Package org.conical.common.bbl.db

Class DbConnectionBroker

java.lang.Object
org.conical.common.bbl.db.DbConnectionBroker
All Implemented Interfaces:
Runnable, Wrapper, CommonDataSource, DataSource
public class DbConnectionBroker extends Object implements DataSource, Runnable
Pooled Data Source Creates and manages a pool of database connections. Modified by Ryan Doherty to implement javax.sql.DataSource, from an original work by Marc Mnich
Version:
1.0.13 3/12/02
Author:
Marc A. Mnich, Ryan R. Doherty

  • Constructor Details

    • DbConnectionBroker

      public DbConnectionBroker(String dbDriver, String dbServer, String dbLogin, String dbPassword, int minConns, int maxConns, double maxConnTime) throws IOException
      Creates a new Connection Broker
      dbDriver: JDBC driver. e.g. 'oracle.jdbc.driver.OracleDriver'
      dbServer: JDBC connect string. e.g. 'jdbc:oracle:thin:@203.92.21.109:1526:orcl'
      dbLogin: Database login name. e.g. 'Scott'
      dbPassword: Database password. e.g. 'Tiger'
      minConns: Minimum number of connections to start with.
      maxConns: Maximum number of connections in dynamic pool.
      logFileString: Absolute path name for log file. e.g. 'c:/temp/mylog.log'
      maxConnTime: Time in days between connection resets. (Reset does a basic cleanup)
      logAppend: Append to logfile (optional)
      maxCheckoutSeconds: Max time a connection can be checked out before being recycled. Zero value turns option off, default is 60 seconds. debugLevel: Level of debug messages output to the log file. 0 -> no messages, 1 -> Errors, 2 -> Warnings, 3 -> Information
      Throws:
      IOException

    • DbConnectionBroker

      public DbConnectionBroker(String dbDriver, String dbServer, String dbLogin, String dbPassword, int minConns, int maxConns, double maxConnTime, boolean logAppend) throws IOException
      Throws:
      IOException

    • DbConnectionBroker

      public DbConnectionBroker(String dbDriver, String dbServer, String dbLogin, String dbPassword, int minConns, int maxConns, double maxConnTime, boolean logAppend, int maxCheckoutSeconds, int debugLevel) throws IOException
      Throws:
      IOException

  • Method Details

    • run

      public void run()
      Housekeeping thread. Runs in the background with low CPU overhead. Connections are checked for warnings and closure and are periodically restarted. This thread is a catchall for corrupted connections and prevents the buildup of open cursors. (Open cursors result when the application fails to close a Statement). This method acts as fault tolerance for bad connection/statement programming.
      Specified by:
      run in interface Runnable

    • getConnection

      public Connection getConnection()
      This method hands out the connections in round-robin order. This prevents a faulty connection from locking up an application entirely. A browser 'refresh' will get the next connection while the faulty connection is cleaned up by the housekeeping thread. If the min number of threads are ever exhausted, new threads are added up the the max thread count. Finally, if all threads are in use, this method waits 2 seconds and tries again, up to ten times. After that, it returns a null.
      Specified by:
      getConnection in interface DataSource

    • freeConnection

      public String freeConnection(Connection conn)
      Frees a connection. Replaces connection back into the main pool for reuse.

    • getAge

      public long getAge(Connection conn)
      Returns the age of a connection -- the time since it was handed out to an application.

    • destroy

      public void destroy(int millis) throws SQLException
      Multi-phase shutdown. having following sequence:
      1. getConnection() will refuse to return connections.
      2. The housekeeping thread is shut down.
        Up to the time of millis milliseconds after shutdown of the housekeeping thread, freeConnection() can still be called to return used connections.
      3. After millis milliseconds after the shutdown of the housekeeping thread, all connections in the pool are closed.
      4. If any connections were in use while being closed then a SQLException is thrown.
      5. The log is closed.

      Call this method from a servlet destroy() method.
      Parameters:
      millis - the time to wait in milliseconds.
      Throws:
      SQLException - if connections were in use after millis.

    • destroy

      public void destroy()
      Less safe shutdown. Uses default timeout value. This method simply calls the destroy() method with a millis value of 10000 (10 seconds) and ignores SQLException thrown by that method.
      See Also:

    • getSize

      public int getSize()
      Returns the number of connections in the dynamic pool.

    • getConnection

      public Connection getConnection(String username, String password) throws SQLException
      Ignores the username and password passed in. Once created, this datasource will only connect as a single user.
      Specified by:
      getConnection in interface DataSource
      Throws:
      SQLException

    • getLoginTimeout

      public int getLoginTimeout() throws SQLException
      Specified by:
      getLoginTimeout in interface CommonDataSource
      Specified by:
      getLoginTimeout in interface DataSource
      Throws:
      SQLException

    • setLoginTimeout

      public void setLoginTimeout(int seconds) throws SQLException
      Specified by:
      setLoginTimeout in interface CommonDataSource
      Specified by:
      setLoginTimeout in interface DataSource
      Throws:
      SQLException

    • isWrapperFor

      public boolean isWrapperFor(Class<?> iface) throws SQLException
      Specified by:
      isWrapperFor in interface Wrapper
      Throws:
      SQLException

    • unwrap

      public <T> T unwrap(Class<T> iface) throws SQLException
      Specified by:
      unwrap in interface Wrapper
      Throws:
      SQLException

    • getLogWriter

      public PrintWriter getLogWriter() throws SQLException
      Specified by:
      getLogWriter in interface CommonDataSource
      Specified by:
      getLogWriter in interface DataSource
      Throws:
      SQLException

    • setLogWriter

      public void setLogWriter(PrintWriter out) throws SQLException
      Specified by:
      setLogWriter in interface CommonDataSource
      Specified by:
      setLogWriter in interface DataSource
      Throws:
      SQLException

    • getParentLogger

      public Logger getParentLogger() throws SQLFeatureNotSupportedException
      Specified by:
      getParentLogger in interface CommonDataSource
      Throws:
      SQLFeatureNotSupportedException