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ScoDoc/ZopeProducts/ZPsycopgDA/db.py

210 lines
7.2 KiB
Python

# ZPsycopgDA/db.py - query execution
#
# Copyright (C) 2004-2010 Federico Di Gregorio <fog@debian.org>
#
# psycopg2 is free software: you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published
# by the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# psycopg2 is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
# License for more details.
# Import modules needed by _psycopg to allow tools like py2exe to do
# their work without bothering about the module dependencies.
from Shared.DC.ZRDB.TM import TM
from Shared.DC.ZRDB import dbi_db
from ZODB.POSException import ConflictError
import site
import pool
import psycopg2
from psycopg2.extensions import INTEGER, LONGINTEGER, FLOAT, BOOLEAN, DATE, TIME
from psycopg2.extensions import TransactionRollbackError, register_type
from psycopg2 import NUMBER, STRING, ROWID, DATETIME
# the DB object, managing all the real query work
class DB(TM, dbi_db.DB):
_p_oid = _p_changed = _registered = None
def __init__(self, dsn, tilevel, typecasts, enc='utf-8'):
self.dsn = dsn
self.tilevel = tilevel
self.typecasts = typecasts
if enc is None or enc == "":
self.encoding = "utf-8"
else:
self.encoding = enc
self.failures = 0
self.calls = 0
self.make_mappings()
def getconn(self, init=True):
# if init is False we are trying to get hold on an already existing
# connection, so we avoid to (re)initialize it risking errors.
conn = pool.getconn(self.dsn)
if init:
# use set_session where available as in these versions
# set_isolation_level generates an extra query.
if psycopg2.__version__ >= '2.4.2':
conn.set_session(isolation_level=int(self.tilevel))
else:
conn.set_isolation_level(int(self.tilevel))
conn.set_client_encoding(self.encoding)
for tc in self.typecasts:
register_type(tc, conn)
return conn
def putconn(self, close=False):
try:
conn = pool.getconn(self.dsn, False)
except AttributeError:
pass
pool.putconn(self.dsn, conn, close)
def getcursor(self):
conn = self.getconn(False)
return conn.cursor()
def _finish(self, *ignored):
try:
conn = self.getconn(False)
conn.commit()
self.putconn()
except AttributeError:
pass
def _abort(self, *ignored):
try:
conn = self.getconn(False)
conn.rollback()
self.putconn()
except AttributeError:
pass
def open(self):
# this will create a new pool for our DSN if not already existing,
# then get and immediately release a connection
self.getconn()
self.putconn()
def close(self):
# FIXME: if this connection is closed we flush all the pool associated
# with the current DSN; does this makes sense?
pool.flushpool(self.dsn)
def sortKey(self):
return 1
def make_mappings(self):
"""Generate the mappings used later by self.convert_description()."""
self.type_mappings = {}
for t, s in [(INTEGER,'i'), (LONGINTEGER, 'i'), (NUMBER, 'n'),
(BOOLEAN,'n'), (ROWID, 'i'),
(DATETIME, 'd'), (DATE, 'd'), (TIME, 'd')]:
for v in t.values:
self.type_mappings[v] = (t, s)
def convert_description(self, desc, use_psycopg_types=False):
"""Convert DBAPI-2.0 description field to Zope format."""
items = []
for name, typ, width, ds, p, scale, null_ok in desc:
m = self.type_mappings.get(typ, (STRING, 's'))
items.append({
'name': name,
'type': use_psycopg_types and m[0] or m[1],
'width': width,
'precision': p,
'scale': scale,
'null': null_ok,
})
return items
## tables and rows ##
def tables(self, rdb=0, _care=('TABLE', 'VIEW')):
self._register()
c = self.getcursor()
c.execute(
"SELECT t.tablename AS NAME, 'TABLE' AS TYPE "
" FROM pg_tables t WHERE tableowner <> 'postgres' "
"UNION SELECT v.viewname AS NAME, 'VIEW' AS TYPE "
" FROM pg_views v WHERE viewowner <> 'postgres' "
"UNION SELECT t.tablename AS NAME, 'SYSTEM_TABLE\' AS TYPE "
" FROM pg_tables t WHERE tableowner = 'postgres' "
"UNION SELECT v.viewname AS NAME, 'SYSTEM_TABLE' AS TYPE "
"FROM pg_views v WHERE viewowner = 'postgres'")
res = []
for name, typ in c.fetchall():
if typ in _care:
res.append({'TABLE_NAME': name, 'TABLE_TYPE': typ})
self.putconn()
return res
def columns(self, table_name):
self._register()
c = self.getcursor()
try:
r = c.execute('SELECT * FROM "%s" WHERE 1=0' % table_name)
except:
return ()
self.putconn()
return self.convert_description(c.description, True)
## query execution ##
def query(self, query_string, max_rows=None, query_data=None):
self._register()
self.calls = self.calls+1
desc = ()
res = []
nselects = 0
c = self.getcursor()
try:
for qs in [x for x in query_string.split('\0') if x]:
try:
if query_data:
c.execute(qs, query_data)
else:
c.execute(qs)
except TransactionRollbackError:
# Ha, here we have to look like we are the ZODB raising conflict errrors, raising ZPublisher.Publish.Retry just doesn't work
#logging.debug("Serialization Error, retrying transaction", exc_info=True)
raise ConflictError("TransactionRollbackError from psycopg2")
except psycopg2.OperationalError:
#logging.exception("Operational error on connection, closing it.")
try:
# Only close our connection
self.putconn(True)
except:
#logging.debug("Something went wrong when we tried to close the pool", exc_info=True)
pass
if c.description is not None:
nselects += 1
if c.description != desc and nselects > 1:
raise psycopg2.ProgrammingError(
'multiple selects in single query not allowed')
if max_rows:
res = c.fetchmany(max_rows)
else:
res = c.fetchall()
desc = c.description
self.failures = 0
except StandardError, err:
self._abort()
raise err
return self.convert_description(desc), res