Bindings_Iterator_T.h

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// -*- C++ -*-

//=============================================================================
/**
 *  @file   Bindings_Iterator_T.h
 *
 *  $Id: Bindings_Iterator_T.h 77276 2007-02-21 08:26:36Z johnnyw $
 *
 *  @author Marina Spivak <marina@cs.wustl.edu>
 */
//=============================================================================


#ifndef TAO_BINDINGS_ITERATOR_T_H
#define TAO_BINDINGS_ITERATOR_T_H
#include /**/ "ace/pre.h"

#include "orbsvcs/Naming/Hash_Naming_Context.h"


TAO_BEGIN_VERSIONED_NAMESPACE_DECL

/**
 * @class TAO_Bindings_Iterator
 *
 * @brief This class implements the <BindingIterator> interface that is
 * part of the <CosNaming> idl module.   This class works with Hash_Map-based
 * implementations of CosNaming::NamingContext.
 *
 * This class is templatized by the types of the underlying
 * hash table iterator and hash table entry, so that it can be
 * used for both TAO_Transient_Naming_Context and
 * TAO_Persistent_Naming_Context (and any other classes with
 * underlying data structures supporting
 * ACE_Hash_Map_Manager/Iterator - like interfaces).
 *
 * Instances of <TAO_Bindings_Iterator>s affect reference counts
 * of corresponding Naming Contexts. Reference count on a
 * Naming Context is incremented by one for a lifetime of each
 * instance of <TAO_Bindings_Iterator> created for that
 * context, i.e., a Naming Context cannot
 * be cleaned up (but, of course, it can be invalidated) before
 * all of its iterators have been cleaned up.  When <destroy>
 * method is invoked on a Naming Context, all of its iterators are
 * destroyed in a "lazy evaluation" fashion, i.e., whenever a next
 * operation is invoked on an iterator, and it can detect that
 * the corresponding Naming Context has been invalidated, the
 * iterator is destroyed.
 */
template <class ITERATOR, class TABLE_ENTRY>
class TAO_Bindings_Iterator : public virtual POA_CosNaming::BindingIterator
{
public:
  // = Intialization and termination methods.
  /**
   * Constructor expects a pointer to a
   * dynamically allocated hash map iterator (destructor
   * deallocates hash map iterator).
   */
  TAO_Bindings_Iterator (TAO_Hash_Naming_Context *context,
                         ITERATOR *hash_iter,
                         PortableServer::POA_ptr poa,
                         TAO_SYNCH_RECURSIVE_MUTEX &lock);


  /// Destructor.
  ~TAO_Bindings_Iterator (void);

  /// Returns the Default POA of this Servant object
  virtual PortableServer::POA_ptr _default_POA (void);

  // = Idl methods.

  /// This operation passes back the next unseen binding.  True is
  /// returned if a binding is passed back, and false is returned otherwise.
  CORBA::Boolean next_one (CosNaming::Binding_out b);

  /**
   * This operation passes back at most <how_many> unseen bindings.
   * True is returned if bindings were passed back, and false is
   * returned if no bindings were passed back.
   */
  CORBA::Boolean next_n (CORBA::ULong how_many,
                         CosNaming::BindingList_out bl);

  /// This operation destroys the iterator.
  void destroy (void);

  // = Helper method.

  /**
   * Helper function used by TAO_*_Naming_Context and
   * TAO_BindingIterator: populate a binding <b> with info contained
   * in <hash_entry>.  Return 1 if everything went smoothly, 0 if an
   * allocation failed.
   */
  static int populate_binding (TABLE_ENTRY *hash_entry, CosNaming::Binding &b);

private:
  /**
   * Flag indicating whether this iterator is still valid.  (The
   * iterator becomes invalid when <destroy> method has been invoked
   * on it, or when <destroy> method has been invoked on the
   * corresponding Naming Context.) This flag is necessary
   * because immediate destruction of this servant might not be possible
   * due to pending requests in the POA.
   */
  bool destroyed_;

  /**
   * Pointer to the Naming Context we are iterating over.  We need
   * this pointer to make sure the context is still valid before
   * each iteration, and to decrement its reference count once we are <destroyed>.
   */
  TAO_Hash_Naming_Context *context_;

  /// A pointer to the hash map iterator.
  ITERATOR *hash_iter_;

  /// Lock passed on from Naming Context to serialize access to the
  /// internal data structure.
  TAO_SYNCH_RECURSIVE_MUTEX &lock_;

  /// Implement a different _default_POA().
  PortableServer::POA_var poa_;
};

TAO_END_VERSIONED_NAMESPACE_DECL

#if defined (ACE_TEMPLATES_REQUIRE_SOURCE)
#include "orbsvcs/Naming/Bindings_Iterator_T.cpp"
#endif /* ACE_TEMPLATES_REQUIRE_SOURCE */

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

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

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