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dbtables.py
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#----------------------------------------------------------------------- # # Copyright (C) 2000, 2001 by Autonomous Zone Industries # Copyright (C) 2002 Gregory P. Smith # # License: This is free software. You may use this software for any # purpose including modification/redistribution, so long as # this header remains intact and that you do not claim any # rights of ownership or authorship of this software. This # software has been tested, but no warranty is expressed or # implied. # # -- Gregory P. Smith <greg@krypto.org> # This provides a simple database table interface built on top of # the Python Berkeley DB 3 interface. # _cvsid = '$Id$' import re import sys import copy import random import struct if sys.version_info[0] >= 3 : import pickle else : if sys.version_info < (2, 6) : import cPickle as pickle else : # When we drop support for python 2.4 # we could use: (in 2.5 we need a __future__ statement) # # with warnings.catch_warnings(): # warnings.filterwarnings(...) # ... # # We can not use "with" as is, because it would be invalid syntax # in python 2.4 and (with no __future__) 2.5. # Here we simulate "with" following PEP 343 : import warnings w = warnings.catch_warnings() w.__enter__() try : warnings.filterwarnings('ignore', message='the cPickle module has been removed in Python 3.0', category=DeprecationWarning) import cPickle as pickle finally : w.__exit__() del w try: # For Pythons w/distutils pybsddb from bsddb3 import db except ImportError: # For Python 2.3 from bsddb import db class TableDBError(StandardError): pass class TableAlreadyExists(TableDBError): pass class Cond: """This condition matches everything""" def __call__(self, s): return 1 class ExactCond(Cond): """Acts as an exact match condition function""" def __init__(self, strtomatch): self.strtomatch = strtomatch def __call__(self, s): return s == self.strtomatch class PrefixCond(Cond): """Acts as a condition function for matching a string prefix""" def __init__(self, prefix): self.prefix = prefix def __call__(self, s): return s[:len(self.prefix)] == self.prefix class PostfixCond(Cond): """Acts as a condition function for matching a string postfix""" def __init__(self, postfix): self.postfix = postfix def __call__(self, s): return s[-len(self.postfix):] == self.postfix class LikeCond(Cond): """ Acts as a function that will match using an SQL 'LIKE' style string. Case insensitive and % signs are wild cards. This isn't perfect but it should work for the simple common cases. """ def __init__(self, likestr, re_flags=re.IGNORECASE): # escape python re characters chars_to_escape = '.*+()[]?' for char in chars_to_escape : likestr = likestr.replace(char, '\\'+char) # convert %s to wildcards self.likestr = likestr.replace('%', '.*') self.re = re.compile('^'+self.likestr+'$', re_flags) def __call__(self, s): return self.re.match(s) # # keys used to store database metadata # _table_names_key = '__TABLE_NAMES__' # list of the tables in this db _columns = '._COLUMNS__' # table_name+this key contains a list of columns def _columns_key(table): return table + _columns # # these keys are found within table sub databases # _data = '._DATA_.' # this+column+this+rowid key contains table data _rowid = '._ROWID_.' # this+rowid+this key contains a unique entry for each # row in the table. (no data is stored) _rowid_str_len = 8 # length in bytes of the unique rowid strings def _data_key(table, col, rowid): return table + _data + col + _data + rowid def _search_col_data_key(table, col): return table + _data + col + _data def _search_all_data_key(table): return table + _data def _rowid_key(table, rowid): return table + _rowid + rowid + _rowid def _search_rowid_key(table): return table + _rowid def contains_metastrings(s) : """Verify that the given string does not contain any metadata strings that might interfere with dbtables database operation. """ if (s.find(_table_names_key) >= 0 or s.find(_columns) >= 0 or s.find(_data) >= 0 or s.find(_rowid) >= 0): # Then return 1 else: return 0 class bsdTableDB : def __init__(self, filename, dbhome, create=0, truncate=0, mode=0600, recover=0, dbflags=0): """bsdTableDB(filename, dbhome, create=0, truncate=0, mode=0600) Open database name in the dbhome Berkeley DB directory. Use