ganeti :: hypervisor :: hv_kvm :: QmpConnection :: Class QmpConnection

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Class QmpConnection

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Connection to the QEMU Monitor using the QEMU Monitor Protocol (QMP).

Instance Methods

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__init__(self, monitor_filename)
Instantiates the QmpConnection object.

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_check_socket(self)

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_check_connection(self)
Make sure that the connection is established.

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connect(self)
Connects to the QMP monitor.

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_ParseMessage(self, buf)
Extract and parse a QMP message from the given buffer.

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QmpMessage

_Recv(self)
Receives a message from QMP and decodes the received JSON object.

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_Send(self, message)
Encodes and sends a message to KVM using QMP.

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dict

Execute(self, command, arguments=None)
Executes a QMP command and returns the response of the server.

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Class Variables

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_FIRST_MESSAGE_KEY = "QMP"

_EVENT_KEY = "event"

_ERROR_KEY = "error"

RETURN_KEY = "return"

_RETURN_KEY = "return"

ACTUAL_KEY = "actual"

_ACTUAL_KEY = "actual"

_ERROR_CLASS_KEY = "class"

_ERROR_DESC_KEY = "desc"

_EXECUTE_KEY = "execute"

_ARGUMENTS_KEY = "arguments"

_CAPABILITIES_COMMAND = "qmp_capabilities"

_MESSAGE_END_TOKEN = "\r\n"

_SOCKET_TIMEOUT = 5

Method Details

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init(self, monitor_filename)
(Constructor)

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Instantiates the QmpConnection object.

Parameters:

monitor_filename (string) - the filename of the UNIX raw socket on which the QMP monitor is listening

connect(self)

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Connects to the QMP monitor.

Connects to the UNIX socket and makes sure that we can actually send and receive data to the kvm instance via QMP.

Raises:

errors.HypervisorError - when there are communication errors
errors.ProgrammerError - when there are data serialization errors

_ParseMessage(self, buf)

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Extract and parse a QMP message from the given buffer.

Seeks for a QMP message in the given buf. If found, it parses it and returns it together with the rest of the characters in the buf. If no message is found, returns None and the whole buffer.

Raises:

errors.ProgrammerError - when there are data serialization errors

_Recv(self)

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Receives a message from QMP and decodes the received JSON object.

Returns: QmpMessage

the received message

Raises:

errors.HypervisorError - when there are communication errors
errors.ProgrammerError - when there are data serialization errors

_Send(self, message)

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Encodes and sends a message to KVM using QMP.

Parameters:

message (QmpMessage) - message to send to KVM

Raises:

errors.HypervisorError - when there are communication errors
errors.ProgrammerError - when there are data serialization errors

Execute(self, command, arguments=None)

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Executes a QMP command and returns the response of the server.

Parameters:

command (str) - the command to execute
arguments (dict) - dictionary of arguments to be passed to the command

Returns: dict

dictionary representing the received JSON object

Raises:

errors.HypervisorError - when there are communication errors
errors.ProgrammerError - when there are data serialization errors

Class QmpConnection

__init__(self, monitor_filename) (Constructor)

connect(self)

_ParseMessage(self, buf)

_Recv(self)

_Send(self, message)

Execute(self, command, arguments=None)

init(self, monitor_filename)
(Constructor)