Logger.java

/*****************************************************************************
 * Copyright (C) 2008 EnterpriseDB Corporation.
 * Copyright (C) 2011 Stado Global Development Group.
 *
 * This file is part of Stado.
 *
 * Stado is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Stado is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Stado.  If not, see <http://www.gnu.org/licenses/>.
 *
 * You can find Stado at http://www.stado.us
 *
 ****************************************************************************/
package org.postgresql.driver.core;

import java.text.SimpleDateFormat;
import java.text.FieldPosition;
import java.sql.DriverManager;
import java.io.PrintWriter;
import java.util.Date;

import org.postgresql.driver.Driver;

/**
 * Poor man's logging infrastructure. This just deals with maintaining a per-
 * connection ID and log level, and timestamping output.
 */
public final class Logger {
    // For brevity we only log the time, not date or timezone (the main reason
    // for the timestamp is to see delays etc. between log lines, not to pin
    // down an instant in time)
    private final SimpleDateFormat dateFormat = new SimpleDateFormat("HH:mm:ss.SSS ");
    private final FieldPosition dummyPosition = new FieldPosition(0);
    private final StringBuffer buffer = new StringBuffer();
    private final String connectionIDString;

    private int level = 0;

    public Logger() {
        connectionIDString = "(driver) ";
    }

    public Logger(int connectionID) {
        connectionIDString = "(" + connectionID + ") ";
    }

    public void setLogLevel(int level) {
        this.level = level;
    }

    public int getLogLevel() {
        return level;
    }

    public boolean logDebug() {
        return level >= Driver.DEBUG;
    }

    public boolean logInfo() {
        return level >= Driver.INFO;
    }

    public void debug(String str) {
        debug(str, null);
    }

    public void debug(String str, Throwable t) {
        if (logDebug())
            log(str, t);
    }

    public void info(String str) {
        info(str, null);
    }

    public void info(String str, Throwable t) {
        if (logInfo())
            log(str, t);
    }

    public void log(String str, Throwable t) {
        PrintWriter writer = DriverManager.getLogWriter();
        if (writer == null)
            return;

        synchronized (this) {
            buffer.setLength(0);
            dateFormat.format(new Date(), buffer, dummyPosition);
            buffer.append(connectionIDString);
            buffer.append(str);
            
            // synchronize to ensure that the exception (if any) does
            // not get split up from the corresponding log message
            synchronized (writer) {
                writer.println(buffer.toString());        
                if (t != null)
                    t.printStackTrace(writer);
            }
        }
    }
}