Cached_Connect_Strategy_T.h

Go to the documentation of this file.

// -*- C++ -*-

//=============================================================================
/**
 *  @file    Cached_Connect_Strategy_T.h
 *
 *  $Id: Cached_Connect_Strategy_T.h 76543 2007-01-24 12:33:06Z johnnyw $
 *
 *  @author Kirthika Parameswaran <kirthika@cs.wustl.edu>
 */
//=============================================================================

#ifndef CACHED_CONNECT_STRATEGY_T_H
#define CACHED_CONNECT_STRATEGY_T_H

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

#include /**/ "ace/config-all.h"

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

#include "ace/Strategies_T.h"
#include "ace/Hash_Cache_Map_Manager_T.h"
#include "ace/Caching_Strategies_T.h"
#include "ace/Functor_T.h"
#include "ace/Pair_T.h"

// For linkers which cant grok long names...
#define ACE_Cached_Connect_Strategy_Ex ACCSE

ACE_BEGIN_VERSIONED_NAMESPACE_DECL

/**
 * @class ACE_Cached_Connect_Strategy_Ex
 *
 * @brief A connection strategy which caches connections to peers
 * (represented by <SVC_HANDLER> instances), thereby allowing
 * subsequent re-use of unused, but available, connections.
 *
 * <Cached_Connect_Strategy> is intended to be used as a
 * plug-in connection strategy for ACE_Strategy_Connector.
 * It's added value is re-use of established connections and
 * tweaking the role of the cache as per the caching strategy.
 */
template <class SVC_HANDLER, ACE_PEER_CONNECTOR_1, class CACHING_STRATEGY, class ATTRIBUTES, class MUTEX>
class ACE_Cached_Connect_Strategy_Ex
 : public ACE_Cached_Connect_Strategy<SVC_HANDLER, ACE_PEER_CONNECTOR_2, MUTEX>
{
public:
  /// Constructor
  ACE_Cached_Connect_Strategy_Ex (
    CACHING_STRATEGY &caching_s,
    ACE_Creation_Strategy<SVC_HANDLER> *cre_s = 0,
    ACE_Concurrency_Strategy<SVC_HANDLER> *con_s = 0,
    ACE_Recycling_Strategy<SVC_HANDLER> *rec_s = 0,
    MUTEX *lock = 0,
    int delete_lock = 0);

  /// Destructor
  virtual ~ACE_Cached_Connect_Strategy_Ex (void);

  /// Explicit purging of connection entries from the connection cache.
  virtual int purge_connections (void);

  /// Mark as closed (non-locking version). This is used during the cleanup of the
  /// connections purged.
  virtual int mark_as_closed_i (const void *recycling_act);

  /**
   * Since g++ version < 2.8 arent happy with templates, this special
   * method had to be devised to avoid memory leaks and perform
   * cleanup of the <connection_cache_>.
   */
  void cleanup (void);

  // = Typedefs for managing the map
  typedef ACE_Refcounted_Hash_Recyclable<ACE_PEER_CONNECTOR_ADDR>
          REFCOUNTED_HASH_RECYCLABLE_ADDRESS;
 typedef ACE_Hash_Cache_Map_Manager<REFCOUNTED_HASH_RECYCLABLE_ADDRESS,
                                    SVC_HANDLER *,
                                    ACE_Hash<REFCOUNTED_HASH_RECYCLABLE_ADDRESS>,
                                    ACE_Equal_To<REFCOUNTED_HASH_RECYCLABLE_ADDRESS>,
                                    CACHING_STRATEGY,
                                    ATTRIBUTES>
          CONNECTION_CACHE;
  typedef typename CONNECTION_CACHE::CACHE_ENTRY CONNECTION_CACHE_ENTRY;
  typedef typename CONNECTION_CACHE::key_type KEY;
  typedef typename CONNECTION_CACHE::mapped_type VALUE;