keyword arguments when calling this constructor. """ self.db = None myflags = db.DB_THREAD if create: myflags |= db.DB_CREATE flagsforenv = (db.DB_INIT_MPOOL | db.DB_INIT_LOCK | db.DB_INIT_LOG | db.DB_INIT_TXN | dbflags) # DB_AUTO_COMMIT isn't a valid flag for env.open() try: dbflags |= db.DB_AUTO_COMMIT except AttributeError: pass if recover: flagsforenv = flagsforenv | db.DB_RECOVER self.env = db.DBEnv() # enable auto deadlock avoidance self.env.set_lk_detect(db.DB_LOCK_DEFAULT) self.env.open(dbhome, myflags | flagsforenv) if truncate: myflags |= db.DB_TRUNCATE self.db = db.DB(self.env) # this code relies on DBCursor.set* methods to raise exceptions # rather than returning None self.db.set_get_returns_none(1) # allow duplicate entries [warning: be careful w/ metadata] self.db.set_flags(db.DB_DUP) self.db.open(filename, db.DB_BTREE, dbflags | myflags, mode) self.dbfilename = filename if sys.version_info[0] >= 3 : class cursor_py3k(object) : def __init__(self, dbcursor) : self._dbcursor = dbcursor def close(self) : return self._dbcursor.close() def set_range(self, search) : v = self._dbcursor.set_range(bytes(search, "iso8859-1")) if v is not None : v = (v[0].decode("iso8859-1"), v[1].decode("iso8859-1")) return v def __next__(self) : v = getattr(self._dbcursor, "next")() if v is not None : v = (v[0].decode("iso8859-1"), v[1].decode("iso8859-1")) return v class db_py3k(object) : def __init__(self, db) : self._db = db def cursor(self, txn=None) : return cursor_py3k(self._db.cursor(txn=txn)) def has_key(self, key, txn=None) : return getattr(self._db,"has_key")(bytes(key, "iso8859-1"), txn=txn) def put(self, key, value, flags=0, txn=None) : key = bytes(key, "iso8859-1") if value is not None : value = bytes(value, "iso8859-1") return self._db.put(key, value, flags=flags, txn=txn) def put_bytes(self, key, value, txn=None) : key = bytes(key, "iso8859-1") return self._db.put(key, value, txn=txn) def get(self, key, txn=None, flags=0) : key = bytes(key, "iso8859-1") v = self._db.get(key, txn=txn, flags=flags) if v is not None : v = v.decode("iso8859-1") return v def get_bytes(self, key, txn=None, flags=0) : key = bytes(key, "iso8859-1") return self._db.get(key, txn=txn, flags=flags) def delete(self, key, txn=None) : key = bytes(key, "iso8859-1") return self._db.delete(key, txn=txn) def close (self) : return self._db.close() self.db = db_py3k(self.db) else : # Python 2.x pass # Initialize the table names list if this is a new database txn = self.env.txn_begin() try: if not getattr(self.db, "has_key")(_table_names_key, txn): getattr(self.db, "put_bytes", self.db.put) \ (_table_names_key, pickle.dumps([], 1), txn=txn) # Yes, bare except except: txn.abort() raise else: txn.commit() # TODO verify more of the database's metadata? self.__tablecolumns = {} def __del__(self): self.close() def close(self): if self.db is not None: self.db.close() self.db = None if self.env is not None: self.env.close() self.env = None def checkpoint(self, mins=0): self.env.txn_checkpoint(mins) def sync(self): self.db.sync() def _db_print(self) : """Print the database to stdout for debugging""" print "******** Printing raw database for debugging ********" cur = self.db.cursor() try: key, data = cur.first() while 1: print repr({key: data}) next = cur.next() if next: key, data = next else: cur.close() return except db.DBNotFoundError: cur.close() def CreateTable(self, table, columns): """CreateTable(table, columns) - Create a new table in the database. raises TableDBError if it already exists or for other DB errors. """ assert isinstance(columns, list) txn = None try: # checking sanity of the table and column names here on # table creation will prevent problems elsewhere. if contains_metastrings(table): raise ValueError( "bad table name: contains reserved metastrings") for column in columns : if contains_metastrings(column): raise ValueError( "bad column name: contains reserved metastrings") columnlist_key = _columns_key(table) if getattr(self.db, "has_key")(columnlist_key): raise TableAlreadyExists, "table already exists" txn = self.env.txn_begin() # store the table's column info getattr(self.db, "put_bytes", self.db.put)(columnlist_key, pickle.dumps(columns, 1), txn=txn) # add the table name to the tablelist tablelist = pickle.loads(getattr(self.db, "get_bytes", self.db.get) (_table_names_key, txn=txn, flags=db.DB_RMW)) tablelist.append(table) # delete 