diff --git a/extras/config.example b/extras/config.example
index e77c0b21bfe700649866f0d0cc460bc2a0dbc27c..7b365494be22bb0d326b8c90a999c7235e5cb643 100644
--- a/extras/config.example
+++ b/extras/config.example
@@ -42,7 +42,10 @@ LocalMySQLuser = "mutalyzer"
# Host name for the local databases.
LocalMySQLhost = "localhost"
-# Automatically reconnect to MySQL server (see Trac issue #91).
+# Automatically reconnect to MySQL server using the MySQLdb reconnect option.
+# Note that this may not always be available and if not will result in an
+# error if used. Mutalyzer also implements its own reconnecting mechanism now
+# which is always on. See Trac issue #91.
autoReconnect = yes
diff --git a/extras/migrations/006-config-add-autoreconnect.migration b/extras/migrations/006-config-add-autoreconnect.migration
index 7b4512b757dd1c387f1fd6cbbfcef2ff974fa469..6c9a66f75a0a885777afe0e43587fe7587f54e68 100755
--- a/extras/migrations/006-config-add-autoreconnect.migration
+++ b/extras/migrations/006-config-add-autoreconnect.migration
@@ -19,7 +19,10 @@ if [ -e /etc/mutalyzer/config ] && ! $(grep -q 'autoReconnect' /etc/mutalyzer/co
# Insert after LocalMySQLhost line
if $(grep -q '^LocalMySQLhost' /etc/mutalyzer/config && sed -i '/^LocalMySQLhost/ a\
\
-# Automatically reconnect to MySQL server (see Trac issue #91).\
+# Automatically reconnect to MySQL server using the MySQLdb reconnect option.\
+# Note that this may not always be available and if not will result in an\
+# error if used. Mutalyzer also implements its own reconnecting mechanism now\
+# which is always on. See Trac issue #91.\
autoReconnect = yes' /etc/mutalyzer/config); then
echo -e "${COLOR_INFO}Added autoReconnect = yes to /etc/mutalyzer/config${COLOR_END}"
echo 'Performed migration.'
diff --git a/mutalyzer/Db.py b/mutalyzer/Db.py
index 2e23fbcab718fe83c5c8d3c4ee4f35f1f9f3a808..a704e8bd72cb9ac6fc9ed5a3351c0a0a918ddd6e 100644
--- a/mutalyzer/Db.py
+++ b/mutalyzer/Db.py
@@ -35,57 +35,59 @@ from mutalyzer import config
# rewritten when this bug is fixed.
#
-class Db() :
+class Db():
"""
- Log in to a database and keep it open for queries.
+ Query the database server (and lazily keep a connection open to it).
- Private variables:
- - __db ; Interface to the database.
-
- Special methods:
- - __init__(dbName, mySqlUser, mySqlHost) ; Do the login.
-
- Public methods:
- - query(statement) ; General query function.
+ This class is subclassed below to create specific interfaces to the
+ database.
"""
- def __init__(self, dbName, mySqlUser, mySqlHost) :
+ def __init__(self, database, user, host):
"""
- Log in to the database.
+ Create an interface to the database.
- Private variables (altered):
- - __db ; The interface to the database.
+ @arg database: Name of the database to use.
+ @type database: str
+ @arg user: User name for the database.
+ @type user: str
+ @arg host: Host name for the database.
+ @type host: str
+ """
+ self._database = database
+ self._user = user
+ self._host = host
- @arg dbName: The name of the database to use
- @type dbName: string
- @arg mySqlUser: User name for the database
- @type mySqlUser: string
- @arg mySqlHost: Host name for the database
- @type mySqlHost: string
+ # The connection to the database server is created lazily in the query
+ # method.
+ self._connection = None
+ #__init__
- Note: Depending on a configuration setting, we automatically reconnect
- to the MySQL server. This is expecially useful for long-running
- processes such as the batch deamon, which would otherwise loose
- their connection on an event such as restarting the MySQL server.
+ def _connect(self):
+ """
+ Connect to the database server.
+
+ Note: We would like to automatically reconnect to the database server.
+ This is especially useful for long-running processes such as the
+ batch deamon, which would otherwise loose their connection on an
+ event such as restarting the database server.
+ The MySQL client libraries provide a reconnect option, but this
+ is unfortunately not implemented in (most versions of) the Python
+ MySQLdb module.
+ Therefore we manually implement automatic reconnects in the query
+ method, but also optionally use the reconnect option from MySQLdb
+ if specified in the Mutalyzer configuration.
Also see Trac ticket #91.
- Be alarmed though, that this messes up transactions. Fortunately,
- Mutalyzer doesn't use transactions at the moment.
- Additionally, this feature has been removed from the MySQLdb
- library starting from Debian Wheezy. Again, see #91.
"""
- kwargs = dict(user=mySqlUser, db=dbName, host=mySqlHost)
+ kwargs = dict(user=self._user, db=self._database, host=self._host)
if config.get('autoReconnect'):
kwargs.update(reconnect=True)
+ self._connection = MySQLdb.connect(**kwargs)
+ #_connect
- self.__db = MySQLdb.connect(**kwargs)
- #__init__
-
- def query(self, statement) :
+ def query(self, statement):
"""
Query the database.
- Private variables:
- - __db ; Interface to the database.
-
@arg statement: The statement that is to be queried
@type statement: tuple (string, (args))
@@ -112,9 +114,17 @@ class Db() :
escaped_args.append(None)
#if
- # And do the query.
- cursor = self.__db.cursor()
- cursor.execute(statement[0], tuple(escaped_args))
+ # Do the query, but first connect to the database server if needed.
+ # This makes sure lost connections are re-created automatically (e.g.
+ # in case the server was restarted for maintenance).
+ try:
+ cursor = self._connection.cursor()
+ cursor.execute(statement[0], tuple(escaped_args))
+ except (AttributeError, MySQLdb.OperationalError):
+ self._connect()
+ cursor = self._connection.cursor()
+ cursor.execute(statement[0], tuple(escaped_args))
+
result = cursor.fetchall()
cursor.close()