from ganeti import errors
from ganeti import confd
from ganeti import ssconf
+from ganeti import compat
class ConfdAsyncUDPClient(daemon.AsyncUDPSocket):
self.client.HandleResponse(payload, ip, port)
+class _Request(object):
+ """Request status structure.
+
+ @ivar request: the request data
+ @ivar args: any extra arguments for the callback
+ @ivar expiry: the expiry timestamp of the request
+ @ivar sent: the set of contacted peers
+ @ivar rcvd: the set of peers who replied
+
+ """
+ def __init__(self, request, args, expiry, sent):
+ self.request = request
+ self.args = args
+ self.expiry = expiry
+ self.sent = frozenset(sent)
+ self.rcvd = set()
+
+
class ConfdClient:
"""Send queries to confd, and get back answers.
getting back answers, this is an asynchronous library. It can either work
through asyncore or with your own handling.
+ @type _requests: dict
+ @ivar _requests: dictionary indexes by salt, which contains data
+ about the outstanding requests; the values are objects of type
+ L{_Request}
+
"""
def __init__(self, hmac_key, peers, callback, port=None, logger=None):
"""Constructor for ConfdClient
self._confd_port = port
self._logger = logger
self._requests = {}
- self._expire_requests = []
if self._confd_port is None:
self._confd_port = utils.GetDaemonPort(constants.CONFD)
"""
now = time.time()
- while self._expire_requests:
- expire_time, rsalt = self._expire_requests[0]
- if now >= expire_time:
- self._expire_requests.pop(0)
- (request, args) = self._requests[rsalt]
+ for rsalt, rq in self._requests.items():
+ if now >= rq.expiry:
del self._requests[rsalt]
client_reply = ConfdUpcallPayload(salt=rsalt,
type=UPCALL_EXPIRE,
- orig_request=request,
- extra_args=args,
+ orig_request=rq.request,
+ extra_args=rq.args,
client=self,
)
self._callback(client_reply)
- else:
- break
- def SendRequest(self, request, args=None, coverage=None, async=True):
+ def SendRequest(self, request, args=None, coverage=0, async=True):
"""Send a confd request to some MCs
@type request: L{objects.ConfdRequest}
@type args: tuple
@param args: additional callback arguments
@type coverage: integer
- @param coverage: number of remote nodes to contact
+ @param coverage: number of remote nodes to contact; if default
+ (0), it will use a reasonable default
+ (L{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
@type async: boolean
@param async: handle the write asynchronously
"""
- if coverage is None:
+ if coverage == 0:
coverage = min(len(self._peers), constants.CONFD_DEFAULT_REQ_COVERAGE)
+ elif coverage == -1:
+ coverage = len(self._peers)
if coverage > len(self._peers):
raise errors.ConfdClientError("Not enough MCs known to provide the"
except errors.UdpDataSizeError:
raise errors.ConfdClientError("Request too big")
- self._requests[request.rsalt] = (request, args)
expire_time = now + constants.CONFD_CLIENT_EXPIRE_TIMEOUT
- self._expire_requests.append((expire_time, request.rsalt))
+ self._requests[request.rsalt] = _Request(request, args, expire_time,
+ targets)
if not async:
self.FlushSendQueue()
return
try:
- (request, args) = self._requests[salt]
+ rq = self._requests[salt]
except KeyError:
if self._logger:
self._logger.debug("Discarding unknown (expired?) reply: %s" % err)
return
+ rq.rcvd.add(ip)
+
client_reply = ConfdUpcallPayload(salt=salt,
type=UPCALL_REPLY,
server_reply=answer,
- orig_request=request,
+ orig_request=rq.request,
server_ip=ip,
server_port=port,
- extra_args=args,
+ extra_args=rq.args,
client=self,
)
self._callback(client_reply)
"""
return self._socket.process_next_packet(timeout=timeout)
+ @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.
+
+ @type peer_cnt: int
+ @param peer_cnt: the number of peers contacted
+ @rtype: int
+ @return: the number of replies which should give a safe coverage
+
+ """
+ if peer_cnt < 3:
+ return peer_cnt
+ elif peer_cnt < 5:
+ return peer_cnt - 1
+ else:
+ return int(peer_cnt/2) + 1
+
+ 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 L{_NeededReplies}) of replies are
+ received for the given salt. It is useful when doing synchronous
+ calls to this library.
+
+ @param salt: the salt of the request we want responses for
+ @param timeout: the maximum timeout (should be less or equal to
+ L{ganeti.constants.CONFD_CLIENT_EXPIRE_TIMEOUT}
+ @rtype: tuple
+ @return: 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
+
+ """
+ def _CheckResponse():
+ if salt not in self._requests:
+ # expired?
+ if self._logger:
+ self._logger.debug("Discarding unknown/expired request: %s" % salt)
+ return MISSING
+ rq = self._requests[salt]
+ if len(rq.rcvd) >= expected:
+ # already got all replies
+ return (False, len(rq.sent), len(rq.rcvd))
+ # else wait, using default timeout
+ self.ReceiveReply()
+ raise utils.RetryAgain()
+
+ MISSING = (True, 0, 0)
+
+ if salt not in self._requests:
+ return MISSING
+ # extend the expire time with the current timeout, so that we
+ # don't get the request expired from under us
+ rq = self._requests[salt]
+ rq.expiry += timeout
+ sent = len(rq.sent)
+ expected = self._NeededReplies(sent)
+
+ try:
+ return utils.Retry(_CheckResponse, 0, timeout)
+ except utils.RetryTimeout:
+ if salt in self._requests:
+ rq = self._requests[salt]
+ return (True, len(rq.sent), len(rq.rcvd))
+ else:
+ return MISSING
+
# UPCALL_REPLY: server reply upcall
# has all ConfdUpcallPayload fields populated
"""Have all the registered queries received at least an answer?
"""
- return utils.all(self._answers.values())
+ return compat.all(self._answers.values())
def _HandleExpire(self, up):
# if we have no answer we have received none, before the expiration.
self._HandleExpire(up)
self._callback(up)
+
+class StoreResultCallback:
+ """Callback that simply stores the most recent answer.
+
+ @ivar _answers: dict of salt to (have_answer, reply)
+
+ """
+ _NO_KEY = (False, None)
+
+ def __init__(self):
+ """Constructor for StoreResultCallback
+
+ """
+ # answers contains a dict of salt -> best result
+ self._answers = {}
+
+ def GetResponse(self, salt):
+ """Return the best match for a salt
+
+ """
+ return self._answers.get(salt, self._NO_KEY)
+
+ def _HandleExpire(self, up):
+ """Expiration handler.
+
+ """
+ if up.salt in self._answers and self._answers[up.salt] == self._NO_KEY:
+ del self._answers[up.salt]
+
+ def _HandleReply(self, up):
+ """Handle a single confd reply, and decide whether to filter it.
+
+ """
+ self._answers[up.salt] = (True, up)
+
+ def __call__(self, up):
+ """Filtering callback
+
+ @type up: L{ConfdUpcallPayload}
+ @param up: upper callback
+
+ """
+ if up.type == UPCALL_REPLY:
+ self._HandleReply(up)
+ elif up.type == UPCALL_EXPIRE:
+ self._HandleExpire(up)
+
+
def GetConfdClient(callback):
"""Return a client configured using the given callback.