1#
2# Copyright 2007 Google Inc. Released under the GPL v2
3
4"""
5This module defines the base classes for the server Host hierarchy.
6
7Implementation details:
8You should import the "hosts" package instead of importing each type of host.
9
10        Host: a machine on which you can run programs
11        RemoteHost: a remote machine on which you can run programs
12"""
13
14__author__ = """
15mbligh@google.com (Martin J. Bligh),
16poirier@google.com (Benjamin Poirier),
17stutsman@google.com (Ryan Stutsman)
18"""
19
20from autotest_lib.client.common_lib import hosts
21from autotest_lib.server import utils
22
23
24class Host(hosts.Host):
25    """
26    This class represents a machine on which you can run programs.
27
28    It may be a local machine, the one autoserv is running on, a remote
29    machine or a virtual machine.
30
31    Implementation details:
32    This is an abstract class, leaf subclasses must implement the methods
33    listed here. You must not instantiate this class but should
34    instantiate one of those leaf subclasses.
35
36    When overriding methods that raise NotImplementedError, the leaf class
37    is fully responsible for the implementation and should not chain calls
38    to super. When overriding methods that are a NOP in Host, the subclass
39    should chain calls to super(). The criteria for fitting a new method into
40    one category or the other should be:
41        1. If two separate generic implementations could reasonably be
42           concatenated, then the abstract implementation should pass and
43           subclasses should chain calls to super.
44        2. If only one class could reasonably perform the stated function
45           (e.g. two separate run() implementations cannot both be executed)
46           then the method should raise NotImplementedError in Host, and
47           the implementor should NOT chain calls to super, to ensure that
48           only one implementation ever gets executed.
49    """
50
51    bootloader = None
52
53
54    def __init__(self, *args, **dargs):
55        super(Host, self).__init__(*args, **dargs)
56
57        self.start_loggers()
58        if self.job:
59            self.job.hosts.add(self)
60
61
62    def _initialize(self, *args, **dargs):
63        super(Host, self)._initialize(*args, **dargs)
64
65        self.serverdir = utils.get_server_dir()
66        self.env = {}
67
68
69    def close(self):
70        """Release resources held by this Host instance."""
71        super(Host, self).close()
72
73        if self.job:
74            self.job.hosts.discard(self)
75