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package com.avaje.ebeaninternal.server.lib;

import com.avaje.ebean.common.SpiContainer;
import com.avaje.ebeaninternal.api.ClassUtil;
import com.avaje.ebeaninternal.api.SpiEbeanServer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;

/**
 * Manages the shutdown of the JVM Runtime.
 * 
 * Makes sure all the resources are shutdown properly and in order.
 * 
 */
public final class ShutdownManager {

	private static final Logger logger = LoggerFactory.getLogger(ShutdownManager.class);

	static final List servers = new ArrayList();

	static final ShutdownHook shutdownHook = new ShutdownHook();

	static boolean stopping;

	static SpiContainer container;

	static {
		// Register the Shutdown hook
		registerShutdownHook();
	}

	/**
	 * Disallow construction.
	 */
	private ShutdownManager() {
	}

	public static void registerContainer(SpiContainer ebeanContainer){
		container = ebeanContainer;
	}
	
	/**
	 * Make sure the ShutdownManager is activated.
	 */
	public static void touch() {
	  // Do nothing
	}

	/**
	 * Return true if the system is in the process of stopping.
	 */
	public static boolean isStopping() {
		synchronized (servers) {
			return stopping;
		}
	}

	/**
	 * Deregister the Shutdown hook.
   * 
   * In calling this method it is expected that application code will invoke
   * the shutdown() method.
   * 
	 * 
	 * For running in a Servlet Container a redeploy will cause a shutdown, and
	 * for that case we need to make sure the shutdown hook is deregistered.
	 * 
	 */
	public static void deregisterShutdownHook() {
		synchronized (servers) {
			try {
				Runtime.getRuntime().removeShutdownHook(shutdownHook);
			} catch (IllegalStateException ex) {
				if (!ex.getMessage().equals("Shutdown in progress")) {
					throw ex;
				}
			}
		}
	}

	/**
	 * Register the shutdown hook with the Runtime.
	 */
	protected static void registerShutdownHook() {
		synchronized (servers) {
			try {
        String value = System.getProperty("ebean.registerShutdownHook");
        if (value == null || !value.trim().equalsIgnoreCase("false")) {
          Runtime.getRuntime().addShutdownHook(shutdownHook);
        }
			} catch (IllegalStateException ex) {
				if (!ex.getMessage().equals("Shutdown in progress")) {
					throw ex;
				}
			}
		}
	}

  /**
   * Shutdown gracefully cleaning up any resources as required.
   * 
   * This is typically invoked via JVM shutdown hook.
   * 
   */
  public static void shutdown() {
    synchronized (servers) {
      if (stopping) {
        // Already run shutdown...
        return;
      }

      if (logger.isDebugEnabled()) {
        logger.debug("Shutting down");
      }

      stopping = true;

      deregisterShutdownHook();

      String shutdownRunner = System.getProperty("ebean.shutdown.runnable");
      if (shutdownRunner != null) {
        try {
          // A custom runnable executed at the start of shutdown
          Runnable r = (Runnable) ClassUtil.newInstance(shutdownRunner);
          r.run();
        } catch (Exception e) {
          logger.error("Error running custom shutdown runnable", e);
        }
      }
      
      if (container != null) {
        // shutdown cluster networking if active
        container.shutdown();
      }

      // shutdown any registered servers that have not
      // already been shutdown manually
      for (SpiEbeanServer server : servers) {
        try {
          server.shutdownManaged();
        } catch (Exception ex) {
          logger.error("Error executing shutdown runnable", ex);
          ex.printStackTrace();
        }
      }
      
      if ("true".equalsIgnoreCase(System.getProperty("ebean.datasource.deregisterAllDrivers", "false"))) {
        deregisterAllJdbcDrivers();
      }  
    }
  }

  private static void deregisterAllJdbcDrivers() {
    // This manually deregisters all JDBC drivers
    Enumeration drivers = DriverManager.getDrivers();
    while (drivers.hasMoreElements()) {
      Driver driver = drivers.nextElement();
      try {
        logger.info("Deregistering jdbc driver: "+driver);
        DriverManager.deregisterDriver(driver);
      } catch (SQLException e) {
        logger.error("Error deregistering driver "+driver, e);
      }
    }
  }
	
	/**
	 * Register an ebeanServer to be shutdown when the JVM is shutdown. 
	 */
	public static void registerEbeanServer(SpiEbeanServer server) {
		synchronized (servers) {
			servers.add(server);
		}
	}
	
	/**
	 * Deregister an ebeanServer.
	 * 
	 * This is done when the ebeanServer is shutdown manually.
	 * 
	 */
  public static void unregisterEbeanServer(SpiEbeanServer server) {
    synchronized (servers) {
      servers.remove(server);
    }
  }
}