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cpython/Lib/bsddb/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@electricrain.com>
# This provides a simple database table interface built on top of
# the Python BerkeleyDB 3 interface.
#
_cvsid = '$Id$'
import string
import sys
try:
import cPickle
pickle = cPickle
except ImportError:
import pickle
import whrandom
import xdrlib
import re
import copy
from bsddb.db import *
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 = string.replace(likestr, char, '\\'+char)
# convert %s to wildcards
self.likestr = string.replace(likestr, '%', '.*')
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 string.find(s, _table_names_key) >= 0 or \
string.find(s, _columns) >= 0 or \
string.find(s, _data) >= 0 or \
string.find(s, _rowid) >= 0 :
return 1
else :
return 0
class bsdTableDB :
# Save close() from bombing out if __init__() failed
db = None
env = None
def __init__(self, filename, dbhome, create=0, truncate=0, mode=0600, recover=0, dbflags=0) :
"""bsdTableDB.open(filename, dbhome, create=0, truncate=0, mode=0600)
Open database name in the dbhome BerkeleyDB directory.
Use keyword arguments when calling this constructor.
"""
myflags = DB_THREAD
if create :
myflags = myflags | DB_CREATE
flagsforenv = DB_INIT_MPOOL | DB_INIT_LOCK | DB_INIT_LOG | DB_INIT_TXN | dbflags
if recover :
flagsforenv = flagsforenv | DB_RECOVER
self.env = DBEnv()
self.env.set_lk_detect(DB_LOCK_DEFAULT) # enable auto deadlock avoidance
self.env.open(dbhome, myflags | flagsforenv)
if truncate :
myflags = myflags | DB_TRUNCATE
self.db = DB(self.env)
self.db.set_flags(DB_DUP) # allow duplicate entries [warning: be careful w/ metadata]
self.db.open(filename, DB_BTREE, myflags, mode)
self.dbfilename = filename
# Initialize the table names list if this is a new database
if not self.db.has_key(_table_names_key) :
self.db.put(_table_names_key, pickle.dumps([], 1))
# 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 `{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 type(columns) == type([])
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)
self.db.delete(_table_names_key, txn) # delete 1st, incase we opened with DB_DUP
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 type(table) == type('')
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 type(columns) == type([])
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: " + `table`
if not tcolpickles:
raise TableDBError, "unknown table: " + `table`
self.__tablecolumns[table] = pickle.loads(tcolpickles)
def __new_rowid(self, table, txn=None) :
"""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(whrandom.random()*2147483647))
p.pack_int(int(whrandom.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 DBKeyExistsError:
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: "+`column`
# get a unique row identifier for this row
rowid = self.__new_rowid(table)
txn = self.env.txn_begin()
# 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:
if txn :
txn.abort()
self.db.delete(_rowid_key(table, rowid))
raise TableDBError, dberror[1]
def Modify(self, table, conditions={}, mappings={}) :
"""Modify(table, conditions) - Modify in rows matching 'conditions'
using mapping functions in 'mappings'
* conditions is a dictionary keyed on column names
containing condition functions expecting the data string as an
argument and returning a boolean.
* mappings is a dictionary keyed on column names containint condition
functions 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:
dataitem = None # XXXXXXX row key somehow didn't exist, assume no error
dataitem = mappings[column](dataitem)
if dataitem <> None:
self.db.put(_data_key(table, column, rowid), dataitem, txn=txn)
txn.commit()
txn = None
except DBError, dberror:
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 is 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:
pass # XXXXXXX column may not exist, assume no error
try:
self.db.delete(_rowid_key(table, rowid), txn)
except DBNotFoundError:
pass # XXXXXXX row key somehow didn't exist, assume no error
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, conditions) - retrieve specific row data
Returns a list of row column->value mapping dictionaries.
* columns is a list of which column data to return. If
columns is None, all columns will be returned.
* conditions is 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: "+`column`
# keyed on rows that match so far, containings dicts keyed on
# column names containing the data for that row and column.
matching_rowids = {}
rejected_rowids = {} # keys are rowids that do not match
# 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) == type(b) :
if isinstance(a, PrefixCond) and isinstance(b, PrefixCond):
return cmp(len(b.prefix), len(a.prefix)) # longest prefix first
if isinstance(a, LikeCond) and isinstance(b, LikeCond):
return cmp(len(b.likestr), len(a.likestr)) # longest likestr first
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:
pass # hmm, it wasn't there, oh well, that's what we want.
self.db.delete(_table_names_key, txn) # delete 1st, incase we opened with DB_DUP
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]
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