ganeti.confd.client.ConfdClient

class documentation

class ConfdClient(object):

Send queries to confd, and get back answers.

Since the confd model works by querying multiple master candidates, and getting back answers, this is an asynchronous library. It can either work through asyncore or with your own handling.

Method	`__init__`	Constructor for ConfdClient
Method	`ExpireRequests`	Delete all the expired requests.
Method	`FlushSendQueue`	Send out all pending requests.
Method	`HandleResponse`	Asynchronous handler for a confd reply
Method	`ReceiveReply`	Receive one reply.
Method	`SendRequest`	Send a confd request to some MCs
Method	`UpdatePeerList`	Update the list of peers
Method	`WaitForReply`	Wait for replies to a given request.
Static Method	`_NeededReplies`	Compute the minimum safe number of replies for a query.
Method	`_PackRequest`	Prepare a request to be sent on the wire.
Method	`_SetPeersAddressFamily`	Undocumented
Method	`_UnpackReply`	Undocumented
Instance Variable	`_callback`	Undocumented
Instance Variable	`_confd_port`	Undocumented
Instance Variable	`_family`	Undocumented
Instance Variable	`_hmac_key`	Undocumented
Instance Variable	`_logger`	Undocumented
Instance Variable	`_peers`	Undocumented
Instance Variable	`_requests`	dictionary indexes by salt, which contains data about the outstanding requests; the values are objects of type `_Request`
Instance Variable	`_socket`	Undocumented

def __init__(self, hmac_key, peers, callback, port=None, logger=None): ¶

Constructor for ConfdClient

Parameters
hmac_key:string	hmac key to talk to confd
peers:list	list of peer nodes
callback:f(`ConfdUpcallPayload`)	function to call when getting answers
port:integer	confd port (default: use GetDaemonPort)
logger:logging.Logger	optional logger for internal conditions

def ExpireRequests(self): ¶

Delete all the expired requests.

def FlushSendQueue(self): ¶

Send out all pending requests.

Can be used for synchronous client use.

def HandleResponse(self, payload, ip, port): ¶

Asynchronous handler for a confd reply

Call the relevant callback associated to the current request.

def ReceiveReply(self, timeout=1): ¶

Receive one reply.

Parameters
timeout:float	how long to wait for the reply
Returns
boolean	True if some data has been handled, False otherwise

def SendRequest(self, request, args=None, coverage=0, async_=True): ¶

Send a confd request to some MCs

Parameters
request:`objects.ConfdRequest`	the request to send
args:tuple	additional callback arguments
coverage:integer	number of remote nodes to contact; if default (0), it will use a reasonable default (`ganeti.constants.CONFD_DEFAULT_REQ_COVERAGE`), if -1 is passed, it will use the maximum number of peers, otherwise the number passed in will be used
async_:boolean	handle the write asynchronously

def UpdatePeerList(self, peers): ¶

Update the list of peers

Parameters
peers:list	list of peer nodes

def WaitForReply(self, salt, timeout=constants.CONFD_CLIENT_EXPIRE_TIMEOUT): ¶

Wait for replies to a given request.

This method will wait until either the timeout expires or a minimum number (computed using _NeededReplies) of replies are received for the given salt. It is useful when doing synchronous calls to this library.

Parameters
salt	the salt of the request we want responses for
timeout	the maximum timeout (should be less or equal to `ganeti.constants.CONFD_CLIENT_EXPIRE_TIMEOUT`
Returns
tuple	a tuple of (timed_out, sent_cnt, recv_cnt); if the request is unknown, timed_out will be true and the counters will be zero

@staticmethod
def _NeededReplies(peer_cnt): ¶

Compute the minimum safe number of replies for a query.

The algorithm is designed to work well for both small and big number of peers:

for less than three, we require all responses
for less than five, we allow one miss
otherwise, half the number plus one

This guarantees that we progress monotonically: 1->1, 2->2, 3->2, 4->2, 5->3, 6->3, 7->4, etc.

Parameters
peer_cnt:int	the number of peers contacted
Returns
int	the number of replies which should give a safe coverage

def _PackRequest(self, request, now=None): ¶

Prepare a request to be sent on the wire.

This function puts a proper salt in a confd request, puts the proper salt, and adds the correct magic number.

def _SetPeersAddressFamily(self): ¶

Undocumented

def _UnpackReply(self, payload): ¶

Undocumented

_callback = ¶

Undocumented

_confd_port = ¶

Undocumented

_family = ¶

Undocumented

_hmac_key = ¶

Undocumented

_logger = ¶

Undocumented

_peers = ¶

Undocumented

_requests: dict = ¶

dictionary indexes by salt, which contains data about the outstanding requests; the values are objects of type _Request

_socket = ¶

Undocumented