textcache.java

hsql是很有名的嵌入式数据库

/* Copyright (c) 2001-2005, The HSQL Development Group
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the HSQL Development Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


package org.hsqldb.persist;

import java.io.IOException;
import java.io.UnsupportedEncodingException;

import org.hsqldb.HsqlException;
import org.hsqldb.Table;
import org.hsqldb.Trace;
import org.hsqldb.lib.FileUtil;
import org.hsqldb.lib.HsqlByteArrayOutputStream;
import org.hsqldb.rowio.RowInputInterface;
import org.hsqldb.rowio.RowInputText;
import org.hsqldb.rowio.RowInputTextQuoted;
import org.hsqldb.rowio.RowOutputText;
import org.hsqldb.rowio.RowOutputTextQuoted;
import org.hsqldb.scriptio.ScriptWriterText;
import org.hsqldb.store.ObjectCacheHashMap;

// Ito Kazumitsu 20030328 - patch 1.7.2 - character encoding support
// Dimitri Maziuk - patch for NL in string support
// sqlbob@users - updated for 1.8.0 to allow new-lines in fields
// fredt@users - updated for 1.8.0 to allow correct behaviour with transactions

/**
 * Acts as a buffer manager for a single TEXT table with respect its Row data.<p>
 *
 * Handles read/write operations on the table's text format data file using a
 * compatible pair of org.hsqldb.rowio input/output class instances.
 *
 *
 * @author sqlbob@users (RMP)
 * @version 1.8.0
 * @since 1.7.0
 */
public class TextCache extends DataFileCache {

    //state of Cache
    public static final String NL = System.getProperty("line.separator");
    public String              fs;
    public String              vs;
    public String              lvs;
    public String              stringEncoding;
    public boolean             isQuoted;
    public boolean             isAllQuoted;
    public boolean             ignoreFirst;
    protected String           header;
    protected Table            table;
    private ObjectCacheHashMap uncommittedCache;

    //

    /**
     *  The source string for a cached table is evaluated and the parameters
     *  are used to open the source file.<p>
     *
     *  Settings are used in this order: (1) settings specified in the
     *  source string for the table (2) global database settings in
     *  *.properties file (3) program defaults
     */
    TextCache(Table table, String name) throws HsqlException {

        super(table.database, name, null);

        this.table       = table;
        uncommittedCache = new ObjectCacheHashMap(5);
    }

    protected void initParams() throws HsqlException {

        // fredt - this used to write rows as soon as they are inserted
        // but now this is subject to session autoCommit / or commit
        // storeOnInsert = true;
        HsqlProperties tableprops =
            HsqlProperties.delimitedArgPairsToProps(fileName, "=", ";", null);

        //-- Get file name
        switch (tableprops.errorCodes.length) {

            case 0 :
                throw Trace.error(Trace.TEXT_TABLE_SOURCE,
                                  Trace.TEXT_TABLE_SOURCE_FILENAME);
            case 1 :

                // source file name is the only key without a value
                fileName = tableprops.errorKeys[0].trim();
                break;

            default :
                throw Trace.error(Trace.TEXT_TABLE_SOURCE,
                                  Trace.TEXT_TABLE_SOURCE_VALUE_MISSING,
                                  tableprops.errorKeys[1]);
        }

        //-- Get separators:
        HsqlDatabaseProperties dbProps = database.getProperties();

        fs = translateSep(tableprops.getProperty("fs",
                dbProps.getProperty(HsqlDatabaseProperties.textdb_fs, ",")));
        vs = translateSep(tableprops.getProperty("vs",
                dbProps.getProperty(HsqlDatabaseProperties.textdb_vs, fs)));
        lvs = translateSep(tableprops.getProperty("lvs",
                dbProps.getProperty(HsqlDatabaseProperties.textdb_lvs, fs)));

        if (fs.length() == 0 || vs.length() == 0 || lvs.length() == 0) {
            throw Trace.error(Trace.TEXT_TABLE_SOURCE,
                              Trace.TEXT_TABLE_SOURCE_SEPARATOR);
        }

        //-- Get booleans
        ignoreFirst = tableprops.isPropertyTrue(
            "ignore_first",
            dbProps.isPropertyTrue(
                HsqlDatabaseProperties.textdb_ignore_first, false));
        isQuoted = tableprops.isPropertyTrue(
            "quoted",
            dbProps.isPropertyTrue(
                HsqlDatabaseProperties.textdb_quoted, true));
        isAllQuoted = tableprops.isPropertyTrue(
            "all_quoted",
            dbProps.isPropertyTrue(
                HsqlDatabaseProperties.textdb_all_quoted, false));

        //-- Get encoding
        stringEncoding = translateSep(tableprops.getProperty("encoding",
                dbProps.getProperty(HsqlDatabaseProperties.textdb_encoding,
                                    "ASCII")));

