net.sf.hajdbc.balancer

Class AbstractBalancer<D>

java.lang.Object

net.sf.hajdbc.balancer.AbstractBalancer<D>

Type Parameters:

D - either java.sql.Driver or javax.sql.DataSource

All Implemented Interfaces:

Balancer<D>

Direct Known Subclasses:

RandomBalancer, RoundRobinBalancer, SimpleBalancer

public abstract class AbstractBalancer<D>
extends java.lang.Object
implements Balancer<D>

Thread-safe abstract balancer implementation that implements most of the Balancer interface, except Balancer.next(). Uses A copy-on-write algorithm for add(Database), remove(Database), and clear(). Calls to all() are non-blocking.

Author:

Paul Ferraro

Field Summary

Fields

Modifier and Type	Field and Description
protected java.util.SortedSet<Database<D>>	databaseSet
protected java.util.concurrent.locks.Lock	lock

Constructor Summary

Constructors

Constructor and Description
AbstractBalancer()

Method Summary

Modifier and Type	Method and Description
boolean	add(Database<D> database) Adds the specified database to this balancer.
protected abstract void	added(Database<D> database) Called when a database was added to the set.
void	afterInvocation(Database<D> database) Called after an operation is performed on the specified database retrieved via Balancer.next().
java.util.Set<Database<D>>	all() Returns an unmodifiable collection of databases known to this balancer
void	beforeInvocation(Database<D> database) Called before an operation is performed on the specified database retrieved via Balancer.next().
void	clear() Removes all databases from this balancer.
protected abstract void	cleared() Called when the set was cleared.
boolean	remove(Database<D> database) Removes the specified database from this balancer.
protected abstract void	removed(Database<D> database) Called when a database was removed from the set.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface net.sf.hajdbc.Balancer

next

Field Detail

lock

protected java.util.concurrent.locks.Lock lock

databaseSet

protected volatile java.util.SortedSet<Database<D>> databaseSet

Constructor Detail

AbstractBalancer

public AbstractBalancer()

Method Detail

beforeInvocation

public void beforeInvocation(Database<D> database)

Description copied from interface: Balancer

Called before an operation is performed on the specified database retrieved via Balancer.next().

Specified by:

beforeInvocation in interface Balancer<D>

Parameters:

database - a database descriptor

See Also:

Balancer.beforeInvocation(net.sf.hajdbc.Database)

afterInvocation

public void afterInvocation(Database<D> database)

Description copied from interface: Balancer

Called after an operation is performed on the specified database retrieved via Balancer.next().

Specified by:

afterInvocation in interface Balancer<D>

Parameters:

database - a database descriptor

See Also:

Balancer.afterInvocation(net.sf.hajdbc.Database)

remove

public boolean remove(Database<D> database)

Description copied from interface: Balancer

Removes the specified database from this balancer.

Specified by:

remove in interface Balancer<D>

Parameters:

database - a database descriptor

Returns:

true, if the database was removed successfully, false if it did not exist.

See Also:

Balancer.remove(net.sf.hajdbc.Database)

removed

protected abstract void removed(Database<D> database)

Called when a database was removed from the set.

Parameters:

database - a database descriptor

add

public boolean add(Database<D> database)

Description copied from interface: Balancer

Adds the specified database to this balancer.

Specified by:

add in interface Balancer<D>

Parameters:

database - a database descriptor

Returns:

true, if the database was added successfully, false if already existed.

See Also:

Balancer.add(net.sf.hajdbc.Database)

added

protected abstract void added(Database<D> database)

Called when a database was added to the set.

Parameters:

database - a database descriptor

all

public java.util.Set<Database<D>> all()

Description copied from interface: Balancer

Returns an unmodifiable collection of databases known to this balancer

Specified by:

all in interface Balancer<D>

Returns:

a collection of database descriptors

See Also:

Balancer.all()

clear

public void clear()

Description copied from interface: Balancer

Removes all databases from this balancer.

Specified by:

clear in interface Balancer<D>

See Also:

Balancer.clear()

cleared

protected abstract void cleared()

Called when the set was cleared.