org.tentackle.db
Interface DbPool

All Known Implementing Classes:

DefaultDbPool

public interface DbPool

A pool of logical Db connections.

The DbPool manages a pool of Db instances. From an application's point of view, a DbPool resembles to what is known as a "connection pool" in traditional (mostly J2EE) server-based applications. However, because a Db does not necessarily correspond to a physical connection (this is up to a ConnectionManager), a DbPool is one abstraction level above a typical connection pool. In fact, Tentackle servers use a DbPool, but only to optimize caching. The Db instances will run on an MpxConnectionManager, which actually does the multiplexing of physical connections. So don't mix up a DbPool with a multiplexing connection manager!
Of course, you can use a DbPool with a non-multiplexing connection manager. This can make sense in pure web-applications providing their own session management (JSP, for example). For fat-client application servers, however, this is not a good idea, because the client is associated with a Db (in fact two Dbs) for as long as it is logged in and not just for the duration of a rather short-timed http-request/response roundtrip.

Author:

harald

Method Summary

Db	getDb() Gets a Db instance from the pool.
int	getMaxSize() Gets the maximum poolsize.
int	getSize() Gets the current number of Db instances.
void	putDb(Db db) Returns a Db instance to the pool.
void	shutdown() Closes all databases in the pool, cleans up and makes the pool unusable.

Method Detail

getMaxSize

int getMaxSize()

Gets the maximum poolsize.

Returns:

the max. number of concurrent Db instances, 0 = unlimited

getSize

int getSize()

Gets the current number of Db instances.

Returns:

the number of Db managed by this pool

getDb

Db getDb()
         throws DbRuntimeException

Gets a Db instance from the pool.

Returns:

an open Db ready for use, never null

Throws:

DbRuntimeException - if pool is exhausted

putDb

void putDb(Db db)
           throws DbRuntimeException

Returns a Db instance to the pool.

Notice: returning a Db to the pool more than once is allowed.

Parameters:

db - the Db instance

Throws:

DbRuntimeException - if the Db cannot be returned

shutdown

void shutdown()

Closes all databases in the pool, cleans up and makes the pool unusable.