1st, in case we opened with DB_DUP self.db.delete(_table_names_key, txn=txn) getattr(self.db, "put_bytes", self.db.put)(_table_names_key, pickle.dumps(tablelist, 1), txn=txn) txn.commit() txn = None except db.DBError, dberror: if txn: txn.abort() if sys.version_info < (2, 6) : raise TableDBError, dberror[1] else : raise TableDBError, dberror.args[1] def ListTableColumns(self, table): """Return a list of columns in the given table. [] if the table doesn't exist. """ assert isinstance(table, str) if contains_metastrings(table): raise ValueError, "bad table name: contains reserved metastrings" columnlist_key = _columns_key(table) if not getattr(self.db, "has_key")(columnlist_key): return [] pickledcolumnlist = getattr(self.db, "get_bytes", self.db.get)(columnlist_key) if pickledcolumnlist: return pickle.loads(pickledcolumnlist) else: return [] def ListTables(self): """Return a list of tables in this database.""" pickledtablelist = self.db.get_get(_table_names_key) if pickledtablelist: return pickle.loads(pickledtablelist) else: return [] def CreateOrExtendTable(self, table, columns): """CreateOrExtendTable(table, columns) Create a new table in the database. If a table of this name already exists, extend it to have any additional columns present in the given list as well as all of its current columns. """ assert isinstance(columns, list) try: self.CreateTable(table, columns) except TableAlreadyExists: # the table already existed, add any new columns txn = None try: columnlist_key = _columns_key(table) txn = self.env.txn_begin() # load the current column list oldcolumnlist = pickle.loads( getattr(self.db, "get_bytes", self.db.get)(columnlist_key, txn=txn, flags=db.DB_RMW)) # create a hash table for fast lookups of column names in the # loop below oldcolumnhash = {} for c in oldcolumnlist: oldcolumnhash[c] = c # create a new column list containing both the old and new # column names newcolumnlist = copy.copy(oldcolumnlist) for c in columns: if not c in oldcolumnhash: newcolumnlist.append(c) # store the table's new extended column list if newcolumnlist != oldcolumnlist : # delete the old one first since we opened with DB_DUP self.db.delete(columnlist_key, txn=txn) getattr(self.db, "put_bytes", self.db.put)(columnlist_key, pickle.dumps(newcolumnlist, 1), txn=txn) txn.commit() txn = None self.__load_column_info(table) except db.DBError, dberror: if txn: txn.abort() if sys.version_info < (2, 6) : raise TableDBError, dberror[1] else : raise TableDBError, dberror.args[1] def __load_column_info(self, table) : """initialize the self.__tablecolumns dict""" # check the column names try: tcolpickles = getattr(self.db, "get_bytes", self.db.get)(_columns_key(table)) except db.DBNotFoundError: raise TableDBError, "unknown table: %r" % (table,) if not tcolpickles: raise TableDBError, "unknown table: %r" % (table,) self.__tablecolumns[table] = pickle.loads(tcolpickles) def __new_rowid(self, table, txn) : """Create a new unique row identifier""" unique = 0 while not unique: # Generate a random 64-bit row ID string # (note: might have <64 bits of true randomness # but it's plenty for our database id needs!) blist = [] for x in xrange(_rowid_str_len): blist.append(random.randint(0,255)) newid = struct.pack('B'*_rowid_str_len, *blist) if sys.version_info[0] >= 3 : newid = newid.decode("iso8859-1") # 8 bits # Guarantee uniqueness by adding this key to the database try: self.db.put(_rowid_key(table, newid), None, txn=txn, flags=db.DB_NOOVERWRITE) except db.DBKeyExistError: pass else: unique = 1 return newid def Insert(self, table, rowdict) : """Insert(table, datadict) - Insert a new row into the table using the keys+values from rowdict as the column values. """ txn = None try: if not getattr(self.db, "has_key")(_columns_key(table)): raise TableDBError, "unknown table" # check the validity of each column name if not table in self.__tablecolumns: self.__load_column_info(table) for column in rowdict.keys() : if not self.__tablecolumns[table].count(column): raise TableDBError, "unknown column: %r" % (column,) # get a unique row identifier for this row txn = self.env.txn_begin() rowid = self.