=' + self._qtest_path,
                      '-accel', 'qtest'])
         return args
-- 
2.21.3

[PATCH v3 10/16] python/machine.py: Handle None events in events_wait

[John Snow]

If the timeout is 0, we can get None back. Handle this explicitly.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 python/qemu/machine.py | 27 ++++++++++++++++++++-------
 1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/python/qemu/machine.py b/python/qemu/machine.py
index 92528a44097..4afd67a9351 100644
--- a/python/qemu/machine.py
+++ b/python/qemu/machine.py
@@ -33,7 +33,7 @@
 from types import TracebackType
 
 from . import qmp
-from .qmp import SocketAddrT
+from .qmp import SocketAddrT, QMPMessage
 
 LOG = logging.getLogger(__name__)
 
@@ -544,13 +544,20 @@ def event_wait(self, name, timeout=60.0, match=None):
 
     def events_wait(self, events, timeout=60.0):
         """
-        events_wait waits for and returns a named event
-        from QMP with a timeout.
+        events_wait waits for and returns a single named event from QMP.
+        In the case of multiple qualifying events, this function returns the
+        first one.
 
-        events: a sequence of (name, match_criteria) tuples.
-                The match criteria are optional and may be None.
-                See event_match for details.
-        timeout: QEMUMonitorProtocol.pull_event timeout parameter.
+        :param events: A sequence of (name, match_criteria) tuples.
+                       The match criteria are optional and may be None.
+                       See event_match for details.
+        :param timeout: Optional timeout, in seconds.
+                        See QEMUMonitorProtocol.pull_event.
+
+        :raise QMPTimeoutError: If timeout was non-zero and no matching events
+                                were found.
+        :return: A QMP event matching the filter criteria.
+                 If timeout was 0 and no event matched, None.
         """
         def _match(event):
             for name, match in events:
@@ -558,6 +565,8 @@ def _match(event):
                     return True
             return False
 
+        event: Optional[QMPMessage]
+
         # Search cached events
         for event in self._events:
             if _match(event):
@@ -567,6 +576,10 @@ def _match(event):
         # Poll for new events
         while True:
             event = self._qmp.pull_event(wait=timeout)
+            if event is None:
+                # NB: None is only returned when timeout is false-ish.
+                # Timeouts raise QMPTimeoutError instead!
+                break
             if _match(event):
                 return event
             self._events.append(event)
-- 
2.21.3

[PATCH v3 11/16] python/machine.py: use qmp.command

[John Snow]

machine.py and qmp.py both do the same thing here; refactor machine.py
to use qmp.py's functionality more directly.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 python/qemu/machine.py | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/python/qemu/machine.py b/python/qemu/machine.py
index 4afd67a9351..d8289936816 100644
--- a/python/qemu/machine.py
+++ b/python/qemu/machine.py
@@ -26,6 +26,8 @@
 import socket
 import tempfile
 from typing import (
+    Any,
+    Dict,
     List,
     Optional,
     Type,
@@ -455,17 +457,23 @@ def set_qmp_monitor(self, enabled=True):
             self._qmp_set = False
             self._qmp = None
 
-    def qmp(self, cmd, conv_keys=True, **args):
-        """
-        Invoke a QMP command and return the response dict
-        """
+    @classmethod
+    def _qmp_args(cls, _conv_keys: bool = True, **args: Any) -> Dict[str, Any]:
         qmp_args = dict()
         for key, value in args.items():
-            if conv_keys:
+            if _conv_keys:
                 qmp_args[key.replace('_', '-')] = value
             else:
                 qmp_args[key] = value
+        return qmp_args
 
+    def qmp(self, cmd: str,
+            conv_keys: bool = True,
+            **args: Any) -> QMPMessage:
+        """
+        Invoke a QMP command and return the response dict
+        """
+        qmp_args = self._qmp_args(conv_keys, **args)
         return self._qmp.cmd(cmd, args=qmp_args)
 
     def command(self, cmd, conv_keys=True, **args):
@@ -474,12 +482,8 @@ def command(self, cmd, conv_keys=True, **args):
         On success return the response dict.
         On failure raise an exception.
         """
-        reply = self.qmp(cmd, conv_keys, **args)
-        if reply is None:
-            raise qmp.QMPError("Monitor is closed")
-        if "error" in reply:
-            raise qmp.QMPResponseError(reply)
-        return reply["return"]
+        qmp_args = self._qmp_args(conv_keys, **args)
+        return self._qmp.command(cmd, **qmp_args)
 
     def get_qmp_event(self, wait=False):
         """
-- 
2.21.3

[PATCH v3 12/16] python/machine.py: Add _qmp access shim

[John Snow]

Like many other Optional[] types, it's not always a given that this
object will be set. Wrap it in a type-shim that raises a meaningful
error and will always return a concrete type.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 python/qemu/machine.py | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/python/qemu/machine.py b/python/qemu/machine.py
index d8289936816..a451f9000d6 100644
--- a/python/qemu/machine.py
+++ b/python/qemu/machine.py
@@ -118,7 +118,7 @@ def __init__(self, binary, args=None, wrapper=None, name=None,
         self._events = []
         self._iolog = None
         self._qmp_set = True   # Enable QMP monitor by default.
-        self._qmp = None
+        self._qmp_connection: Optional[qmp.QEMUMonitorProtocol] = None
         self._qemu_full_args = None
         self._temp_dir = None
         self._launched = False
@@ -285,7 +285,7 @@ def _pre_launch(self):
             if self._remove_monitor_sockfile:
                 assert isinstance(self._monitor_address, str)
                 self._remove_files.append(self._monitor_address)
-            self._qmp = qmp.QEMUMonitorProtocol(
+            self._qmp_connection = qmp.QEMUMonitorProtocol(
                 self._monitor_address,
                 server=True,
                 nickname=self._name
@@ -455,7 +455,13 @@ def set_qmp_monitor(self, enabled=True):
             self._qmp_set = True
         else:
             self._qmp_set = False
-            self._qmp = None
+            self._qmp_connection = None
+
+    @property
+    def _qmp(self) -> qmp.QEMUMonitorProtocol:
+        if self._qmp_connection is None:
+            raise QEMUMachineError("Attempt to access QMP with no connection")
+        return self._qmp_connection
 
     @classmethod
     def _qmp_args(cls, _conv_keys: bool = True, **args: Any) -> Dict[str, Any]:
-- 
2.21.3

[PATCH v3 13/16] python/machine.py: fix _popen access

[John Snow]

As always, Optional[T] causes problems with unchecked access. Add a
helper that asserts the pipe is present before we attempt to talk with
it.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 python/qemu/machine.py | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/python/qemu/machine.py b/python/qemu/machine.py
index a451f9000d6..a81a422b60e 100644
--- a/python/qemu/machine.py
+++ b/python/qemu/machine.py
@@ -114,7 +114,7 @@ def __init__(self, binary, args=None, wrapper=None, name=None,
         # Runstate
         self._qemu_log_path = None
         self._qemu_log_file = None
-        self._popen = None
+        self._popen: Optional['subprocess.Popen[bytes]'] = None
         self._events = []
         self._iolog = None
         self._qmp_set = True   # Enable QMP monitor by default.
@@ -227,6 +227,12 @@ def is_running(self):
         """Returns true if the VM is running."""
         return self._popen is not None and self._popen.poll() is None
 
+    @property
+    def _subp(self) -> 'subprocess.Popen[bytes]':
+        if self._popen is None:
+            raise QEMUMachineError('Subprocess pipe not present')
+        return self._popen
+
     def exitcode(self):
         """Returns the exit code if possible, or None."""
         if self._popen is None:
@@ -237,7 +243,7 @@ def get_pid(self):
         """Returns the PID of the running process, or None."""
         if not self.is_running():
             return None
-        return self._popen.pid
+        return self._subp.pid
 
     def _load_io_log(self):
         if self._qemu_log_path is not None:
@@ -369,7 +375,7 @@ def wait(self):
         """
         Wait for the VM to power off
         """
-        self._popen.wait()
+        self._subp.wait()
         if self._qmp:
             self._qmp.close()
         self._post_shutdown()
@@ -381,8 +387,8 @@ def _hard_shutdown(self) -> None:
         if not self.is_running():
             return
 
-        self._popen.kill()
-        self._popen.wait(timeout=60)
+        self._subp.kill()
+        self._subp.wait(timeout=60)
 
     def _soft_shutdown(self, has_quit: bool = False, timeout: int = 3) -> None:
         """
@@ -399,7 +405,7 @@ def _soft_shutdown(self, has_quit: bool = False, timeout: int = 3) -> None:
                 self._qmp.cmd('quit')
             self._qmp.close()
 
-        self._popen.wait(timeout=timeout)
+        self._subp.wait(timeout=timeout)
 
     def _do_shutdown(self, has_quit: bool = False, timeout: int = 3) -> None:
         """
-- 
2.21.3

[PATCH v3 14/16] python/qemu: make 'args' style arguments immutable

[John Snow]

These arguments don't need to be mutable and aren't really used as
such. Clarify their types as immutable and adjust code to match where
necessary.

