---

Connector.h

Go to the documentation of this file.

// -*- C++ -*-

//=============================================================================
/**
 *  @file    Connector.h
 *
 *  $Id: Connector.h,v 1.1.1.4 2003/02/21 18:36:32 chad Exp $
 *
 *  @author Douglas C. Schmidt <schmidt@cs.wustl.edu>
 */
//=============================================================================

#ifndef ACE_CONNECTOR_H
#define ACE_CONNECTOR_H

#include "ace/pre.h"

#include "ace/Service_Config.h"

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

#include "ace/Service_Object.h"
#include "ace/Map_Manager.h"
#include "ace/Svc_Handler.h"
#include "ace/Strategies_T.h"

/**
 * @class ACE_Svc_Tuple
 *
 * @brief Holds the ACE_Svc_Handler and its argument and
 * <ACE_Timer_Handle> until an asynchronous connection completes.
 *
 * This is a no-brainer...
 */
template <class SVC_HANDLER>
class ACE_Svc_Tuple
{
public:

  // = Initialization methods.
  ACE_Svc_Tuple (SVC_HANDLER *,
                 ACE_HANDLE,
                 const void * = 0,
                 long timer_id = -1);

  /// Get SVC_HANDLER.
  SVC_HANDLER *svc_handler (void);

  // = Get/set handle.
  /// Get handle.
  ACE_HANDLE handle (void);

  /// Set handle.
  void handle (ACE_HANDLE);

  // = Get/set argument.
  /// Get argument.
  const void *arg (void);

  /// Set argument.
  void arg (const void *);

  // = Set/get timer cancellation handle.
  /// Get cancellation id.
  long cancellation_id (void);

  /// Set cancellation id.
  void cancellation_id (long timer_id);

  /// Increment and decrement refcount within the context of the lock
  /// on the ACE_Connector
  long incr_refcount (void);

  long decr_refcount (void);

  /// Dump the state of an object.
  void dump (void) const;

  /// Declare the dynamic allocation hooks.
  ACE_ALLOC_HOOK_DECLARE;

protected:
  /// Prevent direct deletion
  ~ACE_Svc_Tuple (void);

private:
  /// Associated SVC_HANDLER.
  SVC_HANDLER *svc_handler_;

  /// IPC <HANDLE> that we are trying to connect.
  ACE_HANDLE handle_;

  /// Associated argument.
  const void *arg_;

  /// Associated cancellation id.
  long cancellation_id_;

  /// Reference count manipulated within the context of the connector
  /// lock.
  /// @@ TODO: Things will change after 5.3 goes out of the way.
  long refcount_;
};

/**
 * @class ACE_Connector
 *
 * @brief Generic factory for actively connecting clients and creating
 * service handlers (SVC_HANDLERs).
 *
 * Implements the strategy for actively establishing connections
 * with clients.  An ACE_Connector is parameterized by concrete
 * types that conform to the interfaces of PEER_CONNECTOR and
 * SVC_HANDLER.  The PEER_CONNECTOR is instantiated with a
 * transport mechanism that passively establishes connections.
 * The SVC_HANDLER is instantiated with a concrete type that
 * performs the application-specific service.  An ACE_Connector
 * inherits from ACE_Service_Object, which in turn inherits from
 * ACE_Event_Handler.  This enables the ACE_Reactor to dispatch
 * the ACE_Connector's handle_output method when connections
 * complete asynchronously.  The handle_output method performs
 * the connector's active connection establishment and service
 * activation strategy.
 */
template <class SVC_HANDLER, ACE_PEER_CONNECTOR_1>
class ACE_Connector : public ACE_Service_Object
{
public:

  // Useful STL-style traits.
  typedef ACE_TYPENAME SVC_HANDLER::addr_type    addr_type;
  typedef ACE_PEER_CONNECTOR                     connector_type;
  typedef SVC_HANDLER                            handler_type;
  typedef ACE_TYPENAME SVC_HANDLER::stream_type  stream_type;


  // typedef ACE_TYPENAME ACE_PEER_CONNECTOR_ADDR PEER_ADDR;
#if defined (ACE_HAS_TYPENAME_KEYWORD)
  typedef ACE_PEER_CONNECTOR_ADDR ACE_PEER_ADDR_TYPEDEF;
#endif /* ACE_HAS_TYPENAME_KEYWORD */

  typedef ACE_TYPENAME _ACE_PEER_CONNECTOR::PEER_ADDR
          ACE_TYPENAME_ACE_PEER_CONNECTOR_PEER_ADDR;

