Examples with PersistentPageFile de.lmu.ifi.dbs.elki.persistent.PersistentPageFile used on opensource projects

Example 1 with PersistentPageFile

use of de.lmu.ifi.dbs.elki.persistent.PersistentPageFile in project elki by elki-project.

the class AbstractXTree method initializeFromFile.

/**
 * To be called via the constructor if the tree is to be read from file.
 */
@Override
public void initializeFromFile(TreeIndexHeader hdr, PageFile<N> file) {
    XTreeHeader header = (XTreeHeader) hdr;
    super.dirCapacity = header.getDirCapacity();
    super.leafCapacity = header.getLeafCapacity();
    super.dirMinimum = header.getDirMinimum();
    super.leafMinimum = header.getLeafMinimum();
    settings.min_fanout = header.getMin_fanout();
    this.num_elements = header.getNumberOfElements();
    this.dimensionality = header.getDimensionality();
    settings.max_overlap = header.getMaxOverlap();
    long superNodeOffset = header.getSupernode_offset();
    if (getLogger().isDebugging()) {
        getLogger().debugFine(new StringBuilder(200).append(getClass()).append("\n file = ").append(file.getClass()).toString());
    }
    // reset page id maintenance
    file.setNextPageID((int) (superNodeOffset / header.getPageSize()));
    // read supernodes (if there are any)
    if (superNodeOffset > 0) {
        RandomAccessFile ra_file = ((PersistentPageFile<?>) file).getFile();
        long offset = header.getReservedPages() * file.getPageSize() + superNodeOffset;
        int bs = // omit this: 4 // EMPTY_PAGE or FILLED_PAGE ?
        0 + // id
        4 + // isLeaf
        1 + // isSupernode
        1 + // number of entries
        4 + // capacity
        4;
        byte[] buffer = new byte[bs];
        try {
            // go to supernode region
            ra_file.seek(offset);
            while (ra_file.getFilePointer() + file.getPageSize() <= ra_file.length()) {
                // file.countRead();
                ra_file.read(buffer);
                ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(buffer));
                int id = ois.readInt();
                // iLeaf
                ois.readBoolean();
                boolean supernode = ois.readBoolean();
                if (!supernode) {
                    throw new IllegalStateException("Non-supernode at supernode position '" + superNodeOffset + "'");
                }
                int numEntries = ois.readInt();
                int capacity = ois.readInt();
                ois.close();
                N page;
                try {
                    page = getNodeClass().newInstance();
                } catch (IllegalAccessException e) {
                    throw new AbortException("AccessException instantiating a supernode", e);
                } catch (InstantiationException e) {
                    throw new AbortException("InstantiationException instantiating a supernode", e);
                }
                // file.countRead();
                ra_file.seek(offset);
                byte[] superbuffer = new byte[file.getPageSize() * (int) Math.ceil((double) capacity / dirCapacity)];
                // increase offset for the next position seek
                offset += superbuffer.length;
                ra_file.read(superbuffer);
                ois = new ObjectInputStream(new ByteArrayInputStream(buffer));
                try {
                    // read from file and add to supernode map
                    page.readSuperNode(ois, this);
                } catch (ClassNotFoundException e) {
                    throw new AbortException("ClassNotFoundException when loading a supernode", e);
                }
                assert numEntries == page.getNumEntries();
                assert capacity == page.getCapacity();
                assert id == page.getPageID();
            }
        } catch (IOException e) {
            throw new RuntimeException("IOException caught when loading tree from file." + e);
        }
    }
    super.initialized = true;
    // compute height
    super.height = computeHeight();
    if (getLogger().isDebugging()) {
        getLogger().debugFine(new StringBuilder(100).append(getClass()).append("\n height = ").append(height).toString());
    }
}