In general, It's probably best not to accept a user-defined mutable
object and store it as internal object state unless there's a strong
justification for doing so. Instead, try to use generic types as input
with empty tuples as the default, and coerce to list where necessary.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 python/qemu/machine.py | 30 +++++++++++++++++-------------
 python/qemu/qtest.py   | 16 ++++++++++++----
 2 files changed, 29 insertions(+), 17 deletions(-)

diff --git a/python/qemu/machine.py b/python/qemu/machine.py
index a81a422b60e..c053c946401 100644
--- a/python/qemu/machine.py
+++ b/python/qemu/machine.py
@@ -18,6 +18,7 @@
 #
 
 import errno
+from itertools import chain
 import logging
 import os
 import subprocess
@@ -30,6 +31,8 @@
     Dict,
     List,
     Optional,
+    Sequence,
+    Tuple,
     Type,
 )
 from types import TracebackType
@@ -68,8 +71,12 @@ class QEMUMachine:
         # vm is guaranteed to be shut down here
     """
 
-    def __init__(self, binary, args=None, wrapper=None, name=None,
-                 test_dir="/var/tmp",
+    def __init__(self,
+                 binary: str,
+                 args: Sequence[str] = (),
+                 wrapper: Sequence[str] = (),
+                 name: Optional[str] = None,
+                 test_dir: str = "/var/tmp",
                  monitor_address: Optional[SocketAddrT] = None,
                  socket_scm_helper=None, sock_dir=None):
         '''
@@ -87,14 +94,7 @@ def __init__(self, binary, args=None, wrapper=None, name=None,
         # Direct user configuration
 
         self._binary = binary
-
-        if args is None:
-            args = []
-        # Copy mutable input: we will be modifying our copy
         self._args = list(args)
-
-        if wrapper is None:
-            wrapper = []
         self._wrapper = wrapper
 
         self._name = name or "qemu-%d" % os.getpid()
@@ -119,7 +119,7 @@ def __init__(self, binary, args=None, wrapper=None, name=None,
         self._iolog = None
         self._qmp_set = True   # Enable QMP monitor by default.
         self._qmp_connection: Optional[qmp.QEMUMonitorProtocol] = None
-        self._qemu_full_args = None
+        self._qemu_full_args: Tuple[str, ...] = ()
         self._temp_dir = None
         self._launched = False
         self._machine = None
@@ -340,7 +340,7 @@ def launch(self):
             raise QEMUMachineError('VM already launched')
 
         self._iolog = None
-        self._qemu_full_args = None
+        self._qemu_full_args = ()
         try:
             self._launch()
             self._launched = True
@@ -360,8 +360,12 @@ def _launch(self):
         """
         devnull = open(os.path.devnull, 'rb')
         self._pre_launch()
-        self._qemu_full_args = (self._wrapper + [self._binary] +
-                                self._base_args + self._args)
+        self._qemu_full_args = tuple(
+            chain(self._wrapper,
+                  [self._binary],
+                  self._base_args,
+                  self._args)
+        )
         LOG.debug('VM launch command: %r', ' '.join(self._qemu_full_args))
         self._popen = subprocess.Popen(self._qemu_full_args,
                                        stdin=devnull,
diff --git a/python/qemu/qtest.py b/python/qemu/qtest.py
index 05c63a1d583..ae4661d4d3e 100644
--- a/python/qemu/qtest.py
+++ b/python/qemu/qtest.py
@@ -22,6 +22,7 @@
 from typing import (
     List,
     Optional,
+    Sequence,
     TextIO,
 )
 
@@ -103,8 +104,13 @@ class QEMUQtestMachine(QEMUMachine):
     A QEMU VM, with a qtest socket available.
     """
 
-    def __init__(self, binary, args=None, name=None, test_dir="/var/tmp",
-                 socket_scm_helper=None, sock_dir=None):
+    def __init__(self,
+                 binary: str,
+                 args: Sequence[str] = (),
+                 name: Optional[str] = None,
+                 test_dir: str = "/var/tmp",
+                 socket_scm_helper: Optional[str] = None,
+                 sock_dir: Optional[str] = None):
         if name is None:
             name = "qemu-%d" % os.getpid()
         if sock_dir is None:
@@ -118,8 +124,10 @@ def __init__(self, binary, args=None, name=None, test_dir="/var/tmp",
     @property
     def _base_args(self) -> List[str]:
         args = super()._base_args
-        args.extend(['-qtest', 'unix:path=' + self._qtest_path,
-                     '-accel', 'qtest'])
+        args.extend([
+            '-qtest', f"unix:path={self._qtest_path}",
+            '-accel', 'qtest'
+        ])
         return args
 
     def _pre_launch(self):
-- 
2.21.3

[PATCH v3 15/16] iotests.py: Adjust HMP kwargs typing

[John Snow]

mypy wants to ensure there's consistency between the kwargs arguments
types and any unspecified keyword arguments. In this case, conv_keys is
a bool, but the remaining keys are Any type. Mypy (correctly) infers the
**kwargs type to be **Dict[str, str], which is not compatible with
conv_keys: bool.

Because QMP typing is a little fraught right now anyway, re-type kwargs
to Dict[str, Any] which has the benefit of silencing this check right
now.

A future re-design might type these more aggressively, but this will
give us a baseline to work from with minimal disruption.

(Thanks Kevin Wolf for the debugging assist here)

Signed-off-by: John Snow <jsnow@redhat.com>
---
 tests/qemu-iotests/iotests.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/qemu-iotests/iotests.py b/tests/qemu-iotests/iotests.py
index 7c1773bba37..19b22bee618 100644
--- a/tests/qemu-iotests/iotests.py
+++ b/tests/qemu-iotests/iotests.py
@@ -553,7 +553,7 @@ def add_incoming(self, addr):
 
     def hmp(self, command_line: str, use_log: bool = False) -> QMPMessage:
         cmd = 'human-monitor-command'
-        kwargs = {'command-line': command_line}
+        kwargs: Dict[str, Any] = {'command-line': command_line}
         if use_log:
             return self.qmp_log(cmd, **kwargs)
         else:
-- 
2.21.3

[PATCH v3 16/16] python/qemu: Add mypy type annotations

[John Snow]

These should all be purely annotations with no changes in behavior at
all. You need to be in the python folder, but you should be able to
confirm that these annotations are correct (or at least self-consistent)
by running `mypy --strict qemu`.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 python/qemu/accel.py   |  8 ++--
 python/qemu/machine.py | 94 ++++++++++++++++++++++++------------------
 python/qemu/qmp.py     | 44 +++++++++++---------
 python/qemu/qtest.py   | 26 +++++++-----
 4 files changed, 98 insertions(+), 74 deletions(-)

diff --git a/python/qemu/accel.py b/python/qemu/accel.py
index 7fabe629208..4325114e51f 100644
--- a/python/qemu/accel.py
+++ b/python/qemu/accel.py
@@ -17,6 +17,7 @@
 import logging
 import os
 import subprocess
+from typing import List, Optional
 
 LOG = logging.getLogger(__name__)
 
@@ -29,7 +30,7 @@
 }
 
 
-def list_accel(qemu_bin):
+def list_accel(qemu_bin: str) -> List[str]:
     """
     List accelerators enabled in the QEMU binary.
 
@@ -49,7 +50,8 @@ def list_accel(qemu_bin):
     return [acc.strip() for acc in out.splitlines()[1:]]
 
 
-def kvm_available(target_arch=None, qemu_bin=None):
+def kvm_available(target_arch: Optional[str] = None,
+                  qemu_bin: Optional[str] = None) -> bool:
     """
     Check if KVM is available using the following heuristic:
       - Kernel module is present in the host;
@@ -72,7 +74,7 @@ def kvm_available(target_arch=None, qemu_bin=None):
     return True
 
 
-def tcg_available(qemu_bin):
+def tcg_available(qemu_bin: str) -> bool:
     """
     Check if TCG is available.
 
diff --git a/python/qemu/machine.py b/python/qemu/machine.py
index c053c946401..d4da4e8ce15 100644
--- a/python/qemu/machine.py
+++ b/python/qemu/machine.py
@@ -28,6 +28,7 @@
 import tempfile
 from typing import (
     Any,
+    BinaryIO,
     Dict,
     List,
     Optional,
@@ -38,7 +39,7 @@
 from types import TracebackType
 
 from . import qmp
-from .qmp import SocketAddrT, QMPMessage
+from .qmp import QMPMessage, QMPReturnValue, SocketAddrT
 
 LOG = logging.getLogger(__name__)
 
@@ -61,7 +62,7 @@ class QEMUMachineAddDeviceError(QEMUMachineError):
 
 class QEMUMachine:
     """
-    A QEMU VM
+    A QEMU VM.
 
     Use this object as a context manager to ensure
     the QEMU process terminates::
@@ -78,7 +79,8 @@ def __init__(self,
                  name: Optional[str] = None,
                  test_dir: str = "/var/tmp",
                  monitor_address: Optional[SocketAddrT] = None,
-                 socket_scm_helper=None, sock_dir=None):
+                 socket_scm_helper: Optional[str] = None,
+                 sock_dir: Optional[str] = None):
         '''
         Initialize a QEMUMachine
 
@@ -112,28 +114,28 @@ def __init__(self,
             self._remove_monitor_sockfile = True
 
         # Runstate
-        self._qemu_log_path = None
-        self._qemu_log_file = None
+        self._qemu_log_path: Optional[str] = None
+        self._qemu_log_file: Optional[BinaryIO] = None
         self._popen: Optional['subprocess.Popen[bytes]'] = None
-        self._events = []
-        self._iolog = None
+        self._events: List[QMPMessage] = []
+        self._iolog: Optional[str] = None
         self._qmp_set = True   # Enable QMP monitor by default.
         self._qmp_connection: Optional[qmp.QEMUMonitorProtocol] = None
         self._qemu_full_args: Tuple[str, ...] = ()
-        self._temp_dir = None
+        self._temp_dir: Optional[str] = None
         self._launched = False
-        self._machine = None
+        self._machine: Optional[str] = None
         self._console_index = 0
         self._console_set = False
-        self._console_device_type = None
+        self._console_device_type: Optional[str] = None
         self._console_address = os.path.join(
             self._sock_dir, f"{self._name}-console.sock"
         )
-        self._console_socket = None
-        self._remove_files = []
+        self._console_socket: Optional[socket.socket] = None
+        self._remove_files: List[str] = []
         self._killed = False
 
-    def __enter__(self):
+    def __enter__(self) -> 'QEMUMachine':
         return self
 
     def __exit__(self,
@@ -142,14 +144,15 @@ def __exit__(self,
                  exc_tb: Optional[TracebackType]) -> None:
         self.shutdown()
 
-    def add_monitor_null(self):
+    def add_monitor_null(self) -> None:
         """
         This can be used to add an unused monitor instance.
         """
         self._args.append('-monitor')
         self._args.append('null')
 
-    def add_fd(self, fd, fdset, opaque, opts=''):
+    def add_fd(self, fd: int, fdset: int,
+               opaque: str, opts: str = '') -> 'QEMUMachine':
         """
         Pass a file descriptor to the VM
         """
@@ -168,7 +171,8 @@ def add_fd(self, fd, fdset, opaque, opts=''):
         self._args.append(','.join(options))
         return self
 
-    def send_fd_scm(self, fd=None, file_path=None):
+    def send_fd_scm(self, fd: Optional[int] = None,
+                    file_path: Optional[str] = None) -> int:
         """
         Send an fd or file_path to socket_scm_helper.
 
