Class SlowQueryReportJmx.PoolJmx

java.lang.Object
org.apache.tomcat.jdbc.pool.interceptor.SlowQueryReportJmx.PoolJmx
Enclosing class:
SlowQueryReportJmx
protected static class SlowQueryReportJmx.PoolJmx extends Object
Everything this class publishes for one pool: the notification broadcaster its clients attach their listeners to and, in the notifyPool=false mode, the ObjectName the pool's MBean occupies.

The state hangs from the pool's statistics store (see SlowQueryReport.PoolStatistics.getJmxState()), which is 1:1 with the pool, and nothing a pool published can be given up by another pool's close. It is built by the first borrower that needs it and given up by the release of the store it hangs from, which is what the close of the pool is.

The publication is attempted once per pool: JMX is a best-effort management channel, so a refusal is logged and not retried by later borrows. Publication and release are serialised against each other by this object's monitor, and the MBeanServer is called outside it: a borrow either publishes, finds that the attempt has already been made, or finds the state already superseded by the pool's close - in which case the borrow gives back the publication it just made. A published MBean can therefore never outlive the state that published it, and the ObjectName a release gives up is the one this state recorded when it published, whatever class or objectName property the interceptor instance running the close happens to carry.

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    protected
    PoolJmx(String poolName)
    Creates the JMX state of one pool.

  • Method Summary

    Modifier and Type
    Method
    Description
    protected boolean
    beginPublication()
    Decides whether the calling borrow is to make this pool's one publication attempt.
    protected NotificationBroadcasterSupport
    broadcaster()
    Returns the broadcaster all interceptor instances of this pool send their notifications through, building it on the first need.
    protected String
    getPoolName()
    Returns the name of the pool this state belongs to.
    protected boolean
    isReleased()
    Returns whether the close of this pool has given this state up.
    protected boolean
    published(ObjectName oname)
    Records a publication the MBeanServer accepted.
    protected ObjectName
    publishedUnder()
    Returns the ObjectName this pool's MBean is published under.
    protected void
    released()
    Gives up everything this state holds: the ObjectName the pool's MBean occupied, which the MBeanServer is asked to release, and with it the broadcaster the pool's clients' listeners are attached to.

    Methods inherited from class Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • PoolJmx

      protected PoolJmx(String poolName)
      Creates the JMX state of one pool.
      Parameters:
      poolName - the name the pool's registrations are keyed under

  • Method Details

    • getPoolName

      protected String getPoolName()
      Returns the name of the pool this state belongs to.
      Returns:
      the name recorded at the pool's start

    • publishedUnder

      protected ObjectName publishedUnder()
      Returns the ObjectName this pool's MBean is published under.
      Returns:
      the published ObjectName, or null while nothing is published for this pool

    • isReleased

      protected boolean isReleased()
      Returns whether the close of this pool has given this state up.
      Returns:
      true if the pool has closed

    • broadcaster

      protected NotificationBroadcasterSupport broadcaster()
      Returns the broadcaster all interceptor instances of this pool send their notifications through, building it on the first need.
      Returns:
      this pool's broadcaster; never null

    • beginPublication

      protected boolean beginPublication()
      Decides whether the calling borrow is to make this pool's one publication attempt.
      Returns:
      true if the caller is to attempt the publication - none has been made or attempted yet, and the pool has not closed - and false when there is nothing left to do

    • published

      protected boolean published(ObjectName oname)
      Records a publication the MBeanServer accepted.
      Parameters:
      oname - the ObjectName the MBean was published under
      Returns:
      true if the publication stands and is now this pool's MBean, and false when the pool's close landed while the MBeanServer was taking it in - nothing else in this JVM will ever learn of that publication, so the borrow that made it has to give it back

    • released

      protected void released()
      Gives up everything this state holds: the ObjectName the pool's MBean occupied, which the MBeanServer is asked to release, and with it the broadcaster the pool's clients' listeners are attached to. The close of the pool's statistics store calls this, and it is idempotent: a later call, from any thread, does nothing.

      The broadcaster itself is left in place rather than dropped: whoever still holds this pool's registration can subscribe to it, and a subscription made after the pool came down is served by a broadcaster nothing will ever send through, which is what a released registration has to answer a stale handle with. What must not survive the release is the published MBean, and it does not: the ObjectName is given up here, against the name this state recorded when it published.