ref: a3b5e3994f7f2897ab1b5bb20b91224d145c1fc1
dir: /sys/lib/python/bsddb/dbtables.py/
#-----------------------------------------------------------------------
#
# 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 <[email protected]>
# This provides a simple database table interface built on top of
# the Python BerkeleyDB 3 interface.
#
_cvsid = '$Id: dbtables.py 46858 2006-06-11 08:35:14Z neal.norwitz $'
import re
import sys
import copy
import xdrlib
import random
from types import ListType, StringType
import cPickle as pickle
try:
# For Pythons w/distutils pybsddb
from bsddb3.db import *
except ImportError:
# For Python 2.3
from bsddb.db import *
# XXX(nnorwitz): is this correct? DBIncompleteError is conditional in _bsddb.c
try:
DBIncompleteError
except NameError:
class DBIncompleteError(Exception):
pass
class TableDBError(StandardError):
pass
class TableAlreadyExists(TableDBError):
pass
class Cond:
"""This condition matches everything"""
def __call__(self, s):
return 1
class ExactCond(Cond):
"""Acts as an exact match condition function"""
def __init__(self, strtomatch):
self.strtomatch = strtomatch
def __call__(self, s):
return s == self.strtomatch
class PrefixCond(Cond):
"""Acts as a condition function for matching a string prefix"""
def __init__(self, prefix):
self.prefix = prefix
def __call__(self, s):
return s[:len(self.prefix)] == self.prefix
class PostfixCond(Cond):
"""Acts as a condition function for matching a string postfix"""
def __init__(self, postfix):
self.postfix = postfix
def __call__(self, s):
return s[-len(self.postfix):] == self.postfix
class LikeCond(Cond):
"""
Acts as a function that will match using an SQL 'LIKE' style
string. Case insensitive and % signs are wild cards.
This isn't perfect but it should work for the simple common cases.
"""
def __init__(self, likestr, re_flags=re.IGNORECASE):
# escape python re characters
chars_to_escape = '.*+()[]?'
for char in chars_to_escape :
likestr = likestr.replace(char, '\\'+char)
# convert %s to wildcards
self.likestr = likestr.replace('%', '.*')
self.re = re.compile('^'+self.likestr+'$', 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 BerkeleyDB directory.
Use keyword arguments when calling this constructor.
"""
self.db = None
myflags = DB_THREAD
if create:
myflags |= DB_CREATE
flagsforenv = (DB_INIT_MPOOL | DB_INIT_LOCK | DB_INIT_LOG |
DB_INIT_TXN | dbflags)
# DB_AUTO_COMMIT isn't a valid flag for env.open()
try:
dbflags |= DB_AUTO_COMMIT
except AttributeError:
pass
if recover:
flagsforenv = flagsforenv | DB_RECOVER
self.env = DBEnv()
# enable auto deadlock avoidance
self.env.set_lk_detect(DB_LOCK_DEFAULT)
self.env.open(dbhome, myflags | flagsforenv)
if truncate:
myflags |= DB_TRUNCATE
self.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_DUP)
self.db.open(filename, DB_BTREE, dbflags | myflags, mode)
self.dbfilename = filename
# Initialize the table names list if this is a new database
txn = self.env.txn_begin()
try:
if not self.db.has_key(_table_names_key, txn):
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):
try:
self.env.txn_checkpoint(mins)
except DBIncompleteError:
pass
def sync(self):
try:
self.db.sync()
except DBIncompleteError:
pass
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 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, ListType)
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 self.db.has_key(columnlist_key):
raise TableAlreadyExists, "table already exists"
txn = self.env.txn_begin()
# store the table's column info
self.db.put(columnlist_key, pickle.dumps(columns, 1), txn=txn)
# add the table name to the tablelist
tablelist = pickle.loads(self.db.get(_table_names_key, txn=txn,
flags=DB_RMW))
tablelist.append(table)
# delete 1st, in case we opened with DB_DUP
self.db.delete(_table_names_key, txn)
self.db.put(_table_names_key, pickle.dumps(tablelist, 1), txn=txn)
txn.commit()
txn = None
except DBError, dberror:
if txn:
txn.abort()
raise TableDBError, dberror[1]
def ListTableColumns(self, table):
"""Return a list of columns in the given table.