@@ -212,7 +216,7 @@ def send_fd_scm(self, fd=None, file_path=None):
         return proc.returncode
 
     @staticmethod
-    def _remove_if_exists(path):
+    def _remove_if_exists(path: str) -> None:
         """
         Remove file object at path if it exists
         """
@@ -223,7 +227,7 @@ def _remove_if_exists(path):
                 return
             raise
 
-    def is_running(self):
+    def is_running(self) -> bool:
         """Returns true if the VM is running."""
         return self._popen is not None and self._popen.poll() is None
 
@@ -233,19 +237,19 @@ def _subp(self) -> 'subprocess.Popen[bytes]':
             raise QEMUMachineError('Subprocess pipe not present')
         return self._popen
 
-    def exitcode(self):
+    def exitcode(self) -> Optional[int]:
         """Returns the exit code if possible, or None."""
         if self._popen is None:
             return None
         return self._popen.poll()
 
-    def get_pid(self):
+    def get_pid(self) -> Optional[int]:
         """Returns the PID of the running process, or None."""
         if not self.is_running():
             return None
         return self._subp.pid
 
-    def _load_io_log(self):
+    def _load_io_log(self) -> None:
         if self._qemu_log_path is not None:
             with open(self._qemu_log_path, "r") as iolog:
                 self._iolog = iolog.read()
@@ -279,7 +283,7 @@ def _base_args(self) -> List[str]:
                 args.extend(['-device', device])
         return args
 
-    def _pre_launch(self):
+    def _pre_launch(self) -> None:
         self._temp_dir = tempfile.mkdtemp(dir=self._test_dir)
         self._qemu_log_path = os.path.join(self._temp_dir, self._name + ".log")
         self._qemu_log_file = open(self._qemu_log_path, 'wb')
@@ -297,7 +301,7 @@ def _pre_launch(self):
                 nickname=self._name
             )
 
-    def _post_launch(self):
+    def _post_launch(self) -> None:
         if self._qmp:
             self._qmp.accept()
 
@@ -330,7 +334,7 @@ def _post_shutdown(self) -> None:
         self._killed = False
         self._launched = False
 
-    def launch(self):
+    def launch(self) -> None:
         """
         Launch the VM and make sure we cleanup and expose the
         command line/output in case of exception
@@ -354,7 +358,7 @@ def launch(self):
                 LOG.debug('Output: %r', self._iolog)
             raise
 
-    def _launch(self):
+    def _launch(self) -> None:
         """
         Launch the VM and establish a QMP connection
         """
@@ -375,7 +379,7 @@ def _launch(self):
                                        close_fds=False)
         self._post_launch()
 
-    def wait(self):
+    def wait(self) -> None:
         """
         Wait for the VM to power off
         """
@@ -446,13 +450,13 @@ def shutdown(self, has_quit: bool = False, hard: bool = False) -> None:
         finally:
             self._post_shutdown()
 
-    def kill(self):
+    def kill(self) -> None:
         """
         Terminate the VM forcefully and perform cleanup.
         """
         self.shutdown(hard=True)
 
-    def set_qmp_monitor(self, enabled=True):
+    def set_qmp_monitor(self, enabled: bool = True) -> None:
         """
         Set the QMP monitor.
 
@@ -492,7 +496,9 @@ def qmp(self, cmd: str,
         qmp_args = self._qmp_args(conv_keys, **args)
         return self._qmp.cmd(cmd, args=qmp_args)
 
-    def command(self, cmd, conv_keys=True, **args):
+    def command(self, cmd: str,
+                conv_keys: bool = True,
+                **args: Any) -> QMPReturnValue:
         """
         Invoke a QMP command.
         On success return the response dict.
@@ -501,7 +507,7 @@ def command(self, cmd, conv_keys=True, **args):
         qmp_args = self._qmp_args(conv_keys, **args)
         return self._qmp.command(cmd, **qmp_args)
 
-    def get_qmp_event(self, wait=False):
+    def get_qmp_event(self, wait: bool = False) -> Optional[QMPMessage]:
         """
         Poll for one queued QMP events and return it
         """
@@ -509,7 +515,7 @@ def get_qmp_event(self, wait=False):
             return self._events.pop(0)
         return self._qmp.pull_event(wait=wait)
 
-    def get_qmp_events(self, wait=False):
+    def get_qmp_events(self, wait: bool = False) -> List[QMPMessage]:
         """
         Poll for queued QMP events and return a list of dicts
         """
@@ -520,7 +526,7 @@ def get_qmp_events(self, wait=False):
         return events
 
     @staticmethod
-    def event_match(event, match=None):
+    def event_match(event: Any, match: Optional[Any]) -> bool:
         """
         Check if an event matches optional match criteria.
 
@@ -550,9 +556,11 @@ def event_match(event, match=None):
             return True
         except TypeError:
             # either match or event wasn't iterable (not a dict)
-            return match == event
+            return bool(match == event)
 
-    def event_wait(self, name, timeout=60.0, match=None):
+    def event_wait(self, name: str,
+                   timeout: float = 60.0,
+                   match: Optional[QMPMessage] = None) -> Optional[QMPMessage]:
         """
         event_wait waits for and returns a named event from QMP with a timeout.
 
@@ -562,7 +570,9 @@ def event_wait(self, name, timeout=60.0, match=None):
         """
         return self.events_wait([(name, match)], timeout)
 
-    def events_wait(self, events, timeout=60.0):
+    def events_wait(self,
+                    events: Sequence[Tuple[str, Any]],
+                    timeout: float = 60.0) -> Optional[QMPMessage]:
         """
         events_wait waits for and returns a single named event from QMP.
         In the case of multiple qualifying events, this function returns the
@@ -579,7 +589,7 @@ def events_wait(self, events, timeout=60.0):
         :return: A QMP event matching the filter criteria.
                  If timeout was 0 and no event matched, None.
         """
-        def _match(event):
+        def _match(event: QMPMessage) -> bool:
             for name, match in events:
                 if event['event'] == name and self.event_match(event, match):
                     return True
@@ -606,20 +616,20 @@ def _match(event):
 
         return None
 
-    def get_log(self):
+    def get_log(self) -> Optional[str]:
         """
         After self.shutdown or failed qemu execution, this returns the output
         of the qemu process.
         """
         return self._iolog
 
-    def add_args(self, *args):
+    def add_args(self, *args: str) -> None:
         """
         Adds to the list of extra arguments to be given to the QEMU binary
         """
         self._args.extend(args)
 
-    def set_machine(self, machine_type):
+    def set_machine(self, machine_type: str) -> None:
         """
         Sets the machine type
 
@@ -628,7 +638,9 @@ def set_machine(self, machine_type):
         """
         self._machine = machine_type
 
-    def set_console(self, device_type=None, console_index=0):
+    def set_console(self,
+                    device_type: Optional[str] = None,
+                    console_index: int = 0) -> None:
         """
         Sets the device type for a console device
 
@@ -659,7 +671,7 @@ def set_console(self, device_type=None, console_index=0):
         self._console_index = console_index
 
     @property
-    def console_socket(self):
+    def console_socket(self) -> socket.socket:
         """
         Returns a socket connected to the console
         """
diff --git a/python/qemu/qmp.py b/python/qemu/qmp.py
index 7935dababbf..303e82ee6b4 100644
--- a/python/qemu/qmp.py
+++ b/python/qemu/qmp.py
@@ -15,6 +15,7 @@
     Any,
     cast,
     Dict,
+    List,
     Optional,
     TextIO,
     Type,
@@ -90,7 +91,9 @@ class QEMUMonitorProtocol:
     #: Logger object for debugging messages
     logger = logging.getLogger('QMP')
 
-    def __init__(self, address, server=False, nickname=None):
+    def __init__(self, address: SocketAddrT,
+                 server: bool = False,
+                 nickname: Optional[str] = None):
         """
         Create a QEMUMonitorProtocol class.
 
@@ -102,7 +105,7 @@ def __init__(self, address, server=False, nickname=None):
         @note No connection is established, this is done by the connect() or
               accept() methods
         """
-        self.__events = []
+        self.__events: List[QMPMessage] = []
         self.__address = address
         self.__sock = self.__get_sock()
         self.__sockfile: Optional[TextIO] = None
@@ -114,14 +117,14 @@ def __init__(self, address, server=False, nickname=None):
             self.__sock.bind(self.__address)
             self.__sock.listen(1)
 
-    def __get_sock(self):
+    def __get_sock(self) -> socket.socket:
         if isinstance(self.__address, tuple):
             family = socket.AF_INET
         else:
             family = socket.AF_UNIX
         return socket.socket(family, socket.SOCK_STREAM)
 
-    def __negotiate_capabilities(self):
+    def __negotiate_capabilities(self) -> QMPMessage:
         greeting = self.__json_read()
         if greeting is None or "QMP" not in greeting:
             raise QMPConnectError
@@ -131,7 +134,7 @@ def __negotiate_capabilities(self):
             return greeting
         raise QMPCapabilitiesError
 
-    def __json_read(self, only_event=False):
+    def __json_read(self, only_event: bool = False) -> Optional[QMPMessage]:
         assert self.__sockfile is not None
         while True:
             data = self.__sockfile.readline()
@@ -148,7 +151,7 @@ def __json_read(self, only_event=False):
                     continue
             return resp
 
-    def __get_events(self, wait=False):
+    def __get_events(self, wait: Union[bool, float] = False) -> None:
         """
         Check for new events in the stream and cache them in __events.
 
@@ -186,7 +189,7 @@ def __get_events(self, wait=False):
                 raise QMPConnectError("Error while reading from socket")
             self.__sock.settimeout(None)
 
-    def __enter__(self):
+    def __enter__(self) -> 'QEMUMonitorProtocol':
         # Implement context manager enter function.
         return self
 
@@ -199,7 +202,7 @@ def __exit__(self,
         # Implement context manager exit function.
         self.close()
 
-    def connect(self, negotiate=True):
+    def connect(self, negotiate: bool = True) -> Optional[QMPMessage]:
         """
         Connect to the QMP Monitor and perform capabilities negotiation.
 
