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HUE-730 [core] Database greenlet support for MySQL

Database greenlet support for MySQL using eventlet.db_pool.TpooledConnectionPool.
TpooledConnectionPool creates a eventlet proxy based Connection Pool.
These proxies are used to execute something using native threads, which will
block the currently executing greenlet by calling 'wait'. 'wait' forces
the current thread of execution to give up control to the next greenlet.
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1 parent 4f5ca03 commit aaafb8c21a234c0502ce9324ffed002bcd8256a7 @abec abec committed Dec 18, 2012
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+This version of Moxy is maintained separately from the original branch.
+The original author is R. Tyler Croy.
+See for more information.
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+### What it is
+"Moxy" is a Django database backend for MySQL. Built on top of MySQLdb [0]
+and Eventlet [1], it uses eventlet.db_pool to provide a greenthread-safe
+means of accessing MySQL via MySQLdb's blocking calls.
+### Why Moxy?
+Another member of the `#eventlet` channel on Freenode was soliciting for names
+of a reverse proxying HTTP server he wrote built off of Eventlet. I suggested
+the name "Moxy" which was well received until everybody started listing examples
+of other projects named "Moxy".
+Since then it's become a kind of lame inside joke to suggest "Moxy" as the name for
+any new project.
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+#!/usr/bin/env python
+__version__ = '1.0.0'
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+#!/usr/bin/env python
+ MySQL database backend for Django using MySQLdb and Eventlet
+import eventlet.db_pool
+from django.db.backends import BaseDatabaseWrapper, BaseDatabaseFeatures, BaseDatabaseOperations, util
+ import MySQLdb
+except ImportError, e:
+ from django.core.exceptions import ImproperlyConfigured
+ raise ImproperlyConfigured("Error loading MySQLdb module: %s" % e)
+import re
+from MySQLdb.converters import conversions
+from MySQLdb.constants import FIELD_TYPE, FLAG, CLIENT
+from django.db.backends import *
+from django.db.backends.mysql import base as mysqldb_base
+from django.db.backends.mysql.client import DatabaseClient
+from django.db.backends.mysql.creation import DatabaseCreation
+from django.db.backends.mysql.introspection import DatabaseIntrospection
+from django.db.backends.mysql.validation import DatabaseValidation
+from django.db.backends.signals import connection_created
+from django.utils.safestring import SafeString, SafeUnicode
+# Raise exceptions for database warnings if DEBUG is on
+from django.conf import settings
+DatabaseError = MySQLdb.DatabaseError
+IntegrityError = MySQLdb.IntegrityError
+# MySQLdb-1.2.1 returns TIME columns as timedelta -- they are more like
+# timedelta in terms of actual behavior as they are signed and include days --
+# and Django expects time, so we still need to override that. We also need to
+# add special handling for SafeUnicode and SafeString as MySQLdb's type
+# checking is too tight to catch those (see Django ticket #6052).
+django_conversions = conversions.copy()
+ FIELD_TYPE.TIME: util.typecast_time,
+ FIELD_TYPE.DECIMAL: util.typecast_decimal,
+ FIELD_TYPE.NEWDECIMAL: util.typecast_decimal,
+# This should match the numerical portion of the version numbers (we can treat
+# versions like 5.0.24 and 5.0.24a as the same). Based on the list of version
+# at and
+# .
+server_version_re = re.compile(r'(\d{1,2})\.(\d{1,2})\.(\d{1,2})')
+# MySQLdb-1.2.1 and newer automatically makes use of SHOW WARNINGS on
+# MySQL-4.1 and newer, so the MysqlDebugWrapper is unnecessary. Since the
+# point is to raise Warnings as exceptions, this can be done with the Python
+# warning module, and this is setup when the connection is created, and the
+# standard util.CursorDebugWrapper can be used. Also, using sql_mode
+# TRADITIONAL will automatically cause most warnings to be treated as errors.
+class DatabaseFeatures(mysqldb_base.DatabaseFeatures):
+ pass
+class DatabaseWrapper(BaseDatabaseWrapper):
+ operators = {
+ 'exact': '= %s',
+ 'iexact': 'LIKE %s',
+ 'contains': 'LIKE BINARY %s',
+ 'icontains': 'LIKE %s',
+ 'regex': 'REGEXP BINARY %s',
+ 'iregex': 'REGEXP %s',
+ 'gt': '> %s',
+ 'gte': '>= %s',
+ 'lt': '< %s',
+ 'lte': '<= %s',
+ 'startswith': 'LIKE BINARY %s',
+ 'endswith': 'LIKE BINARY %s',
+ 'istartswith': 'LIKE %s',
+ 'iendswith': 'LIKE %s',
+ }
+ def __init__(self, *args, **kwargs):
+ super(DatabaseWrapper, self).__init__(*args, **kwargs)
+ self.server_version = None
+ self.features = DatabaseFeatures()
+ self.ops = mysqldb_base.DatabaseOperations()
+ self.client = DatabaseClient(self)
+ self.creation = DatabaseCreation(self)
+ self.introspection = DatabaseIntrospection(self)
+ self.validation = DatabaseValidation(self)
+ self.pool = None
+ def _valid_connection(self):
+ if self.connection is not None:
+ try:
+ return True
+ except DatabaseError:
+ self.put(self.connection)
+ self.connection = None
+ return False
+ def _cursor(self):
+ if not self.pool:
+ kwargs = {
+ 'conv': django_conversions,
+ 'charset': 'utf8',
+ 'use_unicode': True,
+ }
+ settings_dict = self.settings_dict
+ if settings_dict['USER']:
+ kwargs['user'] = settings_dict['USER']
+ if settings_dict['NAME']:
+ kwargs['db'] = settings_dict['NAME']
+ if settings_dict['PASSWORD']:
+ kwargs['passwd'] = settings_dict['PASSWORD']
+ if settings_dict['HOST'].startswith('/'):
+ kwargs['unix_socket'] = settings_dict['HOST']
+ elif settings_dict['HOST']:
+ kwargs['host'] = settings_dict['HOST']
+ if settings_dict['PORT']:
+ kwargs['port'] = int(settings_dict['PORT'])
+ kwargs['client_flag'] = CLIENT.FOUND_ROWS
+ kwargs.update(settings_dict['OPTIONS'])
+ self.pool = eventlet.db_pool.TpooledConnectionPool(MySQLdb, min_size=1, max_size=16, **kwargs)
+ if not self._valid_connection():
+ self.connection = self.pool.get()
+ connection_created.send(sender=self.__class__)
+ cursor = mysqldb_base.CursorWrapper(self.connection.cursor())
+ return cursor
+ def _rollback(self):
+ try:
+ BaseDatabaseWrapper._rollback(self)
+ except Database.NotSupportedError:
+ pass
+ def get_server_version(self):
+ if not self.server_version:
+ if not self._valid_connection():
+ self.cursor()
+ m = server_version_re.match(self.connection._base.get_server_info())
+ if not m:
+ raise Exception('Unable to determine MySQL version from version string %r' % self.connection.get_server_info())
+ self.server_version = tuple([int(x) for x in m.groups()])
+ return self.server_version
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