// -*- C++ -*-

//=============================================================================
/**
 *  @file    Hash_Cache_Map_Manager_T.h
 *
 *  @author Kirthika Parameswaran <kirthika@cs.wustl.edu>
 */
//=============================================================================


#ifndef HASH_CACHE_MAP_MANAGER_T_H
#define HASH_CACHE_MAP_MANAGER_T_H

#include /**/ "ace/pre.h"

#include "ace/Hash_Map_Manager_T.h"
#include "ace/Cache_Map_Manager_T.h"

#if !defined (ACE_LACKS_PRAGMA_ONCE)
#pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */

#include "ace/Null_Mutex.h"

ACE_BEGIN_VERSIONED_NAMESPACE_DECL

// Forward declaration.
class ACE_Allocator;

#define ACE_CACHE_MAP_MANAGER \
        ACE_Cache_Map_Manager<KEY, \
                              VALUE, \
                              ACE_Hash_Map_Manager_Ex<KEY, std::pair<VALUE, ATTRIBUTES>, HASH_KEY, COMPARE_KEYS, ACE_Null_Mutex>, \
                              ACE_Hash_Map_Iterator_Ex<KEY, std::pair<VALUE, ATTRIBUTES>, HASH_KEY, COMPARE_KEYS, ACE_Null_Mutex>, \
                              ACE_Hash_Map_Reverse_Iterator_Ex<KEY, std::pair<VALUE, ATTRIBUTES>, HASH_KEY, COMPARE_KEYS, ACE_Null_Mutex>, \
                              CACHING_STRATEGY, \
                              ATTRIBUTES>

 /**
  * @class ACE_Hash_Cache_Map_Manager
  *
  * @brief Defines a abstraction which will purge entries from a map.
  * The map considered is the ACE_Hash_Map_Manager_Ex.
  *
  * The Hash_Cache_Map_Manager will manage the map it contains
  * and provide purging on demand from the map. The strategy for
  * caching is decided by the user and provided to the Cache
  * Manager.  The Cache Manager acts as a agent and communicates
  * between the Map and the Strategy for purging entries from the
  * map.  To tap the optimal methods like find(key,value,entry)
  * present in the ACE_Hash_Map_Manager,
  * Hash_Cache_Map_Manager provides extra functionality on top
  * of the Cache_Map_Manager.
  * No locking mechanism provided since locking at this level
  * isn't efficient.  Locking has to be provided by the
  * application.
  */
template <class KEY, class VALUE, class HASH_KEY, class COMPARE_KEYS, class CACHING_STRATEGY, class ATTRIBUTES>
class ACE_Hash_Cache_Map_Manager : public ACE_CACHE_MAP_MANAGER
{
 public:

  /**
   * The actual value mapped to the key in the map. The <attributes>
   * are used by the strategy and is transparent to the user of this
   * class.
   */
  typedef std::pair<VALUE, ATTRIBUTES> CACHE_VALUE;
  typedef ACE_Hash_Map_Manager_Ex<KEY, CACHE_VALUE, HASH_KEY, COMPARE_KEYS, ACE_Null_Mutex> HASH_MAP;
  typedef ACE_Hash_Map_Entry<KEY, CACHE_VALUE> CACHE_ENTRY;
  typedef KEY key_type;
  typedef VALUE mapped_type;

  // = Initialization and termination methods.
  /// Initialize a <Hash_Cache_Map_Manager> with @a size entries.
  ACE_Hash_Cache_Map_Manager (CACHING_STRATEGY &caching_s,
                              size_t size = ACE_DEFAULT_MAP_SIZE,
                              ACE_Allocator *alloc = 0);

  /// Close down a <Cache_Map_Manager> and release dynamically allocated
  /// resources.
  ~ACE_Hash_Cache_Map_Manager (void);

  /**
   * Associate @a key with @a value.  If @a key is already in the
   * MAP then the ENTRY is not changed.  Returns 0 if a new entry is
   * bound successfully, returns 1 if an attempt is made to bind an
   * existing entry, and returns -1 if failures occur.
   */
  int bind (const KEY &key,
            const VALUE &value);