@@ -214,7 +217,7 @@ def connect(self, negotiate=True):
             return self.__negotiate_capabilities()
         return None
 
-    def accept(self, timeout=15.0):
+    def accept(self, timeout: float = 15.0) -> QMPMessage:
         """
         Await connection from QMP Monitor and perform capabilities negotiation.
 
@@ -250,7 +253,9 @@ def cmd_obj(self, qmp_cmd: QMPMessage) -> QMPMessage:
         self.logger.debug("<<< %s", resp)
         return resp
 
-    def cmd(self, name, args=None, cmd_id=None):
+    def cmd(self, name: str,
+            args: Optional[Dict[str, Any]] = None,
+            cmd_id: Optional[Any] = None) -> QMPMessage:
         """
         Build a QMP command and send it to the QMP Monitor.
 
@@ -258,14 +263,14 @@ def cmd(self, name, args=None, cmd_id=None):
         @param args: command arguments (dict)
         @param cmd_id: command id (dict, list, string or int)
         """
-        qmp_cmd = {'execute': name}
+        qmp_cmd: QMPMessage = {'execute': name}
         if args:
             qmp_cmd['arguments'] = args
         if cmd_id:
             qmp_cmd['id'] = cmd_id
         return self.cmd_obj(qmp_cmd)
 
-    def command(self, cmd, **kwds):
+    def command(self, cmd: str, **kwds: Any) -> QMPReturnValue:
         """
         Build and send a QMP command to the monitor, report errors if any
         """
@@ -278,7 +283,8 @@ def command(self, cmd, **kwds):
             )
         return cast(QMPReturnValue, ret['return'])
 
-    def pull_event(self, wait=False):
+    def pull_event(self,
+                   wait: Union[bool, float] = False) -> Optional[QMPMessage]:
         """
         Pulls a single event.
 
@@ -298,7 +304,7 @@ def pull_event(self, wait=False):
             return self.__events.pop(0)
         return None
 
-    def get_events(self, wait=False):
+    def get_events(self, wait: bool = False) -> List[QMPMessage]:
         """
         Get a list of available QMP events.
 
@@ -315,13 +321,13 @@ def get_events(self, wait=False):
         self.__get_events(wait)
         return self.__events
 
-    def clear_events(self):
+    def clear_events(self) -> None:
         """
         Clear current list of pending events.
         """
         self.__events = []
 
-    def close(self):
+    def close(self) -> None:
         """
         Close the socket and socket file.
         """
@@ -330,7 +336,7 @@ def close(self):
         if self.__sockfile:
             self.__sockfile.close()
 
-    def settimeout(self, timeout):
+    def settimeout(self, timeout: float) -> None:
         """
         Set the socket timeout.
 
@@ -339,7 +345,7 @@ def settimeout(self, timeout):
         """
         self.__sock.settimeout(timeout)
 
-    def get_sock_fd(self):
+    def get_sock_fd(self) -> int:
         """
         Get the socket file descriptor.
 
@@ -347,7 +353,7 @@ def get_sock_fd(self):
         """
         return self.__sock.fileno()
 
-    def is_scm_available(self):
+    def is_scm_available(self) -> bool:
         """
         Check if the socket allows for SCM_RIGHTS.
 
diff --git a/python/qemu/qtest.py b/python/qemu/qtest.py
index ae4661d4d3e..49c04bc98d9 100644
--- a/python/qemu/qtest.py
+++ b/python/qemu/qtest.py
@@ -27,6 +27,7 @@
 )
 
 from .machine import QEMUMachine
+from .qmp import SocketAddrT
 
 
 class QEMUQtestProtocol:
@@ -43,7 +44,8 @@ class QEMUQtestProtocol:
        No conection is estabalished by __init__(), this is done
        by the connect() or accept() methods.
     """
-    def __init__(self, address, server=False):
+    def __init__(self, address: SocketAddrT,
+                 server: bool = False):
         self._address = address
         self._sock = self._get_sock()
         self._sockfile: Optional[TextIO] = None
@@ -51,14 +53,14 @@ def __init__(self, address, server=False):
             self._sock.bind(self._address)
             self._sock.listen(1)
 
-    def _get_sock(self):
+    def _get_sock(self) -> socket.socket:
         if isinstance(self._address, tuple):
             family = socket.AF_INET
         else:
             family = socket.AF_UNIX
         return socket.socket(family, socket.SOCK_STREAM)
 
-    def connect(self):
+    def connect(self) -> None:
         """
         Connect to the qtest socket.
 
@@ -67,7 +69,7 @@ def connect(self):
         self._sock.connect(self._address)
         self._sockfile = self._sock.makefile(mode='r')
 
-    def accept(self):
+    def accept(self) -> None:
         """
         Await connection from QEMU.
 
@@ -76,7 +78,7 @@ def accept(self):
         self._sock, _ = self._sock.accept()
         self._sockfile = self._sock.makefile(mode='r')
 
-    def cmd(self, qtest_cmd):
+    def cmd(self, qtest_cmd: str) -> str:
         """
         Send a qtest command on the wire.
 
@@ -87,14 +89,16 @@ def cmd(self, qtest_cmd):
         resp = self._sockfile.readline()
         return resp
 
-    def close(self):
-        """Close this socket."""
+    def close(self) -> None:
+        """
+        Close this socket.
+        """
         self._sock.close()
         if self._sockfile:
             self._sockfile.close()
             self._sockfile = None
 
-    def settimeout(self, timeout):
+    def settimeout(self, timeout: Optional[float]) -> None:
         """Set a timeout, in seconds."""
         self._sock.settimeout(timeout)
 
@@ -118,7 +122,7 @@ def __init__(self,
         super().__init__(binary, args, name=name, test_dir=test_dir,
                          socket_scm_helper=socket_scm_helper,
                          sock_dir=sock_dir)
-        self._qtest = None
+        self._qtest: Optional[QEMUQtestProtocol] = None
         self._qtest_path = os.path.join(sock_dir, name + "-qtest.sock")
 
     @property
@@ -130,7 +134,7 @@ def _base_args(self) -> List[str]:
         ])
         return args
 
-    def _pre_launch(self):
+    def _pre_launch(self) -> None:
         super()._pre_launch()
         self._qtest = QEMUQtestProtocol(self._qtest_path, server=True)
 
@@ -139,7 +143,7 @@ def _post_launch(self) -> None:
         super()._post_launch()
         self._qtest.accept()
 
-    def _post_shutdown(self):
+    def _post_shutdown(self) -> None:
         super()._post_shutdown()
         self._remove_if_exists(self._qtest_path)
 
-- 
2.21.3

Re: [PATCH v3 00/16] python: add mypy support to python/qemu

[Kevin Wolf]

Am 04.06.2020 um 22:22 hat John Snow geschrieben:
> Based-on: 20200604195252.20739-1-jsnow@redhat.com
> 
> This series is extracted from my larger series that attempted to bundle
> our python module as an installable module. These fixes don't require that,
> so they are being sent first as I think there's less up for debate in here.
> 
> This requires my "refactor shutdown" patch as a pre-requisite.

You didn't like my previous R-b? Here's a new one. :-)

Reviewed-by: Kevin Wolf <kwolf@redhat.com>

Re: [PATCH v3 00/16] python: add mypy support to python/qemu

[John Snow]

On 6/5/20 5:26 AM, Kevin Wolf wrote:
> Am 04.06.2020 um 22:22 hat John Snow geschrieben:
>> Based-on: 20200604195252.20739-1-jsnow@redhat.com
>>
>> This series is extracted from my larger series that attempted to bundle
>> our python module as an installable module. These fixes don't require that,
>> so they are being sent first as I think there's less up for debate in here.
>>
>> This requires my "refactor shutdown" patch as a pre-requisite.
> 
> You didn't like my previous R-b? Here's a new one. :-)
> 
> Reviewed-by: Kevin Wolf <kwolf@redhat.com>
> 

I felt like I should address the feedback, and though I could have
applied the R-B to patches I didn't change, it was ... faster to just
re-send it.

Serious question: How do you apply people's R-Bs to your patches? At the
moment, it's pretty manually intensive for me. I use stgit and I pop all
of the patches off (stg pop -n 100), and then one-at-a-time I `stg push;
stg edit` and copy-paste the R-B into it.

It's easier when I'm just pulling other people's patches from the ML,
the patches tool handles it for me. It's updating my own patches that's
a drag and prone to error.

--js

Re: [PATCH v3 00/16] python: add mypy support to python/qemu

[Kevin Wolf]

Am 08.06.2020 um 17:19 hat John Snow geschrieben:
> 
> 
> On 6/5/20 5:26 AM, Kevin Wolf wrote:
> > Am 04.06.2020 um 22:22 hat John Snow geschrieben:
> >> Based-on: 20200604195252.20739-1-jsnow@redhat.com
> >>
> >> This series is extracted from my larger series that attempted to bundle
> >> our python module as an installable module. These fixes don't require that,
> >> so they are being sent first as I think there's less up for debate in here.
> >>
> >> This requires my "refactor shutdown" patch as a pre-requisite.
> > 
> > You didn't like my previous R-b? Here's a new one. :-)
> > 
> > Reviewed-by: Kevin Wolf <kwolf@redhat.com>
> > 
> 
> I felt like I should address the feedback, and though I could have
> applied the R-B to patches I didn't change, it was ... faster to just
> re-send it.
> 
> Serious question: How do you apply people's R-Bs to your patches? At the
> moment, it's pretty manually intensive for me. I use stgit and I pop all
> of the patches off (stg pop -n 100), and then one-at-a-time I `stg push;
> stg edit` and copy-paste the R-B into it.
> 
> It's easier when I'm just pulling other people's patches from the ML,
> the patches tool handles it for me. It's updating my own patches that's
> a drag and prone to error.

It's a manual process for me, too. Just that I don't use stgit, but
'git rebase -i'.

