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comparison src/org/dancres/blitz/config/Fifo.java @ 0:3dc0c5604566

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Initial checkin of blitz 2.0 fcs - no installer yet.
author Dan Creswell <dan.creswell@gmail.com>
date Sat, 21 Mar 2009 11:00:06 +0000
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1 package org.dancres.blitz.config;
2
3 /**
4 <p>Fifo constraint causes searching of Entry's to be done in approximately
5 oldest first order.</p>
6
7 <p>FIFO ordering is, essentially, cache defeating in that it
8 demands loading the <em>least</em> recently used Entry's rather than
9 favouring <em>most recently</em> used Entry's. Therefore, enabling
10 FIFO will reduce overall performance of Blitz which may be countered
11 by assumptions you can make in your JavaSpaces code</p>
12
13 <p>Note that FIFO is <em>not</em> a requirement of the JavaSpaces spec and
14 you cannot assume all JavaSpaces implementations provide FIFO support.
15 Thus, by using the Blitz FIFO facility, you are potentially locking
16 yourself in.</p>
17
18 <p>Note that the number of pending dirty writes can significantly affect
19 FIFO performance. Normally, one configures Blitz with a large pending
20 writes buffer to reduce IO and increase performance. When FIFO is enabled,
21 large write buffers introduce significant amounts of additional processing
22 thus you are advised to reduce the size of <code>desiredPendingWrites</code>
23 to of the order of <code>100</code>.</p>
24 */
25 public class Fifo implements EntryConstraint {
26 private static final String TYPE = "FIFO";
27
28 public Fifo() {
29 }
30
31 public int hashCode() {
32 return TYPE.hashCode();
33 }
34
35 public boolean equals(Object anObject) {
36 return (anObject instanceof Fifo);
37 }
38 }