ACE_Pair_Caching_Utility< KEY, VALUE, CONTAINER, ITERATOR, ATTRIBUTES > Class Template Reference

Defines a helper class for the Caching Strategies. More...

#include <Caching_Utility_T.h>

Collaboration diagram for ACE_Pair_Caching_Utility< KEY, VALUE, CONTAINER, ITERATOR, ATTRIBUTES >:

List of all members.

Public Types
typedef ACE_Cleanup_Strategy < KEY, VALUE, CONTAINER >	CLEANUP_STRATEGY
Public Member Functions
	ACE_Pair_Caching_Utility (ACE_Cleanup_Strategy< KEY, VALUE, CONTAINER > *cleanup_strategy=0, int delete_cleanup_strategy=0)
	Constructor.
	~ACE_Pair_Caching_Utility (void)
	Destructor.
int	clear_cache (CONTAINER &container, double purge_percent)
Protected Member Functions
void	minimum (CONTAINER &container, KEY *&key_to_remove, VALUE *&value_to_remove)
	Find the entry with minimum caching attributes.
void	operator= (const APUTIL< KEY, VALUE, CONTAINER, ITERATOR, ATTRIBUTES > &)
	APUTIL (const APUTIL< KEY, VALUE, CONTAINER, ITERATOR, ATTRIBUTES > &)
Protected Attributes
CLEANUP_STRATEGY *	cleanup_strategy_
int	delete_cleanup_strategy_
	Whether the cleanup_strategy should be destroyed or not.

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Detailed Description

template<class KEY, class VALUE, class CONTAINER, class ITERATOR, class ATTRIBUTES>
class ACE_Pair_Caching_Utility< KEY, VALUE, CONTAINER, ITERATOR, ATTRIBUTES >

Defines a helper class for the Caching Strategies.

This class defines the methods commonly used by the different caching strategies. For instance: <clear_cache> method which decides and purges the entry from the container.

Note:

This class helps in the caching_strategies using a container containing entries of <KEY, ACE_Pair<VALUE, attributes>> kind. The attributes helps in deciding the entries to be purged. The Cleanup_Strategy is the callback class to which the entries to be cleaned up will be delegated.

Definition at line 47 of file Caching_Utility_T.h.

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Member Typedef Documentation

template<class KEY, class VALUE, class CONTAINER, class ITERATOR, class ATTRIBUTES>

typedef ACE_Cleanup_Strategy<KEY, VALUE, CONTAINER> ACE_Pair_Caching_Utility< KEY, VALUE, CONTAINER, ITERATOR, ATTRIBUTES >::CLEANUP_STRATEGY

Definition at line 51 of file Caching_Utility_T.h.

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Constructor & Destructor Documentation

template<class KEY , class VALUE , class CONTAINER , class ITERATOR , class ATTRIBUTES >

ACE_Pair_Caching_Utility< KEY, VALUE, CONTAINER, ITERATOR, ATTRIBUTES >::ACE_Pair_Caching_Utility	(	ACE_Cleanup_Strategy< KEY, VALUE, CONTAINER > *	cleanup_strategy = 0,
		int	delete_cleanup_strategy = 0
	)

Constructor.

Definition at line 21 of file Caching_Utility_T.cpp.

  : cleanup_strategy_ (cleanup_strategy),
    delete_cleanup_strategy_ (delete_cleanup_strategy)
{
  if (cleanup_strategy == 0)
    {
      ACE_NEW (this->cleanup_strategy_,
               CLEANUP_STRATEGY);
      this->delete_cleanup_strategy_ = 1;
    }
}

template<class KEY , class VALUE , class CONTAINER , class ITERATOR , class ATTRIBUTES >

ACE_Pair_Caching_Utility< KEY, VALUE, CONTAINER, ITERATOR, ATTRIBUTES >::~ACE_Pair_Caching_Utility

(

void

)

Destructor.

Definition at line 35 of file Caching_Utility_T.cpp.