        //-- Get size and scale
        int cacheScale = tableprops.getIntegerProperty(
            "cache_scale",
            dbProps.getIntegerProperty(
                HsqlDatabaseProperties.textdb_cache_scale, 10, 8, 16));
        int cacheSizeScale = tableprops.getIntegerProperty(
            "cache_size_scale",
            dbProps.getIntegerProperty(
                HsqlDatabaseProperties.textdb_cache_size_scale, 10, 8, 20));
        int lookupTableLength = 1 << cacheScale;
        int avgRowBytes       = 1 << cacheSizeScale;

        maxCacheSize     = lookupTableLength * 3;
        maxCacheBytes    = maxCacheSize * avgRowBytes;
        maxDataFileSize  = Integer.MAX_VALUE;
        cachedRowPadding = 1;
        cacheFileScale   = 1;
    }

    protected void initBuffers() {

        if (isQuoted || isAllQuoted) {
            rowIn = new RowInputTextQuoted(fs, vs, lvs, isAllQuoted);
            rowOut = new RowOutputTextQuoted(fs, vs, lvs, isAllQuoted,
                                             stringEncoding);
        } else {
            rowIn  = new RowInputText(fs, vs, lvs, false);
            rowOut = new RowOutputText(fs, vs, lvs, false, stringEncoding);
        }
    }

    private String translateSep(String sep) {
        return translateSep(sep, false);
    }

    /**
     * Translates the escaped characters in a separator string and returns
     * the non-escaped string.
     */
    private String translateSep(String sep, boolean isProperty) {

        if (sep == null) {
            return (null);
        }

        int next = 0;

        if ((next = sep.indexOf('\\')) != -1) {
            int          start    = 0;
            char[]       sepArray = sep.toCharArray();
            char         ch       = 0;
            int          len      = sep.length();
            StringBuffer realSep  = new StringBuffer(len);

            do {
                realSep.append(sepArray, start, next - start);

                start = ++next;

                if (next >= len) {
                    realSep.append('\\');

                    break;
                }

                if (!isProperty) {
                    ch = sepArray[next];
                }

                if (ch == 'n') {
                    realSep.append('\n');

                    start++;
                } else if (ch == 'r') {
                    realSep.append('\r');

                    start++;
                } else if (ch == 't') {
                    realSep.append('\t');

                    start++;
                } else if (ch == '\\') {
                    realSep.append('\\');

                    start++;
                } else if (ch == 'u') {
                    start++;

                    realSep.append(
                        (char) Integer.parseInt(
                            sep.substring(start, start + 4), 16));

                    start += 4;
                } else if (sep.startsWith("semi", next)) {
                    realSep.append(';');

                    start += 4;
                } else if (sep.startsWith("space", next)) {
                    realSep.append(' ');

                    start += 5;
                } else if (sep.startsWith("quote", next)) {
                    realSep.append('\"');

                    start += 5;
                } else if (sep.startsWith("apos", next)) {
                    realSep.append('\'');

                    start += 4;
                } else {
                    realSep.append('\\');
                    realSep.append(sepArray[next]);

                    start++;
                }
            } while ((next = sep.indexOf('\\', start)) != -1);

            realSep.append(sepArray, start, len - start);

            sep = realSep.toString();
        }

        return sep;
    }

    /**
     *  Opens a data source file.
     */
    public void open(boolean readonly) throws HsqlException {

        fileFreePosition = 0;

        try {
            dataFile = ScaledRAFile.newScaledRAFile(fileName, readonly,
                    ScaledRAFile.DATA_FILE_RAF, null, null);
            fileFreePosition = dataFile.length();

            if (fileFreePosition > Integer.MAX_VALUE) {
                throw new IOException();
            }

            initBuffers();
        } catch (Exception e) {
            throw Trace.error(Trace.FILE_IO_ERROR,
                              Trace.TextCache_openning_file_error,
                              new Object[] {
                fileName, e
            });
        }

        cacheReadonly = readonly;
    }

    void reopen() throws HsqlException {
        open(cacheReadonly);
    }

    /**
     *  Writes newly created rows to disk. In the current implentation,
     *  such rows have already been saved, so this method just removes a
     *  source file that has no rows.
     */
    public void close(boolean write) throws HsqlException {

        if (dataFile == null) {
            return;
        }

        try {
            cache.saveAll();

            boolean empty = (dataFile.length() <= NL.length());

            dataFile.close();

            dataFile = null;

            if (empty &&!cacheReadonly) {
                FileUtil.delete(fileName);
            }
        } catch (Exception e) {
            throw Trace.error(Trace.FILE_IO_ERROR,
                              Trace.TextCache_closing_file_error,
                              new Object[] {
                fileName, e
            });
        }
    }