Examples of org.apache.derby.impl.services.daemon.BasicDaemon

Package org.apache.derby.impl.services.daemon

Examples of org.apache.derby.impl.services.daemon.BasicDaemon

org.apache.derby.impl.services.daemon.BasicDaemon
A BasicDaemon is a background worker thread which does asynchronous I/O and general clean up. It should not be used as a general worker thread for parallel execution. One cannot count on the order of request or count on when the daemon will wake up, even with serviceNow requests. Request are not persistent and not recoverable, they are all lost when the system crashes or is shutdown. System shutdown, even orderly ones, do not wait for daemons to finish its work or empty its queue. Furthermore, any Serviceable subscriptions, including onDemandOnly, must tolerate spurious services. The BasicDaemon will setup a context manager with no context on it. The Serviceable object's performWork must provide useful context on the context manager to do its work. The BasicDaemon will wrap performWork call with try / catch block and will use the ContextManager's error handling to clean up any error. The BasicDaemon will guarentee serviceNow request will not be lost as long as the jbms does not crash - however, if N serviceNow requests are made by the same client, it may only be serviced once, not N times. Many Serviceable object will subscribe to the same BasicDaemon. Their performWork method should be well behaved - in other words, it should not take too long or hog too many resources or deadlock with anyone else. And it cannot (should not) error out. The BasicDaemon implementation manages the DaemonService's data structure, handles subscriptions and enqueues requests, and determine the service schedule for its Serviceable objects. The BasicDaemon keeps an array (Vector) of Serviceable subscriptions it also keeps 2 queues for clients that uses it for one time service - the 1st queue is for a serviceNow enqueue request, the 2nd queue is for non serviceNow enqueue request. This BasicDaemon services its clients in the following order: 1. any subscribed client that have made a serviceNow request that has not been fulfilled 2. serviceable clients on the 1st queue 3. all subscribed clients that are not onDemandOnly 4. serviceable clients 2nd queue

   */


  /* make a daemon service with the default timer */
  public DaemonService createNewDaemon(String name)
  {
    BasicDaemon daemon = new BasicDaemon(contextService);


    Thread daemonThread = Monitor.getMonitor().getDaemonThread(daemon, name, false);
    daemonThread.start();
    return daemon;
  }

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   */


  /* make a daemon service with the default timer */
  public DaemonService createNewDaemon(String name)
  {
    BasicDaemon daemon = new BasicDaemon(contextService);


    final Thread daemonThread = Monitor.getMonitor().getDaemonThread(daemon, name, false);
    // DERBY-3745.  setContextClassLoader for thread to null to avoid
    // leaking class loaders.
    try {

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   */


  /* make a daemon service with the default timer */
  public DaemonService createNewDaemon(String name)
  {
    BasicDaemon daemon = new BasicDaemon(contextService);


    final Thread daemonThread = Monitor.getMonitor().getDaemonThread(daemon, name, false);
    // DERBY-3745.  setContextClassLoader for thread to null to avoid
    // leaking class loaders.
    try {

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   */


  /* make a daemon service with the default timer */
  public DaemonService createNewDaemon(String name)
  {
    BasicDaemon daemon = new BasicDaemon(contextService);


    Thread daemonThread = Monitor.getMonitor().getDaemonThread(daemon, name, false);
    daemonThread.start();
    return daemon;
  }

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Related Classes of org.apache.derby.impl.services.daemon.BasicDaemon

org.apache.derby.iapi.services.context.ContextManager

org.apache.derby.iapi.services.daemon.Serviceable

org.apache.derby.iapi.services.monitor.ModuleFactory

org.apache.derby.impl.services.daemon.SingleThreadDaemonFactory

java.util.Vector

java.util.List

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