{
  if (this->delete_cleanup_strategy_)
    delete this->cleanup_strategy_;
}

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Member Function Documentation

template<class KEY, class VALUE, class CONTAINER, class ITERATOR, class ATTRIBUTES>

ACE_Pair_Caching_Utility< KEY, VALUE, CONTAINER, ITERATOR, ATTRIBUTES >::APUTIL

(

const APUTIL< KEY, VALUE, CONTAINER, ITERATOR, ATTRIBUTES > &

)

[protected]

template<class KEY , class VALUE , class CONTAINER , class ITERATOR , class ATTRIBUTES >

int ACE_Pair_Caching_Utility< KEY, VALUE, CONTAINER, ITERATOR, ATTRIBUTES >::clear_cache	(	CONTAINER &	container,
		double	purge_percent
	)

Purge entries from the container. The Cleanup_Strategy will do the actual job of cleanup once the entries to be cleaned up are decided.

Definition at line 42 of file Caching_Utility_T.cpp.

{
  // Check that the purge_percent is non-zero.
  if (purge_percent == 0)
    return 0;

  // Get the number of entries in the container.
  size_t current_map_size = container.current_size ();

  // Also whether the number of entries in the cache!
  // Oops! then there is no way out but exiting. So return an error.
  if (current_map_size == 0)
    return 0;

  // Calculate the no of entries to remove from the cache depending
  // upon the <purge_percent>.
  size_t const entries_to_remove
    = ACE_MAX (static_cast<size_t> (1),
               static_cast<size_t> (static_cast<double> (purge_percent)
                                    / 100 * current_map_size));
  KEY *key_to_remove = 0;
  VALUE *value_to_remove = 0;

  for (size_t i = 0; i < entries_to_remove ; ++i)
    {
      this->minimum (container,
                     key_to_remove,
                     value_to_remove);

      // Simply verifying that the key is non-zero.
      // This is important for strategies where the minimum
      // entry cant be found due to constraints on the type of entry
      // to remove.
      if (key_to_remove == 0)
        return 0;

      if (this->cleanup_strategy_->cleanup (container,
                                            key_to_remove,
                                            value_to_remove) == -1)
        return -1;

    }

  return 0;
}

template<class KEY , class VALUE , class CONTAINER , class ITERATOR , class ATTRIBUTES >

void ACE_Pair_Caching_Utility< KEY, VALUE, CONTAINER, ITERATOR, ATTRIBUTES >::minimum	(	CONTAINER &	container,
		KEY *&	key_to_remove,
		VALUE *&	value_to_remove
	)			[protected]

Find the entry with minimum caching attributes.

Definition at line 90 of file Caching_Utility_T.cpp.

{
  // Starting values.
  ITERATOR iter = container.begin ();
  ITERATOR end = container.end ();
  ATTRIBUTES min = (*iter).int_id_.second ();
  key_to_remove = &(*iter).ext_id_;
  value_to_remove = &(*iter).int_id_;

  // The iterator moves thru the container searching for the entry
  // with the lowest ATTRIBUTES.
  for (++iter;
       iter != end;
       ++iter)
    {
      if (min > (*iter).int_id_.second ())
        {
          // Ah! an item with lower ATTTRIBUTES...
          min = (*iter).int_id_.second ();
          key_to_remove = &(*iter).ext_id_;
          value_to_remove = &(*iter).int_id_;
        }
    }
}

template<class KEY, class VALUE, class CONTAINER, class ITERATOR, class ATTRIBUTES>

void ACE_Pair_Caching_Utility< KEY, VALUE, CONTAINER, ITERATOR, ATTRIBUTES >::operator=

(

const APUTIL< KEY, VALUE, CONTAINER, ITERATOR, ATTRIBUTES > &

)

[protected]

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Member Data Documentation

template<class KEY, class VALUE, class CONTAINER, class ITERATOR, class ATTRIBUTES>

CLEANUP_STRATEGY* ACE_Pair_Caching_Utility< KEY, VALUE, CONTAINER, ITERATOR, ATTRIBUTES >::cleanup_strategy_ [protected]

The cleanup strategy which can be used to destroy the entries of the container.

Definition at line 76 of file Caching_Utility_T.h.

template<class KEY, class VALUE, class CONTAINER, class ITERATOR, class ATTRIBUTES>

int ACE_Pair_Caching_Utility< KEY, VALUE, CONTAINER, ITERATOR, ATTRIBUTES >::delete_cleanup_strategy_ [protected]

Whether the cleanup_strategy should be destroyed or not.

Definition at line 79 of file Caching_Utility_T.h.

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The documentation for this class was generated from the following files:

• Caching_Utility_T.h
• Caching_Utility_T.cpp