com.tailf.navu

Interface NavuCdbSessionPoolable

public interface NavuCdbSessionPoolable

This NavuCdbSessionPoolable interface should be implemented by any class whose instance are intended to change the default behavior of how CdbSession object is created and used in NAVU.

When using NAVU in with Cdb (passing Cdb object to constructor of the NavuContext ) :

 Cdb cdb = ..;
 NavuContext ctx = new NavuContext(cdb);
 

The argument cdb object to the constructor of NavuContext called the "root Cdb" by default is not used directly. Which means no sessions are created on the root Cdb.

Instead it acts as a key to a map too look up other Cdb objects that in turn starts sessions towards different datastores.

The default implementation contains a map where the key is the "root Cdb" and the value is in turn another map (inner map).

The "inner map" where its key is of the type CdbDBType contains mapping between different datastores and a container that contains "local Cdb objects and corresponding CdbSession.

   Map>Cdb<,Map>CdbDBType,SessionContainer>> map ..
 

    class SessionContainer {
       CdbSession localSession;
       Cdb        localCdb;
       ...
    }
 

When NAVU needs to retrieve a CdbSession it calls the static NavuCdbSessionPool.getCdbSession() which in turn calls the current implementation of this interface getSession method. The getSession(Cdb,CdbDBType) or getSession(Cdb,CdbDBType,EnumSet<CdbLockType>) method must return a CdbSession towards the specified the datastore specified by the second parameter.

The removeCdbSessions(Cdb) must release the associated Cdb session for the corresponding Cdb, which is the corresponding method of getSession(Cdb,CdbDBType).

Regardless it is left to the implementation which Cdb this CdbSession is originated from. The default implementation starts Cdb session from the "local Cdb". And what a "release" really means in case of removeCdbSession(Cdb).

The specify that a implementation should be used the parameter com.tailf.navu.cdb.sessionpool should be set to a binary name ( for example com.foo.NavuCdbSessionPoolImpl) and should be passed to the jvm at startup:

 java -Dcom.tailf.navu.cdb.sessionpool=com.foo.NavuCdbSessionPoolImpl ...
 

It should be noted that the bytecode of the implementation must be available in the system classpath or a exception will be thrown and the default implementation that ships with the library will be used.

Method Summary

Modifier and Type	Method and Description
CdbSession	getSession(Cdb rootCdb, CdbDBType dbType, EnumSet<CdbLockType> locks) Returns a Cdb session to dbType datastore with the locks locks associated with the given Cdb.
boolean	poolInUse() Returns true if the implementation pool is in use.
void	removeAllForCdb(Cdb rootCdb) Removes or closes all CdbSession associated with the supplied Cdb.
void	removeAllSessions() Removes all established session held by any Cdb.

Method Detail

getSession

CdbSession getSession(Cdb rootCdb,
                      CdbDBType dbType,
                      EnumSet<CdbLockType> locks)
               throws IOException,
                      ConfException

Returns a Cdb session to dbType datastore with the locks locks associated with the given Cdb.

Returns:

CdbSession for a specific Cdb and CdbDBType

Throws:

IOException - on I/O failure

ConfException - on protocol error

removeAllForCdb

void removeAllForCdb(Cdb rootCdb)
              throws IOException,
                     ConfException

Removes or closes all CdbSession associated with the supplied Cdb. A remove does not necessary means that it should end the Cdb session associated with the rootCdb it is up to the implementation of what a remove really means. For example for CdbSession started towards the operational store could be added to a pool of free Cdb oper sessions. It is imported to understand that a CdbSession against the configurational data store should be as short lived as possible.

Throws:

IOException - on I/O failure

ConfException - on protocol error

removeAllSessions

void removeAllSessions()
                throws IOException,
                       ConfException

Removes all established session held by any Cdb. A remove on started sessions does not necessarily means that all sessions should be closed, instead it is up to implementation how a remove should be handled.

Throws:

IOException - on I/O failure

ConfException - on protocol error

poolInUse

boolean poolInUse()

Returns true if the implementation pool is in use. If it return true a NavuException is thrown indicating that a implementation is already in use and contains open resources.

Returns:

true/false whether the implementation pool is in use