  typedef ACE_Recyclable_Handler_Cleanup_Strategy<REFCOUNTED_HASH_RECYCLABLE_ADDRESS,
                                                  ACE_Pair<SVC_HANDLER *, ATTRIBUTES>,
                                                  ACE_Hash_Map_Manager_Ex<REFCOUNTED_HASH_RECYCLABLE_ADDRESS,
                                                                          ACE_Pair<SVC_HANDLER *, ATTRIBUTES>,
                                                                          ACE_Hash<REFCOUNTED_HASH_RECYCLABLE_ADDRESS>,
                                                                          ACE_Equal_To<REFCOUNTED_HASH_RECYCLABLE_ADDRESS>,
                                                                          MUTEX> >
          CLEANUP_STRATEGY;

  typedef ACE_Cached_Connect_Strategy<SVC_HANDLER, ACE_PEER_CONNECTOR_2, MUTEX>
          CCSBASE;

  // = Accessor.
  CACHING_STRATEGY &caching_strategy (void);

protected:

  /// Find an idle handle.
  int find (ACE_Refcounted_Hash_Recyclable<ACE_PEER_CONNECTOR_ADDR> &search_addr,
            ACE_Hash_Map_Entry<ACE_Refcounted_Hash_Recyclable<ACE_PEER_CONNECTOR_ADDR>, ACE_Pair<SVC_HANDLER *, ATTRIBUTES> > *&entry);

  /// Remove from cache (non-locking version).
  virtual int purge_i (const void *recycling_act);

  /// Add to cache (non-locking version).
  virtual int cache_i (const void *recycling_act);

  /// Get/Set <recycle_state> (non-locking version).
  virtual int recycle_state_i (const void *recycling_act,
                               ACE_Recyclable_State new_state);
  virtual ACE_Recyclable_State recycle_state_i (const void *recycling_act) const;

  /// Cleanup hint and reset <*act_holder> to zero if <act_holder != 0>.
  virtual int cleanup_hint_i (const void *recycling_act,
                              void **act_holder);

  // = Helpers
  int check_hint_i (SVC_HANDLER *&sh,
                    const ACE_PEER_CONNECTOR_ADDR &remote_addr,
                    ACE_Time_Value *timeout,
                    const ACE_PEER_CONNECTOR_ADDR &local_addr,
                    int reuse_addr,
                    int flags,
                    int perms,
                    ACE_Hash_Map_Entry<ACE_Refcounted_Hash_Recyclable<ACE_PEER_CONNECTOR_ADDR>, ACE_Pair<SVC_HANDLER *, ATTRIBUTES> > *&entry,
                    int &found);

  virtual int find_or_create_svc_handler_i (SVC_HANDLER *&sh,
                                    const ACE_PEER_CONNECTOR_ADDR &remote_addr,
                                    ACE_Time_Value *timeout,
                                    const ACE_PEER_CONNECTOR_ADDR &local_addr,
                                    int reuse_addr,
                                    int flags,
                                    int perms,
                                    ACE_Hash_Map_Entry<ACE_Refcounted_Hash_Recyclable<ACE_PEER_CONNECTOR_ADDR>, ACE_Pair<SVC_HANDLER *, ATTRIBUTES> > *&entry,
                                    int &found);

  virtual int connect_svc_handler_i (SVC_HANDLER *&sh,
                                     const ACE_PEER_CONNECTOR_ADDR &remote_addr,
                                     ACE_Time_Value *timeout,
                                     const ACE_PEER_CONNECTOR_ADDR &local_addr,
                                     int reuse_addr,
                                     int flags,
                                     int perms,
                                     int &found);

