asmuts 02/05/13 11:25:43
Modified: src/java/org/apache/jcs/engine/memory/shrinking
ShrinkerThread.java
Log:
Cleaned and commented
Revision Changes Path
1.6 +113 -140
jakarta-turbine-jcs/src/java/org/apache/jcs/engine/memory/shrinking/ShrinkerThread.java
Index: ShrinkerThread.java
===================================================================
RCS file:
/home/cvs/jakarta-turbine-jcs/src/java/org/apache/jcs/engine/memory/shrinking/ShrinkerThread.java,v
retrieving revision 1.5
retrieving revision 1.6
diff -u -r1.5 -r1.6
--- ShrinkerThread.java 13 May 2002 16:25:42 -0000 1.5
+++ ShrinkerThread.java 13 May 2002 18:25:42 -0000 1.6
@@ -70,7 +70,9 @@
import org.apache.jcs.engine.behavior.ICacheElement;
/**
- * A background memory shrinker. Just started. <u>DON'T USE</u>
+ * A background memory shrinker. Memory problems and concurrent modification
+ * exception caused by acting directly on an iterator of the underlying memory
+ * cache should have been solved.
*
*@author <a href="mailto:[EMAIL PROTECTED]";>Aaron Smuts</a>
*@created February 18, 2002
@@ -97,7 +99,7 @@
}
/**
- * Description of the Method
+ * Graceful shutdown after this round of processing.
*/
public void kill()
{
@@ -128,8 +130,19 @@
return;
}
+
/**
- * Constructor for the shrink object
+ * This method is called when the thread wakes up. A. The method obtains an
+ * array of keys for the cache region. B. It iterates through the keys and
+ * tries to get the item from the cache without affecting the last access
+ * or position of the item. C. Then the item is checked for expiration.
+ * This expiration check has 3 parts: 1. Has the
+ * cacheattributes.MaxMemoryIdleTimeSeconds defined for the region been
+ * exceeded? If so, the item should be move to disk. 2. Has the item
+ * exceeded MaxLifeSeconds defined in the element atributes? If so, remove
+ * it. 3. Has the item exceeded IdleTime defined in the element atributes?
+ * If so, remove it. If there are event listeners registered for the cache
+ * element, they will be called.
*/
protected void shrink()
{
@@ -139,160 +152,120 @@
log.debug( "Shrinking" );
}
- // not thread safe. Could cause problems. Only call remove directly
- // to the map.
try
{
-
-/////////////////////////////////////
-
-
- // creation of the iterator without any change to
- // the underlying collection does not result in
- // increased memory uage
-// java.util.Iterator itr = cache.getIterator();
-//
-// while ( itr.hasNext() )
-// {
-// Map.Entry e = ( Map.Entry ) itr.next();
-// MemoryElementDescriptor me = ( MemoryElementDescriptor )
e.getValue();
-// ICacheElement ce = me.ce;
-
-///////////////////////////////////////
-
-
Object[] keys = cache.getKeyArray();
int size = keys.length;
- for ( int i=0; i < size; i++ ) {
+ for ( int i = 0; i < size; i++ )
+ {
- Serializable key = (Serializable)keys[i];
- ICacheElement ce = cache.getQuiet(key);
+ Serializable key = ( Serializable ) keys[i];
+ ICacheElement ce = cache.getQuiet( key );
+ if ( ce != null )
+ {
-///////////////////////////////////////
+ long now = System.currentTimeMillis();
+ if ( log.isDebugEnabled() )
+ {
+ log.debug( "now = " + now );
+ log.debug( "!ce.getElementAttributes().getIsEternal() = " +
!ce.getElementAttributes().getIsEternal() );
+ log.debug( "ce.getElementAttributes().getMaxLifeSeconds() =
" + ce.getElementAttributes().getMaxLifeSeconds() );
+ log.debug( "now - ce.getElementAttributes().getCreateTime()
