pgtoolkit/pgmanager.py
author Radek Brich <radek.brich@devl.cz>
Thu, 15 Dec 2011 18:21:41 +0100
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parent 23 dc2dbe872fc8
child 26 7f219da7ab71
permissions -rw-r--r--
PgManager: Add partial support for multiprocessing.
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# -*- coding: utf-8 -*-
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#
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# PgManager - manage database connections
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#
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# Requires: Python 2.6, psycopg2
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#
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# Part of pgtoolkit
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# http://hg.devl.cz/pgtoolkit
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#
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# Copyright (c) 2010, 2011  Radek Brich <radek.brich@devl.cz>
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#
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# Permission is hereby granted, free of charge, to any person obtaining a copy
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# of this software and associated documentation files (the "Software"), to deal
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# in the Software without restriction, including without limitation the rights
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# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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# copies of the Software, and to permit persons to whom the Software is
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# furnished to do so, subject to the following conditions:
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#
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# The above copyright notice and this permission notice shall be included in
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# all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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# THE SOFTWARE.
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"""Postgres database connection manager
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PgManager wraps psycopg2 connect function, adding following features:
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 * Manage database connection parameters - link connection parameters
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   to an unique identifier, retrieve connection object by this identifier
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 * Connection pooling - connections with same identifier are pooled and reused
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 * Easy query using the with statement - retrieve cursor directly by connection
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   identifier, don't worry about connections
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 * Dict rows - cursor has additional methods like fetchall_dict(), which
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   returns dict row instead of ordinary list-like row
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Example:
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import pgmanager
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pgm = pgmanager.get_instance()
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pgm.create_conn(hostaddr='127.0.0.1', dbname='postgres')
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with pgm.cursor() as curs:
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    curs.execute('SELECT now() AS now')
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    row = curs.fetchone_dict()
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    print row.now
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First, we have obtained PgManager instance. This is like calling
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PgManager(), although in our example the instance is global. That means
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getting the instance in another module brings us all the defined connections
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etc.
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On second line we have created connection named 'default' (this name can be left out).
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The with statement obtains connection (actually connects to database when needed),
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then returns cursor for this connection. At the end of with statement,
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the connection is returned to the pool or closed (depending on number of connections
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in pool and on setting of keep_open parameter).
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The row returned by fetchone_dict() is special dict object, which can be accessed
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using item or attribute access, that is row['now'] or row.now.
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"""
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from contextlib import contextmanager
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import logging
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import threading
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import multiprocessing
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import select
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import socket
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import psycopg2
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import psycopg2.extensions
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from psycopg2 import DatabaseError, IntegrityError, OperationalError
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log = logging.getLogger("pgmanager")
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class PgManagerError(Exception):
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    pass
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class ConnectionInfo:
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    def __init__(self, dsn, isolation_level=None, keep_alive=True,
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        init_statement=None, keep_open=1):
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        self.dsn = dsn
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        self.isolation_level = isolation_level
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        self.keep_alive = keep_alive
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        self.init_statement = init_statement
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        self.keep_open = keep_open
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class RowDict(dict):
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    def __getattr__(self, key):
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        return self[key]
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class Cursor(psycopg2.extensions.cursor):
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    def execute(self, query, args=None):
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        try:
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            return super(Cursor, self).execute(query, args)
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        finally:
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            if self.query:
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                log.debug(self.query.decode('utf8'))
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    def callproc(self, procname, args=None):
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        try:
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            return super(Cursor, self).callproc(procname, args)
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        finally:
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            if self.query:
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                log.debug(self.query.decode('utf8'))
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    def row_dict(self, row, lstrip=None):
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        adjustname = lambda a: a
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        if lstrip:
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            adjustname = lambda a: a.lstrip(lstrip)
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        return RowDict(zip([adjustname(desc[0]) for desc in self.description], row))
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    def fetchone_dict(self, lstrip=None):
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        row = super(Cursor, self).fetchone()
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        if row is None:
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            return None
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        return self.row_dict(row, lstrip)
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    def fetchall_dict(self, lstrip=None):
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        rows = super(Cursor, self).fetchall()
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        return [self.row_dict(row, lstrip) for row in rows]
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    def fetchone_adapted(self):
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        '''Like fetchone() but values are quoted for direct inclusion in SQL query.
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        This is useful when you need to generate SQL script from data returned
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        by the query. Use mogrify() for simple cases.
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        '''
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        row = super(Cursor, self).fetchone()
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        if row is None:
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            return None
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        return [self.mogrify('%s', [x]).decode('utf8') for x in row]
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    def fetchall_adapted(self):
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        '''Like fetchall() but values are quoted for direct inclusion in SQL query.'''
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        rows = super(Cursor, self).fetchall()
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        return [[self.mogrify('%s', [x]).decode('utf8') for x in row] for row in rows]
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0
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class Connection(psycopg2.extensions.connection):
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    def cursor(self, name=None):
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        if name is None:
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            return super(Connection, self).cursor(cursor_factory=Cursor)
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        else:
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            return super(Connection, self).cursor(name, cursor_factory=Cursor)
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    def keep_alive(self):
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        '''Set socket to keepalive mode. Must be called before any query.'''
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        sock = socket.fromfd(self.fileno(), socket.AF_INET, socket.SOCK_STREAM) 
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        sock.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
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        try:
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            # Maximum keep-alive probes before asuming the connection is lost
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            sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPCNT, 5)
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            # Interval (in seconds) between keep-alive probes
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            sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPINTVL, 2)
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            # Maximum idle time (in seconds) before start sending keep-alive probes
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            sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPIDLE, 10)
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        except socket.error:
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            pass
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class PgManager:
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    def __init__(self):
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        self.conn_known = {}  # available connections
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        self.conn_pool = {}  # active connetions
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        self.lock = threading.Lock()  # mutual exclusion for threads
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        self.pid = multiprocessing.current_process().pid  # forking check
0
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    def __del__(self):
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        for conn in tuple(self.conn_known.keys()):
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            self.destroy_conn(conn)
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    def create_conn(self, name='default', keep_open=1, isolation_level=None, keep_alive=True, dsn=None, **kw):
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        '''Create named connection.
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   198
        
