twisted.enterprise.adbapi.ConnectionPool

class documentation

class ConnectionPool: (source)

Represent a pool of connections to a DB-API 2.0 compliant database.

Method	`__getstate__`	Undocumented
Method	`__init__`	Create a new `ConnectionPool`.
Method	`__setstate__`	Undocumented
Method	`close`	Close all pool connections and shutdown the pool.
Method	`connect`	Return a database connection when one becomes available.
Method	`disconnect`	Disconnect a database connection associated with this pool.
Method	`finalClose`	This should only be called by the shutdown trigger.
Method	`runInteraction`	Interact with the database and return the result.
Method	`runOperation`	Execute an SQL query and return `None`.
Method	`runQuery`	Execute an SQL query and return the result.
Method	`runWithConnection`	Execute a function with a database connection and return the result.
Method	`start`	Start the connection pool.
Constant	`CP_ARGS`	Undocumented
Class Variable	`good_sql`	Undocumented
Class Variable	`name`	Undocumented
Class Variable	`noisy`	Undocumented
Class Variable	`openfun`	Undocumented
Class Variable	`reconnect`	Undocumented
Instance Variable	`__dict__`	Undocumented
Instance Variable	`connargs`	Undocumented
Instance Variable	`connectionFactory`	factory for connections, default to `Connection`.
Instance Variable	`connections`	Undocumented
Instance Variable	`connkw`	Undocumented
Instance Variable	`dbapi`	Undocumented
Instance Variable	`dbapiName`	Undocumented
Instance Variable	`max`	Undocumented
Instance Variable	`min`	Undocumented
Instance Variable	`running`	Undocumented
Instance Variable	`shutdownID`	`None` or a handle on the shutdown event trigger which will be used to stop the connection pool workers when the reactor stops.
Instance Variable	`startID`	Undocumented
Instance Variable	`threadID`	Undocumented
Instance Variable	`threadpool`	Undocumented
Instance Variable	`transactionFactory`	factory for transactions, default to `Transaction`.
Method	`_close`	Undocumented
Method	`_runInteraction`	Undocumented
Method	`_runOperation`	Undocumented
Method	`_runQuery`	Undocumented
Method	`_runWithConnection`	Undocumented
Method	`_start`	Undocumented
Instance Variable	`_reactor`	The reactor which will be used to schedule startup and shutdown events.

def __getstate__(self): (source)

Undocumented

def __init__(self, dbapiName, *connargs, **connkw): (source)

Create a new ConnectionPool.

Any positional or keyword arguments other than those documented here are passed to the DB-API object when connecting. Use these arguments to pass database names, usernames, passwords, etc.

Parameters
dbapiName	an import string to use to obtain a DB-API compatible module (e.g. `'pyPgSQL.PgSQL'`)
*connargs	Undocumented
**connkw	Undocumented
cp_reactor:`IReactorCore` provider	use this reactor instead of the global reactor (added in Twisted 10.2).
cp_min	the minimum number of connections in pool (default 3)
cp_max	the maximum number of connections in pool (default 5)
cp_noisy	generate informational log messages during operation (default `False`)
cp_openfun	a callback invoked after every `connect()` on the underlying DB-API object. The callback is passed a new DB-API connection object. This callback can setup per-connection state such as charset, timezone, etc.
cp_reconnect	detect connections which have failed and reconnect (default `False`). Failed connections may result in `ConnectionLost` exceptions, which indicate the query may need to be re-sent.
cp_good_sql	an sql query which should always succeed and change no state (default `'select 1'`)

def __setstate__(self, state): (source)

Undocumented

def close(self): (source)

Close all pool connections and shutdown the pool.

def connect(self): (source)

Return a database connection when one becomes available.

This method blocks and should be run in a thread from the internal threadpool. Don't call this method directly from non-threaded code. Using this method outside the external threadpool may exceed the maximum number of connections in the pool.

Returns
a database connection from the pool.

def disconnect(self, conn): (source)

Disconnect a database connection associated with this pool.

Note: This function should only be used by the same thread which called ConnectionPool.connect. As with connect, this function is not used in normal non-threaded Twisted code.

def finalClose(self): (source)

This should only be called by the shutdown trigger.

def runInteraction(self, interaction, *args, **kw): (source)

Interact with the database and return the result.

