Re: [Jdbm-general] removal of elements results in StreamCorruptedException

[Alex B. <boi...@in...>]

Christof Dallermassl wrote:
> 
> I tried to insert a couple of elements into a BTree and then remove
> them one by one. After a number or removals, there is always (if more
> than 20 elements in btree) a java.io.StreamCorruptedException thrown.

Well, I finally tracked this one down.  The corruption was happening 
during the BPage insert of the 24rd element, generating a page split 
which wasn't properly linking the existing pages with the newly 
allocated page.

In fact, it had nothing to do with the ObjectCache, which I was 
suspecting at first.  The MRU(1) workaround which I posted earlier 
didn't actually work so I must have goofed at some point when testing 
the workaround.

Anyhow, it is fixed now.  I am posting the diff here for people 
interested but I've already commited it in the CVS.  Following this, I 
will make a new release ASAP.

Thanks again for the reproductible test case.  As mentioned to you 
before, I will be adding it to the test harness.

ciao,
alex



% cvs diff -c BPage.java
Index: BPage.java
===================================================================
RCS file: /cvsroot/jdbm/jdbm/src/main/jdbm/btree/BPage.java,v
retrieving revision 1.1
diff -c -r1.1 BPage.java
*** BPage.java  2001/05/19 14:17:12     1.1
--- BPage.java  2001/08/28 05:32:07
***************
*** 393,398 ****
--- 393,403 ----
               // link newly created BPage
               newPage._previous = _previous;
               newPage._next = _recid;
+             if ( _previous != 0 ) {
+                 BPage previous = loadBPage( _previous );
+                 previous._next = newPage._recid;
+                 _btree._cache.update( _previous, previous );
+             }
               _previous = newPage._recid;
           }