Package org.apache.commons.pool2

Class PoolUtils.ErodingKeyedObjectPool<K,​V>

  • Type Parameters:
    K - object pool key type
    V - object pool value type
    All Implemented Interfaces:
    java.io.Closeable, java.lang.AutoCloseable, KeyedObjectPool<K,​V>
    Direct Known Subclasses:
    PoolUtils.ErodingPerKeyKeyedObjectPool
    Enclosing class:
    PoolUtils
    private static class PoolUtils.ErodingKeyedObjectPool<K,​V>
extends java.lang.Object
implements KeyedObjectPool<K,​V>
    Decorates a keyed object pool, adding "eroding" behavior. Based on the configured erosion factor, objects returning to the pool may be invalidated instead of being added to idle capacity.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void addObject​(K key)
      Creates an object using the factory or other implementation dependent mechanism, passivate it, and then place it in the idle object pool.
      V borrowObject​(K key)
      Borrows an instance from this pool for the specified key.
      void clear()
      Clears the pool, removing all pooled instances (optional operation).
      void clear​(K key)
      Clears the specified pool, removing all pooled instances corresponding to the given key (optional operation).
      void close()
      Closes this pool, and free any resources associated with it.
      protected PoolUtils.ErodingFactor getErodingFactor​(K key)
      Gets the eroding factor for the given key
      protected KeyedObjectPool<K,​V> getKeyedPool()
      Gets the underlying pool
      java.util.List<K> getKeys()
      Gets a copy of the pool key list.
      int getNumActive()
      Gets the total number of instances currently borrowed from this pool but not yet returned.
      int getNumActive​(K key)
      Gets the number of instances currently borrowed from but not yet returned to the pool corresponding to the given key.
      int getNumIdle()
      Gets the total number of instances currently idle in this pool.
      int getNumIdle​(K key)
      Gets the number of instances corresponding to the given key currently idle in this pool.
      void invalidateObject​(K key, V obj)
      Invalidates an object from the pool.
      void returnObject​(K key, V obj)
      Returns obj to the pool, unless erosion is triggered, in which case obj is invalidated.
      java.lang.String toString()

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • ErodingKeyedObjectPool

        private ErodingKeyedObjectPool​(KeyedObjectPool<K,​V> keyedPool,
                               PoolUtils.ErodingFactor erodingFactor)
        Creates an ErodingObjectPool wrapping the given pool using the specified erosion factor.
        Parameters:
        keyedPool - underlying pool - must not be null
        erodingFactor - erosion factor - determines the frequency of erosion events
        See Also:
        erodingFactor

      • ErodingKeyedObjectPool

        private ErodingKeyedObjectPool​(KeyedObjectPool<K,​V> keyedPool,
                               float factor)
        Creates an ErodingObjectPool wrapping the given pool using the specified erosion factor.
        Parameters:
        keyedPool - underlying pool
        factor - erosion factor - determines the frequency of erosion events
        See Also:
        erodingFactor

    • Method Detail

      • addObject

        public void addObject​(K key)
               throws java.lang.Exception
        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 KeyedObjectPool<K,​V>
        Parameters:
        key - the key a new instance should be added to
        Throws:
        java.lang.Exception - when KeyedPooledObjectFactory.makeObject(K) fails.
        java.lang.IllegalStateException - after KeyedObjectPool.close() has been called on this pool.
        java.lang.UnsupportedOperationException - when this pool cannot add new idle objects.

      • borrowObject

        public V borrowObject​(K key)
               throws java.lang.Exception
        Borrows an instance from this pool for the specified key.

        Instances returned from this method will have been either newly created with makeObject or will be a previously idle object and have been activated with activateObject and then (optionally) validated with validateObject.

        By contract, clients must return the borrowed object using returnObject, invalidateObject, or a related method as defined in an implementation or sub-interface, using a key that is equivalent to the one used to borrow the instance in the first place.

        The behavior of this method when the pool has been exhausted is not strictly specified (although it may be specified by implementations).

