01: /*
02: * HA-JDBC: High-Availability JDBC
03: * Copyright (c) 2004-2008 Paul Ferraro
04: *
05: * This library is free software; you can redistribute it and/or modify it
06: * under the terms of the GNU Lesser General Public License as published by the
07: * Free Software Foundation; either version 2.1 of the License, or (at your
08: * option) any later version.
09: *
10: * This library is distributed in the hope that it will be useful, but WITHOUT
11: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12: * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
13: * for more details.
14: *
15: * You should have received a copy of the GNU Lesser General Public License
16: * along with this library; if not, write to the Free Software Foundation,
17: * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18: *
19: * Contact: ferraro@users.sourceforge.net
20: */
21: package net.sf.hajdbc.sql;
22:
23: import java.util.List;
24: import java.util.concurrent.locks.Lock;
25:
26: /**
27: * An invocation strategy decorator that acquires a list of locks before invocation, and releases them afterward.
28: * @author Paul Ferraro
29: * @param <D> Type of the root object (e.g. driver, datasource)
30: * @param <T> Target object type of the invocation
31: * @param <R> Return type of this invocation
32: */
33: public class LockingInvocationStrategy<D, T, R> implements
34: InvocationStrategy<D, T, R> {
35: private InvocationStrategy<D, T, R> strategy;
36: private List<Lock> lockList;
37:
38: /**
39: * @param strategy
40: * @param lockList
41: */
42: public LockingInvocationStrategy(
43: InvocationStrategy<D, T, R> strategy, List<Lock> lockList) {
44: this .strategy = strategy;
45: this .lockList = lockList;
46: }
47:
48: /**
49: * @see net.sf.hajdbc.sql.InvocationStrategy#invoke(net.sf.hajdbc.sql.SQLProxy, net.sf.hajdbc.sql.Invoker)
50: */
51: @Override
52: public R invoke(SQLProxy<D, T> proxy, Invoker<D, T, R> invoker)
53: throws Exception {
54: for (Lock lock : this .lockList) {
55: lock.lock();
56: }
57:
58: try {
59: return this .strategy.invoke(proxy, invoker);
60: } finally {
61: for (Lock lock : this.lockList) {
62: lock.unlock();
63: }
64: }
65: }
66: }
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