= " + String.valueOf( now - ce.getElementAttributes().getCreateTime() ) );
+ log.debug( "ce.getElementAttributes().getMaxLifeSeconds() *
1000 = " + ce.getElementAttributes().getMaxLifeSeconds() * 1000 );
+ }
+
+ // Memory idle, to disk shrinkage
+ if ( cache.getCacheAttributes().getMaxMemoryIdleTimeSeconds()
!= -1 )
+ {
+ long deadAt = ce.getElementAttributes().getLastAccessTime()
+ ( cache.getCacheAttributes().getMaxMemoryIdleTimeSeconds() * 1000 );
+ if ( ( deadAt - now ) < 0 )
+ {
+ if ( log.isInfoEnabled() )
+ {
+ log.info( "Exceeded memory idle time, Pushing item
to disk -- " + ce.getKey() + " over by = " + String.valueOf( deadAt - now ) + " ms." );
+ }
+
+ cache.remove( ce.getKey() );
+
+ cache.waterfal( ce );
+ }
+ }
+
+ ////////////////////////////////////////////////
+ if ( !ce.getElementAttributes().getIsEternal() )
+ {
+ // Exceeded maxLifeSeconds
+ if ( ( ce.getElementAttributes().getMaxLifeSeconds() != -1
) && ( now - ce.getElementAttributes().getCreateTime() ) > (
ce.getElementAttributes().getMaxLifeSeconds() * 1000 ) )
+ {
+ if ( log.isInfoEnabled() )
+ {
+ log.info( "Exceeded maxLifeSeconds -- " +
ce.getKey() );
+ }
+
+ // handle event, might move to a new method
+ ArrayList eventHandlers =
ce.getElementAttributes().getElementEventHandlers();
+ if ( eventHandlers != null )
+ {
+ if ( log.isDebugEnabled() )
+ {
+ log.debug( "Handlers are registered. Event --
ELEMENT_EVENT_EXCEEDED_MAXLIFE_BACKGROUND" );
+ }
+ IElementEvent event = new ElementEvent( ce,
IElementEventConstants.ELEMENT_EVENT_EXCEEDED_MAXLIFE_BACKGROUND );
+ Iterator hIt = eventHandlers.iterator();
+ while ( hIt.hasNext() )
+ {
+ IElementEventHandler hand = (
IElementEventHandler ) hIt.next();
+ hand.handleElementEvent( event );
+ }
+ }
+
+ cache.remove( ce.getKey() );
+ }
+ else
+ // Exceeded maxIdleTime, removal
+ if ( ( ce.getElementAttributes().getIdleTime() != -1 )
&& ( now - ce.getElementAttributes().getLastAccessTime() ) > (
ce.getElementAttributes().getIdleTime() * 1000 ) )
+ {
+ if ( log.isInfoEnabled() )
+ {
+ log.info( "Exceeded maxIdleTime [
ce.getElementAttributes().getIdleTime() = " + ce.getElementAttributes().getIdleTime()
+ " ]-- " + ce.getKey() );
+ }
+
+ // handle event, might move to a new method
+ ArrayList eventHandlers =
ce.getElementAttributes().getElementEventHandlers();
+ if ( eventHandlers != null )
+ {
+ if ( log.isDebugEnabled() )
+ {
+ log.debug( "Handlers are registered. Event --
ELEMENT_EVENT_EXCEEDED_IDLETIME_BACKGROUND" );
+ }
+ IElementEvent event = new ElementEvent( ce,
IElementEventConstants.ELEMENT_EVENT_EXCEEDED_IDLETIME_BACKGROUND );
+ Iterator hIt = eventHandlers.iterator();
+ while ( hIt.hasNext() )
+ {
+ IElementEventHandler hand = (
IElementEventHandler ) hIt.next();
+ hand.handleElementEvent( event );
+ }
+ }
- if ( ce != null )
- {
+ cache.remove( ce.getKey() );
+ }
- long now = System.currentTimeMillis();
+ }// end if not eternal
- if ( log.isDebugEnabled() )
- {
- log.debug( "now = " + now );
- log.debug( "!ce.getElementAttributes().getIsEternal() = " +
!ce.getElementAttributes().getIsEternal() );
- log.debug( "ce.getElementAttributes().getMaxLifeSeconds() = "
+ ce.getElementAttributes().getMaxLifeSeconds() );
- log.debug( "now - ce.getElementAttributes().getCreateTime() =
" + String.valueOf( now - ce.getElementAttributes().getCreateTime() ) );
- log.debug( "ce.getElementAttributes().getMaxLifeSeconds() *
1000 = " + ce.getElementAttributes().getMaxLifeSeconds() * 1000 );
- }
-
- // Memory idle, to disk shrinkage
