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annotate src/org/dancres/blitz/config/Fifo.java @ 32:243c74d599bf

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author Dan Creswell <dan.creswell@gmail.com>
date Sat, 12 Jun 2010 10:41:47 +0100
parents 3dc0c5604566
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3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
Dan Creswell <dan.creswell@gmail.com>
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1 package org.dancres.blitz.config;
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2
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3 /**
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4 <p>Fifo constraint causes searching of Entry's to be done in approximately
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5 oldest first order.</p>
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6
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7 <p>FIFO ordering is, essentially, cache defeating in that it
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8 demands loading the <em>least</em> recently used Entry's rather than
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
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9 favouring <em>most recently</em> used Entry's. Therefore, enabling
3dc0c5604566 Initial checkin of blitz 2.0 fcs - no installer yet.
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10 FIFO will reduce overall performance of Blitz which may be countered
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11 by assumptions you can make in your JavaSpaces code</p>
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13 <p>Note that FIFO is <em>not</em> a requirement of the JavaSpaces spec and
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14 you cannot assume all JavaSpaces implementations provide FIFO support.
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15 Thus, by using the Blitz FIFO facility, you are potentially locking
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16 yourself in.</p>
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18 <p>Note that the number of pending dirty writes can significantly affect
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19 FIFO performance. Normally, one configures Blitz with a large pending
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20 writes buffer to reduce IO and increase performance. When FIFO is enabled,
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21 large write buffers introduce significant amounts of additional processing
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22 thus you are advised to reduce the size of <code>desiredPendingWrites</code>
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23 to of the order of <code>100</code>.</p>
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24 */
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25 public class Fifo implements EntryConstraint {
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26 private static final String TYPE = "FIFO";
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28 public Fifo() {
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29 }
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31 public int hashCode() {
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32 return TYPE.hashCode();
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33 }
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34
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35 public boolean equals(Object anObject) {
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36 return (anObject instanceof Fifo);
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37 }
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38 }