DataFileDefrag.java

/* Copyright (c) 2001-2014, The HSQL Development Group
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package org.hsqldb.persist;

import org.hsqldb.Database;
import org.hsqldb.Table;
import org.hsqldb.TableBase;
import org.hsqldb.error.Error;
import org.hsqldb.error.ErrorCode;
import org.hsqldb.lib.DoubleIntIndex;
import org.hsqldb.lib.HsqlArrayList;
import org.hsqldb.lib.StopWatch;
import org.hsqldb.lib.StringUtil;

/**
 *  Routine to defrag the *.data file.
 *
 *  This method iterates over the primary index of a table to find the
 *  disk position for each row and stores it, together with the new position
 *  in an array.
 *
 *  A second pass over the primary index writes each row to the new disk
 *  image after translating the old pointers to the new.
 *
 * @author Fred Toussi (fredt@users dot sourceforge.net)
 * @version    2.3.2
 * @since      1.7.2
 */
final class DataFileDefrag {

    DataFileCache  dataFileOut;
    StopWatch      stopw = new StopWatch();
    String         dataFileName;
    long[][]       rootsList;
    Database       database;
    DataFileCache  dataCache;
    int            scale;
    DoubleIntIndex pointerLookup;

    DataFileDefrag(Database db, DataFileCache cache, String dataFileName) {

        this.database     = db;
        this.dataCache    = cache;
        this.scale        = cache.getDataFileScale();
        this.dataFileName = dataFileName;
    }

    void process() {

        Throwable error = null;

        database.logger.logDetailEvent("Defrag process begins");

        HsqlArrayList allTables = database.schemaManager.getAllTables(true);

        rootsList = new long[allTables.size()][];

        long maxSize = 0;

        for (int i = 0, tSize = allTables.size(); i < tSize; i++) {
            Table table = (Table) allTables.get(i);

            if (table.getTableType() == TableBase.CACHED_TABLE) {
                PersistentStore store =
                    database.persistentStoreCollection.getStore(table);
                long size = store.elementCount();

                if (size > maxSize) {
                    maxSize = size;
                }
            }
        }

        if (maxSize > Integer.MAX_VALUE) {
            throw Error.error(ErrorCode.X_2200T);
        }

        try {
            pointerLookup = new DoubleIntIndex((int) maxSize, false);
            dataFileOut   = new DataFileCache(database, dataFileName, true);

            pointerLookup.setKeysSearchTarget();

            for (int i = 0, tSize = allTables.size(); i < tSize; i++) {
                Table t = (Table) allTables.get(i);

                if (t.getTableType() == TableBase.CACHED_TABLE) {
                    long[] rootsArray = writeTableToDataFile(t);

                    rootsList[i] = rootsArray;
                } else {
                    rootsList[i] = null;
                }

                database.logger.logDetailEvent("table complete "
                                               + t.getName().name);
            }

            dataFileOut.fileModified = true;

            dataFileOut.close();

            dataFileOut = null;

            for (int i = 0, size = rootsList.length; i < size; i++) {
                long[] roots = rootsList[i];

                if (roots != null) {
                    database.logger.logDetailEvent("roots: "
                                                   + StringUtil.getList(roots,
                                                       ",", ""));
                }
            }
        } catch (OutOfMemoryError e) {
            error = e;

            throw Error.error(ErrorCode.OUT_OF_MEMORY, e);
        } catch (Throwable t) {
            error = t;

            throw Error.error(ErrorCode.GENERAL_ERROR, t);
        } finally {
            try {
                if (dataFileOut != null) {
                    dataFileOut.release();
                }
            } catch (Throwable t) {}

            if (error instanceof OutOfMemoryError) {
                database.logger.logInfoEvent(
                    "defrag failed - out of memory - required: "
                    + maxSize * 8);
            }

            if (error == null) {
                database.logger.logDetailEvent("Defrag transfer complete: "
                                               + stopw.elapsedTime());
            } else {
                database.logger.logSevereEvent("defrag failed ", error);
                database.logger.getFileAccess().removeElement(dataFileName
                        + Logger.newFileExtension);
            }
        }
    }

    long[] writeTableToDataFile(Table table) {

        RowStoreAVLDisk store =
            (RowStoreAVLDisk) table.database.persistentStoreCollection.getStore(
                table);
        long[] rootsArray = table.getIndexRootsArray();

        pointerLookup.clear();
        database.logger.logDetailEvent("lookup begins " + table.getName().name
                                       + " " + stopw.elapsedTime());
        store.moveDataToSpace(dataFileOut, pointerLookup);

        for (int i = 0; i < table.getIndexCount(); i++) {
            if (rootsArray[i] == -1) {
                continue;
            }

            long pos = pointerLookup.lookup(rootsArray[i], -1);

            if (pos == -1) {
                throw Error.error(ErrorCode.DATA_FILE_ERROR);
            }

            rootsArray[i] = pos;
        }

        // log any discrepency in row count
        long count = rootsArray[table.getIndexCount() * 2];

        if (count != pointerLookup.size()) {
            database.logger.logSevereEvent("discrepency in row count "
                                           + table.getName().name + " "
                                           + count + " "
                                           + pointerLookup.size(), null);
        }

        rootsArray[table.getIndexCount()]     = 0;
        rootsArray[table.getIndexCount() * 2] = pointerLookup.size();

        database.logger.logDetailEvent("table written "
                                       + table.getName().name);

        return rootsArray;
    }

    public long[][] getIndexRoots() {
        return rootsList;
    }
}