01: /*
02: * Copyright (c) 1998-2008 Caucho Technology -- all rights reserved
03: *
04: * This file is part of Resin(R) Open Source
05: *
06: * Each copy or derived work must preserve the copyright notice and this
07: * notice unmodified.
08: *
09: * Resin Open Source is free software; you can redistribute it and/or modify
10: * it under the terms of the GNU General Public License as published by
11: * the Free Software Foundation; either version 2 of the License, or
12: * (at your option) any later version.
13: *
14: * Resin Open Source is distributed in the hope that it will be useful,
15: * but WITHOUT ANY WARRANTY; without even the implied warranty of
16: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
17: * of NON-INFRINGEMENT. See the GNU General Public License for more
18: * details.
19: *
20: * You should have received a copy of the GNU General Public License
21: * along with Resin Open Source; if not, write to the
22: *
23: * Free Software Foundation, Inc.
24: * 59 Temple Place, Suite 330
25: * Boston, MA 02111-1307 USA
26: *
27: * @author Scott Ferguson
28: */
29:
30: package com.caucho.make;
31:
32: import com.caucho.loader.Environment;
33: import com.caucho.util.Alarm;
34: import com.caucho.vfs.Dependency;
35:
36: /**
37: * A cached dependency only checks the dependency at an interval.
38: */
39: abstract public class CachedDependency implements Dependency {
40: private long _checkInterval;
41: private long _lastCheckTime;
42: private boolean _isModified;
43:
44: public CachedDependency() {
45: _checkInterval = Environment.getDependencyCheckInterval();
46: }
47:
48: /**
49: * Gets the check interval.
50: */
51: public long getCheckInterval() {
52: return _checkInterval;
53: }
54:
55: /**
56: * Gets the check interval.
57: */
58: public void setCheckInterval(long checkInterval) {
59: _checkInterval = checkInterval;
60: }
61:
62: /**
63: * Returns true if the underlying resource has changed.
64: */
65: public final boolean isModified() {
66: long now = Alarm.getCurrentTime();
67: if (now <= _lastCheckTime + _checkInterval)
68: return _isModified;
69:
70: synchronized (this ) {
71: now = Alarm.getCurrentTime();
72:
73: if (now <= _lastCheckTime + _checkInterval)
74: return _isModified;
75:
76: _lastCheckTime = now;
77: }
78:
79: _isModified = isModifiedImpl();
80:
81: return _isModified;
82: }
83:
84: /**
85: * Returns true if the underlying resource has changed.
86: */
87: abstract public boolean isModifiedImpl();
88: }
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