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#!/usr/bin/env python
#
# This library is free software, distributed under the terms of
# the GNU Lesser General Public License Version 3, or any later version.
# See the COPYING file included in this archive
#
# The docstrings in this module contain epytext markup; API documentation
# may be created by processing this file with epydoc: http://epydoc.sf.net
import UserDict
import sqlite3
import cPickle as pickle
import time
import os
class DataStore(UserDict.DictMixin):
""" Interface for classes implementing physical storage (for data
published via the "STORE" RPC) for the Kademlia DHT
@note: This provides an interface for a dict-like object
"""
def keys(self):
""" Return a list of the keys in this data store """
def lastPublished(self, key):
""" Get the time the C{(key, value)} pair identified by C{key}
was last published """
def originalPublisherID(self, key):
""" Get the original publisher of the data's node ID
@param key: The key that identifies the stored data
@type key: str
@return: Return the node ID of the original publisher of the
C{(key, value)} pair identified by C{key}.
"""
def originalPublishTime(self, key):
""" Get the time the C{(key, value)} pair identified by C{key}
was originally published """
def setItem(self, key, value, lastPublished, originallyPublished, originalPublisherID):
""" Set the value of the (key, value) pair identified by C{key};
this should set the "last published" value for the (key, value)
pair to the current time
"""
def __getitem__(self, key):
""" Get the value identified by C{key} """
def __setitem__(self, key, value):
""" Convenience wrapper to C{setItem}; this accepts a tuple in the
format: (value, lastPublished, originallyPublished, originalPublisherID) """
self.setItem(key, *value)
def __delitem__(self, key):
""" Delete the specified key (and its value) """
class DictDataStore(DataStore):
""" A datastore using an in-memory Python dictionary """
def __init__(self):
# Dictionary format:
# { <key>: (<value>, <lastPublished>, <originallyPublished> <originalPublisherID>) }
self._dict = {}
def keys(self):
""" Return a list of the keys in this data store """
return self._dict.keys()
def lastPublished(self, key):
""" Get the time the C{(key, value)} pair identified by C{key}
was last published """
return self._dict[key][1]
def originalPublisherID(self, key):
""" Get the original publisher of the data's node ID
@param key: The key that identifies the stored data
@type key: str
@return: Return the node ID of the original publisher of the
C{(key, value)} pair identified by C{key}.
"""
return self._dict[key][3]
def originalPublishTime(self, key):
""" Get the time the C{(key, value)} pair identified by C{key}
was originally published """
return self._dict[key][2]
def setItem(self, key, value, lastPublished, originallyPublished, originalPublisherID):
""" Set the value of the (key, value) pair identified by C{key};
this should set the "last published" value for the (key, value)
pair to the current time
"""
self._dict[key] = (value, lastPublished, originallyPublished, originalPublisherID)
def __getitem__(self, key):
""" Get the value identified by C{key} """
return self._dict[key][0]
def __delitem__(self, key):
""" Delete the specified key (and its value) """
del self._dict[key]
class SQLiteDataStore(DataStore):
""" Example of a SQLite database-based datastore
"""
def __init__(self, dbFile=':memory:'):
"""
@param dbFile: The name of the file containing the SQLite database; if
unspecified, an in-memory database is used.
@type dbFile: str
"""
createDB = not os.path.exists(dbFile)
self._db = sqlite3.connect(dbFile)
self._db.isolation_level = None
self._db.text_factory = str
if createDB:
self._db.execute('CREATE TABLE data(key, value, lastPublished, originallyPublished, originalPublisherID)')
self._cursor = self._db.cursor()
def keys(self):
""" Return a list of the keys in this data store """
keys = []
try:
self._cursor.execute("SELECT key FROM data")
for row in self._cursor:
keys.append(row[0].decode('hex'))
finally:
return keys
def lastPublished(self, key):
""" Get the time the C{(key, value)} pair identified by C{key}
was last published """
return int(self._dbQuery(key, 'lastPublished'))
def originalPublisherID(self, key):
""" Get the original publisher of the data's node ID
@param key: The key that identifies the stored data
@type key: str
@return: Return the node ID of the original publisher of the
C{(key, value)} pair identified by C{key}.
"""
return self._dbQuery(key, 'originalPublisherID')
def originalPublishTime(self, key):
""" Get the time the C{(key, value)} pair identified by C{key}
was originally published """
return int(self._dbQuery(key, 'originallyPublished'))
def setItem(self, key, value, lastPublished, originallyPublished, originalPublisherID):
# Encode the key so that it doesn't corrupt the database
encodedKey = key.encode('hex')
self._cursor.execute("select key from data where key=:reqKey", {'reqKey': encodedKey})
if self._cursor.fetchone() == None:
self._cursor.execute('INSERT INTO data(key, value, lastPublished, originallyPublished, originalPublisherID) VALUES (?, ?, ?, ?, ?)', (encodedKey, buffer(pickle.dumps(value, pickle.HIGHEST_PROTOCOL)), lastPublished, originallyPublished, originalPublisherID))
else:
self._cursor.execute('UPDATE data SET value=?, lastPublished=?, originallyPublished=?, originalPublisherID=? WHERE key=?', (buffer(pickle.dumps(value, pickle.HIGHEST_PROTOCOL)), lastPublished, originallyPublished, originalPublisherID, encodedKey))
def _dbQuery(self, key, columnName, unpickle=False):
try:
self._cursor.execute("SELECT %s FROM data WHERE key=:reqKey" % columnName, {'reqKey': key.encode('hex')})
row = self._cursor.fetchone()
value = str(row[0])
except TypeError:
raise KeyError, key
else:
if unpickle:
return pickle.loads(value)
else:
return value
def __getitem__(self, key):
return self._dbQuery(key, 'value', unpickle=True)
def __delitem__(self, key):
self._cursor.execute("DELETE FROM data WHERE key=:reqKey", {'reqKey': key.encode('hex')})
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