--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/pydbkit/mymanager_oursql.py Wed Jul 09 18:03:54 2014 +0200
@@ -0,0 +1,347 @@
+# -*- coding: utf-8 -*-
+#
+# MyManager - manage database connections (MySQL version)
+#
+# Requires: Python 2.6 / 2.7 / 3.2, oursql
+#
+# Part of pydbkit
+# http://hg.devl.cz/pydbkit
+#
+# Copyright (c) 2011, 2013 Radek Brich <radek.brich@devl.cz>
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+
+"""MySQL database connection manager
+
+MyManager wraps oursql in same manner as PgManager wraps psycopg2.
+It's fully compatible so it should work as drop-in replacement for PgManager.
+
+It adds following features over oursql:
+
+ * Save and reuse database connection parameters
+
+ * Connection pooling
+
+ * Easy query using the with statement
+
+ * Dictionary rows
+
+Example:
+
+ from pydbkit import mymanager_oursql
+
+ dbm = mymanager.get_instance()
+ dbm.create_conn(host='127.0.0.1', dbname='default')
+
+ with dbm.cursor() as curs:
+ curs.execute('SELECT now() AS now')
+ row = curs.fetchone_dict()
+ print(row.now)
+
+See PgManager docs for more information.
+
+"""
+
+from contextlib import contextmanager
+from collections import OrderedDict
+import logging
+import threading
+import multiprocessing
+
+import oursql
+
+from oursql import DatabaseError, IntegrityError, OperationalError
+
+
+log_sql = logging.getLogger("mymanager_sql")
+log_sql.addHandler(logging.NullHandler())
+
+
+class MyManagerError(Exception):
+
+ pass
+
+
+class RowDict(OrderedDict):
+ """Special dictionary used for rows returned from queries.
+
+ Items keep order in which columns where returned from database.
+
+ It supports three styles of access:
+
+ Dict style:
+ row['id']
+ for key in row:
+ ...
+
+ Object style (only works if column name does not collide with any method name):
+ row.id
+
+ Tuple style:
+ row[0]
+ id, name = row.values()
+
+ """
+
+ def __getitem__(self, key):
+ if isinstance(key, int):
+ return tuple(self.values())[key]
+ else:
+ return OrderedDict.__getitem__(self, key)
+
+ def __getattr__(self, key):
+ try:
+ return self[key]
+ except KeyError:
+ raise AttributeError(key)
+
+
+class ConnectionInfo:
+
+ def __init__(self, name, isolation_level=None,
+ init_statement=None, pool_size=1, **kw):
+ self.name = name # connection name is logged with SQL queries
+ self.isolation_level = isolation_level
+ self.init_statement = init_statement
+ self.pool_size = pool_size
+ self.parameters = kw
+ self.adjust_parameters()
+
+ def adjust_parameters(self):
+ '''Rename Postgres parameters to proper value for MySQL.'''
+ m = {'dbname' : 'db', 'password' : 'passwd'}
+ res = dict()
+ for k, v in list(self.parameters.items()):
+ if k in m:
+ k = m[k]
+ res[k] = v
+ self.parameters = res
+
+
+class Cursor(oursql.Cursor):
+
+ def execute(self, query, args=[]):
+ try:
+ return super(Cursor, self).execute(query, args)
+ finally:
+ self._log_query(query, args)
+
+ def callproc(self, procname, args=[]):
+ try:
+ return super(Cursor, self).callproc(procname, args)
+ finally:
+ self._log_query(query, args)
+
+ def row_dict(self, row, lstrip=None):
+ adjustname = lambda a: a
+ if lstrip:
+ adjustname = lambda a: a.lstrip(lstrip)
+ return RowDict(zip([adjustname(desc[0]) for desc in self.description], row))
+
+ def fetchone_dict(self, lstrip=None):
+ row = super(Cursor, self).fetchone()
+ if row is None:
+ return None
+ return self.row_dict(row, lstrip)
+
+ def fetchall_dict(self, lstrip=None):
+ rows = super(Cursor, self).fetchall()
+ return [self.row_dict(row, lstrip) for row in rows]
+
+ def _log_query(self, query, args):
+ name = self.connection.name if hasattr(self.connection, 'name') else '-'
+ log_sql.debug('[%s] %s %s' % (name, query, args))
+
+
+class MyManager:
+
+ def __init__(self):
+ self.conn_known = {} # available connections
+ self.conn_pool = {}
+ self.lock = threading.Lock()
+ self.pid = multiprocessing.current_process().pid # forking check
+
+ def __del__(self):
+ for conn in tuple(self.conn_known.keys()):
+ self.destroy_conn(conn)
+
+ def create_conn(self, name='default', isolation_level=None, **kw):
+ '''Create named connection.'''