Kevin

Re: [PATCH v3 00/16] python: add mypy support to python/qemu

[Philippe Mathieu-Daudé]

On 6/8/20 5:33 PM, Kevin Wolf wrote:
> Am 08.06.2020 um 17:19 hat John Snow geschrieben:
>>
>>
>> On 6/5/20 5:26 AM, Kevin Wolf wrote:
>>> Am 04.06.2020 um 22:22 hat John Snow geschrieben:
>>>> Based-on: 20200604195252.20739-1-jsnow@redhat.com
>>>>
>>>> This series is extracted from my larger series that attempted to bundle
>>>> our python module as an installable module. These fixes don't require that,
>>>> so they are being sent first as I think there's less up for debate in here.
>>>>
>>>> This requires my "refactor shutdown" patch as a pre-requisite.
>>>
>>> You didn't like my previous R-b? Here's a new one. :-)
>>>
>>> Reviewed-by: Kevin Wolf <kwolf@redhat.com>
>>>
>>
>> I felt like I should address the feedback, and though I could have
>> applied the R-B to patches I didn't change, it was ... faster to just
>> re-send it.
>>
>> Serious question: How do you apply people's R-Bs to your patches? At the
>> moment, it's pretty manually intensive for me. I use stgit and I pop all
>> of the patches off (stg pop -n 100), and then one-at-a-time I `stg push;
>> stg edit` and copy-paste the R-B into it.

wget https://patchew.org/QEMU/${MSG_ID}/mbox
git am mbox

Where ${MSG_ID} is the Message-Id of the series cover letter.

>>
>> It's easier when I'm just pulling other people's patches from the ML,
>> the patches tool handles it for me. It's updating my own patches that's
>> a drag and prone to error.
> 
> It's a manual process for me, too. Just that I don't use stgit, but
> 'git rebase -i'.
> 
> Kevin
> 

Re: [PATCH v3 00/16] python: add mypy support to python/qemu

[Markus Armbruster]

Philippe Mathieu-Daudé <philmd@redhat.com> writes:

> On 6/8/20 5:33 PM, Kevin Wolf wrote:
>> Am 08.06.2020 um 17:19 hat John Snow geschrieben:
>>>
>>>
>>> On 6/5/20 5:26 AM, Kevin Wolf wrote:
>>>> Am 04.06.2020 um 22:22 hat John Snow geschrieben:
>>>>> Based-on: 20200604195252.20739-1-jsnow@redhat.com
>>>>>
>>>>> This series is extracted from my larger series that attempted to bundle
>>>>> our python module as an installable module. These fixes don't require that,
>>>>> so they are being sent first as I think there's less up for debate in here.
>>>>>
>>>>> This requires my "refactor shutdown" patch as a pre-requisite.
>>>>
>>>> You didn't like my previous R-b? Here's a new one. :-)
>>>>
>>>> Reviewed-by: Kevin Wolf <kwolf@redhat.com>
>>>>
>>>
>>> I felt like I should address the feedback, and though I could have
>>> applied the R-B to patches I didn't change, it was ... faster to just
>>> re-send it.
>>>
>>> Serious question: How do you apply people's R-Bs to your patches? At the
>>> moment, it's pretty manually intensive for me. I use stgit and I pop all
>>> of the patches off (stg pop -n 100), and then one-at-a-time I `stg push;
>>> stg edit` and copy-paste the R-B into it.
>
> wget https://patchew.org/QEMU/${MSG_ID}/mbox
> git am mbox
>
> Where ${MSG_ID} is the Message-Id of the series cover letter.

Patchew's awesomeness is still under-appreciated.

applying mailing list review tags (was: Re: [PATCH v3 00/16] python: add mypy support to python/qemu)

[John Snow]

On 6/9/20 4:58 AM, Markus Armbruster wrote:
> Philippe Mathieu-Daudé <philmd@redhat.com> writes:
> 
>> On 6/8/20 5:33 PM, Kevin Wolf wrote:
>>> Am 08.06.2020 um 17:19 hat John Snow geschrieben:
>>>>
>>>>
>>>> On 6/5/20 5:26 AM, Kevin Wolf wrote:
>>>>> Am 04.06.2020 um 22:22 hat John Snow geschrieben:
>>>>>> Based-on: 20200604195252.20739-1-jsnow@redhat.com
>>>>>>
>>>>>> This series is extracted from my larger series that attempted to bundle
>>>>>> our python module as an installable module. These fixes don't require that,
>>>>>> so they are being sent first as I think there's less up for debate in here.
>>>>>>
>>>>>> This requires my "refactor shutdown" patch as a pre-requisite.
>>>>>
>>>>> You didn't like my previous R-b? Here's a new one. :-)
>>>>>
>>>>> Reviewed-by: Kevin Wolf <kwolf@redhat.com>
>>>>>
>>>>
>>>> I felt like I should address the feedback, and though I could have
>>>> applied the R-B to patches I didn't change, it was ... faster to just
>>>> re-send it.
>>>>
>>>> Serious question: How do you apply people's R-Bs to your patches? At the
>>>> moment, it's pretty manually intensive for me. I use stgit and I pop all
>>>> of the patches off (stg pop -n 100), and then one-at-a-time I `stg push;
>>>> stg edit` and copy-paste the R-B into it.
>>
>> wget https://patchew.org/QEMU/${MSG_ID}/mbox
>> git am mbox
>>
>> Where ${MSG_ID} is the Message-Id of the series cover letter.
> 
> Patchew's awesomeness is still under-appreciated.
> 

Not for lack of appreciating patchew, but the problem with this workflow
is if I have already made modifications to my patches locally, I can't
use this to apply tags from upstream.

It looks like I will continue to do this manually for the time being;
but scripting the ability to "merge tags" from the list would be a cool
trick.

I'm not sure how to do it with git, though. Let's say I've got 16
patches and I've made modifications to some, but not all; so I have a
branch with 16 patches ahead of origin/master.

Does anyone have any cool tricks for being able to script:

1. Correlating a mailing list patch from e.g. patchew to a commit in my
history, even if it's changed a little bit?

(git-backport-diff uses patch names, that might be sufficient... Could
use that as a starting point, at least.)

2. Obtaining the commit message of that patch?
`git show -s --format=%B $SHA` ought to do it...

3. Editing that commit message? This I'm not sure about. I'd need to
understand the tags on the upstream and downstream versions, merge them,
and then re-write the message. Some magic with `git rebase -i` ?

--js

Re: applying mailing list review tags (was: Re: [PATCH v3 00/16] python: add mypy support to python/qemu)

[Philippe Mathieu-Daudé]

On 6/16/20 7:58 PM, John Snow wrote:
> 
> 
> On 6/9/20 4:58 AM, Markus Armbruster wrote:
>> Philippe Mathieu-Daudé <philmd@redhat.com> writes:
>>
>>> On 6/8/20 5:33 PM, Kevin Wolf wrote:
>>>> Am 08.06.2020 um 17:19 hat John Snow geschrieben:
>>>>>
>>>>>
>>>>> On 6/5/20 5:26 AM, Kevin Wolf wrote:
>>>>>> Am 04.06.2020 um 22:22 hat John Snow geschrieben:
>>>>>>> Based-on: 20200604195252.20739-1-jsnow@redhat.com
>>>>>>>
>>>>>>> This series is extracted from my larger series that attempted to bundle
>>>>>>> our python module as an installable module. These fixes don't require that,
>>>>>>> so they are being sent first as I think there's less up for debate in here.
>>>>>>>
>>>>>>> This requires my "refactor shutdown" patch as a pre-requisite.
>>>>>>
>>>>>> You didn't like my previous R-b? Here's a new one. :-)
>>>>>>
>>>>>> Reviewed-by: Kevin Wolf <kwolf@redhat.com>
>>>>>>
>>>>>
>>>>> I felt like I should address the feedback, and though I could have
>>>>> applied the R-B to patches I didn't change, it was ... faster to just
>>>>> re-send it.
>>>>>
>>>>> Serious question: How do you apply people's R-Bs to your patches? At the
>>>>> moment, it's pretty manually intensive for me. I use stgit and I pop all
>>>>> of the patches off (stg pop -n 100), and then one-at-a-time I `stg push;
>>>>> stg edit` and copy-paste the R-B into it.
>>>
>>> wget https://patchew.org/QEMU/${MSG_ID}/mbox
>>> git am mbox
>>>
>>> Where ${MSG_ID} is the Message-Id of the series cover letter.
>>
>> Patchew's awesomeness is still under-appreciated.
>>
> 
> Not for lack of appreciating patchew, but the problem with this workflow
> is if I have already made modifications to my patches locally, I can't
> use this to apply tags from upstream.

Does that mean you want to respin this series?
Else you can consider it applied on python-next.

> 
> It looks like I will continue to do this manually for the time being;
> but scripting the ability to "merge tags" from the list would be a cool
> trick.
> 
> I'm not sure how to do it with git, though. Let's say I've got 16
> patches and I've made modifications to some, but not all; so I have a
> branch with 16 patches ahead of origin/master.
> 
> Does anyone have any cool tricks for being able to script:
> 
> 1. Correlating a mailing list patch from e.g. patchew to a commit in my
> history, even if it's changed a little bit?
> 
> (git-backport-diff uses patch names, that might be sufficient... Could
> use that as a starting point, at least.)
> 
> 2. Obtaining the commit message of that patch?
> `git show -s --format=%B $SHA` ought to do it...
> 
> 3. Editing that commit message? This I'm not sure about. I'd need to
> understand the tags on the upstream and downstream versions, merge them,
> and then re-write the message. Some magic with `git rebase -i` ?
> 
> --js
> 

Re: applying mailing list review tags (was: Re: [PATCH v3 00/16] python: add mypy support to python/qemu)

[Paolo Bonzini]

On 16/06/20 19:58, John Snow wrote:
> 1. Correlating a mailing list patch from e.g. patchew to a commit in my
> history, even if it's changed a little bit?

Use "git am --message-id"?

> (git-backport-diff uses patch names, that might be sufficient... Could
> use that as a starting point, at least.)
> 
> 2. Obtaining the commit message of that patch?
> `git show -s --format=%B $SHA` ought to do it...
> 
> 3. Editing that commit message? This I'm not sure about. I'd need to
> understand the tags on the upstream and downstream versions, merge them,
> and then re-write the message. Some magic with `git rebase -i` ?

