1 | /* WRS 2.0 |
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2 | * Copyright (C) 2009 Anton Patrushev |
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3 | * |
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4 | * This program is free software; you can redistribute it and/or modify |
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5 | * it under the terms of the GNU General Public License as published by |
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6 | * the Free Software Foundation; either version 3 of the License, or |
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7 | * (at your option) any later version. |
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8 | * |
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9 | * This program is distributed in the hope that it will be useful, |
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10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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12 | * GNU General Public License for more details. |
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13 | * |
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14 | * You should have received a copy of the GNU General Public License |
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15 | * along with this program. If not, see <http://www.gnu.org/licenses/>. |
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16 | */ |
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17 | |
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18 | package util; |
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19 | |
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20 | import java.util.Enumeration; |
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21 | import java.util.Hashtable; |
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22 | |
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23 | public abstract class ObjectPool<T> |
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24 | { |
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25 | protected String url; |
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26 | protected String user; |
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27 | protected String password; |
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28 | |
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29 | private long expirationTime; |
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30 | private Hashtable<T, Long> locked, unlocked; |
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31 | private int capacity; |
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32 | |
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33 | public ObjectPool(String url, String user, String password) |
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34 | { |
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35 | this.url = url; |
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36 | this.user = user; |
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37 | this.password = password; |
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38 | |
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39 | expirationTime = 60000; // 1 minute |
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40 | capacity = 10; |
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41 | locked = new Hashtable<T, Long>(); |
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42 | unlocked = new Hashtable<T, Long>(); |
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43 | |
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44 | } |
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45 | |
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46 | protected abstract T create(); |
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47 | |
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48 | public abstract boolean validate(T o); |
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49 | |
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50 | public abstract void expire(T o); |
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51 | |
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52 | public synchronized T checkOut() |
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53 | { |
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54 | long now = System.currentTimeMillis(); |
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55 | T t; |
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56 | |
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57 | if (locked.size() + unlocked.size() < capacity) |
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58 | { |
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59 | if (unlocked.size() > 0) |
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60 | { |
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61 | Enumeration<T> e = unlocked.keys(); |
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62 | |
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63 | while (e.hasMoreElements()) |
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64 | { |
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65 | t = e.nextElement(); |
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66 | |
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67 | if ((now - unlocked.get(t)) > expirationTime) |
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68 | { |
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69 | // object has expired |
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70 | unlocked.remove(t); |
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71 | expire(t); |
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72 | t = null; |
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73 | } |
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74 | else |
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75 | { |
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76 | if (validate(t)) |
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77 | { |
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78 | unlocked.remove(t); |
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79 | locked.put(t, now); |
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80 | return (t); |
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81 | } |
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82 | else |
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83 | { |
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84 | // object failed validation |
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85 | unlocked.remove(t); |
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86 | expire(t); |
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87 | t = null; |
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88 | } |
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89 | } |
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90 | } |
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91 | } |
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92 | |
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93 | // no objects available, create a new one |
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94 | t = create(); |
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95 | locked.put(t, now); |
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96 | return (t); |
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97 | |
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98 | } |
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99 | else |
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100 | { |
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101 | //TODO Process error |
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102 | return null; |
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103 | } |
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104 | |
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105 | } |
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106 | |
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107 | public synchronized void checkIn(T t) |
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108 | { |
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109 | locked.remove(t); |
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110 | unlocked.put(t, System.currentTimeMillis()); |
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111 | } |
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112 | |
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113 | } |
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