io.logspace.jvm.agent.shaded.mchange.v2.coalesce.CoalescerFactory Maven / Gradle / Ivy
/*
* Distributed as part of c3p0 v.0.9.1.1
*
* Copyright (C) 2005 Machinery For Change, Inc.
*
* Author: Steve Waldman
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License version 2.1, as
* published by the Free Software Foundation.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this software; see the file LICENSE. If not, write to the
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307, USA.
*/
package io.logspace.jvm.agent.shaded.mchange.v2.coalesce;
public final class CoalescerFactory
{
/**
* Creates a "Coalescer" that coalesces Objects according to their
* equals() method. Given a set of n Objects among whom equals() would
* return true, calling coalescer.coalesce() in any order on any sequence
* of these Objects will always return a single "canonical" instance.
*
* This method creates a weak, synchronized coalesecer, safe for use
* by multiple Threads.
*/
public static Coalescer createCoalescer()
{ return createCoalescer( true, true ); }
/**
* Creates a "Coalescer" that coalesces Objects according to their
* equals() method. Given a set of n Objects among whom equals() would
* return true, calling coalescer.coalesce() in any order on any sequence
* of these Objects will always return a single "canonical" instance.
*
* @param weak if true, the Coalescer will use WeakReferences to hold
* its canonical instances, allowing them to be garbage
* collected if they are nowhere in use.
*
* @param synced if true, access to the Coalescer will be automatically
* synchronized. if set to false, then users must manually
* synchronize access.
*/
public static Coalescer createCoalescer( boolean weak, boolean synced )
{ return createCoalescer( null, weak, synced ); }
/**
* Creates a "Coalescer" that coalesces Objects according to the
* checkCoalesce() method of a "CoalesceChecker". Given a set of
* n Objects among whom calling cc.checkCoalesce() on any pair would
* return true, calling coalescer.coalesce() in any order on any sequence
* of these Objects will always return a single "canonical" instance.
* This allows one to define immutable value Objects whose equals()
* method is a mere identity test -- one can use a Coalescer in a
* factory method to ensure that no two instances with the same values
* are made available to clients.
*
* @param cc CoalesceChecker that will be used to determine whether two
* objects are equivalent and can be coalesced. [If cc is null, then two
* objects will be coalesced iff o1.equals( o2 ).]
*
* @param weak if true, the Coalescer will use WeakReferences to hold
* its canonical instances, allowing them to be garbage
* collected if they are nowhere in use.
*
* @param synced if true, access to the Coalescer will be automatically
* synchronized. if set to false, then users must manually
* synchronize access.
*/
public static Coalescer createCoalescer( CoalesceChecker cc, boolean weak, boolean synced )
{
Coalescer out;
if ( cc == null )
{
out = ( weak ?
(Coalescer) new WeakEqualsCoalescer() :
(Coalescer) new StrongEqualsCoalescer() );
}
else
{
out = ( weak ?
(Coalescer) new WeakCcCoalescer( cc ) :
(Coalescer) new StrongCcCoalescer( cc ) );
}
return ( synced ? new SyncedCoalescer( out ) : out );
}
}