  /**
   * Same as a normal bind, except the cache entry is also passed back
   * to the caller.  The entry in this case will either be the newly
   * created entry, or the existing one.
   */
  int bind (const KEY &key,
            const VALUE &value,
            CACHE_ENTRY *&entry);

  /// Loopkup entry<key,value> in the cache.
  int find (const KEY &key,
            VALUE &value);

  /// Is @a key in the cache?
  int find (const KEY &key);

  /// Obtain the entry when the find succeeds.
  int find (const KEY &key,
            CACHE_ENTRY *&entry);

  /**
   * Reassociate the @a key with @a value. If the @a key already exists
   * in the cache then returns 1, on a new bind returns 0 and returns
   * -1 in case of any failures.
   */
  int rebind (const KEY &key,
              const VALUE &value);

  /**
   * Reassociate @a key with @a value, storing the old value into the
   * "out" parameter @a old_value.  The function fails if @a key is not
   * in the cache for caches that do not allow user specified keys.
   * However, for caches that allow user specified keys, if the key is
   * not in the cache, a new @a key / @a value association is created.
   */
  int rebind (const KEY &key,
              const VALUE &value,
              VALUE &old_value);

  /**
   * Reassociate @a key with @a value, storing the old key and value
   * into the "out" parameters @a old_key and @a old_value.  The
   * function fails if @a key is not in the cache for caches that do not
   * allow user specified keys.  However, for caches that allow user
   * specified keys, if the key is not in the cache, a new @a key / @a value
   * association is created.
   */
  int rebind (const KEY &key,
              const VALUE &value,
              KEY &old_key,
              VALUE &old_value);

  /**
   * Same as a normal rebind, except the cache entry is also passed back
   * to the caller.  The entry in this case will either be the newly
   * created entry, or the existing one.
   */
  int rebind (const KEY &key,
              const VALUE &value,
              CACHE_ENTRY *&entry);

  /**
   * Associate @a key with @a value if and only if @a key is not in the
   * cache.  If @a key is already in the cache, then the @a value parameter
   * is overwritten with the existing value in the cache. Returns 0 if a
   * new @a key / @a value association is created.  Returns 1 if an
   * attempt is made to bind an existing entry.  This function fails
   * for maps that do not allow user specified keys.
   */
  int trybind (const KEY &key,
               VALUE &value);

  /**
   * Same as a normal trybind, except the cache entry is also passed
   * back to the caller.  The entry in this case will either be the
   * newly created entry, or the existing one.
   */
  int trybind (const KEY &key,
               VALUE &value,
               CACHE_ENTRY *&entry);

  /// Remove @a key from the cache.
  int unbind (const KEY &key);

  /// Remove @a key from the cache, and return the @a value associated with
  /// @a key.
  int unbind (const KEY &key,
              VALUE &value);

  /// Remove entry from map.
  int unbind (CACHE_ENTRY *entry);

protected:
  /// Base class.
  typedef ACE_CACHE_MAP_MANAGER ACE_HCMM_BASE;
};

ACE_END_VERSIONED_NAMESPACE_DECL


#if defined (__ACE_INLINE__)
#include "ace/Hash_Cache_Map_Manager_T.inl"
#endif /* __ACE_INLINE__ */

#if defined (ACE_TEMPLATES_REQUIRE_SOURCE)
#include "ace/Hash_Cache_Map_Manager_T.cpp"
#endif /* ACE_TEMPLATES_REQUIRE_SOURCE */

#if defined (ACE_TEMPLATES_REQUIRE_PRAGMA)
#pragma implementation ("Hash_Cache_Map_Manager_T.cpp")
#endif /* ACE_TEMPLATES_REQUIRE_PRAGMA */

#include /**/ "ace/post.h"

#endif /* HASH_CACHE_MAP_MANAGER_T_H */