  /**
   * Initialize a connector.  @a flags indicates how <SVC_HANDLER>'s
   * should be initialized prior to being activated.  Right now, the
   * only flag that is processed is <ACE_NONBLOCK>, which enabled
   * non-blocking I/O on the <SVC_HANDLER> when it is opened.
   */
  ACE_Connector (ACE_Reactor *r = ACE_Reactor::instance (),
                 int flags = 0);

  /**
   * Initialize a connector.  @a flags indicates how <SVC_HANDLER>'s
   * should be initialized prior to being activated.  Right now, the
   * only flag that is processed is <ACE_NONBLOCK>, which enabled
   * non-blocking I/O on the <SVC_HANDLER> when it is opened.
   */
  virtual int open (ACE_Reactor *r = ACE_Reactor::instance (),
                    int flags = 0);

  /// Shutdown a connector and release resources.
  virtual ~ACE_Connector (void);

  // = Connection establishment methods.

  /**
   * Initiate connection of <svc_handler> to peer at <remote_addr>
   * using <synch_options>.  If the caller wants to designate the
   * selected <local_addr> they can (and can also insist that the
   * <local_addr> be reused by passing a value <reuse_addr> ==
   * 1). <flags> and <perms> can be used to pass any flags that are
   * needed to perform specific operations such as opening a file
   * within connect with certain permissions.  If the connection fails
   * the <close> hook on the <svc_handler> will be called
   * automatically to prevent resource leaks.
   */
  virtual int connect (SVC_HANDLER *&svc_handler,
                       const ACE_PEER_CONNECTOR_ADDR &remote_addr,
                       const ACE_Synch_Options &synch_options = ACE_Synch_Options::defaults,
                       const ACE_PEER_CONNECTOR_ADDR &local_addr
                         = (ACE_TYPENAME_ACE_PEER_CONNECTOR_PEER_ADDR &) ACE_PEER_CONNECTOR_ADDR_ANY,
                       int reuse_addr = 0,
                       int flags = O_RDWR,
                       int perms = 0);

  /**
   * This is a variation on the previous <connect> method.  On cached
   * connectors the <svc_handler_hint> variable can be used as a hint
   * for future lookups.  Since this variable is modified in the
   * context of the internal cache its use is thread-safe.  But the
   * actual svc_handler for the current connection is returned in the
   * second parameter <svc_handler>.  If the connection fails the
   * <close> hook on the <svc_handler> will be called automatically to
   * prevent resource leaks.
   */
  virtual int connect (SVC_HANDLER *&svc_handler_hint,
                       SVC_HANDLER *&svc_handler,
                       const ACE_PEER_CONNECTOR_ADDR &remote_addr,
                       const ACE_Synch_Options &synch_options = ACE_Synch_Options::defaults,
                       const ACE_PEER_CONNECTOR_ADDR &local_addr
                         = (ACE_TYPENAME_ACE_PEER_CONNECTOR_PEER_ADDR &) ACE_PEER_CONNECTOR_ADDR_ANY,
                       int reuse_addr = 0,
                       int flags = O_RDWR,
                       int perms = 0);

  /**
   * Initiate connection of <n> <svc_handlers> to peers at
   * <remote_addrs> using <synch_options>.  Returns -1 if failure
   * occurs and 0 otherwise.  If <failed_svc_handlers> is non-NULL, a
   * 1 is placed in the corresponding index of <failed_svc_handler>
   * for each <svc_handlers[i]> that failed to connect, else a 0 is
   * placed in that index.
   */
  virtual int connect_n (size_t n,
                         SVC_HANDLER *svc_handlers[],
                         ACE_PEER_CONNECTOR_ADDR remote_addrs[],
                         ACE_TCHAR *failed_svc_handlers = 0,
                         const ACE_Synch_Options &synch_options =
                         ACE_Synch_Options::defaults);

  /**
   * Cancel a <svc_handler> that was started asynchronously. Note that
   * this is the only case when the Connector does not actively close
   * the <svc_handler>. It is left up to the caller of <cancel> to
   * decide the fate of the <svc_handler>.
   */
  virtual int cancel (SVC_HANDLER *svc_handler);

  /// Close down the Connector
  virtual int close (void);

  /// Return the underlying PEER_CONNECTOR object.
  virtual ACE_PEER_CONNECTOR &connector (void) const;

  /// Dump the state of an object.
  void dump (void) const;