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        name -- name for connection (default is "default")
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        keep_open -- how many connections will be kept open in pool (more connections will still be created,
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   201
                     but they will be closed by put_conn)
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        isolation_level -- "autocommit", "read_committed", "serializable" or None for driver default
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        keep_alive -- set socket to keepalive mode
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        dsn -- string with connection parameters (dsn means Data Source Name)
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        Alternative for dsn is keyword args (same names as in dsn).
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   207
        
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   208
        '''
0
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        if name in self.conn_known:
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            raise PgManagerError('Connection name "%s" already registered.' % name)
0
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   211
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        if dsn is None:
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   213
            dsn = ' '.join([x[0]+'='+str(x[1]) for x in kw.items() if x[1] is not None])
0
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        isolation_level = self._normalize_isolation_level(isolation_level)
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   216
        ci = ConnectionInfo(dsn, isolation_level, keep_alive, keep_open=keep_open)
0
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        self.conn_known[name] = ci
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        self.conn_pool[name] = []
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   221
    def close_conn(self, name='default'):
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        '''Close all connections of given name.
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        Connection credentials are still saved.
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   225
        
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        '''
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   227
        while len(self.conn_pool[name]):
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   228
            conn = self.conn_pool[name].pop()
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            conn.close()
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   230
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   231
    def destroy_conn(self, name='default'):
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        '''Destroy connection.
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   233
        
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        Counterpart of create_conn.
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   235
        