[] if the table doesn't exist.
"""
assert isinstance(table, StringType)
if contains_metastrings(table):
raise ValueError, "bad table name: contains reserved metastrings"
columnlist_key = _columns_key(table)
if not self.db.has_key(columnlist_key):
return []
pickledcolumnlist = 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(_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, ListType)
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(
self.db.get(columnlist_key, txn=txn, flags=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 oldcolumnhash.has_key(c):
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)
self.db.put(columnlist_key,
pickle.dumps(newcolumnlist, 1),
txn=txn)
txn.commit()
txn = None
self.__load_column_info(table)
except DBError, dberror:
if txn:
txn.abort()
raise TableDBError, dberror[1]
def __load_column_info(self, table) :
"""initialize the self.__tablecolumns dict"""
# check the column names
try:
tcolpickles = self.db.get(_columns_key(table))
except 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: this code has <64 bits of randomness
# but it's plenty for our database id needs!)
p = xdrlib.Packer()
p.pack_int(int(random.random()*2147483647))
p.pack_int(int(random.random()*2147483647))
newid = p.get_buffer()
# Guarantee uniqueness by adding this key to the database
try:
self.db.put(_rowid_key(table, newid), None, txn=txn,
flags=DB_NOOVERWRITE)
except 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 self.db.has_key(_columns_key(table)):
raise TableDBError, "unknown table"
# check the validity of each column name
if not self.__tablecolumns.has_key(table):
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 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))
raise TableDBError, dberror[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)
self.db.delete(
_data_key(table, column, rowid),
txn)
except DBNotFoundError:
# XXXXXXX row key somehow didn't exist, assume no
# error
dataitem = None
dataitem = mappings[column](dataitem)
if dataitem <> 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 DBError, dberror:
raise TableDBError, dberror[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)
except DBNotFoundError:
# XXXXXXX column may not exist, assume no error
pass
try:
self.db.delete(_rowid_key(table, rowid), txn)
except DBNotFoundError:
# XXXXXXX row key somehow didn't exist, assume no error
pass
txn.commit()
txn = None
except DBError, dberror:
if txn:
txn.abort()
raise
except DBError, dberror:
raise TableDBError, dberror[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 self.__tablecolumns.has_key(table):
self.__load_column_info(table)
if columns is None:
columns = self.__tablecolumns[table]
matching_rowids = self.__Select(table, columns, conditions)
except DBError, dberror:
raise TableDBError, dberror[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 self.__tablecolumns.has_key(table):
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):
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
conditionlist = conditions.items()
conditionlist.sort(cmp_conditions)
# 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 rejected_rowids.has_key(rowid):
# if no condition was specified or the condition
# succeeds, add row to our match list.
if not condition or condition(data):
if not matching_rowids.has_key(rowid):
matching_rowids[rowid] = {}
if savethiscolumndata:
matching_rowids[rowid][column] = data
else:
if matching_rowids.has_key(rowid):
del matching_rowids[rowid]
rejected_rowids[rowid] = rowid
key, data = cur.next()
except DBError, dberror:
if dberror[0] != 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 rowdata.has_key(column):
continue
try:
rowdata[column] = self.db.get(
_data_key(table, column, rowid))
except DBError, dberror:
if dberror[0] != 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)
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 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 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(
self.db.get(_table_names_key, txn=txn, flags=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)
self.db.put(_table_names_key, pickle.dumps(tablelist, 1), txn=txn)
txn.commit()
txn = None
if self.__tablecolumns.has_key(table):
del self.__tablecolumns[table]
except DBError, dberror:
if txn:
txn.abort()
raise TableDBError, dberror[1]