Merge branch 'stable-2.16' into stable-2.17
[ganeti-github.git] / lib / metad.py
1 #
2 #
3
4 # Copyright (C) 2014 Google Inc.
5 # All rights reserved.
6 #
7 # Redistribution and use in source and binary forms, with or without
8 # modification, are permitted provided that the following conditions are
9 # met:
10 #
11 # 1. Redistributions of source code must retain the above copyright notice,
12 # this list of conditions and the following disclaimer.
13 #
14 # 2. Redistributions in binary form must reproduce the above copyright
15 # notice, this list of conditions and the following disclaimer in the
16 # documentation and/or other materials provided with the distribution.
17 #
18 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
19 # IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
20 # TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
21 # PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
22 # CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
23 # EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
24 # PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
25 # PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
26 # LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
27 # NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
28 # SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29
30
31 """Module for the Metad protocol
32
33 """
34
35 import logging
36 import random
37 import time
38
39 from ganeti import constants
40 from ganeti import errors
41 import ganeti.rpc.client as cl
42 from ganeti.rpc.transport import Transport
43 from ganeti.rpc.errors import TimeoutError
44
45
46 # If the metadata daemon is disabled, there is no stub generated for it.
47 # So import the module and define the client class only if enabled, otherwise
48 # just generate an empty placeholder class.
49 if constants.ENABLE_METAD:
50 import ganeti.rpc.stub.metad as stub
51
52 class Client(cl.AbstractStubClient, stub.ClientRpcStub):
53 """High-level Metad client implementation.
54
55 This uses a backing Transport-like class on top of which it
56 implements data serialization/deserialization.
57
58 """
59 def __init__(self, timeouts=None, transport=Transport):
60 """Constructor for the Client class.
61
62 Arguments are the same as for L{AbstractClient}.
63
64 """
65 cl.AbstractStubClient.__init__(self, timeouts, transport)
66 stub.ClientRpcStub.__init__(self)
67
68 retries = 12
69 for try_no in range(0, retries):
70 try:
71 self._InitTransport()
72 return
73 except TimeoutError:
74 logging.debug("Timout trying to connect to MetaD")
75 if try_no == retries - 1:
76 raise
77 logging.debug("Will retry")
78 time.sleep(try_no * 10 + 10 * random.random())
79
80 def _InitTransport(self):
81 """(Re)initialize the transport if needed.
82
83 """
84 if self.transport is None:
85 self.transport = self.transport_class(self._GetAddress(),
86 timeouts=self.timeouts,
87 allow_non_master=True)
88
89 else:
90 class Client(object):
91 """An empty client representation that just throws an exception.
92
93 """
94 def __init__(self, _timeouts=None, _transport=None):
95 raise errors.ProgrammerError("The metadata deamon is disabled, yet"
96 " the client has been called")