| DatabaseUtils |
/*--
This file is a part of ZetaGrid, a simple and secure Grid Computing
kernel.
Copyright (c) 2001-2004 Sebastian Wedeniwski. All rights reserved.
Use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:
1. The source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. The origin of this software must not be misrepresented; you must
not claim that you wrote the original software. If you plan to
use this software in a product, please contact the author.
3. Altered source versions must be plainly marked as such, and must
not be misrepresented as being the original software. The author
must be informed about these changes.
4. The name of the author may not be used to endorse or promote
products derived from this software without specific prior written
permission.
THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 THE AUTHOR 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.
Version 1.9.0, February 8, 2004
This program is based on the work of:
H. Haddorp
S. Wedeniwski
--*/
package zeta.util;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.Timestamp;
import javax.servlet.ServletException;
import zeta.ZetaServlet;
/**
* Provides database utilities especially for the servlets.
**/
public class DatabaseUtils {
/**
* Releases a connection's database and JDBC resources immediately instead of waiting for them to be automatically released.
* No exception will be thrown if a database access error occurs.
* @param con the connection to the database
**/
public static void close(Connection con) {
if (con != null) {
try {
con.close();
} catch(SQLException e) {
}
}
}
/**
* Releases a statement object's database and JDBC resources immediately instead of waiting for this to happen when it is automatically closed.
* No exception will be thrown if a database access error occurs.
* @param stmt statement object's database
**/
public static void close(Statement stmt) {
if (stmt != null) {
try {
stmt.close();
} catch(SQLException e) {
}
}
}
/**
* Logging SQL statements in the database to synchronize different servers.
* @param serverId ID of the server
* @param stmt statement object's database
* @param sqlStatement SQL statement which should be logged
* @return the SQL statement where 'CURRENT TIMESTAMP' is replaced by the current timestamp if the synchronization is activated.
* @exception SQLException if a database access error occurs.
**/
public static String log(int serverId, Statement stmt, String sqlStatement) throws SQLException {
if (numberOfServers == -1) {
synchronized (DatabaseUtils.class) {
ResultSet rs = stmt.executeQuery("SELECT COUNT(*) FROM zeta.server");
if (rs.next()) {
numberOfServers = rs.getInt(1);
}
rs.close();
}
}
if (numberOfServers > 1) {
StringBuffer buffer = new StringBuffer(sqlStatement.length()+100);
sqlStatement = getLogStatement(serverId, stmt, sqlStatement, buffer);
stmt.executeUpdate(buffer.toString());
}
return sqlStatement;
}
/**
* Executing and logging a SQL statement in the database to synchronize different servers.
* @param servlet servlet which has a connection to the server database.
* @param sqlStatement SQL statement which should be logged
* @exception SQLException if a database access error occurs.
**/
public static void executeAndLogUpdate(ZetaServlet servlet, String sqlStatement) throws SQLException, ServletException {
Connection con = null;
Statement stmt = null;
boolean deactivateAutoCommit = false;
try {
con = servlet.getConnection();
stmt = con.createStatement();
if (numberOfServers == -1) {
synchronized (DatabaseUtils.class) {
ResultSet rs = stmt.executeQuery("SELECT COUNT(*) FROM zeta.server");
if (rs.next()) {
numberOfServers = rs.getInt(1);
}
rs.close();
}
}
if (numberOfServers > 1) {
StringBuffer buffer = new StringBuffer(sqlStatement.length()+100);
deactivateAutoCommit = true;
con.setAutoCommit(false);
stmt.executeUpdate(getLogStatement(servlet.getServerId(), stmt, sqlStatement, buffer));
stmt.executeUpdate(buffer.toString());
con.commit();
} else {
stmt.executeUpdate(sqlStatement);
}
} catch (SQLException se) {
servlet.log("SQLException: " + se.getMessage() + '\n' + sqlStatement);
throw se;
} finally {
close(stmt);
if (con != null) {
if (deactivateAutoCommit) {
con.setAutoCommit(true);
}
close(con);
}
}
}
/**
* Executing and logging a SQL statement in the database to synchronize different servers.
* @param serverId ID of the server
* @param stmt statement object's database
* @param sqlStatement SQL statement which should be logged
* @exception SQLException if a database access error occurs.