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   236
        '''
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   237
        if not name in self.conn_known:
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   238
            raise PgManagerError('Connection name "%s" not registered.' % name)
0
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   239
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   240
        self.close_conn(name)
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   241
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        del self.conn_known[name]
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   243
        del self.conn_pool[name]
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   244
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   245
    def get_conn(self, name='default'):
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   246
        '''Get connection of name 'name' from pool.'''
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   247
        self._check_fork()
0
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        self.lock.acquire()
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   249
        try:
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   250
            if not name in self.conn_known:
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   251
                raise PgManagerError("Connection name '%s' not registered." % name)
0
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   253
            conn = None
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   254
            while len(self.conn_pool[name]) and conn is None:
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   255
                conn = self.conn_pool[name].pop()
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   256
                if conn.closed:
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   257
                    conn = None
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   258
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   259
            if conn is None:
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   260
                ci = self.conn_known[name]
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   261
                conn = self._connect(ci)
0
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   262
        finally:
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   263
            self.lock.release()
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   264
        return conn
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   265
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   266
    def put_conn(self, conn, name='default'):
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   267
        '''Put connection back to pool.
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   268
        
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   269
        Name must be same as used for get_conn,
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        otherwise things become broken.
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parents:
diff changeset
   271
        
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   272
        '''
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   273
        self.lock.acquire()
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   274
        try:
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   275
            if not name in self.conn_known:
2
efee419b7a2d Fix pgmanager exceptions.
Radek Brich <radek.brich@devl.cz>
parents: 0
diff changeset
   276
                raise PgManagerError("Connection name '%s' not registered." % name)
0
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   277
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   278
            if len(self.conn_pool[name]) >= self.conn_known[name].keep_open:
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   279
                conn.close()
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   280
                return
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   281
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   282
            if conn.get_transaction_status() == psycopg2.extensions.TRANSACTION_STATUS_UNKNOWN:
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   283
                conn.close()
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   284
                return
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   285
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   286
            # connection returned to the pool must not be in transaction
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   287
            if conn.get_transaction_status() != psycopg2.extensions.TRANSACTION_STATUS_IDLE:
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   288
                conn.rollback()
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   289
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   290
            self.conn_pool[name].append(conn)
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   291
        finally:
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   292
            self.lock.release()
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   293
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   294
    @contextmanager
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   295
    def cursor(self, name='default'):
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   296
        '''Cursor context.
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   297
        
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   298
        Uses any connection of name 'name' from pool
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   299
        and returns cursor for that connection.
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   300
        
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   301
        '''
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   302
        conn = self.get_conn(name)
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   303
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   304
        try:
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   305
            curs = conn.cursor()
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   306
            yield curs
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   307
        finally:
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   308
            curs.close()
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   309
            self.put_conn(conn, name)
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   310
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   311
    def wait_for_notify(self, name='default', timeout=5):
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   312
        '''Wait for asynchronous notifies, return the last one.
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   313
        
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   314
        Returns None on timeout.
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   315
        
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   316
        '''
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   317
        conn = self.get_conn(name)
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   318
        
