001/* 002 * HA-JDBC: High-Availability JDBC 003 * Copyright (C) 2012 Paul Ferraro 004 * 005 * This program is free software: you can redistribute it and/or modify 006 * it under the terms of the GNU Lesser General Public License as published by 007 * the Free Software Foundation, either version 3 of the License, or 008 * (at your option) any later version. 009 * 010 * This program is distributed in the hope that it will be useful, 011 * but WITHOUT ANY WARRANTY; without even the implied warranty of 012 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 013 * GNU Lesser General Public License for more details. 014 * 015 * You should have received a copy of the GNU Lesser General Public License 016 * along with this program. If not, see <http://www.gnu.org/licenses/>. 017 */ 018package net.sf.hajdbc.invocation; 019 020import java.util.List; 021import java.util.SortedMap; 022import java.util.concurrent.locks.Lock; 023 024import net.sf.hajdbc.Database; 025import net.sf.hajdbc.sql.ProxyFactory; 026 027/** 028 * An invocation strategy decorator that acquires a list of locks before invocation, and releases them afterward. 029 * @author Paul Ferraro 030 */ 031public class LockingInvocationStrategy implements InvocationStrategy 032{ 033 private InvocationStrategy strategy; 034 private List<Lock> lockList; 035 036 /** 037 * @param strategy 038 * @param lockList 039 */ 040 public LockingInvocationStrategy(InvocationStrategy strategy, List<Lock> lockList) 041 { 042 this.strategy = strategy; 043 this.lockList = lockList; 044 } 045 046 /** 047 * {@inheritDoc} 048 */ 049 @Override 050 public <Z, D extends Database<Z>, T, R, E extends Exception> SortedMap<D, R> invoke(ProxyFactory<Z, D, T, E> proxy, Invoker<Z, D, T, R, E> invoker) throws E 051 { 052 for (Lock lock: this.lockList) 053 { 054 lock.lock(); 055 } 056 057 try 058 { 059 return this.strategy.invoke(proxy, invoker); 060 } 061 finally 062 { 063 for (Lock lock: this.lockList) 064 { 065 lock.unlock(); 066 } 067 } 068 } 069}