+ if name in self.conn_known:
+ raise MyManagerError('Connection name "%s" already registered.' % name)
+
+ isolation_level = self._normalize_isolation_level(isolation_level)
+ ci = ConnectionInfo(name, isolation_level, **kw)
+
+ self.conn_known[name] = ci
+ self.conn_pool[name] = []
+
+ def close_conn(self, name='default'):
+ '''Close all connections of given name.
+
+ Connection credentials are still saved.
+
+ '''
+ while len(self.conn_pool[name]):
+ conn = self.conn_pool[name].pop()
+ conn.close()
+
+ def destroy_conn(self, name='default'):
+ '''Destroy connection.
+
+ Counterpart of create_conn.
+
+ '''
+ if not name in self.conn_known:
+ raise MyManagerError('Connection name "%s" not registered.' % name)
+
+ self.close_conn(name)
+
+ del self.conn_known[name]
+ del self.conn_pool[name]
+
+ def get_conn(self, name='default'):
+ '''Get connection of name 'name' from pool.'''
+ self._check_fork()
+ self.lock.acquire()
+ try:
+ if not name in self.conn_known:
+ raise MyManagerError("Connection name '%s' not registered." % name)
+
+ # connection from pool
+ conn = None
+ while len(self.conn_pool[name]) and conn is None:
+ conn = self.conn_pool[name].pop()
+ try:
+ conn.ping()
+ except oursql.MySQLError:
+ conn.close()
+ conn = None
+
+ if conn is None:
+ ci = self.conn_known[name]
+ conn = self._connect(ci)
+ finally:
+ self.lock.release()
+ return conn
+
+ def put_conn(self, conn, name='default'):
+ '''Put connection back to pool.
+
+ Name must be same as used for get_conn,
+ otherwise things become broken.
+
+ '''
+ self.lock.acquire()
+ try:
+ if not name in self.conn_known:
+ raise MyManagerError("Connection name '%s' not registered." % name)
+
+ if len(self.conn_pool[name]) >= self.conn_known[name].pool_size:
+ conn.close()
+ return
+
+ # connection returned to the pool must not be in transaction
+ try:
+ conn.rollback()
+ except OperationalError:
+ conn.close()
+ return
+
+ self.conn_pool[name].append(conn)
+ finally:
+ self.lock.release()
+
+ @contextmanager
+ def cursor(self, name='default'):
+ '''Cursor context.
+
+ Uses any connection of name 'name' from pool
+ and returns cursor for that connection.
+
+ '''
+ conn = self.get_conn(name)
+
+ try:
+ curs = conn.cursor()
+ yield curs
+ finally:
+ curs.close()
+ self.put_conn(conn, name)
+
+ def _connect(self, ci):
+ conn = oursql.connect(default_cursor=Cursor, **ci.parameters)
+ if not ci.isolation_level is None:
+ if ci.isolation_level == 'AUTOCOMMIT':
+ conn.autocommit(True)
+ else:
+ curs = conn.cursor()
+ curs.execute('SET SESSION TRANSACTION ISOLATION LEVEL ' + ci.isolation_level)
+ curs.close()
+ if ci.init_statement:
+ curs = conn.cursor()
+ curs.execute(ci.init_statement)
+ curs.connection.commit()
+ curs.close()
+ return conn
+
+ def _normalize_isolation_level(self, level):
+ if level is None:
+ return level
+ if type(level) == str:
+ level = level.upper().replace('_', ' ')
+ if level in (
+ 'AUTOCOMMIT',
+ 'READ UNCOMMITTED',
+ 'READ COMMITTED',
+ 'REPEATABLE READ',
+ 'SERIALIZABLE'):
+ return level
+ raise MyManagerError('Unknown isolation level name: "%s"', level)
+
+ def _check_fork(self):
+ '''Check if process was forked (PID has changed).
+
+ If it was, clean parent's connections.
+ New connections are created for children.
+ Known connection credentials are inherited, but not shared.
+
+ '''
+ if self.pid == multiprocessing.current_process().pid:
+ # PID has not changed
+ return
+
+ # update saved PID
+ self.pid = multiprocessing.current_process().pid
+ # reinitialize lock
+ self.lock = threading.Lock()
+ # clean parent's connections
+ for name in self.conn_pool:
+ self.conn_pool[name] = []
+
+ @classmethod
+ def get_instance(cls):
+ if not hasattr(cls, '_instance'):
+ cls._instance = cls()
+ return cls._instance
+
+
+def get_instance():
+ return MyManager.get_instance()
+