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defcb43883
Simplejson is an externally mainainted version of json library available in Python 2.6 and up. It supports Python 2.5 which were are not targetting. It also boasts better speed which is not at all a factor for us.
150 lines
4.3 KiB
Python
150 lines
4.3 KiB
Python
"""filedict.py
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a Persistent Dictionary in Python
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Author: Erez Shinan
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Date : 31-May-2009
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"""
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import json
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import UserDict
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import sqlite3
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class DefaultArg:
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pass
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class Solutions:
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Sqlite3 = 0
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class FileDict(UserDict.DictMixin):
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"A dictionary that stores its data persistantly in a file"
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def __init__(self, solution=Solutions.Sqlite3, **options):
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assert solution == Solutions.Sqlite3
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try:
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self.__conn = options.pop('connection')
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except KeyError:
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filename = options.pop('filename')
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self.__conn = sqlite3.connect(filename)
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self.__tablename = options.pop('table', 'dict')
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self._nocommit = False
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assert not options, "Unrecognized options: %s" % options
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self.__conn.execute('create table if not exists %s (id integer primary key, hash integer, key blob, value blob);'%self.__tablename)
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self.__conn.execute('create index if not exists %s_index ON %s(hash);' % (self.__tablename, self.__tablename))
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self.__conn.commit()
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def _commit(self):
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if self._nocommit:
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return
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self.__conn.commit()
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def __pack(self, value):
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return sqlite3.Binary(json.dumps(value))
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##return sqlite3.Binary(pickle.dumps(value, -1))
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def __unpack(self, value):
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return json.loads(str(value))
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##return pickle.loads(str(value))
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def __get_id(self, key):
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cursor = self.__conn.execute('select key,id from %s where hash=?;'%self.__tablename, (hash(key),))
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for k,id in cursor:
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if self.__unpack(k) == key:
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return id
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raise KeyError(key)
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def __getitem__(self, key):
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cursor = self.__conn.execute('select key,value from %s where hash=?;'%self.__tablename, (hash(key),))
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for k,v in cursor:
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if self.__unpack(k) == key:
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return self.__unpack(v)
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raise KeyError(key)
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def __setitem(self, key, value):
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value_pickle = self.__pack(value)
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try:
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id = self.__get_id(key)
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cursor = self.__conn.execute('update %s set value=? where id=?;'%self.__tablename, (value_pickle, id) )
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except KeyError:
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key_pickle = self.__pack(key)
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cursor = self.__conn.execute('insert into %s (hash, key, value) values (?, ?, ?);'
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%self.__tablename, (hash(key), key_pickle, value_pickle) )
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assert cursor.rowcount == 1
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def __setitem__(self, key, value):
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self.__setitem(key, value)
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self._commit()
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def __delitem__(self, key):
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id = self.__get_id(key)
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cursor = self.__conn.execute('delete from %s where id=?;'%self.__tablename, (id,))
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if cursor.rowcount <= 0:
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raise KeyError(key)
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self._commit()
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def update(self, d):
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for k,v in d.iteritems():
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self.__setitem(k, v)
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self._commit()
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def __iter__(self):
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return (self.__unpack(x[0]) for x in self.__conn.execute('select key from %s;'%self.__tablename) )
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def keys(self):
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return iter(self)
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def values(self):
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return (self.__unpack(x[0]) for x in self.__conn.execute('select value from %s;'%self.__tablename) )
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def items(self):
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return (map(self.__unpack, x) for x in self.__conn.execute('select key,value from %s;'%self.__tablename) )
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def iterkeys(self):
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return self.keys()
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def itervalues(self):
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return self.values()
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def iteritems(self):
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return self.items()
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def __contains__(self, key):
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try:
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self.__get_id(key)
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return True
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except KeyError:
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return False
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def __len__(self):
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return self.__conn.execute('select count(*) from %s;' % self.__tablename).fetchone()[0]
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def __del__(self):
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try:
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self.__conn
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except AttributeError:
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pass
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else:
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self.__conn.commit()
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@property
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def batch(self):
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return self._Batch(self)
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class _Batch:
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def __init__(self, d):
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self.__d = d
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def __enter__(self):
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self.__old_nocommit = self.__d._nocommit
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self.__d._nocommit = True
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return self.__d
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def __exit__(self, type, value, traceback):
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self.__d._nocommit = self.__old_nocommit
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self.__d._commit()
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return True
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