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   319
        try:
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   320
            # any residual notify?
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   321
            # then return it, that should not break anything
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   322
            if conn.notifies:
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   323
                return conn.notifies.pop()
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   324
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   325
            if select.select([conn], [], [], timeout) == ([], [], []):
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   326
                # timeout
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   327
                return None
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   328
            else:
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   329
                conn.poll()
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   330
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   331
                # return just the last notify (we do not care for older ones)
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   332
                if conn.notifies:
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   333
                    return conn.notifies.pop()
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   334
                return None
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   335
        finally:
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   336
            # clean notifies
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   337
            while conn.notifies:
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   338
                conn.notifies.pop()
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   339
            self.put_conn(conn, name)
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   340
8
2911935c524d pgmanager: Add keep_alive support.
Radek Brich <radek.brich@devl.cz>
parents: 7
diff changeset
   341
    def _connect(self, ci):
2911935c524d pgmanager: Add keep_alive support.
Radek Brich <radek.brich@devl.cz>
parents: 7
diff changeset
   342
        conn = psycopg2.connect(ci.dsn, connection_factory=Connection)
19
e526ca146fa9 Add documentation for create_conn(). Fix keep_alive - do not crash if socket settings are not supported.
Radek Brich <radek.brich@devl.cz>
parents: 9
diff changeset
   343
        if ci.keep_alive:
e526ca146fa9 Add documentation for create_conn(). Fix keep_alive - do not crash if socket settings are not supported.
Radek Brich <radek.brich@devl.cz>
parents: 9
diff changeset
   344
            conn.keep_alive()
8
2911935c524d pgmanager: Add keep_alive support.
Radek Brich <radek.brich@devl.cz>
parents: 7
diff changeset
   345
        if not ci.isolation_level is None:
2911935c524d pgmanager: Add keep_alive support.
Radek Brich <radek.brich@devl.cz>
parents: 7
diff changeset
   346
            conn.set_isolation_level(ci.isolation_level)
2911935c524d pgmanager: Add keep_alive support.
Radek Brich <radek.brich@devl.cz>
parents: 7
diff changeset
   347
        if ci.init_statement:
2911935c524d pgmanager: Add keep_alive support.
Radek Brich <radek.brich@devl.cz>
parents: 7
diff changeset
   348
            curs = conn.cursor()
2911935c524d pgmanager: Add keep_alive support.
Radek Brich <radek.brich@devl.cz>
parents: 7
diff changeset
   349
            curs.execute(ci.init_statement)
2911935c524d pgmanager: Add keep_alive support.
Radek Brich <radek.brich@devl.cz>
parents: 7
diff changeset
   350
            curs.close()
2911935c524d pgmanager: Add keep_alive support.
Radek Brich <radek.brich@devl.cz>
parents: 7
diff changeset
   351
        return conn
2911935c524d pgmanager: Add keep_alive support.
Radek Brich <radek.brich@devl.cz>
parents: 7
diff changeset
   352
0
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   353
    def _normalize_isolation_level(self, level):
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   354
        if type(level) == str:
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   355
            if level.lower() == 'autocommit':
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   356
                return psycopg2.extensions.ISOLATION_LEVEL_AUTOCOMMIT
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   357
            if level.lower() == 'read_committed':
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   358
                return psycopg2.extensions.ISOLATION_LEVEL_READ_COMMITTED
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   359
            if level.lower() == 'serializable':
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   360
                return psycopg2.extensions.ISOLATION_LEVEL_SERIALIZABLE
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   361
            raise PgManagerError('Unknown isolation level name: "%s"', level)
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   362
        return level
24
5664afa530e5 PgManager: Add partial support for multiprocessing.
Radek Brich <radek.brich@devl.cz>
parents: 23
diff changeset
   363
    
5664afa530e5 PgManager: Add partial support for multiprocessing.
Radek Brich <radek.brich@devl.cz>
parents: 23
diff changeset
   364
    def _check_fork(self):
5664afa530e5 PgManager: Add partial support for multiprocessing.
Radek Brich <radek.brich@devl.cz>
parents: 23
diff changeset
   365
        '''Check if process was forked (PID has changed).
5664afa530e5 PgManager: Add partial support for multiprocessing.
Radek Brich <radek.brich@devl.cz>
parents: 23
diff changeset
   366
        
5664afa530e5 PgManager: Add partial support for multiprocessing.
Radek Brich <radek.brich@devl.cz>
parents: 23
diff changeset
   367
        If it was, clean parent's connections.
5664afa530e5 PgManager: Add partial support for multiprocessing.
Radek Brich <radek.brich@devl.cz>
parents: 23
diff changeset
   368
        New connections are created for children.
5664afa530e5 PgManager: Add partial support for multiprocessing.
Radek Brich <radek.brich@devl.cz>
parents: 23
diff changeset
   369
        Known connection credentials are inherited, but not shared.
5664afa530e5 PgManager: Add partial support for multiprocessing.
Radek Brich <radek.brich@devl.cz>
parents: 23
diff changeset
   370
        
