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comparison src/org/dancres/blitz/config/Persistent.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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children cd96fcac1487
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1 package org.dancres.blitz.config;
2
3 /**
4 Configures Blitz to be maximally durable with all operations being recorded
5 on disk immediately they are commited.
6
7 @todo Add MAX_LOGS_BEFORE_SYNC disable
8 */
9 public class Persistent extends PersistentBase {
10
11 private boolean useConcurrentBatcher;
12 private int theBatchWriteWindowSize;
13
14 /**
15 @param shouldReset specifies whether to reset the ObjectOutputStream
16 used for logging. This is a performance vs memory tradeoff
17
18 @param shouldClean specifies whether old log files and snapshots should
19 be cleaned up or left for archiving.
20
21 @param aBatchWriteWindowSize specifies a batch-write window for logging.
22 Set this to zero to disable batching. Batch-writing can reduce the
23 number of forced flushes to disk whilst increasing the amount of data
24 written with each flush. This has a positive effect on throughput
25 under concurrent load. Time is specified in ms, first thread into
26 barrier waits this amount of time for other writers. Other writers
27 entering the barrier are now blocked until the first entrant commits all
28 writes to log.
29
30 @param useConcurrent should increase log throughput by allowing the
31 next batch to form whilst the current batch is being written to log.
32
33 @param aMaxLogsBeforeSync is the maximum number of log entries before
34 a checkpoint is forced.
35
36 @param aLogBufferSize especially useful when doing batching.
37 All commands are rendered to the buffer before going to disk in one
38 large block. Without the buffer, each command will trickle to disk as a
39 small update which isn't good for throughput!
40 */
41 public Persistent(boolean shouldReset, boolean shouldClean,
42 int aBatchWriteWindowSize, boolean useConcurrent,
43 int aMaxLogsBeforeSync, int aLogBufferSize) {
44
45 super(shouldReset, shouldClean, aLogBufferSize, aMaxLogsBeforeSync);
46 useConcurrentBatcher = useConcurrent;
47 theBatchWriteWindowSize = aBatchWriteWindowSize;
48 }
49
50 public boolean useConcurrentWriteBatcher() {
51 return useConcurrentBatcher;
52 }
53
54 public int getBatchWriteWindowSize() {
55 return theBatchWriteWindowSize;
56 }
57 }