**/
public static void executeAndLogUpdate(int serverId, Statement stmt, String sqlStatement) throws SQLException {
boolean deactivateAutoCommit = false;
if (numberOfServers == -1) {
synchronized (DatabaseUtils.class) {
ResultSet rs = stmt.executeQuery("SELECT COUNT(*) FROM zeta.server");
numberOfServers = (rs.next())? rs.getInt(1) : 0;
rs.close();
}
}
try {
if (numberOfServers > 1) {
StringBuffer buffer = new StringBuffer(sqlStatement.length()+100);
deactivateAutoCommit = true;
stmt.getConnection().setAutoCommit(false);
stmt.executeUpdate(getLogStatement(serverId, stmt, sqlStatement, buffer));
stmt.executeUpdate(buffer.toString());
stmt.getConnection().commit();
} else {
stmt.executeUpdate(sqlStatement);
}
} finally {
if (deactivateAutoCommit) {
stmt.getConnection().setAutoCommit(true);
}
}
}
/**
* Encodes a name so that it can be stored in the database.
* @param name name to be encoded
* @return encoded name
**/
public static String encodeName(String name) {
if (name != null) {
int i = name.indexOf('\'');
if (i < 0) {
return name;
}
int k = 1;
while (true) {
i = name.indexOf('\'', i+1);
if (i < 0) {
break;
}
++k;
}
int l = name.length();
k += l;
char[] c = new char[k];
name.getChars(0, l, c, 0);
while (k != l) {
if ((c[--k] = c[--l]) == '\'') {
c[--k] = '\'';
}
}
return new String(c);
}
return null;
}
/**
* Executes the Command Line Processor.
* @param db2 DB2 commands which will be sent to the Command Line Processor.
**/
public static void db2CLP(String db2) throws IOException {
FileOutputStream out = null;
File db2File = null;
try {
db2File = File.createTempFile("db2clp", ".ddl");
out = new FileOutputStream(db2File.getAbsolutePath());
out.write(db2.getBytes());
out.close();
out = null;
ProcessUtils.exec("db2cmd -c \"db2 -tf " + db2File.getAbsolutePath() + '\"', System.out, true);
} finally {
StreamUtils.close(out);
if (db2File != null) {
db2File.deleteOnExit();
}
}
}
/**
* Converts days to time millis.
* @param days days
* @return converted days to time millis.
**/
public static long convertDaysToTimeMillis(long days) {
return days*24*3600000L-DB2_DAYS_MILLIS_DIFF;
}
/**
* Converts days to time millis.
* @param days days
* @return converted days to time millis.
**/
public static long convertTimeMillisToDays(long timeMillis) {
return (timeMillis+DB2_DAYS_MILLIS_DIFF)/(24*3600000L);
}
/**
* Generates logging statements.
* @param serverId ID of the server
* @param stmt statement object's database
* @param sqlStatement SQL statement which should be logged
* @return the SQL statement where 'CURRENT TIMESTAMP' is replaced by the current timestamp.
**/
private static String getLogStatement(int serverId, Statement stmt, String sqlStatement, StringBuffer buffer) {
buffer.delete(0, buffer.length());
int l = sqlStatement.length();
String currentTime = new Timestamp(System.currentTimeMillis()).toString();
int idx = 0;
while (idx < l) {
int i = sqlStatement.indexOf("CURRENT TIMESTAMP", idx);
if (i == -1) {
break;
}
buffer.append(sqlStatement.substring(idx, i));
buffer.append('\'');
buffer.append(currentTime);
buffer.append('\'');
idx = i+17;
}
if (idx < l) {
buffer.append(sqlStatement.substring(idx));
}
sqlStatement = buffer.toString();
buffer.delete(0, buffer.length());
buffer.append("INSERT INTO zeta.server_synchronization (server_id,sql_statement) VALUES (");
buffer.append(serverId);
buffer.append(",'");
buffer.append(encodeName(sqlStatement));
buffer.append("')");
return sqlStatement;
}
private static int numberOfServers = -1;
private final static long DB2_DAYS_MILLIS_DIFF = 719162L*24*3600000L;
}
| DatabaseUtils |