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HSQLDB example source code file (ScriptWriterBase.java)

This example HSQLDB source code file (ScriptWriterBase.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - HSQLDB tags/keywords

hsqlexception, hsqlexception, io, ioexception, ioexception, iterator, object, object, outputstream, script_binary_172, scriptwriterbase, string, string, stringbuffer, table

The HSQLDB ScriptWriterBase.java source code

/* Copyright (c) 2001-2008, 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.scriptio;

import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.OutputStream;

import org.hsqldb.HsqlNameManager.HsqlName;
import org.hsqldb.Database;
import org.hsqldb.DatabaseManager;
import org.hsqldb.DatabaseScript;
import org.hsqldb.HsqlException;
import org.hsqldb.NumberSequence;
import org.hsqldb.Result;
import org.hsqldb.Session;
import org.hsqldb.Table;
import org.hsqldb.Token;
import org.hsqldb.Trace;
import org.hsqldb.index.RowIterator;
import org.hsqldb.lib.FileAccess;
import org.hsqldb.lib.FileUtil;
import org.hsqldb.lib.HsqlTimer;
import org.hsqldb.lib.Iterator;
import org.hsqldb.lib.SimpleLog;

//import org.hsqldb.lib.StopWatch;
// todo - can lock the database engine as readonly in a wrapper for this when
// used at checkpoint

/**
 * Handles all logging to file operations. A log consists of three blocks:<p>
 *
 * DDL BLOCK: definition of DB objects, users and rights at startup time<br>
 * DATA BLOCK: all data for MEMORY tables at startup time<br>
 * LOG BLOCK: SQL statements logged since startup or the last CHECKPOINT<br>
 *
 * The implementation of this class and its subclasses support the formats
 * used for writing the data. In versions up to 1.7.2, this data is written
 * to the *.script file for the database. Since 1.7.2 the data can also be
 * written as binray in order to speed up shutdown and startup.<p>
 *
 * In 1.7.2, two separate files are used, one for the DDL + DATA BLOCK and
 * the other for the LOG BLOCK.<p>
 *
 * A related use for this class is for saving a current snapshot of the
 * database data to a user-defined file. This happens in the SHUTDOWN COMPACT
 * process or done as a result of the SCRIPT command. In this case, the
 * DATA block contains the CACHED table data as well.<p>
 *
 * DatabaseScriptReader and its subclasses read back the data at startup time.
 *
 * @author fredt@users
 * @version 1.8.0
 * @since 1.7.2
 */
public abstract class ScriptWriterBase implements Runnable {

    Database            database;
    String              outFile;
    OutputStream        fileStreamOut;
    FileAccess.FileSync outDescriptor;
    int                 tableRowCount;
    HsqlName            schemaToLog;

    /**
     * this determines if the script is the normal script (false) used
     * internally by the engine or a user-initiated snapshot of the DB (true)
     */
    boolean          isDump;
    boolean          includeCachedData;
    long             byteCount;
    volatile boolean needsSync;
    volatile boolean forceSync;
    volatile boolean busyWriting;
    private int      syncCount;
    static final int INSERT             = 0;
    static final int INSERT_WITH_SCHEMA = 1;

    /** the last schema for last sessionId */
    Session                      currentSession;
    public static final String[] LIST_SCRIPT_FORMATS      = new String[] {
        Token.T_TEXT, Token.T_BINARY, null, Token.T_COMPRESSED
    };
    public static final int      SCRIPT_TEXT_170          = 0;
    public static final int      SCRIPT_BINARY_172        = 1;
    public static final int      SCRIPT_ZIPPED_BINARY_172 = 3;

    public static ScriptWriterBase newScriptWriter(Database db, String file,
            boolean includeCachedData, boolean newFile,
            int scriptType) throws HsqlException {

        if (scriptType == SCRIPT_TEXT_170) {
            return new ScriptWriterText(db, file, includeCachedData, newFile,
                                        false);
        } else if (scriptType == SCRIPT_BINARY_172) {
            return new ScriptWriterBinary(db, file, includeCachedData,
                                          newFile);
        } else {
            return new ScriptWriterZipped(db, file, includeCachedData,
                                          newFile);
        }
    }