__new_rowid(table, txn=txn) # insert the row values into the table database for column, dataitem in rowdict.items(): # store the value self.db.put(_data_key(table, column, rowid), dataitem, txn=txn) txn.commit() txn = None except db.DBError, dberror: # WIBNI we could just abort the txn and re-raise the exception? # But no, because TableDBError is not related to DBError via # inheritance, so it would be backwards incompatible. Do the next # best thing. info = sys.exc_info() if txn: txn.abort() self.db.delete(_rowid_key(table, rowid)) if sys.version_info < (2, 6) : raise TableDBError, dberror[1], info[2] else : raise TableDBError, dberror.args[1], info[2] def Modify(self, table, conditions={}, mappings={}): """Modify(table, conditions={}, mappings={}) - Modify items in rows matching 'conditions' using mapping functions in 'mappings' * table - the table name * conditions - a dictionary keyed on column names containing a condition callable expecting the data string as an argument and returning a boolean. * mappings - a dictionary keyed on column names containing a condition callable expecting the data string as an argument and returning the new string for that column. """ try: matching_rowids = self.__Select(table, [], conditions) # modify only requested columns columns = mappings.keys() for rowid in matching_rowids.keys(): txn = None try: for column in columns: txn = self.env.txn_begin() # modify the requested column try: dataitem = self.db.get( _data_key(table, column, rowid), txn=txn) self.db.delete( _data_key(table, column, rowid), txn=txn) except db.DBNotFoundError: # XXXXXXX row key somehow didn't exist, assume no # error dataitem = None dataitem = mappings[column](dataitem) if dataitem is not None: self.db.put( _data_key(table, column, rowid), dataitem, txn=txn) txn.commit() txn = None # catch all exceptions here since we call unknown callables except: if txn: txn.abort() raise except db.DBError, dberror: if sys.version_info < (2, 6) : raise TableDBError, dberror[1] else : raise TableDBError, dberror.args[1] def Delete(self, table, conditions={}): """Delete(table, conditions) - Delete items matching the given conditions from the table. * conditions - a dictionary keyed on column names containing condition functions expecting the data string as an argument and returning a boolean. """ try: matching_rowids = self.__Select(table, [], conditions) # delete row data from all columns columns = self.__tablecolumns[table] for rowid in matching_rowids.keys(): txn = None try: txn = self.env.txn_begin() for column in columns: # delete the data key try: self.db.delete(_data_key(table, column, rowid), txn=txn) except db.DBNotFoundError: # XXXXXXX column may not exist, assume no error pass try: self.db.delete(_rowid_key(table, rowid), txn=txn) except db.DBNotFoundError: # XXXXXXX row key somehow didn't exist, assume no error pass txn.commit() txn = None except db.DBError, dberror: if txn: txn.abort() raise except db.DBError, dberror: if sys.version_info < (2, 6) : raise TableDBError, dberror[1] else : raise TableDBError, dberror.args[1] def Select(self, table, columns, conditions={}): """Select(table, columns, conditions) - retrieve specific row data Returns a list of row column->value mapping dictionaries. * columns - a list of which column data to return. If columns is None, all columns will be returned. * conditions - a dictionary keyed on column names containing callable conditions expecting the data string as an argument and returning a boolean. """ try: if not table in self.__tablecolumns: self.__load_column_info(table) if columns is None: columns = self.__tablecolumns[table] matching_rowids = self.__Select(table, columns, conditions) except db.DBError, dberror: if sys.version_info < (2, 6) : raise TableDBError, dberror[1] else : raise TableDBError, dberror.args[1] # return the matches as a list of dictionaries return matching_rowids.values() def __Select(self, table, columns, conditions): """__Select() - Used to implement Select and Delete (above) Returns a dictionary keyed on rowids containing dicts holding the row data for columns listed in the columns param that match the given conditions. * conditions is a dictionary keyed on column names containing callable conditions expecting the data string as an argument and returning a boolean. """ # check the validity of each column name if not table in self.__tablecolumns: self.__load_column_info(table) if columns is None: columns = self.tablecolumns[table] for column in (columns + conditions.keys()): if not self.