The 'interaction' is a callable object which will be executed in a thread using a pooled connection. It will be passed an Transaction object as an argument (whose interface is identical to that of the database cursor for your DB-API module of choice), and its results will be returned as a Deferred. If running the method raises an exception, the transaction will be rolled back. If the method returns a value, the transaction will be committed.

NOTE that the function you pass is *not* run in the main thread: you may have to worry about thread-safety in the function you pass to this if it tries to use non-local objects.

Parameters
interaction	a callable object whose first argument is an `adbapi.Transaction`.
*args	additional positional arguments to be passed to interaction
**kw	keyword arguments to be passed to interaction
Returns
a Deferred which will fire the return value of `interaction(Transaction(...), args, *kw)`, or a `twisted.python.failure.Failure`.

def runOperation(self, *args, **kw): (source)

Execute an SQL query and return None.

A DB-API cursor which will be invoked with cursor.execute(*args, **kw). The exact nature of the arguments will depend on the specific flavor of DB-API being used, but the first argument in *args will be an SQL statement. This method will not attempt to fetch any results from the query and is thus suitable for INSERT, DELETE, and other SQL statements which do not return values. If the 'execute' method raises an exception, the transaction will be rolled back and a Failure returned.

The *args and *kw arguments will be passed to the DB-API cursor's 'execute' method.

Returns
a `Deferred` which will fire with `None` or a `twisted.python.failure.Failure`.

def runQuery(self, *args, **kw): (source)

Execute an SQL query and return the result.

A DB-API cursor which will be invoked with cursor.execute(*args, **kw). The exact nature of the arguments will depend on the specific flavor of DB-API being used, but the first argument in *args be an SQL statement. The result of a subsequent cursor.fetchall() will be fired to the Deferred which is returned. If either the 'execute' or 'fetchall' methods raise an exception, the transaction will be rolled back and a twisted.python.failure.Failure returned.

The *args and **kw arguments will be passed to the DB-API cursor's 'execute' method.

Returns
a `Deferred` which will fire the return value of a DB-API cursor's 'fetchall' method, or a `twisted.python.failure.Failure`.

def runWithConnection(self, func, *args, **kw): (source)

Execute a function with a database connection and return the result.

Parameters
func	A callable object of one argument which will be executed in a thread with a connection from the pool. It will be passed as its first argument a `Connection` instance (whose interface is mostly identical to that of a connection object for your DB-API module of choice), and its results will be returned as a `Deferred`. If the method raises an exception the transaction will be rolled back. Otherwise, the transaction will be committed. Note that this function is not run in the main thread: it must be threadsafe.
*args	positional arguments to be passed to func
**kw	keyword arguments to be passed to func
Returns
a `Deferred` which will fire the return value of `func(Transaction(...), args, *kw)`, or a `twisted.python.failure.Failure`.

def start(self): (source)

Start the connection pool.

If you are using the reactor normally, this function does *not* need to be called.

CP_ARGS = (source)

Undocumented

Value

"""min max name noisy openfun reconnect good_sql""".split()

good_sql: str = (source)

Undocumented

name = (source)

Undocumented

noisy: bool = (source)

Undocumented

openfun = (source)

Undocumented

reconnect: bool = (source)

Undocumented

__dict__ = (source)

Undocumented

connargs = (source)

Undocumented

connectionFactory: any callable. = (source)

factory for connections, default to Connection.

connections: dict = (source)

Undocumented

connkw = (source)

Undocumented

dbapi = (source)

Undocumented

dbapiName = (source)

Undocumented

max = (source)

Undocumented

min = (source)

Undocumented

running: bool = (source)

Undocumented

shutdownID = (source)

None or a handle on the shutdown event trigger which will be used to stop the connection pool workers when the reactor stops.

startID = (source)

Undocumented

threadID = (source)

Undocumented

threadpool = (source)

Undocumented

transactionFactory: any callable = (source)

factory for transactions, default to Transaction.

def _close(self, conn): (source)

Undocumented

def _runInteraction(self, interaction, *args, **kw): (source)

Undocumented

def _runOperation(self, trans, *args, **kw): (source)

Undocumented

def _runQuery(self, trans, *args, **kw): (source)

Undocumented

def _runWithConnection(self, func, *args, **kw): (source)

Undocumented

def _start(self): (source)

Undocumented

_reactor: IReactorCore provider = (source)

The reactor which will be used to schedule startup and shutdown events.