private void loadRecordManager()

in mavibot/src/main/java/org/apache/directory/mavibot/btree/RecordManager.java [492:615]
58 lines of code
6 McCabe index (conditional complexity)

    private void loadRecordManager() throws IOException, ClassNotFoundException, IllegalAccessException,
        InstantiationException, IllegalArgumentException, SecurityException, NoSuchFieldException, KeyNotFoundException
    {
        if ( fileChannel.size() != 0 )
        {
            ByteBuffer recordManagerHeader = ByteBuffer.allocate( RECORD_MANAGER_HEADER_SIZE );

            // The file exists, we have to load the data now
            fileChannel.read( recordManagerHeader );

            recordManagerHeader.rewind();

            // read the RecordManager Header :
            // +---------------------+
            // | PageSize            | 4 bytes : The size of a physical page (default to 4096)
            // +---------------------+
            // | NbTree              | 4 bytes : The number of managed B-trees (at least 1)
            // +---------------------+
            // | FirstFree           | 8 bytes : The offset of the first free page
            // +---------------------+
            // | current BoB offset  | 8 bytes : The offset of the current B-tree of B-trees
            // +---------------------+
            // | previous BoB offset | 8 bytes : The offset of the previous B-tree of B-trees
            // +---------------------+
            // | current CP offset   | 8 bytes : The offset of the current Copied Pages B-tree
            // +---------------------+
            // | previous CP offset  | 8 bytes : The offset of the previous Copied Pages B-tree
            // +---------------------+

            // The page size
            pageSize = recordManagerHeader.getInt();

            // The number of managed B-trees
            nbBtree = recordManagerHeader.getInt();

            // The first and last free page
            firstFreePage = recordManagerHeader.getLong();

            // Read all the free pages
            checkFreePages();

            // The current BOB offset
            currentBtreeOfBtreesOffset = recordManagerHeader.getLong();

            // The previous BOB offset
            previousBtreeOfBtreesOffset = recordManagerHeader.getLong();

            // The current Copied Pages B-tree offset
            currentCopiedPagesBtreeOffset = recordManagerHeader.getLong();

            // The previous Copied Pages B-tree offset
            previousCopiedPagesBtreeOffset = recordManagerHeader.getLong();

            // read the B-tree of B-trees
            PageIO[] bobHeaderPageIos = readPageIOs( currentBtreeOfBtreesOffset, Long.MAX_VALUE );

            btreeOfBtrees = BTreeFactory.<NameRevision, Long> createPersistedBTree( BTreeTypeEnum.BTREE_OF_BTREES );

            loadBtree( bobHeaderPageIos, btreeOfBtrees );

            // read the copied page B-tree
            PageIO[] copiedPagesPageIos = readPageIOs( currentCopiedPagesBtreeOffset, Long.MAX_VALUE );

            copiedPageBtree = BTreeFactory
                .<RevisionName, long[]> createPersistedBTree( BTreeTypeEnum.COPIED_PAGES_BTREE );

            loadBtree( copiedPagesPageIos, copiedPageBtree );

            // Now, read all the B-trees from the btree of btrees
            TupleCursor<NameRevision, Long> btreeCursor = btreeOfBtrees.browse();
            Map<String, Long> loadedBtrees = new HashMap<String, Long>();

            // loop on all the btrees we have, and keep only the latest revision
            long currentRevision = -1L;

            while ( btreeCursor.hasNext() )
            {
                Tuple<NameRevision, Long> btreeTuple = btreeCursor.next();
                NameRevision nameRevision = btreeTuple.getKey();
                long btreeOffset = btreeTuple.getValue();
                long revision = nameRevision.getValue();

                // Check if we already have processed this B-tree
                Long loadedBtreeRevision = loadedBtrees.get( nameRevision.getName() );

                if ( loadedBtreeRevision != null )
                {
                    // The btree has already been loaded. The revision is necessarily higher
                    if ( revision > currentRevision )
                    {
                        // We have a newer revision : switch to the new revision (we keep the offset atm)
                        loadedBtrees.put( nameRevision.getName(), btreeOffset );
                        currentRevision = revision;
                    }
                }
                else
                {
                    // This is a new B-tree
                    loadedBtrees.put( nameRevision.getName(), btreeOffset );
                    currentRevision = nameRevision.getRevision();
                }
            }

            // TODO : clean up the old revisions...

            // Now, we can load the real btrees using the offsets
            for ( String btreeName : loadedBtrees.keySet() )
            {
                long btreeOffset = loadedBtrees.get( btreeName );

                PageIO[] btreePageIos = readPageIOs( btreeOffset, Long.MAX_VALUE );

                BTree<?, ?> btree = BTreeFactory.<NameRevision, Long> createPersistedBTree();
                //( ( PersistedBTree<NameRevision, Long> ) btree ).setBtreeHeaderOffset( btreeOffset );
                loadBtree( btreePageIos, btree );

                // Add the btree into the map of managed B-trees
                managedBtrees.put( btreeName, ( BTree<Object, Object> ) btree );
            }

            // We are done ! Let's finish with the last initialization parts
            endOfFileOffset = fileChannel.size();
        }
    }