- if ( cache.getCacheAttributes().getMaxMemoryIdleTimeSeconds() !=
-1 )
- {
- long deadAt = ce.getElementAttributes().getLastAccessTime() +
( cache.getCacheAttributes().getMaxMemoryIdleTimeSeconds() * 1000 );
- if ( ( deadAt - now ) < 0 )
- {
- if ( log.isInfoEnabled() )
- {
- log.info( "Exceeded memory idle time, Pushing item to
disk -- " + ce.getKey() + " over by = " + String.valueOf( deadAt - now ) + " ms." );
- }
- //itr.remove();
- cache.remove( ce.getKey() );
-
- cache.waterfal( ce );
- }
- }
-
- if ( !ce.getElementAttributes().getIsEternal() )
- {
- // Exceeded maxLifeSeconds
- if ( ( ce.getElementAttributes().getMaxLifeSeconds() != -1 )
&& ( now - ce.getElementAttributes().getCreateTime() ) > (
ce.getElementAttributes().getMaxLifeSeconds() * 1000 ) )
- {
- if ( log.isInfoEnabled() )
- {
- log.info( "Exceeded maxLifeSeconds -- " + ce.getKey()
);
- }
-
- // handle event, might move to a new method
- ArrayList eventHandlers =
ce.getElementAttributes().getElementEventHandlers();
- if ( eventHandlers != null )
- {
- if ( log.isDebugEnabled() )
- {
- log.debug( "Handlers are registered. Event --
ELEMENT_EVENT_EXCEEDED_MAXLIFE_BACKGROUND" );
- }
- IElementEvent event = new ElementEvent( ce,
IElementEventConstants.ELEMENT_EVENT_EXCEEDED_MAXLIFE_BACKGROUND );
- Iterator hIt = eventHandlers.iterator();
- while ( hIt.hasNext() )
- {
- IElementEventHandler hand = (
IElementEventHandler ) hIt.next();
- hand.handleElementEvent( event );
- }
- }
-
- //itr.remove();
- // TODO: this needs to go through the remove chanel
- // since an old copy could be on disk and we may want
- // to clean up the other caches.
- // probably need to call both
- cache.remove( ce.getKey() );
- }
- else
- // Exceeded maxIdleTime, removal
- if ( ( ce.getElementAttributes().getIdleTime() != -1 ) &&
( now - ce.getElementAttributes().getLastAccessTime() ) > (
ce.getElementAttributes().getIdleTime() * 1000 ) )
- {
- if ( log.isInfoEnabled() )
- {
- log.info( "Exceeded maxIdleTime [
ce.getElementAttributes().getIdleTime() = " + ce.getElementAttributes().getIdleTime()
+ " ]-- " + ce.getKey() );
- }
-
- // handle event, might move to a new method
- ArrayList eventHandlers =
ce.getElementAttributes().getElementEventHandlers();
- if ( eventHandlers != null )
- {
- if ( log.isDebugEnabled() )
- {
- log.debug( "Handlers are registered. Event --
ELEMENT_EVENT_EXCEEDED_IDLETIME_BACKGROUND" );
- }
- IElementEvent event = new ElementEvent( ce,
IElementEventConstants.ELEMENT_EVENT_EXCEEDED_IDLETIME_BACKGROUND );
- Iterator hIt = eventHandlers.iterator();
- while ( hIt.hasNext() )
- {
- IElementEventHandler hand = (
IElementEventHandler ) hIt.next();
- hand.handleElementEvent( event );
- }
- }
-
- //itr.remove();
-
- cache.remove( ce.getKey() );
- }
- }
-
- } // end if ce != null
-
-/////////////////////////////////////
-
-
- }
-
-
-////////////////////////////////////
-
-// }
-//
-// itr = null;
+ }// end if ce != null
-////////////////////////////////////
+ }// end for
}
catch ( Throwable t )
{
- log.info( "Expected trouble in shrink cycle", t );
- // keep going?
- // concurrent modifications will be a serious problem here
- // there is no good way yo interate througha map without locking it
+ log.info( "Unexpected trouble in shrink cycle", t );
+
+ // concurrent modifications should no longer be a problem
+ // It is up to the IMemoryCache to return an array of keys
//stop for now
return;
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