    ScriptWriterBase() {}

    ScriptWriterBase(Database db, String file, boolean includeCachedData,
                     boolean isNewFile, boolean isDump) throws HsqlException {

        this.isDump = isDump;

        initBuffers();

        boolean exists = false;

        if (isDump) {
            exists = FileUtil.getDefaultInstance().exists(file);
        } else {
            exists = db.getFileAccess().isStreamElement(file);
        }

        if (exists && isNewFile) {
            throw Trace.error(Trace.FILE_IO_ERROR, file);
        }

        this.database          = db;
        this.includeCachedData = includeCachedData;
        outFile                = file;
        currentSession         = database.sessionManager.getSysSession();

        // start with neutral schema - no SET SCHEMA to log
        schemaToLog = currentSession.loggedSchema =
            currentSession.currentSchema;

        openFile();
    }

    public void reopen() throws HsqlException {
        openFile();
    }

    protected abstract void initBuffers();

    /**
     *  Called internally or externally in write delay intervals.
     */
    public synchronized void sync() {

        if (needsSync && fileStreamOut != null) {
            if (busyWriting) {
                forceSync = true;

                return;
            }

            try {
                fileStreamOut.flush();
                outDescriptor.sync();

                syncCount++;
            } catch (IOException e) {
                Trace.printSystemOut("flush() or sync() error: "
                                     + e.toString());
            }

            needsSync = false;
            forceSync = false;
        }
    }

    /**
     *  Called externally.
     */
    public synchronized void forceSync() {

        if (fileStreamOut != null) {
            try {
                fileStreamOut.flush();
                outDescriptor.sync();

                syncCount++;
            } catch (IOException e) {
                Trace.printSystemOut("flush() or sync() error: "
                                     + e.toString());
            }

            needsSync = false;
            forceSync = false;
        }
    }

    public void close() throws HsqlException {

        stop();

        try {
            if (fileStreamOut != null) {
                fileStreamOut.flush();
                outDescriptor.sync();
                fileStreamOut.close();

                fileStreamOut = null;
            }
        } catch (IOException e) {
            throw Trace.error(Trace.FILE_IO_ERROR);
        }

        byteCount = 0;
    }

    public long size() {
        return byteCount;
    }

    public void writeAll() throws HsqlException {

        try {
            writeDDL();
            writeExistingData();
            finishStream();
        } catch (IOException e) {
            throw Trace.error(Trace.FILE_IO_ERROR);
        }
    }

    /**
     *  File is opened in append mode although in current usage the file
     *  never pre-exists
     */
    protected void openFile() throws HsqlException {

        try {
            FileAccess   fa  = isDump ? FileUtil.getDefaultInstance()
                                      : database.getFileAccess();
            OutputStream fos = fa.openOutputStreamElement(outFile);

            outDescriptor = fa.getFileSync(fos);
            fileStreamOut = new BufferedOutputStream(fos, 2 << 12);
        } catch (IOException e) {
            throw Trace.error(Trace.FILE_IO_ERROR, Trace.Message_Pair,
                              new Object[] {
                e.toString(), outFile
            });
        }
    }

    /**
     * This is not really useful in the current usage but may be if this
     * class is used in a different way.
     */
    protected void finishStream() throws IOException {}

    protected void writeDDL() throws IOException, HsqlException {

        Result ddlPart = DatabaseScript.getScript(database,
            !includeCachedData);

        writeSingleColumnResult(ddlPart);
    }

    protected void writeExistingData() throws HsqlException, IOException {

        // start with blank schema - SET SCHEMA to log
        currentSession.loggedSchema = null;