"patchew apply" actually uses "git filter-branch --msg-filter" to add the
tags  after a successful "git am", so you can do something similar yourself.
(Actually I have pending patches to patchew that switch it to server-side
application of tags using the "mbox" URL that Philippe mentioned earlier, but
they've been pending for quite some time now).

To get the upstream tags you can use the Patchew REST API:

   $ MSGID=20200521153616.307100-1-stefanha@redhat.com
   $ curl -L https://patchew.org/api/v1/projects/by-name/QEMU/messages/$MSGID/ | jq -r '.tags[]'
   Reported-by: Philippe Mathieu-Daudé <philmd@redhat.com>
   Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

So you'd have to take a commit, look for a Message-Id header, fetch the
tags from above mentioned Patchew API URL and add the tags to the commit
message.

The commit message can be either emitted to stdout (and the script
used with "git filter-branch)" or, for the faint of heart, the script
could do a "git commit --amend" and you can use "git rebase -i --exec"
to execute the script on all commits in a range.

This script is for the latter option:

   #! /bin/bash
   BODY=$(git show -s --format=%B)
   MSGID=$(git interpret-trailers --parse <<< $BODY | sed -n 's/^Message-Id: <\(.*\)>/\1/ip')
   USER="$(git config user.name) <$(git config user.email)>"
   BODY=$(curl -L https://patchew.org/api/v1/projects/by-name/QEMU/messages/$MSGID/ | \
     jq -r '.tags[]' | ( \
       args=()
       while read x; do
         args+=(--trailer "$x")
       done
       git interpret-trailers \
         --if-exists doNothing "${args[@]}" \
         --if-exists replace --if-missing doNothing --trailer "Signed-off-by: $USER" <<< $BODY
   ))
   git commit --amend -m"$BODY"

The script will also move your Signed-off-by line at the end of the commit
message, this might be a problem if there is more than one such line and
you want to keep them all.

Paolo

Re: [PATCH v3 00/16] python: add mypy support to python/qemu

[John Snow]

On 6/16/20 11:33 PM, Philippe Mathieu-Daudé wrote:
> Does that mean you want to respin this series?
> Else you can consider it applied on python-next.

No no - you're all set. Just taking the opportunity to discuss tooling
that I find cumbersome at the moment.

Thank you Philippe :)

--js

Re: [PATCH v3 00/16] python: add mypy support to python/qemu

[Philippe Mathieu-Daudé]

On 6/4/20 10:22 PM, John Snow wrote:
> Based-on: 20200604195252.20739-1-jsnow@redhat.com
> 
> This series is extracted from my larger series that attempted to bundle
> our python module as an installable module. These fixes don't require that,
> so they are being sent first as I think there's less up for debate in here.
> 
[...]
> 
> John Snow (16):
>   python/qmp.py: Define common types
>   iotests.py: use qemu.qmp type aliases
>   python/qmp.py: re-absorb MonitorResponseError
>   python/qmp.py: Do not return None from cmd_obj
>   python/qmp.py: add casts to JSON deserialization
>   python/qmp.py: add QMPProtocolError
>   python/machine.py: Fix monitor address typing
>   python/machine.py: reorder __init__
>   python/machine.py: Don't modify state in _base_args()
>   python/machine.py: Handle None events in events_wait
>   python/machine.py: use qmp.command
>   python/machine.py: Add _qmp access shim
>   python/machine.py: fix _popen access
>   python/qemu: make 'args' style arguments immutable
>   iotests.py: Adjust HMP kwargs typing
>   python/qemu: Add mypy type annotations
> 
>  python/qemu/accel.py          |   8 +-
>  python/qemu/machine.py        | 286 ++++++++++++++++++++--------------
>  python/qemu/qmp.py            | 111 +++++++++----
>  python/qemu/qtest.py          |  53 ++++---
>  scripts/render_block_graph.py |   7 +-
>  tests/qemu-iotests/iotests.py |  11 +-
>  6 files changed, 298 insertions(+), 178 deletions(-)
> 

Thanks, applied to my python-next tree:
https://gitlab.com/philmd/qemu/commits/python-next

Re: [PATCH v3 00/16] python: add mypy support to python/qemu

[John Snow]

On 6/17/20 1:18 PM, Philippe Mathieu-Daudé wrote:
> On 6/4/20 10:22 PM, John Snow wrote:
>> Based-on: 20200604195252.20739-1-jsnow@redhat.com
>>
>> This series is extracted from my larger series that attempted to bundle
>> our python module as an installable module. These fixes don't require that,
>> so they are being sent first as I think there's less up for debate in here.
>>
> [...]
>>
>> John Snow (16):
>>   python/qmp.py: Define common types
>>   iotests.py: use qemu.qmp type aliases
>>   python/qmp.py: re-absorb MonitorResponseError
>>   python/qmp.py: Do not return None from cmd_obj
>>   python/qmp.py: add casts to JSON deserialization
>>   python/qmp.py: add QMPProtocolError
>>   python/machine.py: Fix monitor address typing
>>   python/machine.py: reorder __init__
>>   python/machine.py: Don't modify state in _base_args()
>>   python/machine.py: Handle None events in events_wait
>>   python/machine.py: use qmp.command
>>   python/machine.py: Add _qmp access shim
>>   python/machine.py: fix _popen access
>>   python/qemu: make 'args' style arguments immutable
>>   iotests.py: Adjust HMP kwargs typing
>>   python/qemu: Add mypy type annotations
>>
>>  python/qemu/accel.py          |   8 +-
>>  python/qemu/machine.py        | 286 ++++++++++++++++++++--------------
>>  python/qemu/qmp.py            | 111 +++++++++----
>>  python/qemu/qtest.py          |  53 ++++---
>>  scripts/render_block_graph.py |   7 +-
>>  tests/qemu-iotests/iotests.py |  11 +-
>>  6 files changed, 298 insertions(+), 178 deletions(-)
>>
> 
> Thanks, applied to my python-next tree:
> https://gitlab.com/philmd/qemu/commits/python-next
> 

Awesome, thanks!

Re: [PATCH v3 12/16] python/machine.py: Add _qmp access shim

[Philippe Mathieu-Daudé]

On 6/4/20 10:22 PM, John Snow wrote:
> Like many other Optional[] types, it's not always a given that this
> object will be set. Wrap it in a type-shim that raises a meaningful
> error and will always return a concrete type.
> 
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  python/qemu/machine.py | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/python/qemu/machine.py b/python/qemu/machine.py
> index d8289936816..a451f9000d6 100644
> --- a/python/qemu/machine.py
> +++ b/python/qemu/machine.py
> @@ -118,7 +118,7 @@ def __init__(self, binary, args=None, wrapper=None, name=None,
>          self._events = []
>          self._iolog = None
>          self._qmp_set = True   # Enable QMP monitor by default.
> -        self._qmp = None
> +        self._qmp_connection: Optional[qmp.QEMUMonitorProtocol] = None
>          self._qemu_full_args = None
>          self._temp_dir = None
>          self._launched = False
> @@ -285,7 +285,7 @@ def _pre_launch(self):
>              if self._remove_monitor_sockfile:
>                  assert isinstance(self._monitor_address, str)
>                  self._remove_files.append(self._monitor_address)
> -            self._qmp = qmp.QEMUMonitorProtocol(
> +            self._qmp_connection = qmp.QEMUMonitorProtocol(
>                  self._monitor_address,
>                  server=True,
>                  nickname=self._name
> @@ -455,7 +455,13 @@ def set_qmp_monitor(self, enabled=True):
>              self._qmp_set = True
>          else:
>              self._qmp_set = False
> -            self._qmp = None
> +            self._qmp_connection = None
> +
> +    @property
> +    def _qmp(self) -> qmp.QEMUMonitorProtocol:
> +        if self._qmp_connection is None:
> +            raise QEMUMachineError("Attempt to access QMP with no connection")
> +        return self._qmp_connection
>  
>      @classmethod
>      def _qmp_args(cls, _conv_keys: bool = True, **args: Any) -> Dict[str, Any]:
> 

This patch breaks the EmptyCPUModel test:

(043/101) tests/acceptance/empty_cpu_model.py:EmptyCPUModel.test:
ERROR: Attempt to access QMP with no connection (0.03 s)

Re: [PATCH v3 12/16] python/machine.py: Add _qmp access shim

[Philippe Mathieu-Daudé]

On Sat, Jun 20, 2020 at 10:14 AM Philippe Mathieu-Daudé
<philmd@redhat.com> wrote:
>
> On 6/4/20 10:22 PM, John Snow wrote:
> > Like many other Optional[] types, it's not always a given that this
> > object will be set. Wrap it in a type-shim that raises a meaningful
> > error and will always return a concrete type.
> >
> > Signed-off-by: John Snow <jsnow@redhat.com>
> > ---
> >  python/qemu/machine.py | 12 +++++++++---
> >  1 file changed, 9 insertions(+), 3 deletions(-)
> >
> > diff --git a/python/qemu/machine.py b/python/qemu/machine.py
> > index d8289936816..a451f9000d6 100644
> > --- a/python/qemu/machine.py
> > +++ b/python/qemu/machine.py
> > @@ -118,7 +118,7 @@ def __init__(self, binary, args=None, wrapper=None, name=None,
> >          self._events = []
> >          self._iolog = None
> >          self._qmp_set = True   # Enable QMP monitor by default.
> > -        self._qmp = None
> > +        self._qmp_connection: Optional[qmp.QEMUMonitorProtocol] = None
> >          self._qemu_full_args = None
> >          self._temp_dir = None
> >          self._launched = False
> > @@ -285,7 +285,7 @@ def _pre_launch(self):
> >              if self._remove_monitor_sockfile:
> >                  assert isinstance(self._monitor_address, str)
> >                  self._remove_files.append(self._monitor_address)
> > -            self._qmp = qmp.QEMUMonitorProtocol(
> > +            self._qmp_connection = qmp.QEMUMonitorProtocol(
> >                  self._monitor_address,
> >                  server=True,
> >                  nickname=self._name
> > @@ -455,7 +455,13 @@ def set_qmp_monitor(self, enabled=True):
> >              self._qmp_set = True
> >          else:
> >              self._qmp_set = False
> > -            self._qmp = None
> > +            self._qmp_connection = None
> > +
> > +    @property
> > +    def _qmp(self) -> qmp.QEMUMonitorProtocol:
> > +        if self._qmp_connection is None:
> > +            raise QEMUMachineError("Attempt to access QMP with no connection")
> > +        return self._qmp_connection
> >
> >      @classmethod
> >      def _qmp_args(cls, _conv_keys: bool = True, **args: Any) -> Dict[str, Any]:
> >
>
> This patch breaks the EmptyCPUModel test:
>
> (043/101) tests/acceptance/empty_cpu_model.py:EmptyCPUModel.test:
> ERROR: Attempt to access QMP with no connection (0.03 s)

Fixed with:

-- >8 --
diff --git a/python/qemu/machine.py b/python/qemu/machine.py
index ba6397dd7e..26ae7be89b 100644
--- a/python/qemu/machine.py
+++ b/python/qemu/machine.py
@@ -480,7 +480,7 @@ def set_qmp_monitor(self, enabled: bool = True) -> None:

     @property
     def _qmp(self) -> qmp.QEMUMonitorProtocol:
-        if self._qmp_connection is None:
+        if self._qmp_set and self._qmp_connection is None:
             raise QEMUMachineError("Attempt to access QMP with no connection")
         return self._qmp_connection

---

Does that sound reasonable to you?

