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1 /*******************************************************************************
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2
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3 copyright: Copyright (c) 2004 Kris Bell. All rights reserved
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4
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5 license: BSD style: $(LICENSE)
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6
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7 version: July 2004: Initial release
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8
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9 author: Kris
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10
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11 *******************************************************************************/
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12
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13 module tango.net.cluster.CacheInvalidator;
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14
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15 package import tango.net.cluster.NetworkClient;
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16
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17 private import tango.net.cluster.NetworkMessage;
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18
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19 /*******************************************************************************
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20
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21 Utility class to invalidate specific cache entries across a
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22 network. Any active CacheInvalidatee objects listening upon
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23 the channel specified for this class will "wake up" whenever
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24 the invalidate() method is invoked.
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25
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26 *******************************************************************************/
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27
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28 class CacheInvalidator : NetworkClient
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29 {
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30 private InvalidatorPayload filter;
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31
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32 /***********************************************************************
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33
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34 Construct an invalidator on the specified channel. Only
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35 those CacheInvalidatee instances configured for the same
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36 channel will be listening to this invalidator.
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37
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38 ***********************************************************************/
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39
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40 this (ICluster cluster, char[] channel)
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41 {
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42 assert (channel.length);
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43 super (cluster, channel);
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44
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45 // this is what we'll send as an invalidation notification ...
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46 this.filter = new InvalidatorPayload;
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47 }
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48
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49 /***********************************************************************
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50
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51 Invalidate all network cache instances on this channel
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52 using the specified key. When 'timeLimit' is specified,
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53 only those cache entries with a time lesser or equal to
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54 that specified will be removed. This is often useful if
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55 you wish to avoid invalidating a cache (local or remote)
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56 that has just been updated; simply pass the time value
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57 of the 'old' IMessage as the argument.
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58
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59 Note that this is asynchronous! An invalidation is just
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60 a request to remove the item within a short time period.
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61 If you need the entry removed synchronously, you should
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62 use the NetworkCache extract() method instead.
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63
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64 ***********************************************************************/
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65
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66 void invalidate (char[] key, Time timeLimit = Time.max)
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67 {
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68 assert (key.length);
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69 filter.key (key);
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70 filter.time (timeLimit);
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71
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72 // broadcast a message across the cluster
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73 channel.broadcast (filter);
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74 }
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75 }
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76
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77
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78 /*******************************************************************************
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79
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80 *******************************************************************************/
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81
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82 private class InvalidatorPayload : NetworkMessage
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83 {
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84 private char[] key_;
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85
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86 /***********************************************************************
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87
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88 ***********************************************************************/
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89
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90 char[] key ()
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91 {
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92 return key_;
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93 }
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94
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95 /***********************************************************************
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96
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97 ***********************************************************************/
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98
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99 void key (char[] key)
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100 {
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101 assert (key.length);
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102 key_ = key;
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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 Read our attributes, after telling our superclass to do
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108 likewise. The order of this is important with respect to
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109 inheritance, such that a subclass and superclass may be
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110 populated in isolation where appropriate.
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111
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112 Note that we slice our text attribute, rather than copying
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113 it. Since this class is temporal we can forego allocation
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114 of memory, and just map it directly from the input buffer.
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115
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116 ***********************************************************************/
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117
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118 override void read (IReader input)
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119 {
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120 super.read (input);
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121 input (key_);
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122 }
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123
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124 /***********************************************************************
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125
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126 ***********************************************************************/
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127
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128 override void write (IWriter output)
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129 {
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130 super.write (output);
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131 output (key_);
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132 }
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133 }
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134
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