001: /*
002: * $Id: CheckFileStateCommand.java,v 1.18 2005/05/02 22:24:33 ahimanikya Exp $
003: * =======================================================================
004: * Copyright (c) 2002-2005 Axion Development Team. All rights reserved.
005: *
006: * Redistribution and use in source and binary forms, with or without
007: * modification, are permitted provided that the following conditions
008: * are met:
009: *
010: * 1. Redistributions of source code must retain the above
011: * copyright notice, this list of conditions and the following
012: * disclaimer.
013: *
014: * 2. Redistributions in binary form must reproduce the above copyright
015: * notice, this list of conditions and the following disclaimer in
016: * the documentation and/or other materials provided with the
017: * distribution.
018: *
019: * 3. The names "Tigris", "Axion", nor the names of its contributors may
020: * not be used to endorse or promote products derived from this
021: * software without specific prior written permission.
022: *
023: * 4. Products derived from this software may not be called "Axion", nor
024: * may "Tigris" or "Axion" appear in their names without specific prior
025: * written permission.
026: *
027: * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
028: * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
029: * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
030: * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
031: * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
032: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
033: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
034: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
035: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
036: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
037: * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
038: * =======================================================================
039: */
040:
041: package org.axiondb.engine.commands;
042:
043: import java.io.File;
044: import java.util.HashMap;
045: import java.util.Map;
046:
047: import org.axiondb.AxionException;
048: import org.axiondb.ColumnIdentifier;
049: import org.axiondb.Database;
050: import org.axiondb.RowDecorator;
051: import org.axiondb.TableIdentifier;
052: import org.axiondb.Transaction;
053: import org.axiondb.engine.DiskDatabase;
054: import org.axiondb.engine.rowiterators.EmptyRowIterator;
055: import org.axiondb.engine.rowiterators.RowIteratorRowDecoratorIterator;
056: import org.axiondb.engine.rowiterators.SingleRowIterator;
057: import org.axiondb.engine.rows.SimpleRow;
058: import org.axiondb.jdbc.AxionResultSet;
059: import org.axiondb.types.CharacterVaryingType;
060:
061: /**
062: * A <code>CHECKFILESTATE</code> query. Generates a non-empty {@link java.sql.ResultSet}
063: * if the database's files are accessible, an empty one otherwise.
064: *
065: * @version $Revision: 1.18 $ $Date: 2005/05/02 22:24:33 $
066: * @author Rodney Waldhoff
067: */
068: public class CheckFileStateCommand extends BaseAxionCommand {
069: public CheckFileStateCommand() {
070: }
071:
072: public boolean execute(Database db) throws AxionException {
073: setResultSet(executeQuery(db));
074: return (getResultSet() != null);
075: }
076:
077: public AxionResultSet executeQuery(Database db)
078: throws AxionException {
079: boolean success = false;
080: while (db instanceof Transaction) {
081: db = ((Transaction) db).getOpenOnTransaction();
082: }
083: if (db instanceof DiskDatabase) {
084: DiskDatabase diskdb = (DiskDatabase) db;
085: File file = diskdb.getDBDirectory();
086: if (!file.exists()) {
087: success = false;
088: } else {
089: success = true;
090: }
091: } else {
092: success = true;
093: }
094:
095: if (success) {
096: return createSuccessResultSet();
097: }
098: return createFailureResultSet();
099: }
100:
101: public AxionResultSet createSuccessResultSet() {
102: SimpleRow row = new SimpleRow(1);
103: row.set(0, "X");
104: SingleRowIterator iter = new SingleRowIterator(row);
105: RowDecorator decorator = new RowDecorator(MAP);
106: RowIteratorRowDecoratorIterator deciter = new RowIteratorRowDecoratorIterator(
107: iter, decorator);
108: return new AxionResultSet(deciter, SELECTED, null);
109: }
110:
111: public AxionResultSet createFailureResultSet() {
112: RowDecorator decorator = new RowDecorator(MAP);
113: RowIteratorRowDecoratorIterator deciter = new RowIteratorRowDecoratorIterator(
114: EmptyRowIterator.INSTANCE, decorator);
115: return new AxionResultSet(deciter, SELECTED, null);
116: }
117:
118: public int executeUpdate(Database database) throws AxionException {
119: throw new UnsupportedOperationException("Use execute query.");
120: }
121:
122: public String toString() {
123: return "CHECK FILE STATE";
124: }
125:
126: private static final ColumnIdentifier[] SELECTED = new ColumnIdentifier[] { new ColumnIdentifier(
127: new TableIdentifier(null), "DUMMY", null,
128: new CharacterVaryingType(1)) };
129: private static final Map MAP = new HashMap();
130: static {
131: MAP.put(SELECTED[0], new Integer(0));
132: }
133:
134: }
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