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From "Corin Moss" <Corin.M...@tvnz.co.nz>
Subject RE: cvs commit:jakarta-turbine-jcs/src/java/org/apache/jcs/auxiliary/diskAbstractDiskCache.java
Date Thu, 15 Apr 2004 02:38:36 GMT

Hi Aaron,

Regarding this round of fixes, I noticed mention of a fix relating to
the removal of expired elements.  Does this ensure that things stored
with the on disk store aren't left there after key deletion? 

I just noticed whilst browsing the code the following:

    /**
     * Returns true if the removal was successful; or false if there is
nothing
     * to remove. Current implementation always result in a disk orphan.
     *
     * @return
     * @param key
     */
    public boolean doRemove( Serializable key )

The bit about the disk orphan (if still true) is in my mind incredibly
dangerous.  It means that you have no control over the size of your
cache - which can result in a disk blow-out.

Am I right in this? I have noticed that my data file is always growing,
never shrinking - this would definitely explain this.  

Does anyone have any comments on this? If my assumptions are correct,
does anyone have a fix in the works? :)

Thanks,

Corin

-----Original Message-----
From: asmuts@apache.org [mailto:asmuts@apache.org]
Sent: Thursday, 15 April 2004 5:06 a.m.
To: jakarta-turbine-jcs-cvs@apache.org
Subject: cvs
commit:jakarta-turbine-jcs/src/java/org/apache/jcs/auxiliary/diskAbstrac
tDiskCache.java


asmuts      2004/04/14 10:06:12

  Modified:    src/java/org/apache/jcs/utils/locking ReadWriteLock.java
               src/java/org/apache/jcs/auxiliary/disk/indexed
                        IndexedDiskCache.java
               src/java/org/apache/jcs/auxiliary/disk
                        AbstractDiskCache.java
  Log:
  It should be safe to dispose now.  Kill queue, optimize, then play
dead.
 
  Fixed a problem in the ReadWriteLock class that let the number of
writelocks get below zero.  This seems to have solved many problems.
However, I can't find out why there are more done calls than lock calls.
Added a break into the wait on the readlock in case noone calls notify.
 
  This may have fixed the mysterious locking problem that I've never
been able to duplicate.
 
  Revision  Changes    Path
  1.3       +14 -3
jakarta-turbine-jcs/src/java/org/apache/jcs/utils/locking/ReadWriteLock.
java
 
  Index: ReadWriteLock.java
  ===================================================================
  RCS file:
/home/cvs/jakarta-turbine-jcs/src/java/org/apache/jcs/utils/locking/Read
WriteLock.java,v
  retrieving revision 1.2
  retrieving revision 1.3
  diff -u -r1.2 -r1.3
  --- ReadWriteLock.java	22 Aug 2003 11:57:19 -0000	1.2
  +++ ReadWriteLock.java	14 Apr 2004 17:06:12 -0000	1.3
  @@ -117,7 +117,7 @@
           while ( writeLockedThread != null )
           {
               log.debug( "readLock wait" );
  -            wait();
  +            wait(20);
               log.debug( "wake up from readLock wait" );
           }
  
  @@ -211,9 +211,20 @@
               }
               return;
           }
  +
           if ( Thread.currentThread() == writeLockedThread )
           {
  -            outstandingWriteLocks--;
  +
  +            //log.info( "outstandingWriteLocks= " +
outstandingWriteLocks );
  +            if ( outstandingWriteLocks > 0 )
  +            {
  +                outstandingWriteLocks--;
  +            }
  +            else
  +            {
  +                log.warn( "extra lock release, writelocks are " +
outstandingWriteLocks + "and done was called" );
  +            }
  +
               if ( outstandingWriteLocks > 0 )
               {
                   log.debug( "writeLock released for a nested writeLock
request." );
  @@ -243,7 +254,7 @@
                   if ( waitingForReadLock > 0 )
                   {
                       log.debug( "writeLock released, notified waiting
readers" );
  -                   
  +
                       notifyAll();
                   }
                   else
 
 
 
  1.9       +18 -2
jakarta-turbine-jcs/src/java/org/apache/jcs/auxiliary/disk/indexed/Index
edDiskCache.java
 
  Index: IndexedDiskCache.java
  ===================================================================
  RCS file:
/home/cvs/jakarta-turbine-jcs/src/java/org/apache/jcs/auxiliary/disk/ind
exed/IndexedDiskCache.java,v
  retrieving revision 1.8
  retrieving revision 1.9
  diff -u -r1.8 -r1.9
  --- IndexedDiskCache.java	14 Apr 2004 06:24:18 -0000	1.8
  +++ IndexedDiskCache.java	14 Apr 2004 17:06:12 -0000	1.9
  @@ -300,6 +300,7 @@
               {
                   storageLock.done();
               }
  +
               if ( log.isDebugEnabled() )
               {
                   log.debug( "Put to file: " + fileName +
  @@ -469,8 +470,15 @@
               }
               else
               {
  +
  +                if ( log.isDebugEnabled() )
  +                {
  +                    log.debug( "Disk removal: Removed from key hash,
key " + key );
  +                }
  +
                   // remove single item.
                   return keyHash.remove( key ) != null;
  +
               }
           }
           catch ( Exception e )
  @@ -588,7 +596,14 @@
           finally
           {
               alive = false;
  -            storageLock.done();
  +
  +            try
  +            {
  +              storageLock.done();
  +            } catch ( Exception e )
  +            {
  +                log.error( "Failure releasing lock on shutdown " + e
);
  +            }
           }
       }
  
  @@ -673,6 +688,7 @@
                       log.debug( fileName + " -- newData.length() = " +
                           newData.length() );
                   }
  +
                   newData.renameTo( newFileName );
               }
               keyHash = keyHashTemp;
 
 
 
  1.19      +4 -6
jakarta-turbine-jcs/src/java/org/apache/jcs/auxiliary/disk/AbstractDiskC
ache.java
 
  Index: AbstractDiskCache.java
  ===================================================================
  RCS file:
/home/cvs/jakarta-turbine-jcs/src/java/org/apache/jcs/auxiliary/disk/Abs
tractDiskCache.java,v
  retrieving revision 1.18
  retrieving revision 1.19
  diff -u -r1.18 -r1.19
  --- AbstractDiskCache.java	14 Apr 2004 06:24:18 -0000	1.18
  +++ AbstractDiskCache.java	14 Apr 2004 17:06:12 -0000	1.19
  @@ -300,13 +300,11 @@
       public final void dispose()
       {
  
  -        // Invoke any implementation specific disposal code
  -
  -        doDispose();
  -
           // FIXME: May lose the end of the queue, need to be more
graceful
  -
           cacheEventQueue.destroy();
  +
  +        // Invoke any implementation specific disposal code
  +        doDispose();
  
           alive = false;
  
 
 
 

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