Class PoolUtils.SynchronizedObjectPool<T>

  • Type Parameters:
    T - type of objects in the pool
    All Implemented Interfaces:
    java.io.Closeable, java.lang.AutoCloseable, ObjectPool<T>
    Enclosing class:
    PoolUtils

    private static final class PoolUtils.SynchronizedObjectPool<T>
    extends java.lang.Object
    implements ObjectPool<T>
    A synchronized (thread-safe) ObjectPool backed by the specified ObjectPool.

    Note: This should not be used on pool implementations that already provide proper synchronization such as the pools provided in the Commons Pool library. Wrapping a pool that waits for poolable objects to be returned before allowing another one to be borrowed with another layer of synchronization will cause liveliness issues or a deadlock.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      private ObjectPool<T> pool
      the underlying object pool
      private java.util.concurrent.locks.ReentrantReadWriteLock readWriteLock
      Object whose monitor is used to synchronize methods on the wrapped pool.
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void addObject()
      Creates an object using the factory or other implementation dependent mechanism, passivate it, and then place it in the idle object pool.
      T borrowObject()
      Obtains an instance from this pool.
      void clear()
      Clears any objects sitting idle in the pool, releasing any associated resources (optional operation).
      void close()
      Closes this pool, and free any resources associated with it.
      int getNumActive()
      Returns the number of instances currently borrowed from this pool.
      int getNumIdle()
      Returns the number of instances currently idle in this pool.
      void invalidateObject​(T obj)
      Invalidates an object from the pool.
      void returnObject​(T obj)
      Returns an instance to the pool.
      java.lang.String toString()
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
      • Methods inherited from interface org.datanucleus.store.rdbms.datasource.dbcp2.pool2.ObjectPool

        addObjects
    • Field Detail

      • readWriteLock

        private final java.util.concurrent.locks.ReentrantReadWriteLock readWriteLock
        Object whose monitor is used to synchronize methods on the wrapped pool.
      • pool

        private final ObjectPool<T> pool
        the underlying object pool
    • Constructor Detail

      • SynchronizedObjectPool

        SynchronizedObjectPool​(ObjectPool<T> pool)
                        throws java.lang.IllegalArgumentException
        Creates a new SynchronizedObjectPool wrapping the given pool.
        Parameters:
        pool - the ObjectPool to be "wrapped" in a synchronized ObjectPool.
        Throws:
        java.lang.IllegalArgumentException - if the pool is null
    • Method Detail

      • returnObject

        public void returnObject​(T obj)
        Returns an instance to the pool. By contract, obj must have been obtained using ObjectPool.borrowObject() or a related method as defined in an implementation or sub-interface.
        Specified by:
        returnObject in interface ObjectPool<T>
        Parameters:
        obj - a borrowed instance to be returned.
      • invalidateObject

        public void invalidateObject​(T obj)
        Invalidates an object from the pool.

        By contract, obj must have been obtained using ObjectPool.borrowObject() or a related method as defined in an implementation or sub-interface.

        This method should be used when an object that has been borrowed is determined (due to an exception or other problem) to be invalid.

        Specified by:
        invalidateObject in interface ObjectPool<T>
        Parameters:
        obj - a borrowed instance to be disposed.
      • addObject

        public void addObject()
                       throws java.lang.Exception,
                              java.lang.IllegalStateException,
                              java.lang.UnsupportedOperationException
        Creates an object using the factory or other implementation dependent mechanism, passivate it, and then place it in the idle object pool. addObject is useful for "pre-loading" a pool with idle objects. (Optional operation).
        Specified by:
        addObject in interface ObjectPool<T>
        Throws:
        java.lang.Exception - when PooledObjectFactory.makeObject() fails.
        java.lang.IllegalStateException - after ObjectPool.close() has been called on this pool.
        java.lang.UnsupportedOperationException - when this pool cannot add new idle objects.
      • getNumIdle

        public int getNumIdle()
        Returns the number of instances currently idle in this pool. This may be considered an approximation of the number of objects that can be borrowed without creating any new instances. Returns a negative value if this information is not available.
        Specified by:
        getNumIdle in interface ObjectPool<T>
        Returns:
        the number of instances currently idle in this pool.
      • getNumActive

        public int getNumActive()
        Returns the number of instances currently borrowed from this pool. Returns a negative value if this information is not available.
        Specified by:
        getNumActive in interface ObjectPool<T>
        Returns:
        the number of instances currently borrowed from this pool.
      • clear

        public void clear()
                   throws java.lang.Exception,
                          java.lang.UnsupportedOperationException
        Clears any objects sitting idle in the pool, releasing any associated resources (optional operation). Idle objects cleared must be PooledObjectFactory.destroyObject(PooledObject).
        Specified by:
        clear in interface ObjectPool<T>
        Throws:
        java.lang.UnsupportedOperationException - if this implementation does not support the operation
        java.lang.Exception - if the pool cannot be cleared
      • close

        public void close()
        Closes this pool, and free any resources associated with it.

        Calling ObjectPool.addObject() or ObjectPool.borrowObject() after invoking this method on a pool will cause them to throw an IllegalStateException.

        Implementations should silently fail if not all resources can be freed.

        Specified by:
        close in interface java.lang.AutoCloseable
        Specified by:
        close in interface java.io.Closeable
        Specified by:
        close in interface ObjectPool<T>
      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object