  /**
   * Connection of the svc_handler with the remote host.  This method
   * also encapsulates the connection done with auto_purging under the
   * hood. If the connect failed due to the process running out of
   * file descriptors then, auto_purging of some connections are done
   * from the CONNECTION_CACHE. This frees the descriptors which get
   * used in the connect process and hence the connect operation can
   * succeed.
   */
  virtual int cached_connect (SVC_HANDLER *&sh,
                              const ACE_PEER_CONNECTOR_ADDR &remote_addr,
                              ACE_Time_Value *timeout,
                              const ACE_PEER_CONNECTOR_ADDR &local_addr,
                              int reuse_addr,
                              int flags,
                              int perms);

  /// Table that maintains the cache of connected <SVC_HANDLER>s.
  CONNECTION_CACHE connection_cache_;
};

/////////////////////////////////////////////////////////////////////////////

// For linkers which cant grok long names...
#define ACE_Bounded_Cached_Connect_Strategy ABCCS

/**
 * @class ACE_Bounded_Cached_Connect_Strategy
 *
 * @brief A connection strategy which caches connections to peers
 *     (represented by <SVC_HANDLER> instances), thereby allowing
 *     subsequent re-use of unused, but available, connections.
 *     This strategy should be used when the cache is bounded by
 *     maximum size.
 *
 *       <Bounded_Cached_Connect_Strategy> is intended to be used as a
 *     plug-in connection strategy for ACE_Strategy_Connector.
 *     It's added value is re-use of established connections and
 *     tweaking the role of the cache as per the caching strategy.
 *     Thanks to Edan Ayal  <edana@bandwiz.com> for contributing this
 *     class and Susan Liebeskind  <shl@janis.gtri.gatech.edu> for
 *     brainstorming about it.
 */
template <class SVC_HANDLER, ACE_PEER_CONNECTOR_1,
          class CACHING_STRATEGY, class ATTRIBUTES,
          class MUTEX>
class ACE_Bounded_Cached_Connect_Strategy
  : public ACE_Cached_Connect_Strategy_Ex<SVC_HANDLER, ACE_PEER_CONNECTOR_2, CACHING_STRATEGY, ATTRIBUTES, MUTEX>
{

   typedef ACE_Cached_Connect_Strategy_Ex<SVC_HANDLER, ACE_PEER_CONNECTOR_2, CACHING_STRATEGY, ATTRIBUTES, MUTEX>
   CCSEBASE;

  // = Typedefs for managing the map
  typedef ACE_Refcounted_Hash_Recyclable<ACE_PEER_CONNECTOR_ADDR>
          REFCOUNTED_HASH_RECYCLABLE_ADDRESS;

public:

  /// Constructor
  ACE_Bounded_Cached_Connect_Strategy (size_t  max_size,
                                       CACHING_STRATEGY &caching_s,
                                       ACE_Creation_Strategy<SVC_HANDLER> *cre_s = 0,
                                       ACE_Concurrency_Strategy<SVC_HANDLER> *con_s = 0,
                                       ACE_Recycling_Strategy<SVC_HANDLER> *rec_s = 0,
                                       MUTEX *lock = 0,
                                       int delete_lock = 0);

   /// Destructor
   virtual ~ACE_Bounded_Cached_Connect_Strategy (void);

   /// Declare the dynamic allocation hooks.
   ACE_ALLOC_HOOK_DECLARE;

protected:

  virtual int find_or_create_svc_handler_i (SVC_HANDLER *&sh,
                                            const ACE_PEER_CONNECTOR_ADDR &remote_addr,
                                            ACE_Time_Value *timeout,
                                            const ACE_PEER_CONNECTOR_ADDR &local_addr,
                                            int reuse_addr,
                                            int flags,
                                            int perms,
                                            ACE_Hash_Map_Entry<ACE_Refcounted_Hash_Recyclable<ACE_PEER_CONNECTOR_ADDR>,
                                            ACE_Pair<SVC_HANDLER *, ATTRIBUTES> > *&entry,
                                            int &found);

protected:

  /// max items in the cache, used as a bound for the creation of svc_handlers.
  size_t  max_size_;
};

ACE_END_VERSIONED_NAMESPACE_DECL

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

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

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

---