Re: [PATCH v3 12/16] python/machine.py: Add _qmp access shim

[Kevin Wolf]

Am 20.06.2020 um 10:20 hat Philippe Mathieu-Daudé geschrieben:
> On Sat, Jun 20, 2020 at 10:14 AM Philippe Mathieu-Daudé
> <philmd@redhat.com> wrote:
> >
> > On 6/4/20 10:22 PM, John Snow wrote:
> > > Like many other Optional[] types, it's not always a given that this
> > > object will be set. Wrap it in a type-shim that raises a meaningful
> > > error and will always return a concrete type.
> > >
> > > Signed-off-by: John Snow <jsnow@redhat.com>
> > > ---
> > >  python/qemu/machine.py | 12 +++++++++---
> > >  1 file changed, 9 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/python/qemu/machine.py b/python/qemu/machine.py
> > > index d8289936816..a451f9000d6 100644
> > > --- a/python/qemu/machine.py
> > > +++ b/python/qemu/machine.py
> > > @@ -118,7 +118,7 @@ def __init__(self, binary, args=None, wrapper=None, name=None,
> > >          self._events = []
> > >          self._iolog = None
> > >          self._qmp_set = True   # Enable QMP monitor by default.
> > > -        self._qmp = None
> > > +        self._qmp_connection: Optional[qmp.QEMUMonitorProtocol] = None
> > >          self._qemu_full_args = None
> > >          self._temp_dir = None
> > >          self._launched = False
> > > @@ -285,7 +285,7 @@ def _pre_launch(self):
> > >              if self._remove_monitor_sockfile:
> > >                  assert isinstance(self._monitor_address, str)
> > >                  self._remove_files.append(self._monitor_address)
> > > -            self._qmp = qmp.QEMUMonitorProtocol(
> > > +            self._qmp_connection = qmp.QEMUMonitorProtocol(
> > >                  self._monitor_address,
> > >                  server=True,
> > >                  nickname=self._name
> > > @@ -455,7 +455,13 @@ def set_qmp_monitor(self, enabled=True):
> > >              self._qmp_set = True
> > >          else:
> > >              self._qmp_set = False
> > > -            self._qmp = None
> > > +            self._qmp_connection = None
> > > +
> > > +    @property
> > > +    def _qmp(self) -> qmp.QEMUMonitorProtocol:
> > > +        if self._qmp_connection is None:
> > > +            raise QEMUMachineError("Attempt to access QMP with no connection")
> > > +        return self._qmp_connection
> > >
> > >      @classmethod
> > >      def _qmp_args(cls, _conv_keys: bool = True, **args: Any) -> Dict[str, Any]:
> > >
> >
> > This patch breaks the EmptyCPUModel test:
> >
> > (043/101) tests/acceptance/empty_cpu_model.py:EmptyCPUModel.test:
> > ERROR: Attempt to access QMP with no connection (0.03 s)
> 
> Fixed with:
> 
> -- >8 --
> diff --git a/python/qemu/machine.py b/python/qemu/machine.py
> index ba6397dd7e..26ae7be89b 100644
> --- a/python/qemu/machine.py
> +++ b/python/qemu/machine.py
> @@ -480,7 +480,7 @@ def set_qmp_monitor(self, enabled: bool = True) -> None:
> 
>      @property
>      def _qmp(self) -> qmp.QEMUMonitorProtocol:
> -        if self._qmp_connection is None:
> +        if self._qmp_set and self._qmp_connection is None:
>              raise QEMUMachineError("Attempt to access QMP with no connection")
>          return self._qmp_connection
> 
> ---
> 
> Does that sound reasonable to you?

Wouldn't that make the return type Optional[qmp.QEMUMonitorProtocol]?
Maybe this is what we want, but then we don't need the shim that this
patch adds but can just declare the variable this way.

And why does the feeling code even try to acess _qmp when _qmp_set is
False? Shouldn't it first check whether it's even valid?

Or maybe going a step back, why do we even have a separate _qmp_set
instead of only using None for _qmp?

Kevin

Re: [PATCH v3 12/16] python/machine.py: Add _qmp access shim

[Philippe Mathieu-Daudé]

On 6/22/20 12:23 PM, Kevin Wolf wrote:
> Am 20.06.2020 um 10:20 hat Philippe Mathieu-Daudé geschrieben:
>> On Sat, Jun 20, 2020 at 10:14 AM Philippe Mathieu-Daudé
>> <philmd@redhat.com> wrote:
>>>
>>> On 6/4/20 10:22 PM, John Snow wrote:
>>>> Like many other Optional[] types, it's not always a given that this
>>>> object will be set. Wrap it in a type-shim that raises a meaningful
>>>> error and will always return a concrete type.
>>>>
>>>> Signed-off-by: John Snow <jsnow@redhat.com>
>>>> ---
>>>>  python/qemu/machine.py | 12 +++++++++---
>>>>  1 file changed, 9 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/python/qemu/machine.py b/python/qemu/machine.py
>>>> index d8289936816..a451f9000d6 100644
>>>> --- a/python/qemu/machine.py
>>>> +++ b/python/qemu/machine.py
>>>> @@ -118,7 +118,7 @@ def __init__(self, binary, args=None, wrapper=None, name=None,
>>>>          self._events = []
>>>>          self._iolog = None
>>>>          self._qmp_set = True   # Enable QMP monitor by default.
>>>> -        self._qmp = None
>>>> +        self._qmp_connection: Optional[qmp.QEMUMonitorProtocol] = None
>>>>          self._qemu_full_args = None
>>>>          self._temp_dir = None
>>>>          self._launched = False
>>>> @@ -285,7 +285,7 @@ def _pre_launch(self):
>>>>              if self._remove_monitor_sockfile:
>>>>                  assert isinstance(self._monitor_address, str)
>>>>                  self._remove_files.append(self._monitor_address)
>>>> -            self._qmp = qmp.QEMUMonitorProtocol(
>>>> +            self._qmp_connection = qmp.QEMUMonitorProtocol(
>>>>                  self._monitor_address,
>>>>                  server=True,
>>>>                  nickname=self._name
>>>> @@ -455,7 +455,13 @@ def set_qmp_monitor(self, enabled=True):
>>>>              self._qmp_set = True
>>>>          else:
>>>>              self._qmp_set = False
>>>> -            self._qmp = None
>>>> +            self._qmp_connection = None
>>>> +
>>>> +    @property
>>>> +    def _qmp(self) -> qmp.QEMUMonitorProtocol:
>>>> +        if self._qmp_connection is None:
>>>> +            raise QEMUMachineError("Attempt to access QMP with no connection")
>>>> +        return self._qmp_connection
>>>>
>>>>      @classmethod
>>>>      def _qmp_args(cls, _conv_keys: bool = True, **args: Any) -> Dict[str, Any]:
>>>>
>>>
>>> This patch breaks the EmptyCPUModel test:
>>>
>>> (043/101) tests/acceptance/empty_cpu_model.py:EmptyCPUModel.test:
>>> ERROR: Attempt to access QMP with no connection (0.03 s)
>>
>> Fixed with:
>>
>> -- >8 --
>> diff --git a/python/qemu/machine.py b/python/qemu/machine.py
>> index ba6397dd7e..26ae7be89b 100644
>> --- a/python/qemu/machine.py
>> +++ b/python/qemu/machine.py
>> @@ -480,7 +480,7 @@ def set_qmp_monitor(self, enabled: bool = True) -> None:
>>
>>      @property
>>      def _qmp(self) -> qmp.QEMUMonitorProtocol:
>> -        if self._qmp_connection is None:
>> +        if self._qmp_set and self._qmp_connection is None:
>>              raise QEMUMachineError("Attempt to access QMP with no connection")
>>          return self._qmp_connection
>>
>> ---
>>
>> Does that sound reasonable to you?
> 
> Wouldn't that make the return type Optional[qmp.QEMUMonitorProtocol]?
> Maybe this is what we want, but then we don't need the shim that this
> patch adds but can just declare the variable this way.
> 
> And why does the feeling code even try to acess _qmp when _qmp_set is
> False? Shouldn't it first check whether it's even valid?
> 
> Or maybe going a step back, why do we even have a separate _qmp_set
> instead of only using None for _qmp?

Better indeed.

John, at this point from a maintenance perspective it is easier
if you respin the series (and please, run the Travis-CI tests).

Regards,

Phil.

