m_lib/hash/ZODBhash.py

   1 """(g)dbm-compatible interface to ZODB"""
   2
   3 import sys
   4 try:
   5     from ZODB import FileStorage, DB, POSException
   6 except ImportError:
   7     # prevent a second import of this module from spuriously succeeding
   8     del sys.modules[__name__]
   9     raise
  10
  11
  12 __all__ = ["error", "open"]
  13
  14 error = POSException.POSError                     # Exported for anydbm
  15
  16
  17 class ZODBhash:
  18     def __init__(self, file, flag, mode=0o666, trans_threshold=1000):
  19         create = (flag == 'n') # force recreation
  20         # if flag == 'w' or 'c' and file does not exist FileStorage will set it to 1 for us
  21
  22         self.read_only = read_only = (flag == 'r')
  23         self._closed = 0
  24
  25         self.trans_threshold = trans_threshold
  26         self._transcount = 0 # transactions counter - for commiting transactions
  27
  28         storage = FileStorage.FileStorage(file, create=create, read_only = read_only)
  29         db = DB(storage)
  30         self.conn = conn = db.open()
  31         self.dbroot = conn.root()
  32
  33     def __del__(self):
  34         self.close()
  35
  36     def keys(self):
  37         return self.dbroot.keys()
  38
  39     def __len__(self):
  40         return len(self.dbroot)
  41
  42     def has_key(self, key):
  43         return self.dbroot.has_key(key)
  44
  45     def get(self, key, default=None):
  46         if self.dbroot.has_key(key):
  47             return self[key]
  48         return default
  49
  50     def __getitem__(self, key):
  51         return self.dbroot[key]
  52
  53     def __setitem__(self, key, value):
  54         self.dbroot[key] = value
  55         self._add_tran()
  56
  57     def __delitem__(self, key):
  58         del self.dbroot[key]
  59         self._add_tran()
  60
  61     def close(self):
  62         if self._closed: return
  63         if not self.read_only:
  64             get_transaction().commit()
  65             self.conn.db().close()
  66         self.conn.close()
  67         self._closed = 1
  68
  69     def _add_tran(self):
  70         self._transcount = self._transcount + 1
  71         if self._transcount == self.trans_threshold:
  72             self._transcount = 0
  73             get_transaction().commit()
  74
  75
  76 def open(file, flag, mode=0o666):
  77     return ZODBhash(file, flag, mode)