  /// Declare the dynamic allocation hooks.
  ACE_ALLOC_HOOK_DECLARE;

protected:
  // = Helpful typedefs.

  typedef ACE_Svc_Tuple<SVC_HANDLER>
          AST;

  typedef ACE_Map_Manager<ACE_HANDLE, ACE_Svc_Tuple<SVC_HANDLER> *, ACE_SYNCH_RW_MUTEX>
          MAP_MANAGER;
  typedef ACE_Map_Iterator<ACE_HANDLE, ACE_Svc_Tuple<SVC_HANDLER> *, ACE_SYNCH_RW_MUTEX>
          MAP_ITERATOR;
  typedef ACE_Map_Entry<ACE_HANDLE, ACE_Svc_Tuple<SVC_HANDLER> *>
          MAP_ENTRY;

  // = The following two methods define the Connector's strategies for
  // creating, connecting, and activating SVC_HANDLER's, respectively.

  /**
   * Bridge method for creating a SVC_HANDLER.  The default is to
   * create a new SVC_HANDLER only if <sh> == 0, else <sh> is
   * unchanged.  However, subclasses can override this policy to
   * perform SVC_HANDLER creation in any way that they like (such as
   * creating subclass instances of SVC_HANDLER, using a singleton,
   * dynamically linking the handler, etc.).  Returns -1 if failure,
   * else 0.
   */
  virtual int make_svc_handler (SVC_HANDLER *&sh);

  /**
   * Bridge method for connecting the <svc_handler> to the
   * <remote_addr>.  The default behavior delegates to the
   * <PEER_CONNECTOR::connect>.
   */
  virtual int connect_svc_handler (SVC_HANDLER *&svc_handler,
                                   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);
  virtual int connect_svc_handler (SVC_HANDLER *&svc_handler,
                                   SVC_HANDLER *&sh_copy,
                                   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);

  /**
   * Bridge method for activating a <svc_handler> with the appropriate
   * concurrency strategy.  The default behavior of this method is to
   * activate the SVC_HANDLER by calling its <open> method (which
   * allows the SVC_HANDLER to define its own concurrency strategy).
   * However, subclasses can override this strategy to do more
   * sophisticated concurrency activations (such as creating the
   * SVC_HANDLER as an "active object" via multi-threading or
   * multi-processing).
   */
  virtual int activate_svc_handler (SVC_HANDLER *svc_handler);

  /// Called by ACE_Reactor when asynchronous connections fail.
  virtual int handle_input (ACE_HANDLE);

  /// Called by ACE_Reactor when asynchronous connections succeed.
  virtual int handle_output (ACE_HANDLE);

  virtual int resume_handler (void);

  /// Called by ACE_Reactor when asynchronous connections complete (on
  /// some platforms only).
  virtual int handle_exception (ACE_HANDLE fd = ACE_INVALID_HANDLE);

  // = Dynamic linking hooks.
  /// Default version does no work and returns -1.  Must be overloaded
  /// by application developer to do anything meaningful.
  virtual int init (int argc, ACE_TCHAR *argv[]);

  /// Calls <handle_close> to shutdown the Connector gracefully.
  virtual int fini (void);

  /// Default version returns address info in <buf>.
  virtual int info (ACE_TCHAR **, size_t) const;

  // = Demultiplexing hooks.
  /**
   * Terminate the Client ACE_Connector by iterating over any
   * unconnected ACE_Svc_Handler's and removing them from the
   * ACE_Reactor.
   */
  virtual int handle_close (ACE_HANDLE = ACE_INVALID_HANDLE,
                            ACE_Reactor_Mask = ACE_Event_Handler::ALL_EVENTS_MASK);

  /// This method is called if a connection times out before
  /// completing.
  virtual int handle_timeout (const ACE_Time_Value &tv,
                              const void *arg);

  // = Service management hooks.
  /// Default version does no work and returns -1.  Must be overloaded
  /// by application developer to do anything meaningful.
  virtual int suspend (void);

  /// Default version does no work and returns -1.  Must be overloaded
  /// by application developer to do anything meaningful.
  virtual int resume (void);

  /// Creates and inserts an ACE_Svc_Tuple into the <handler_map_>.
  /// so that we can continue accepting this connection asynchronously.
  int create_AST (SVC_HANDLER *,
                  const ACE_Synch_Options &);

  /// Cleanup the <handler_map_> and returns the appropriate
  /// ACE_Svc_Tuple (which is 0 if there is no associated tuple).
  int cleanup_AST (ACE_HANDLE handle, AST *&ast);