Re: [PATCH v3 12/16] python/machine.py: Add _qmp access shim

[John Snow]

On 6/22/20 6:23 AM, Kevin Wolf wrote:
> Am 20.06.2020 um 10:20 hat Philippe Mathieu-Daudé geschrieben:
>> On Sat, Jun 20, 2020 at 10:14 AM Philippe Mathieu-Daudé
>> <philmd@redhat.com> wrote:
>>>
>>> On 6/4/20 10:22 PM, John Snow wrote:
>>>> Like many other Optional[] types, it's not always a given that this
>>>> object will be set. Wrap it in a type-shim that raises a meaningful
>>>> error and will always return a concrete type.
>>>>
>>>> Signed-off-by: John Snow <jsnow@redhat.com>
>>>> ---
>>>>  python/qemu/machine.py | 12 +++++++++---
>>>>  1 file changed, 9 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/python/qemu/machine.py b/python/qemu/machine.py
>>>> index d8289936816..a451f9000d6 100644
>>>> --- a/python/qemu/machine.py
>>>> +++ b/python/qemu/machine.py
>>>> @@ -118,7 +118,7 @@ def __init__(self, binary, args=None, wrapper=None, name=None,
>>>>          self._events = []
>>>>          self._iolog = None
>>>>          self._qmp_set = True   # Enable QMP monitor by default.
>>>> -        self._qmp = None
>>>> +        self._qmp_connection: Optional[qmp.QEMUMonitorProtocol] = None
>>>>          self._qemu_full_args = None
>>>>          self._temp_dir = None
>>>>          self._launched = False
>>>> @@ -285,7 +285,7 @@ def _pre_launch(self):
>>>>              if self._remove_monitor_sockfile:
>>>>                  assert isinstance(self._monitor_address, str)
>>>>                  self._remove_files.append(self._monitor_address)
>>>> -            self._qmp = qmp.QEMUMonitorProtocol(
>>>> +            self._qmp_connection = qmp.QEMUMonitorProtocol(
>>>>                  self._monitor_address,
>>>>                  server=True,
>>>>                  nickname=self._name
>>>> @@ -455,7 +455,13 @@ def set_qmp_monitor(self, enabled=True):
>>>>              self._qmp_set = True
>>>>          else:
>>>>              self._qmp_set = False
>>>> -            self._qmp = None
>>>> +            self._qmp_connection = None
>>>> +
>>>> +    @property
>>>> +    def _qmp(self) -> qmp.QEMUMonitorProtocol:
>>>> +        if self._qmp_connection is None:
>>>> +            raise QEMUMachineError("Attempt to access QMP with no connection")
>>>> +        return self._qmp_connection
>>>>
>>>>      @classmethod
>>>>      def _qmp_args(cls, _conv_keys: bool = True, **args: Any) -> Dict[str, Any]:
>>>>
>>>
>>> This patch breaks the EmptyCPUModel test:
>>>
>>> (043/101) tests/acceptance/empty_cpu_model.py:EmptyCPUModel.test:
>>> ERROR: Attempt to access QMP with no connection (0.03 s)
>>
>> Fixed with:
>>
>> -- >8 --
>> diff --git a/python/qemu/machine.py b/python/qemu/machine.py
>> index ba6397dd7e..26ae7be89b 100644
>> --- a/python/qemu/machine.py
>> +++ b/python/qemu/machine.py
>> @@ -480,7 +480,7 @@ def set_qmp_monitor(self, enabled: bool = True) -> None:
>>
>>      @property
>>      def _qmp(self) -> qmp.QEMUMonitorProtocol:
>> -        if self._qmp_connection is None:
>> +        if self._qmp_set and self._qmp_connection is None:
>>              raise QEMUMachineError("Attempt to access QMP with no connection")
>>          return self._qmp_connection
>>
>> ---
>>
>> Does that sound reasonable to you?
> 
> Wouldn't that make the return type Optional[qmp.QEMUMonitorProtocol]?
> Maybe this is what we want, but then we don't need the shim that this
> patch adds but can just declare the variable this way.
> 
> And why does the feeling code even try to acess _qmp when _qmp_set is
> False? Shouldn't it first check whether it's even valid?
> 
> Or maybe going a step back, why do we even have a separate _qmp_set
> instead of only using None for _qmp?
> 
> Kevin
> 

Using Optional[qmp.QEMUMonitorProtocol] does work; it does require a lot
more "if not None" checks littered everywhere.

From memory, it was just difficult to type a qmp(...) passthrough
command that integrated the "if self._qmp_socket" check -- the faster
hack was the shim around accessing the socket itself.

IIRC, mypy had difficulty reasoning about constraints otherwise -- but
I'll look into it again. At this point it warrants stronger effort.

--js

Re: [PATCH v3 12/16] python/machine.py: Add _qmp access shim

[John Snow]

On 6/22/20 7:32 AM, Philippe Mathieu-Daudé wrote:
> On 6/22/20 12:23 PM, Kevin Wolf wrote:
>> Am 20.06.2020 um 10:20 hat Philippe Mathieu-Daudé geschrieben:
>>> On Sat, Jun 20, 2020 at 10:14 AM Philippe Mathieu-Daudé
>>> <philmd@redhat.com> wrote:
>>>>
>>>> On 6/4/20 10:22 PM, John Snow wrote:
>>>>> Like many other Optional[] types, it's not always a given that this
>>>>> object will be set. Wrap it in a type-shim that raises a meaningful
>>>>> error and will always return a concrete type.
>>>>>
>>>>> Signed-off-by: John Snow <jsnow@redhat.com>
>>>>> ---
>>>>>  python/qemu/machine.py | 12 +++++++++---
>>>>>  1 file changed, 9 insertions(+), 3 deletions(-)
>>>>>
>>>>> diff --git a/python/qemu/machine.py b/python/qemu/machine.py
>>>>> index d8289936816..a451f9000d6 100644
>>>>> --- a/python/qemu/machine.py
>>>>> +++ b/python/qemu/machine.py
>>>>> @@ -118,7 +118,7 @@ def __init__(self, binary, args=None, wrapper=None, name=None,
>>>>>          self._events = []
>>>>>          self._iolog = None
>>>>>          self._qmp_set = True   # Enable QMP monitor by default.
>>>>> -        self._qmp = None
>>>>> +        self._qmp_connection: Optional[qmp.QEMUMonitorProtocol] = None
>>>>>          self._qemu_full_args = None
>>>>>          self._temp_dir = None
>>>>>          self._launched = False
>>>>> @@ -285,7 +285,7 @@ def _pre_launch(self):
>>>>>              if self._remove_monitor_sockfile:
>>>>>                  assert isinstance(self._monitor_address, str)
>>>>>                  self._remove_files.append(self._monitor_address)
>>>>> -            self._qmp = qmp.QEMUMonitorProtocol(
>>>>> +            self._qmp_connection = qmp.QEMUMonitorProtocol(
>>>>>                  self._monitor_address,
>>>>>                  server=True,
>>>>>                  nickname=self._name
>>>>> @@ -455,7 +455,13 @@ def set_qmp_monitor(self, enabled=True):
>>>>>              self._qmp_set = True
>>>>>          else:
>>>>>              self._qmp_set = False
>>>>> -            self._qmp = None
>>>>> +            self._qmp_connection = None
>>>>> +
>>>>> +    @property
>>>>> +    def _qmp(self) -> qmp.QEMUMonitorProtocol:
>>>>> +        if self._qmp_connection is None:
>>>>> +            raise QEMUMachineError("Attempt to access QMP with no connection")
>>>>> +        return self._qmp_connection
>>>>>
>>>>>      @classmethod
>>>>>      def _qmp_args(cls, _conv_keys: bool = True, **args: Any) -> Dict[str, Any]:
>>>>>
>>>>
>>>> This patch breaks the EmptyCPUModel test:
>>>>
>>>> (043/101) tests/acceptance/empty_cpu_model.py:EmptyCPUModel.test:
>>>> ERROR: Attempt to access QMP with no connection (0.03 s)
>>>
>>> Fixed with:
>>>
>>> -- >8 --
>>> diff --git a/python/qemu/machine.py b/python/qemu/machine.py
>>> index ba6397dd7e..26ae7be89b 100644
>>> --- a/python/qemu/machine.py
>>> +++ b/python/qemu/machine.py
>>> @@ -480,7 +480,7 @@ def set_qmp_monitor(self, enabled: bool = True) -> None:
>>>
>>>      @property
>>>      def _qmp(self) -> qmp.QEMUMonitorProtocol:
>>> -        if self._qmp_connection is None:
>>> +        if self._qmp_set and self._qmp_connection is None:
>>>              raise QEMUMachineError("Attempt to access QMP with no connection")
>>>          return self._qmp_connection
>>>
>>> ---
>>>
>>> Does that sound reasonable to you?
>>

Not entirely; the idea is to protect access to the socket in all cases
where the socket was not created, for any and all reasons.

>> Wouldn't that make the return type Optional[qmp.QEMUMonitorProtocol]?
>> Maybe this is what we want, but then we don't need the shim that this
>> patch adds but can just declare the variable this way.
>>

The _qmp_connection variable is already Optional[], so you could indeed
remove the shim. The shim is here to peel away the Optional[] so you
don't need the "if qmp" checks everywhere.

>> And why does the feeling code even try to acess _qmp when _qmp_set is
>> False? Shouldn't it first check whether it's even valid?
>>

Yup. The code in lifetime management functions should check for the
socket. Code in qmp-centric commands should assume it's there with the shim.

>> Or maybe going a step back, why do we even have a separate _qmp_set
>> instead of only using None for _qmp?

Because the socket isn't initialized until after launch, so "_qmp_set"
is a request/instruction and not reflective of current state.

_qmp_set is the flag for a desire to create QMP or not,
_qmp_connection is the actual connection.

set | conn |
 T     F   | OK (we are pre-launch)
 T     T   | OK (we are running)
 F     F   | OK (we set no QMP before launch)
 F     T   | Set QMP false after launch

The last one doesn't make a lot of sense. Worse, it just None's the
socket variable so we can't even close it properly.

That's sorta busted, so I am patching it to just simply set the variable.

> 
> Better indeed.
> 
> John, at this point from a maintenance perspective it is easier
> if you respin the series (and please, run the Travis-CI tests).
> 
> Regards,
> 
> Phil.
> 

OK, I am resending. I didn't make any big changes, but I thought about it.

(Read as: I tried, didn't like how it looked, and came back to this
patchset which is fairly close as-is.)

--js