source: trunk/packages/sipb-xen-www/code/webcommon.py @ 607

Last change on this file since 607 was 578, checked in by ecprice, 16 years ago

Avoid per-request global state.

File size: 1.8 KB
Line 
1"""Exceptions for the web interface."""
2
3import time
4from sipb_xen_database import Machine, MachineAccess
5
6class MyException(Exception):
7    """Base class for my exceptions"""
8    pass
9
10class InvalidInput(MyException):
11    """Exception for user-provided input is invalid but maybe in good faith.
12
13    This would include setting memory to negative (which might be a
14    typo) but not setting an invalid boot CD (which requires bypassing
15    the select box).
16    """
17    def __init__(self, err_field, err_value, expl=None):
18        MyException.__init__(self, expl)
19        self.err_field = err_field
20        self.err_value = err_value
21
22class CodeError(MyException):
23    """Exception for internal errors or bad faith input."""
24    pass
25
26import controls
27
28def cachedproperty(func):
29    name = '__cache_' + func.__name__ + '_' + str(id(func))
30    def getter(self):
31        try:
32            return getattr(self, name)
33        except AttributeError:
34            value = func(self)
35            setattr(self, name, value)
36            return value
37    return property(getter)
38
39class State(object):
40    """State for a request"""
41    def __init__(self, user):
42        self.username = user
43
44    machines = cachedproperty(lambda self:
45                                  Machine.query().join('acl').select_by(user=self.username))
46    xmlist_raw = cachedproperty(lambda self: controls.getList())
47    xmlist = cachedproperty(lambda self:
48                                dict((m, self.xmlist_raw[m.name])
49                                     for m in self.machines
50                                     if m.name in self.xmlist_raw))
51
52    def clear(self):
53        """Clear the state so future accesses reload it."""
54        for attr in list(self.__dict__):
55            if attr.startswith('__cache_'):
56                delattr(self, attr)
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