Source Code for Module buildbot.db.base

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14  # Copyright Buildbot Team Members 
15   
16  """ 
17  Base classes for database handling 
18  """ 
19   
20 -class DBConnectorComponent(object): 
21      """ 
22      A fixed component of the DBConnector, handling one particular aspect of the 
23      database.  Instances of subclasses are assigned to attributes of the 
24      DBConnector object, so that they are available at e.g., C{master.db.model} 
25      or C{master.db.changes}.  This parent class takes care of the necessary 
26      backlinks and other housekeeping. 
27      """ 
28   
29      connector = None 
30   
31 -    def __init__(self, connector): 
32          self.db = connector 
33          "backlink to the DBConnector object" 
34   
35          # set up caches 
36          for method in dir(self.__class__): 
37              o = getattr(self, method) 
38              if isinstance(o, CachedMethod): 
39                  setattr(self, method, o.get_cached_method(self)) 
40   
41 -class CachedMethod(object): 
42 -    def __init__(self, cache_name, method): 
43          self.cache_name = cache_name 
44          self.method = method 
45   
46 -    def get_cached_method(self, component): 
47          meth = self.method 
48   
49          meth_name = meth.__name__ 
50          cache = component.db.master.caches.get_cache(self.cache_name, 
51                  lambda key : meth(component, key)) 
52          def wrap(key, no_cache=0): 
53              if no_cache: 
54                  return meth(component, key) 
55              return cache.get(key) 
56          wrap.__name__ = meth_name + " (wrapped)" 
57          wrap.__module__ = meth.__module__ 
58          wrap.__doc__ = meth.__doc__ 
59          wrap.cache = cache 
60          return wrap 
61   
62 -def cached(cache_name): 
63      """ 
64      A decorator for "getter" functions that fetch an object from the database 
65      based on a single key.  The wrapped method will only be called if the named 
66      cache does not contain the key. 
67   
68      The wrapped function must take one argument (the key); the wrapper will 
69      take a key plus an optional C{no_cache} argument which, if true, will cause 
70      it to invoke the underlying method even if the key is in the cache. 
71   
72      The resulting method will have a C{cache} attribute which can be used to 
73      access the underlying cache. 
74   
75      @param cache_name: name of the cache to use 
76      """ 
77      return lambda method : CachedMethod(cache_name, method) 
78