        Specified by:
        borrowObject in interface KeyedObjectPool<K,​V>
        Parameters:
        key - the key used to obtain the object
        Returns:
        an instance from this pool.
        Throws:
        java.lang.IllegalStateException - after close has been called on this pool
        java.lang.Exception - when makeObject throws an exception
        java.util.NoSuchElementException - when the pool is exhausted and cannot or will not return another instance

      • clear

        public void clear()
           throws java.lang.Exception
        Clears the pool, removing all pooled instances (optional operation).
        Specified by:
        clear in interface KeyedObjectPool<K,​V>
        Throws:
        java.lang.UnsupportedOperationException - when this implementation doesn't support the operation
        java.lang.Exception - if the pool cannot be cleared

      • clear

        public void clear​(K key)
           throws java.lang.Exception
        Clears the specified pool, removing all pooled instances corresponding to the given key (optional operation).
        Specified by:
        clear in interface KeyedObjectPool<K,​V>
        Parameters:
        key - the key to clear
        Throws:
        java.lang.UnsupportedOperationException - when this implementation doesn't support the operation
        java.lang.Exception - if the key cannot be cleared

      • close

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

        Calling addObject or 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 KeyedObjectPool<K,​V>

      • getErodingFactor

        protected PoolUtils.ErodingFactor getErodingFactor​(K key)
        Gets the eroding factor for the given key
        Parameters:
        key - key
        Returns:
        eroding factor for the given keyed pool

      • getKeyedPool

        protected KeyedObjectPool<K,​V> getKeyedPool()
        Gets the underlying pool
        Returns:
        the keyed pool that this ErodingKeyedObjectPool wraps

      • getKeys

        public java.util.List<K> getKeys()
        Gets a copy of the pool key list.

        Note: The default implementation returns an empty list. Implementations should override this method.

        Specified by:
        getKeys in interface KeyedObjectPool<K,​V>
        Returns:
        a copy of the pool key list.

      • getNumActive

        public int getNumActive()
        Gets the total number of instances currently borrowed from this pool but not yet returned. Returns a negative value if this information is not available.
        Specified by:
        getNumActive in interface KeyedObjectPool<K,​V>
        Returns:
        the total number of instances currently borrowed from this pool but not yet returned.

      • getNumActive

        public int getNumActive​(K key)
        Gets the number of instances currently borrowed from but not yet returned to the pool corresponding to the given key. Returns a negative value if this information is not available.
        Specified by:
        getNumActive in interface KeyedObjectPool<K,​V>
        Parameters:
        key - the key to query
        Returns:
        the number of instances currently borrowed from but not yet returned to the pool corresponding to the given key.

      • getNumIdle

        public int getNumIdle()
        Gets the total number of instances currently idle in this pool. Returns a negative value if this information is not available.
        Specified by:
        getNumIdle in interface KeyedObjectPool<K,​V>
        Returns:
        the total number of instances currently idle in this pool.

      • getNumIdle

        public int getNumIdle​(K key)
        Gets the number of instances corresponding to the given key currently idle in this pool. Returns a negative value if this information is not available.
        Specified by:
        getNumIdle in interface KeyedObjectPool<K,​V>
        Parameters:
        key - the key to query
        Returns:
        the number of instances corresponding to the given key currently idle in this pool.

      • invalidateObject

        public void invalidateObject​(K key,
                             V obj)
        Invalidates an object from the pool.

        By contract, obj must have been obtained using borrowObject or a related method as defined in an implementation or sub-interface using a key that is equivalent to the one used to borrow the Object in the first place.

        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 KeyedObjectPool<K,​V>
        Parameters:
        key - the key used to obtain the object
        obj - a borrowed instance to be returned.

      • returnObject

        public void returnObject​(K key,
                         V obj)
                  throws java.lang.Exception
        Returns obj to the pool, unless erosion is triggered, in which case obj is invalidated. Erosion is triggered when there are idle instances in the pool associated with the given key and more than the configured erosion factor time has elapsed since the last returnObject activation.
        Specified by:
        returnObject in interface KeyedObjectPool<K,​V>
        Parameters:
        obj - object to return or invalidate
        key - key
        Throws:
        java.lang.IllegalStateException - if an attempt is made to return an object to the pool that is in any state other than allocated (i.e. borrowed). Attempting to return an object more than once or attempting to return an object that was never borrowed from the pool will trigger this exception.
        java.lang.Exception - if an instance cannot be returned to the pool
        See Also:
        erodingFactor

      • toString

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