        Iterator schemas = database.schemaManager.userSchemaNameIterator();

        while (schemas.hasNext()) {
            String   schema = (String) schemas.next();
            Iterator tables = database.schemaManager.tablesIterator(schema);

            while (tables.hasNext()) {
                Table t = (Table) tables.next();

                // write all memory table data
                // write cached table data unless index roots have been written
                // write all text table data apart from readonly text tables
                // unless index roots have been written
                boolean script = false;

                switch (t.getTableType()) {

                    case Table.MEMORY_TABLE :
                        script = true;
                        break;

                    case Table.CACHED_TABLE :
                        script = includeCachedData;
                        break;

                    case Table.TEXT_TABLE :
                        script = includeCachedData && !t.isReadOnly();
                        break;
                }

                int rowCount = 0;

                try {
                    if (script) {
                        schemaToLog = t.getName().schema;

                        writeTableInit(t);

                        RowIterator it = t.rowIterator(currentSession);

                        rowCount = 0;

                        while (it.hasNext()) {
                            writeRow(currentSession, t, it.next().getData());

                            rowCount++;
                        }

                        writeTableTerm(t);
                    }
                } catch (Throwable e) {
                    this.database.logger.appLog.logContext(
                        SimpleLog.LOG_ERROR,
                        t.getName().name + " problem after row " + rowCount);
                    System.gc();

                    throw Trace.error(Trace.ASSERT_FAILED, e.toString());
                }
            }
        }

        writeDataTerm();
    }

    protected void writeTableInit(Table t) throws HsqlException, IOException {}

    protected void writeTableTerm(Table t) throws HsqlException, IOException {

        if (t.isDataReadOnly() && !t.isTemp() && !t.isText()) {
            StringBuffer a = new StringBuffer("SET TABLE ");

            a.append(t.getName().statementName);
            a.append(" READONLY TRUE");
            writeLogStatement(currentSession, a.toString());
        }
    }

    protected void writeSingleColumnResult(Result r)
    throws HsqlException, IOException {

        Iterator it = r.iterator();

        while (it.hasNext()) {
            Object[] data = (Object[]) it.next();

            writeLogStatement(currentSession, (String) data[0]);
        }
    }

    abstract void writeRow(Session session, Table table,
                           Object[] data) throws HsqlException, IOException;

    protected abstract void writeDataTerm() throws IOException;

    protected abstract void addSessionId(Session session) throws IOException;

    public abstract void writeLogStatement(Session session,
                                           String s)
                                           throws IOException, HsqlException;

    public abstract void writeInsertStatement(Session session, Table table,
            Object[] data) throws HsqlException, IOException;

    public abstract void writeDeleteStatement(Session session, Table table,
            Object[] data) throws HsqlException, IOException;

    public abstract void writeSequenceStatement(Session session,
            NumberSequence seq) throws HsqlException, IOException;

    public abstract void writeCommitStatement(Session session)
    throws HsqlException, IOException;

    //
    private Object timerTask;

    // long write delay for scripts : 60s
    protected volatile int writeDelay = 60000;

    public void run() {

        try {
            if (writeDelay != 0) {
                sync();
            }

            // todo: try to do Cache.cleanUp() here, too
        } catch (Exception e) {

            // ignore exceptions
            // may be InterruptedException or IOException
            if (Trace.TRACE) {
                Trace.printSystemOut(e.toString());
            }
        }
    }

    public void setWriteDelay(int delay) {
        writeDelay = delay;
    }

    public void start() {

        if (writeDelay > 0) {
            timerTask = DatabaseManager.getTimer().schedulePeriodicallyAfter(0,
                    writeDelay, this, false);
        }
    }

    public void stop() {

        if (timerTask != null) {
            HsqlTimer.cancel(timerTask);

            timerTask = null;
        }
    }

    public int getWriteDelay() {
        return writeDelay;
    }
}

Other HSQLDB examples (source code examples)

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