  /// Implementation the <connect> methods.
  virtual int connect_i (SVC_HANDLER *&svc_handler,
                         SVC_HANDLER **sh_copy,
                         const ACE_PEER_CONNECTOR_ADDR &remote_addr,
                         const ACE_Synch_Options &synch_options,
                         const ACE_PEER_CONNECTOR_ADDR &local_addr,
                         int reuse_addr,
                         int flags,
                         int perms);


  /// Helper method for manipulating the refcount on AST. It holds the
  /// lock before manipulating the refcount on AST.
  /// @@ TODO: Needs to be out after 5.3
  long incr_ast_refcount (AST *ast);
  long decr_ast_refcount (AST *ast);

  /// Lookup table that maps an I/O handle to a SVC_HANDLER *.
  MAP_MANAGER handler_map_;
private:
  /// This is the concrete connector factory (it keeps no state so the
  /// <ACE_Connector> is reentrant).
  ACE_PEER_CONNECTOR connector_;

  /// Keeps track of whether we are in the process of closing (required
  /// to avoid circular calls to <handle_close>).
  char closing_;

  /**
   * Flags that indicate how <SVC_HANDLER>'s should be initialized
   * prior to being activated.  Right now, the only flag that is
   * processed is <ACE_NONBLOCK>, which enabled non-blocking I/O on
   * the <SVC_HANDLER> when it is opened.
   */
  int flags_;

  /// Lock to synchronize access to the internal state of the
  /// connector.
  /// @@TODO: This needs to go after 1.3
  ACE_SYNCH_MUTEX mutex_;
};

/**
 * @class ACE_Strategy_Connector
 *
 * @brief Abstract factory for creating a service handler
 * (SVC_HANDLER), connecting the SVC_HANDLER, and activating the
 * SVC_HANDLER.
 *
 * Implements a flexible and extensible set of strategies for
 * actively establishing connections with clients.  There are
 * three main strategies: (1) creating a SVC_HANDLER, (2)
 * actively initiating a new connection from the client,
 * and (3) activating the SVC_HANDLER with a
 * particular concurrency mechanism after the connection is established.
 */
template <class SVC_HANDLER, ACE_PEER_CONNECTOR_1>
class ACE_Strategy_Connector
  : public ACE_Connector <SVC_HANDLER, ACE_PEER_CONNECTOR_2>
{
public:

  // Useful STL-style traits.
  typedef ACE_Creation_Strategy<SVC_HANDLER>
          creation_strategy_type;
  typedef ACE_Connect_Strategy<SVC_HANDLER, ACE_PEER_CONNECTOR_2>
          connect_strategy_type;
  typedef ACE_Concurrency_Strategy<SVC_HANDLER>
          concurrency_strategy_type;
  typedef ACE_Connector <SVC_HANDLER, ACE_PEER_CONNECTOR_2>
          base_type;

  // = Define some useful (old style) traits.
  typedef ACE_Creation_Strategy<SVC_HANDLER>
          CREATION_STRATEGY;
  typedef ACE_Connect_Strategy<SVC_HANDLER, ACE_PEER_CONNECTOR_2>
          CONNECT_STRATEGY;
  typedef ACE_Concurrency_Strategy<SVC_HANDLER>
          CONCURRENCY_STRATEGY;
  typedef ACE_Connector <SVC_HANDLER, ACE_PEER_CONNECTOR_2>
          SUPER;

  /**
   * Initialize a connector.  <flags> indicates how <SVC_HANDLER>'s
   * should be initialized prior to being activated.  Right now, the
   * only flag that is processed is <ACE_NONBLOCK>, which enabled
   * non-blocking I/O on the <SVC_HANDLER> when it is opened.
   */
  ACE_Strategy_Connector (ACE_Reactor *r = ACE_Reactor::instance (),
                          ACE_Creation_Strategy<SVC_HANDLER> * = 0,
                          ACE_Connect_Strategy<SVC_HANDLER, ACE_PEER_CONNECTOR_2> * = 0,
                          ACE_Concurrency_Strategy<SVC_HANDLER> * = 0,
                          int flags = 0);

  /**
   * Initialize a connector.  <flags> indicates how <SVC_HANDLER>'s
   * should be initialized prior to being activated.  Right now, the
   * only flag that is processed is <ACE_NONBLOCK>, which enabled
   * non-blocking I/O on the <SVC_HANDLER> when it is opened.
   * Default strategies would be created and used.
   */
  virtual int open (ACE_Reactor *r,
                    int flags);