__tablecolumns[table].count(column): raise TableDBError, "unknown column: %r" % (column,) # keyed on rows that match so far, containings dicts keyed on # column names containing the data for that row and column. matching_rowids = {} # keys are rowids that do not match rejected_rowids = {} # attempt to sort the conditions in such a way as to minimize full # column lookups def cmp_conditions(atuple, btuple): a = atuple[1] b = btuple[1] if type(a) is type(b): # Needed for python 3. "cmp" vanished in 3.0.1 def cmp(a, b) : if a==b : return 0 if a<b : return -1 return 1 if isinstance(a, PrefixCond) and isinstance(b, PrefixCond): # longest prefix first return cmp(len(b.prefix), len(a.prefix)) if isinstance(a, LikeCond) and isinstance(b, LikeCond): # longest likestr first return cmp(len(b.likestr), len(a.likestr)) return 0 if isinstance(a, ExactCond): return -1 if isinstance(b, ExactCond): return 1 if isinstance(a, PrefixCond): return -1 if isinstance(b, PrefixCond): return 1 # leave all unknown condition callables alone as equals return 0 if sys.version_info < (2, 6) : conditionlist = conditions.items() conditionlist.sort(cmp_conditions) else : # Insertion Sort. Please, improve conditionlist = [] for i in conditions.items() : for j, k in enumerate(conditionlist) : r = cmp_conditions(k, i) if r == 1 : conditionlist.insert(j, i) break else : conditionlist.append(i) # Apply conditions to column data to find what we want cur = self.db.cursor() column_num = -1 for column, condition in conditionlist: column_num = column_num + 1 searchkey = _search_col_data_key(table, column) # speedup: don't linear search columns within loop if column in columns: savethiscolumndata = 1 # save the data for return else: savethiscolumndata = 0 # data only used for selection try: key, data = cur.set_range(searchkey) while key[:len(searchkey)] == searchkey: # extract the rowid from the key rowid = key[-_rowid_str_len:] if not rowid in rejected_rowids: # if no condition was specified or the condition # succeeds, add row to our match list. if not condition or condition(data): if not rowid in matching_rowids: matching_rowids[rowid] = {} if savethiscolumndata: matching_rowids[rowid][column] = data else: if rowid in matching_rowids: del matching_rowids[rowid] rejected_rowids[rowid] = rowid key, data = cur.next() except db.DBError, dberror: if dberror.args[0] != db.DB_NOTFOUND: raise continue cur.close() # we're done selecting rows, garbage collect the reject list del rejected_rowids # extract any remaining desired column data from the # database for the matching rows. if len(columns) > 0: for rowid, rowdata in matching_rowids.items(): for column in columns: if column in rowdata: continue try: rowdata[column] = self.db.get( _data_key(table, column, rowid)) except db.DBError, dberror: if sys.version_info < (2, 6) : if dberror[0] != db.DB_NOTFOUND: raise else : if dberror.args[0] != db.DB_NOTFOUND: raise rowdata[column] = None # return the matches return matching_rowids def Drop(self, table): """Remove an entire table from the database""" txn = None try: txn = self.env.txn_begin() # delete the column list self.db.delete(_columns_key(table), txn=txn) cur = self.db.cursor(txn) # delete all keys containing this tables column and row info table_key = _search_all_data_key(table) while 1: try: key, data = cur.set_range(table_key) except db.DBNotFoundError: break # only delete items in this table if key[:len(table_key)] != table_key: break cur.delete() # delete all rowids used by this table table_key = _search_rowid_key(table) while 1: try: key, data = cur.set_range(table_key) except db.DBNotFoundError: break # only delete items in this table if key[:len(table_key)] != table_key: break cur.delete() cur.close() # delete the tablename from the table name list tablelist = pickle.loads( getattr(self.db, "get_bytes", self.db.get)(_table_names_key, txn=txn, flags=db.DB_RMW)) try: tablelist.remove(table) except ValueError: # hmm, it wasn't there, oh well, that's what we want. pass # delete 1st, incase we opened with DB_DUP self.db.delete(_table_names_key, txn=txn) getattr(self.db, "put_bytes", self.db.put)(_table_names_key, pickle.dumps(tablelist, 1), txn=txn) txn.commit() txn = None if table in self.__tablecolumns: del self.__tablecolumns[table] except db.DBError, dberror: if txn: txn.abort() raise TableDBError(dberror.args[1])
