Package org.apache.commons.pool2

Class PoolUtils.ErodingKeyedObjectPool<K,V>

java.lang.Object
org.apache.commons.pool2.PoolUtils.ErodingKeyedObjectPool<K,V>
Type Parameters:
K - object pool key type
V - object pool value type
All Implemented Interfaces:
Closeable, AutoCloseable, KeyedObjectPool<K,V>
Direct Known Subclasses:
PoolUtils.ErodingPerKeyKeyedObjectPool
Enclosing class:
PoolUtils
private static class PoolUtils.ErodingKeyedObjectPool<K,V> extends 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.

  • Field Details

  • Constructor Details

    • ErodingKeyedObjectPool

      protected 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:

    • ErodingKeyedObjectPool

      public 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:

  • Method Details

    • addObject

      public void addObject(K key) throws 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:
      Exception - when KeyedPooledObjectFactory.makeObject(K) fails.
      IllegalStateException - after KeyedObjectPool.close() has been called on this pool.
      UnsupportedOperationException - when this pool cannot add new idle objects.

    • borrowObject

      public V borrowObject(K key) throws 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:
      IllegalStateException - after close has been called on this pool
      Exception - when makeObject throws an exception
      NoSuchElementException - when the pool is exhausted and cannot or will not return another instance

    • clear

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

    • clear

      public void clear(K key) throws 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:
      UnsupportedOperationException - when this implementation doesn't support the operation
      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 AutoCloseable
      Specified by:
      close in interface 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 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 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:
      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.
      Exception - if an instance cannot be returned to the pool
      See Also:

    • toString

      public String toString()
      Overrides:
      toString in class Object