  /**
   * Initialize a connector.  <flags> indicates how <SVC_HANDLER>'s
   * should be initialized prior to being activated.  Right now, the
   * only flag that is processed is <ACE_NONBLOCK>, which enabled
   * non-blocking I/O on the <SVC_HANDLER> when it is opened.
   */
  virtual int open (ACE_Reactor *r = ACE_Reactor::instance (),
                    ACE_Creation_Strategy<SVC_HANDLER> * = 0,
                    ACE_Connect_Strategy<SVC_HANDLER, ACE_PEER_CONNECTOR_2> * = 0,
                    ACE_Concurrency_Strategy<SVC_HANDLER> * = 0,
                    int flags = 0);

  /// Shutdown a connector and release resources.
  virtual ~ACE_Strategy_Connector (void);

  /// Close down the Connector
  virtual int close (void);

  // = Strategies accessors
  virtual ACE_Creation_Strategy<SVC_HANDLER> *creation_strategy (void) const;
  virtual ACE_Connect_Strategy<SVC_HANDLER, ACE_PEER_CONNECTOR_2> *connect_strategy (void) const;
  virtual ACE_Concurrency_Strategy<SVC_HANDLER> *concurrency_strategy (void) const;

protected:
  // = The following three methods define the <Connector>'s strategies
  // for creating, connecting, and activating <SVC_HANDLER>'s,
  // respectively.

  /**
   * Bridge method for creating a <SVC_HANDLER>.  The strategy for
   * creating a <SVC_HANDLER> are configured into the Connector via
   * it's <creation_strategy_>.  The default is to create a new
   * <SVC_HANDLER> only if <sh> == 0, else <sh> is unchanged.
   * However, subclasses can override this policy to perform
   * <SVC_HANDLER> creation in any way that they like (such as
   * creating subclass instances of <SVC_HANDLER>, using a singleton,
   * dynamically linking the handler, etc.).  Returns -1 if failure,
   * else 0.
   */
  virtual int make_svc_handler (SVC_HANDLER *&sh);

  /**
   * Bridge method for connecting the new connection into the
   * <SVC_HANDLER>.  The default behavior delegates to the
   * <PEER_CONNECTOR::connect> in the <Connect_Strategy>.
   */
  virtual int connect_svc_handler (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);

  /**
   * Bridge method for connecting the new connection into the
   * <SVC_HANDLER>.  The default behavior delegates to the
   * <PEER_CONNECTOR::connect> in the <Connect_Strategy>.
   * <sh_copy> is used to obtain a copy of the <sh> pointer, but that
   * can be kept in the stack; the motivation is a bit too long to
   * include here, but basically we want to modify <sh> safely, using
   * the internal locks in the Connect_Strategy, while saving a TSS
   * copy in <sh_copy>, usually located in the stack.
   */
  virtual int connect_svc_handler (SVC_HANDLER *&sh,
                                   SVC_HANDLER *&sh_copy,
                                   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);

  /**
   * Bridge method for activating a <SVC_HANDLER> with the appropriate
   * concurrency strategy.  The default behavior of this method is to
   * activate the <SVC_HANDLER> by calling its <open> method (which
   * allows the <SVC_HANDLER> to define its own concurrency strategy).
   * However, subclasses can override this strategy to do more
   * sophisticated concurrency activations (such as creating the
   * <SVC_HANDLER> as an "active object" via multi-threading or
   * multi-processing).
   */
  virtual int activate_svc_handler (SVC_HANDLER *svc_handler);

  // = Strategy objects.

  /// Creation strategy for an <Connector>.
  CREATION_STRATEGY *creation_strategy_;

  /// 1 if <Connector> created the creation strategy and thus should
  /// delete it, else 0.
  int delete_creation_strategy_;

  /// Connect strategy for a <Connector>.
  CONNECT_STRATEGY *connect_strategy_;

  /// 1 if <Connector> created the connect strategy and thus should
  /// delete it, else 0.
  int delete_connect_strategy_;

  /// Concurrency strategy for an <Connector>.
  CONCURRENCY_STRATEGY *concurrency_strategy_;

  /// 1 if <Connector> created the concurrency strategy and thus should
  /// delete it, else 0.
  int delete_concurrency_strategy_;
};

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

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

#include "ace/post.h"

#endif /* ACE_CONNECTOR_H */

---