Hi guys, I have been quite busy those last weeks, with very few hours available to work on ApacheDS, and more specifically Mavibot.
2 weeks ago, I forked Mavibot in order to be able to work in a branch and not breaking the trunk, and all my modifications (plenty of them) since january have been committed there. As I stated earlier, I'm trying to implement transactions and revisions in Mavibot, now that we have a working system with no revision (it's actually a MVCC Btree, but with locks : nothing really different from a standard btree...). I'm done with the in memory B-tree, and I'm currently working on the persisted b-tree, which proves to be wayy more complex, mainly due to the fact that I have to hexdump the file and analyze its content to see if all is correct, something which takes forever... I'm also missing some cycles to do that corectly (ie, I need a few hours in a row, something I don't have). However, I'm progressing. Some big structure changes have been done : - I have modified the BTreeHeader to not contain any BTree informations, and I moved those inforamtions into the BTree structure - The layout on disk has changed : - we have now a separate page to contain the common b-tree info (serializer, page size, etc). - the BTreeHeader contain a reference to the rootPage and the btree info, but that's all - the BtreeOfBtrees contain reference to a btreeHeader associated to a tuple <btree, revision> - I have added the beginTransaction/commit/roolback methods, but I wasn't very successfull with the idea of mixing auto-commit and declared commit. Atm, it's all auto-commit (ie, one can't have more than one operation per transaction.) - I'm trying to implement these algorithms : manage BTree ============ - create new BtreeInfo -> BIO - create new RootPage -> RPO - create new BtreeHeader<BIO, RPO> -> BHO - insert the BtreeHeader into the BOB btree <rev, BHO> - create a new RP -> BOB-RP[i+1] - create a new Header -> BOB-Header[i+1] <BOB-I, BOB-RP[i+1]> - add the copied pages of i into the free list - add the BOB-RP[i] page into the free-list - add the BOB-Header[i] page into the free-list - update the current BOB and the old BOB pointers - update the recordManager header Add element =========== - create a new RP -> Tree-RP[n+1] - create a new Header -> Tree-Header[n+1] <Tree-I, Tree-RP[n+1]> - add the copied pages into the CPB (Tree-RP[n], Tree-Header[n], copied nodes and leaves) - create a new RP -> CPB-RP[i+1] - create a new Header -> CPB-Header[i+1] <CPB-I, CPB-RP[i+1]> - add the copied pages of i into the free list - add the CPB-RP[i] page into the free-list - add the CPB-Header[i] page into the free-list - update the current CPB and the old CPB pointers - add the new header into the BOB tree - create a new RP -> BOB-RP[j+1] - create a new Header -> BOB-Header[j+1] <BOB-I, BOB-RP[j+1]> - add the copied pages of j into the free list - add the BOB-RP[j] page into the free-list - add the BOB-Header[j] page into the free-list - update the current BOB and the old BOB pointers - update the recordManager header It's almost done (atm, I'm able to write down a new BTree). I do think it's a matter of a couple of days to get this done, I'll try to squeeze some time next week. Thanks ! -- Regards, Cordialement, Emmanuel Lécharny www.iktek.com