5664afa530e5 PgManager: Add partial support for multiprocessing.
Radek Brich <radek.brich@devl.cz>
parents: 23
diff changeset
   371
        '''
5664afa530e5 PgManager: Add partial support for multiprocessing.
Radek Brich <radek.brich@devl.cz>
parents: 23
diff changeset
   372
        if self.pid == multiprocessing.current_process().pid:
5664afa530e5 PgManager: Add partial support for multiprocessing.
Radek Brich <radek.brich@devl.cz>
parents: 23
diff changeset
   373
            # PID has not changed
5664afa530e5 PgManager: Add partial support for multiprocessing.
Radek Brich <radek.brich@devl.cz>
parents: 23
diff changeset
   374
            return
5664afa530e5 PgManager: Add partial support for multiprocessing.
Radek Brich <radek.brich@devl.cz>
parents: 23
diff changeset
   375
        
5664afa530e5 PgManager: Add partial support for multiprocessing.
Radek Brich <radek.brich@devl.cz>
parents: 23
diff changeset
   376
        # update saved PID
5664afa530e5 PgManager: Add partial support for multiprocessing.
Radek Brich <radek.brich@devl.cz>
parents: 23
diff changeset
   377
        self.pid = multiprocessing.current_process().pid
5664afa530e5 PgManager: Add partial support for multiprocessing.
Radek Brich <radek.brich@devl.cz>
parents: 23
diff changeset
   378
        # reinitialize lock
5664afa530e5 PgManager: Add partial support for multiprocessing.
Radek Brich <radek.brich@devl.cz>
parents: 23
diff changeset
   379
        self.lock = threading.Lock()
5664afa530e5 PgManager: Add partial support for multiprocessing.
Radek Brich <radek.brich@devl.cz>
parents: 23
diff changeset
   380
        # clean parent's connections
5664afa530e5 PgManager: Add partial support for multiprocessing.
Radek Brich <radek.brich@devl.cz>
parents: 23
diff changeset
   381
        for name in self.conn_pool:
5664afa530e5 PgManager: Add partial support for multiprocessing.
Radek Brich <radek.brich@devl.cz>
parents: 23
diff changeset
   382
            self.conn_pool[name] = []
0
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   383
20
73f0d53fef6b PgManager: Do not add NullHandler to logger. Rewrite get_instance(). ToolBase: fix prepare_conns() method.
Radek Brich <radek.brich@devl.cz>
parents: 19
diff changeset
   384
    @classmethod
73f0d53fef6b PgManager: Do not add NullHandler to logger. Rewrite get_instance(). ToolBase: fix prepare_conns() method.
Radek Brich <radek.brich@devl.cz>
parents: 19
diff changeset
   385
    def get_instance(cls):
73f0d53fef6b PgManager: Do not add NullHandler to logger. Rewrite get_instance(). ToolBase: fix prepare_conns() method.
Radek Brich <radek.brich@devl.cz>
parents: 19
diff changeset
   386
        if not hasattr(cls, '_instance'):
73f0d53fef6b PgManager: Do not add NullHandler to logger. Rewrite get_instance(). ToolBase: fix prepare_conns() method.
Radek Brich <radek.brich@devl.cz>
parents: 19
diff changeset
   387
            cls._instance = cls()
73f0d53fef6b PgManager: Do not add NullHandler to logger. Rewrite get_instance(). ToolBase: fix prepare_conns() method.
Radek Brich <radek.brich@devl.cz>
parents: 19
diff changeset
   388
        return cls._instance
0
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   389
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   390
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   391
def get_instance():
20
73f0d53fef6b PgManager: Do not add NullHandler to logger. Rewrite get_instance(). ToolBase: fix prepare_conns() method.
Radek Brich <radek.brich@devl.cz>
parents: 19
diff changeset
   392
    return PgManager.get_instance()
0
eaae9539e910 Postgres tools.
Radek Brich <radek.brich@devl.cz>
parents:
diff changeset
   393