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org.apache.jcs.auxiliary.disk.jdbc.ShrinkerThread	88%	98%

1		package org.apache.jcs.auxiliary.disk.jdbc;
2
3		/*
4		* Licensed to the Apache Software Foundation (ASF) under one
5		* or more contributor license agreements. See the NOTICE file
6		* distributed with this work for additional information
7		* regarding copyright ownership. The ASF licenses this file
8		* to you under the Apache License, Version 2.0 (the
9		* "License"); you may not use this file except in compliance
10		* with the License. You may obtain a copy of the License at
11		*
12		* http://www.apache.org/licenses/LICENSE-2.0
13		*
14		* Unless required by applicable law or agreed to in writing,
15		* software distributed under the License is distributed on an
16		* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17		* KIND, either express or implied. See the License for the
18		* specific language governing permissions and limitations
19		* under the License.
20		*/
21
22		import java.util.Collections;
23		import java.util.HashSet;
24		import java.util.Set;
25
26		import org.apache.commons.logging.Log;
27		import org.apache.commons.logging.LogFactory;
28
29		/**
30		* Calls delete expired on the disk caches. The shrinker is run by a clock daemon. The shrinker
31		* calls delete on each region. It pauses between calls.
32		* <p>
33		* @author Aaron Smuts
34		*/
35		public class ShrinkerThread
36		implements Runnable
37		{
38		/** The logger. */
39	56	private final static Log log = LogFactory.getLog( ShrinkerThread.class );
40
41		/** A set of JDBCDiskCache objects to call deleteExpired on. */
42	28	private Set shrinkSet = Collections.synchronizedSet( new HashSet() );
43
44		/**
45		* Default time period to use.
46		*/
47		private static final long DEFAULT_PAUSE_BETWEEN_REGION_CALLS_MILLIS = 5000;
48
49		/**
50		* How long should we wait between calls to deleteExpired when we are iterating through the list
51		* of regions. Delete can lock the table. We want to give clients a chance to get some work
52		* done.
53		*/
54	28	private long pauseBetweenRegionCallsMillis = DEFAULT_PAUSE_BETWEEN_REGION_CALLS_MILLIS;
55
56		/**
57		* Does nothing special.
58		* <p>
59		* @param diskCache
60		*/
61		protected ShrinkerThread()
62		{
63	28	super();
64	28	}
65
66		/**
67		* Adds a JDBC disk cache to the set of disk cache to shrink.
68		* <p>
69		* @param diskCache
70		*/
71		public void addDiskCacheToShrinkList( JDBCDiskCache diskCache )
72		{
73		// the set will prevent dupes.
74		// we could also just add these to a hasmap by region name
75		// but that might cause a problem if you wanted to use two different
76		// jbdc disk caches for the same region.
77	42	shrinkSet.add( diskCache );
78	42	}
79
80		/**
81		* Calls deleteExpired on each item in the set. It pauses between each call.
82		*/
83		public void run()
84		{
85	13	if ( log.isInfoEnabled() )
86		{
87	13	log.info( "Running JDBC disk cache shrinker. Number of regions [" + shrinkSet.size() + "]" );
88		}
89
90	13	Object[] caches = null;
91
92	13	synchronized ( shrinkSet )
93		{
94	13	caches = this.shrinkSet.toArray();
95	13	}
96
97	13	if ( caches != null )
98		{
99	32	for ( int i = 0; i < caches.length; i++ )
100		{
101	26	JDBCDiskCache cache = (JDBCDiskCache) caches[i];
102
103	26	long start = System.currentTimeMillis();
104	26	int deleted = cache.deleteExpired();
105	26	long end = System.currentTimeMillis();
106
107	26	if ( log.isInfoEnabled() )
108		{
109	26	log.info( "Deleted [" + deleted + "] expired for region [" + cache.getCacheName() + "] for table ["
110		+ cache.getTableName() + "] in " + ( end - start ) + " ms." );
111		}
112
113		// don't pause after the last call to delete expired.
114	26	if ( i < caches.length - 1 )
115		{
116	20	if ( log.isInfoEnabled() )
117		{
118	20	log.info( "Pausing for [" + this.getPauseBetweenRegionCallsMillis()
119		+ "] ms. before shinker the next region." );
120		}
121
122		try
123		{
124	20	Thread.sleep( this.getPauseBetweenRegionCallsMillis() );
125		}
126	0	catch ( InterruptedException e )
127		{
128	0	log.warn( "Interrupted while waiting to delete expired for the enxt region." );
129	13	}
130		}
131		}
132		}
133	6	}
134
135		/**
136		* How long should we wait between calls to deleteExpired when we are iterating through the list
137		* of regions.
138		* <p>
139		* @param pauseBetweenRegionCallsMillis The pauseBetweenRegionCallsMillis to set.
140		*/
141		public void setPauseBetweenRegionCallsMillis( long pauseBetweenRegionCallsMillis )
142		{
143	0	this.pauseBetweenRegionCallsMillis = pauseBetweenRegionCallsMillis;
144	0	}
145
146		/**
147		* How long should we wait between calls to deleteExpired when we are iterating through the list
148		* of regions.
149		* <p>
150		* @return Returns the pauseBetweenRegionCallsMillis.
151		*/
152		public long getPauseBetweenRegionCallsMillis()
153		{
154	40	return pauseBetweenRegionCallsMillis;
155		}
156		}

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