python/aqmp: copy qmp docstrings to qemu.aqmp.legacy

Copy the docstrings out of qemu.qmp, adjusting them as necessary to
more accurately reflect the current state of this class.

(Licensing: This is copying and modifying GPLv2-only licensed docstrings
into a GPLv2-only file.)

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Beraldo Leal <bleal@redhat.com>
Message-id: 20220330172812.3427355-5-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

python/qemu/aqmp/legacy.py

@@ -1,7 +1,13 @@
 """
-Sync QMP Wrapper
+(Legacy) Sync QMP Wrapper
 
-This class pretends to be qemu.qmp.QEMUMonitorProtocol.
+This module provides the `QEMUMonitorProtocol` class, which is a
+synchronous wrapper around `QMPClient`.
+
+Its design closely resembles that of the original QEMUMonitorProtocol
+class, originally written by Luiz Capitulino. It is provided here for
+compatibility with scripts inside the QEMU source tree that expect the
+old interface.
 """
 
 #
@@ -50,9 +56,6 @@ QMPObject = Dict[str, object]
 # {} is the QMPReturnValue.
 
 
-# pylint: disable=missing-docstring
-
-
 class QMPBadPortError(QMPError):
     """
     Unable to parse socket address: Port was non-numerical.
@@ -60,6 +63,17 @@ class QMPBadPortError(QMPError):
 
 
 class QEMUMonitorProtocol:
+    """
+    Provide an API to connect to QEMU via QEMU Monitor Protocol (QMP)
+    and then allow to handle commands and events.
+
+    :param address:  QEMU address, can be either a unix socket path (string)
+                     or a tuple in the form ( address, port ) for a TCP
+                     connection
+    :param server:   Act as the socket server. (See 'accept')
+    :param nickname: Optional nickname used for logging.
+    """
+
     def __init__(self, address: SocketAddrT,
                  server: bool = False,
                  nickname: Optional[str] = None):
@@ -121,6 +135,12 @@ class QEMUMonitorProtocol:
         return address
 
     def connect(self, negotiate: bool = True) -> Optional[QMPMessage]:
+        """
+        Connect to the QMP Monitor and perform capabilities negotiation.
+
+        :return: QMP greeting dict, or None if negotiate is false
+        :raise ConnectError: on connection errors
+        """
         self._aqmp.await_greeting = negotiate
         self._aqmp.negotiate = negotiate
 
@@ -130,6 +150,16 @@ class QEMUMonitorProtocol:
         return self._get_greeting()
 
     def accept(self, timeout: Optional[float] = 15.0) -> QMPMessage:
+        """
+        Await connection from QMP Monitor and perform capabilities negotiation.
+
+        :param timeout:
+            timeout in seconds (nonnegative float number, or None).
+            If None, there is no timeout, and this may block forever.
+
+        :return: QMP greeting dict
+        :raise ConnectError: on connection errors
+        """
         self._aqmp.await_greeting = True
         self._aqmp.negotiate = True
 
@@ -140,6 +170,12 @@ class QEMUMonitorProtocol:
         return ret
 
     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
+        """
         return dict(
             self._sync(
                 # pylint: disable=protected-access
@@ -158,9 +194,9 @@ class QEMUMonitorProtocol:
         """
         Build a QMP command and send it to the QMP Monitor.
 
-        @param name: command name (string)
-        @param args: command arguments (dict)
-        @param cmd_id: command id (dict, list, string or int)
+        :param name: command name (string)
+        :param args: command arguments (dict)
+        :param cmd_id: command id (dict, list, string or int)
         """
         qmp_cmd: QMPMessage = {'execute': name}
         if args:
@@ -170,6 +206,9 @@ class QEMUMonitorProtocol:
         return self.cmd_obj(qmp_cmd)
 
     def command(self, cmd: str, **kwds: object) -> QMPReturnValue:
+        """
+        Build and send a QMP command to the monitor, report errors if any
+        """
         return self._sync(
             self._aqmp.execute(cmd, kwds),
             self._timeout
@@ -177,6 +216,19 @@ class QEMUMonitorProtocol:
 
     def pull_event(self,
                    wait: Union[bool, float] = False) -> Optional[QMPMessage]:
+        """
+        Pulls a single event.
+
+        :param wait:
+            If False or 0, do not wait. Return None if no events ready.
+            If True, wait forever until the next event.
+            Otherwise, wait for the specified number of seconds.
+
+        :raise asyncio.TimeoutError:
+            When a timeout is requested and the timeout period elapses.
+
+        :return: The first available QMP event, or None.
+        """
         if not wait:
             # wait is False/0: "do not wait, do not except."
             if self._aqmp.events.empty():
@@ -197,6 +249,20 @@ class QEMUMonitorProtocol:
         )
 
     def get_events(self, wait: Union[bool, float] = False) -> List[QMPMessage]:
+        """
+        Get a list of QMP events and clear all pending events.
+
+        :param wait:
+            If False or 0, do not wait. Return None if no events ready.
+            If True, wait until we have at least one event.
+            Otherwise, wait for up to the specified number of seconds for at
+            least one event.
+
+        :raise asyncio.TimeoutError:
+            When a timeout is requested and the timeout period elapses.
+
+        :return: A list of QMP events.
+        """
         events = [dict(x) for x in self._aqmp.events.clear()]
         if events:
             return events
@@ -205,17 +271,33 @@ class QEMUMonitorProtocol:
         return [event] if event is not None else []
 
     def clear_events(self) -> None:
+        """Clear current list of pending events."""
         self._aqmp.events.clear()
 
     def close(self) -> None:
+        """Close the connection."""
         self._sync(
             self._aqmp.disconnect()
         )
 
     def settimeout(self, timeout: Optional[float]) -> None:
+        """
+        Set the timeout for QMP RPC execution.
+
+        This timeout affects the `cmd`, `cmd_obj`, and `command` methods.
+        The `accept`, `pull_event` and `get_event` methods have their
+        own configurable timeouts.
+
+        :param timeout:
+            timeout in seconds, or None.
+            None will wait indefinitely.
+        """
         self._timeout = timeout
 
     def send_fd_scm(self, fd: int) -> None:
+        """
+        Send a file descriptor to the remote via SCM_RIGHTS.
+        """
         self._aqmp.send_fd_scm(fd)
 
     def __del__(self) -> None: