path: root/ace/Asynch_IO.h

/* -*- C++ -*- */

//=============================================================================
/**
 *  @file    Asynch_IO.h
 *
 *  $Id$
 *
 *  This works on Win32 (#if defined (ACE_WIN32) && !defined
 *  (ACE_HAS_WINCE)) platforms and on POSIX4 platforms with <aio_*>
 *  routines (#if defined (ACE_HAS_AIO_CALLS))
 *
 *  On Win32 platforms, the implementation of
 *  <ACE_Asynch_Transmit_File> and <ACE_Asynch_Accept> are only
 *  supported if ACE_HAS_WINSOCK2 is defined or you are on WinNT 4.0
 *  or higher.
 *
 *  @author Irfan Pyarali <irfan@cs.wustl.edu>
 *  @author Tim Harrison <harrison@cs.wustl.edu>
 *  @author Alexander Babu Arulanthu <alex@cs.wustl.edu>
 *  @author Roger Tragin <r.tragin@computer.org>
 */
//=============================================================================

#ifndef ACE_ASYNCH_IO_H
#define ACE_ASYNCH_IO_H
#include "ace/pre.h"

#include "ace/OS.h"

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

#if (defined (ACE_WIN32) && !defined (ACE_HAS_WINCE)) || (defined (ACE_HAS_AIO_CALLS))

// Forward declarations
class ACE_Proactor;
class ACE_Handler;
class ACE_Message_Block;
class ACE_INET_Addr;

// Forward declarations
class ACE_Asynch_Result_Impl;

/**
 * @class ACE_Asynch_Result
 *
 * @brief An interface base class which allows users access to common
 * information related to an asynchronous operation.
 *
 * An interface base class from which you can obtain some basic
 * information like the number of bytes transferred, the ACT
 * associated with the asynchronous operation, indication of
 * success or failure, etc. Subclasses may want to store more
 * information that is particular to the asynchronous operation
 * it represents.
 */
class ACE_Export ACE_Asynch_Result
{

public:
  /// Number of bytes transferred by the operation.
  u_long bytes_transferred (void) const;

  /// ACT associated with the operation.
  const void *act (void) const;

  /// Did the operation succeed?
  int success (void) const;

  /**
   * This is the ACT associated with the handle on which the
   * Asynch_Operation takes place.
   *
   * On WIN32, this returns the ACT associated with the handle when it
   * was registered with the I/O completion port.
   *
   * @@ This is not implemented for POSIX4 platforms. Returns 0.
   */
  const void *completion_key (void) const;

  /// Error value if the operation fails.
  u_long error (void) const;

  /**
   * On WIN32, this returns the event associated with the OVERLAPPED
   * structure.
   *
   * This returns ACE_INVALID_HANDLE on POSIX4-Unix platforms.
   */
  ACE_HANDLE event (void) const;

  /**
   * This really makes sense only when doing file I/O.
   *
   * On WIN32, these are represented in the OVERLAPPED datastructure.
   *
   * @@ On POSIX4-Unix, offset_high should be supported using
   *    aiocb64.
   */
  u_long offset (void) const;
  u_long offset_high (void) const;

  /**
   * Priority of the operation.
   *
   * On POSIX4-Unix, this is supported. Priority works like <nice> in
   * Unix. Negative values are not allowed. 0 means priority of the
   * operation same as the process priority. 1 means priority of the
   * operation is one less than process. And so forth.
   *
   * On Win32, this is a no-op.
   */
  int priority (void) const;

  /**
   * POSIX4 real-time signal number to be used for the
   * operation. <signal_number> ranges from ACE_SIGRTMIN to ACE_SIGRTMAX. By
   * default, ACE_SIGRTMIN is used to issue <aio_> calls. This is a no-op
   * on non-POSIX4 systems and returns 0.
   */
  int signal_number (void) const;


  /// Destructor.
  virtual ~ACE_Asynch_Result (void);

protected:
  /// Constructor. This implementation will not be deleted.  The
  /// implementation will be deleted by the Proactor.
  ACE_Asynch_Result (ACE_Asynch_Result_Impl *implementation);

  /// Get the implementation class.
  ACE_Asynch_Result_Impl *implementation (void) const;

  /// Implementation class.
  ACE_Asynch_Result_Impl *implementation_;
};

// Forward declarations
class ACE_Asynch_Operation_Impl;

/**
 * @class ACE_Asynch_Operation
 *
 * @brief This is an interface base class for all asynch
 * operations. The resposiblility of this class is to forward
 * all methods to its delegation/implementation class, e.g.,
 * <ACE_WIN32_Asynch_Operation> or <ACE_POSIX_Asynch_Operation>.
 *
 * There are some attributes and functionality which is common
 * to all asychronous operations. The delegation classes of this
 * class will factor out this code.
 */
class ACE_Export ACE_Asynch_Operation
{

public:
  /**
   * Initializes the factory with information which will be used with
   * each asynchronous call.  If (<handle> == ACE_INVALID_HANDLE),
   * <ACE_Handler::handle> will be called on the <handler> to get the
   * correct handle.
   */
  int open (ACE_Handler &handler,
            ACE_HANDLE handle,
            const void *completion_key,
            ACE_Proactor *proactor);

  /**
   * (Attempts to) cancel the asynchronous operation pending against
   * the <handle> registered with this Operation.
   *
   * All completion notifications for the I/O operations will occur
   * normally.
   *
   * = Return Values:
   *
   * -1 : Operation failed. (can get only in POSIX).
   *  0 : All the operations were cancelled.
   *  1 : All the operations were already finished in this
   *      handle. Unable to cancel them.
   *  2 : Atleast one of the requested operations cannot be
   *      cancelled.
   *
   * There is slight difference in the semantics between NT and POSIX
   * platforms which is given below.
   *
   * = Win32 :
   *
   *   cancels all pending accepts operations that were issued by the
   *   calling thread.  The function does not cancel asynchronous
   *   operations issued by other threads.
   *   All I/O operations that are canceled will complete with the
   *   error ERROR_OPERATION_ABORTED.
   *
   * = POSIX:
   *
   *   Attempts to cancel one or more asynchronous I/O requests
   *   currently outstanding against the <handle> registered in this
   *   operation.
   *   For requested operations that are successfully canceled, the
   *   associated  error  status is set to ECANCELED.
   */
  int cancel (void);


  // = Access methods.

  /// Return the underlying proactor.
  ACE_Proactor* proactor (void) const;

  /// Destructor.
  virtual ~ACE_Asynch_Operation (void);

protected:
  /// Constructor.
  ACE_Asynch_Operation (void);

  /// Return the underlying implementation class.
  ACE_Asynch_Operation_Impl *implementation (void) const;

  /// Set the implementation class.
  void implementation (ACE_Asynch_Operation_Impl *implementation);

  /// Get a proactor for/from the user
  ACE_Proactor *get_proactor (ACE_Proactor *user_proactor,
                              ACE_Handler &handler) const;

  /// Implementation class.
  ACE_Asynch_Operation_Impl *implementation_;
};

// Forward declarations
class ACE_Asynch_Read_Stream_Result_Impl;
class ACE_Asynch_Read_Stream_Impl;

/**
 * @class ACE_Asynch_Read_Stream
 *
 * @brief This class is a factory for starting off asynchronous reads
 * on a stream. This class forwards all methods to its
 * implementation class.
 *
 * Once <open> is called, multiple asynchronous <read>s can
 * started using this class.  An ACE_Asynch_Read_Stream::Result
 * will be passed back to the <handler> when the asynchronous
 * reads completes through the <ACE_Handler::handle_read_stream>
 * callback.
 */
class ACE_Export ACE_Asynch_Read_Stream : public ACE_Asynch_Operation
{

public:
  /// A do nothing constructor.
  ACE_Asynch_Read_Stream (void);

  /// Destructor
  virtual ~ACE_Asynch_Read_Stream (void);

  /**
   * Initializes the factory with information which will be used with
   * each asynchronous call. If (<handle> == ACE_INVALID_HANDLE),
   * <ACE_Handler::handle> will be called on the <handler> to get the
   * correct handle.
   */
  int open (ACE_Handler &handler,
            ACE_HANDLE handle = ACE_INVALID_HANDLE,
            const void *completion_key = 0,
            ACE_Proactor *proactor = 0);

  /**
   * This starts off an asynchronous read.  Upto <bytes_to_read> will
   * be read and stored in the <message_block>. <message_block>'s
   * <wr_ptr> will be updated to reflect the added bytes if the read
   * operation is successful completed. Priority of the
   * operation is specified by <priority>. On POSIX4-Unix, this is
   * supported. Works like <nice> in Unix. Negative values are not
   * allowed. 0 means priority of the operation same as the process
   * priority. 1 means priority of the operation is one less than
   * process. And so forth. On Win32, <priority> is a no-op.
   * <signal_number> is the POSIX4 real-time signal number to be used
   * for the operation. <signal_number> ranges from ACE_SIGRTMIN to
   * ACE_SIGRTMAX. This argument is a no-op on non-POSIX4 systems.
   */
  int read (ACE_Message_Block &message_block,
            u_long num_bytes_to_read,
            const void *act = 0,
            int priority = 0,
            int signal_number = ACE_SIGRTMIN);

  /// Return the underlying implementation class.
  ACE_Asynch_Read_Stream_Impl *implementation (void) const;

protected:
  /// Set the implementation class.
  void implementation (ACE_Asynch_Read_Stream_Impl *implementation);

  /// Implementation class that all methods will be forwarded to.
  ACE_Asynch_Read_Stream_Impl *implementation_;

public:
/**
 * @class Result
 *
 * @brief This is the class which will be passed back to the
 * <handler> when the asynchronous read completes. This class
 * forwards all the methods to the implementation classes.
 *
 * This class has all the information necessary for the
 * <handler> to uniquiely identify the completion of the
 * asynchronous read.
 */
  class ACE_Export Result : public ACE_Asynch_Result
  {

    /// The concrete implementation result classes only construct this
    /// class.
    friend class ACE_POSIX_Asynch_Read_Stream_Result;
    friend class ACE_WIN32_Asynch_Read_Stream_Result;

  public:
    /// The number of bytes which were requested at the start of the
    /// asynchronous read.
    u_long bytes_to_read (void) const;

    /// Message block which contains the read data.
    ACE_Message_Block &message_block (void) const;

    /// I/O handle used for reading.
    ACE_HANDLE handle (void) const;

    /// Get the implementation class.
    ACE_Asynch_Read_Stream_Result_Impl *implementation (void) const;

  protected:
    /// Constructor.
    Result (ACE_Asynch_Read_Stream_Result_Impl *implementation);

    /// Destructor.
    virtual ~Result (void);

    /// The implementation class.
    ACE_Asynch_Read_Stream_Result_Impl *implementation_;
  };
};

// Forward declarations
class ACE_Asynch_Write_Stream_Impl;
class ACE_Asynch_Write_Stream_Result_Impl;

/**
 * @class ACE_Asynch_Write_Stream
 *
 * @brief This class is a factory for starting off asynchronous writes
 * on a stream. This class forwards all methods to its
 * implementation class.
 *
 * Once <open> is called, multiple asynchronous <writes>s can
 * started using this class.  An ACE_Asynch_Write_Stream::Result
 * will be passed back to the <handler> when the asynchronous
 * write completes through the
 * <ACE_Handler::handle_write_stream> callback.
 */
class ACE_Export ACE_Asynch_Write_Stream : public ACE_Asynch_Operation
{

public:
  /// A do nothing constructor.
  ACE_Asynch_Write_Stream (void);

  /// Destructor.
  virtual ~ACE_Asynch_Write_Stream (void);

  /**
   * Initializes the factory with information which will be used with
   * each asynchronous call. If (<handle> == ACE_INVALID_HANDLE),
   * <ACE_Handler::handle> will be called on the <handler> to get the
   * correct handle.
   */
  int open (ACE_Handler &handler,
            ACE_HANDLE handle = ACE_INVALID_HANDLE,
            const void *completion_key = 0,
            ACE_Proactor *proactor = 0);

  /**
   * This starts off an asynchronous write.  Upto <bytes_to_write>
   * will be written from the <message_block>. Upon successful completion
   * of the write operation, <message_block>'s <rd_ptr> is updated to
   * reflect the data that was written. Priority of the
   * operation is specified by <priority>. On POSIX4-Unix, this is
   * supported. Works like <nice> in Unix. Negative values are not
   * allowed. 0 means priority of the operation same as the process
   * priority. 1 means priority of the operation is one less than
   * process. And so forth. On Win32, this argument is a no-op.
   * <signal_number> is the POSIX4 real-time signal number to be used
   * for the operation. <signal_number> ranges from ACE_SIGRTMIN to
   * ACE_SIGRTMAX. This argument is a no-op on non-POSIX4 systems.
   */
  int write (ACE_Message_Block &message_block,
             u_long bytes_to_write,
             const void *act = 0,
             int priority = 0,
             int signal_number = ACE_SIGRTMIN);

  /// Return the underlying implementation class.
  ACE_Asynch_Write_Stream_Impl *implementation (void) const;

protected:
  /// Set the implementation class.
  void implementation (ACE_Asynch_Write_Stream_Impl *implementation);

  /// Implementation class that all methods will be forwarded to.
  ACE_Asynch_Write_Stream_Impl *implementation_;

public:
/**
 * @class
 *
 * @brief This is that class which will be passed back to the
 * <handler> when the asynchronous write completes. This class
 * forwards all the methods to the implementation class.
 *
 * This class has all the information necessary for the
 * <handler> to uniquiely identify the completion of the
 * asynchronous write.
 */
  class ACE_Export Result : public ACE_Asynch_Result
  {

    /// The concrete implementation result classes only construct this
    /// class.
    friend class ACE_POSIX_Asynch_Write_Stream_Result;
    friend class ACE_WIN32_Asynch_Write_Stream_Result;

  public:
    /// The number of bytes which were requested at the start of the
    /// asynchronous write.
    u_long bytes_to_write (void) const;

    /// Message block that contains the data to be written.
    ACE_Message_Block &message_block (void) const;

    /// I/O handle used for writing.
    ACE_HANDLE handle (void) const;

    /// Get the implementation class.
    ACE_Asynch_Write_Stream_Result_Impl *implementation (void) const;

  protected:
    /// Constrcutor.
    Result (ACE_Asynch_Write_Stream_Result_Impl *implementation);

    /// Destructor.
    virtual ~Result (void);

    /// Implementation class.
    ACE_Asynch_Write_Stream_Result_Impl *implementation_;
  };
};

// Forward declarations
class ACE_Asynch_Read_File_Impl;
class ACE_Asynch_Read_File_Result_Impl;

/**
 * @class ACE_Asynch_Read_File
 *
 * @brief This class is a factory for starting off asynchronous reads
 * on a file. This class forwards all methods to its
 * implementation class.
 *
 * Once <open> is called, multiple asynchronous <read>s can
 * started using this class. An ACE_Asynch_Read_File::Result
 * will be passed back to the <handler> when the asynchronous
 * reads completes through the <ACE_Handler::handle_read_file>
 * callback.
 * This class differs slightly from ACE_Asynch_Read_Stream as it
 * allows the user to specify an offset for the read.
 */
class ACE_Export ACE_Asynch_Read_File : public ACE_Asynch_Read_Stream
{

public:
  /// A do nothing constructor.
  ACE_Asynch_Read_File (void);

  /// Destructor.
  virtual ~ACE_Asynch_Read_File (void);

  /**
   * Initializes the factory with information which will be used with
   * each asynchronous call. If (<handle> == ACE_INVALID_HANDLE),
   * <ACE_Handler::handle> will be called on the <handler> to get the
   * correct handle.
   */
  int open (ACE_Handler &handler,
            ACE_HANDLE handle = ACE_INVALID_HANDLE,
            const void *completion_key = 0,
            ACE_Proactor *proactor = 0);

  /**
   * This starts off an asynchronous read.  Upto <bytes_to_read> will
   * be read and stored in the <message_block>.  The read will start
   * at <offset> from the beginning of the file. Priority of the
   * operation is specified by <priority>. On POSIX4-Unix, this is
   * supported. Works like <nice> in Unix. Negative values are not
   * allowed. 0 means priority of the operation same as the process
   * priority. 1 means priority of the operation is one less than
   * process. And so forth. On Win32, this argument is a no-op.
   * <signal_number> is the POSIX4 real-time signal number to be used
   * for the operation. <signal_number> ranges from ACE_SIGRTMIN to
   * ACE_SIGRTMAX. This argument is a no-op on non-POSIX4 systems.
   */
  int read (ACE_Message_Block &message_block,
            u_long bytes_to_read,
            u_long offset = 0,
            u_long offset_high = 0,
            const void *act = 0,
            int priority = 0,
            int signal_number = ACE_SIGRTMIN);

  /// Return the underlying implementation class.
  ACE_Asynch_Read_File_Impl *implementation (void) const;

protected:
  /// Set the implementation class.
  void implementation (ACE_Asynch_Read_File_Impl *implementation);

  /// Delegation/implementation class that all methods will be
  /// forwarded to.
  ACE_Asynch_Read_File_Impl *implementation_;

public:
/**
 * @class Result
 *
 * @brief This is that class which will be passed back to the
 * <handler> when the asynchronous read completes. This class
 * forwards all the methods to the implementation class.
 *
 * This class has all the information necessary for the
 * <handler> to uniquiely identify the completion of the
 * asynchronous read.
 * This class differs slightly from
 * ACE_Asynch_Read_Stream::Result as it calls back
 * <ACE_Handler::handle_read_file> on the <handler> instead of
 * <ACE_Handler::handle_read_stream>.  No additional state is
 * required by this class as ACE_Asynch_Result can store the
 * <offset>.
 */
  class ACE_Export Result : public ACE_Asynch_Read_Stream::Result
  {

    /// The concrete implementation result classes only construct this
    /// class.
    friend class ACE_POSIX_Asynch_Read_File_Result;
    friend class ACE_WIN32_Asynch_Read_File_Result;

  public:
    /// Get the implementation class.
    ACE_Asynch_Read_File_Result_Impl *implementation (void) const;

  protected:
    /// Constructor. This implementation will not be deleted.
    Result (ACE_Asynch_Read_File_Result_Impl *implementation);

    /// Destructor.
    virtual ~Result (void);

    /// The implementation class.
    ACE_Asynch_Read_File_Result_Impl *implementation_;

  private:
    /// Here just to provide an dummpy implementation, since the
    /// one auto generated by MSVC is flagged as infinitely recursive
    void operator= (Result &) {}
  };
};

// Forward declarations
class ACE_Asynch_Write_File_Impl;
class ACE_Asynch_Write_File_Result_Impl;

/**
 * @class ACE_Asynch_Write_File
 *
 * @brief This class is a factory for starting off asynchronous writes
 * on a file. This class forwards all methods to its
 * implementation class.
 *
 * Once <open> is called, multiple asynchronous <write>s can be
 * started using this class.  A ACE_Asynch_Write_File::Result
 * will be passed back to the <handler> when the asynchronous
 * writes completes through the <ACE_Handler::handle_write_file>
 * callback.
 * This class differs slightly from ACE_Asynch_Write_Stream as
 * it allows the user to specify an offset for the write.
 */
class ACE_Export ACE_Asynch_Write_File : public ACE_Asynch_Write_Stream
{

public:
  /// A do nothing constructor.
  ACE_Asynch_Write_File (void);

  /// Destructor.
  virtual ~ACE_Asynch_Write_File (void);

  /**
   * Initializes the factory with information which will be used with
   * each asynchronous call. If (<handle> == ACE_INVALID_HANDLE),
   * <ACE_Handler::handle> will be called on the <handler> to get the
   * correct handle.
   */
  int open (ACE_Handler &handler,
            ACE_HANDLE handle = ACE_INVALID_HANDLE,
            const void *completion_key = 0,
            ACE_Proactor *proactor = 0);

  /**
   * This starts off an asynchronous write.  Upto <bytes_to_write>
   * will be written from the <message_block>, starting at the
   * block's <rd_ptr>.  The write will go to the file, starting
   * <offset> bytes from the beginning of the file. Priority of the
   * operation is specified by <priority>. On POSIX4-Unix, this is
   * supported. Works like <nice> in Unix. Negative values are not
   * allowed. 0 means priority of the operation same as the process
   * priority. 1 means priority of the operation is one less than
   * process. And so forth. On Win32, this is a no-op.
   * <signal_number> is the POSIX4 real-time signal number to be used
   * for the operation. <signal_number> ranges from ACE_SIGRTMIN to
   * ACE_SIGRTMAX. This argument is a no-op on non-POSIX4 systems.
   */
  int write (ACE_Message_Block &message_block,
             u_long bytes_to_write,
             u_long offset = 0,
             u_long offset_high = 0,
             const void *act = 0,
             int priority = 0,
             int signal_number = ACE_SIGRTMIN);

  /// Return the underlying implementation class.
  ACE_Asynch_Write_File_Impl *implementation (void) const;

protected:
  /// Set the implementation.
  void implementation (ACE_Asynch_Write_File_Impl *implementation);

  /// Implementation object.
  ACE_Asynch_Write_File_Impl *implementation_;

public:
/**
 * @class Result
 *
 * @brief This is that class which will be passed back to the
 * <handler> when the asynchronous write completes. This class
 * forwards all the methods to the implementation class.
 *
 * This class has all the information necessary for the
 * <handler> to uniquiely identify the completion of the
 * asynchronous write.
 * This class differs slightly from
 * ACE_Asynch_Write_Stream::Result as it calls back
 * <ACE_Handler::handle_write_file> on the <handler> instead
 * of <ACE_Handler::handle_write_stream>.  No additional state
 * is required by this class as ACE_Asynch_Result can store
 * the <offset>.
 */
  class ACE_Export Result : public ACE_Asynch_Write_Stream::Result
  {

    /// The concrete implementation result classes only construct this
    /// class.
    friend class ACE_POSIX_Asynch_Write_File_Result;
    friend class ACE_WIN32_Asynch_Write_File_Result;

  public:
    ///  Get the implementation class.
    ACE_Asynch_Write_File_Result_Impl *implementation (void) const;

  protected:
    /// Constructor. This implementation will not be deleted.
    Result (ACE_Asynch_Write_File_Result_Impl *implementation);

    /// Destructor.
    virtual ~Result (void);

    /// The implementation class.
    ACE_Asynch_Write_File_Result_Impl *implementation_;

  private:
    /// Here just to provide an dummpy implementation, since the
    /// one auto generated by MSVC is flagged as infinitely recursive
    void operator= (Result &) {};
  };
};

// Forward declarations
class ACE_Asynch_Accept_Result_Impl;
class ACE_Asynch_Accept_Impl;

/**
 * @class ACE_Asynch_Accept
 *
 * @brief This class is a factory for starting off asynchronous accepts
 * on a listen handle. This class forwards all methods to its
 * implementation class.
 *
 * Once <open> is called, multiple asynchronous <accept>s can
 * started using this class.  A ACE_Asynch_Accept::Result will
 * be passed back to the <handler> when the asynchronous accept
 * completes through the <ACE_Handler::handle_accept>
 * callback.
 */
class ACE_Export ACE_Asynch_Accept : public ACE_Asynch_Operation
{

public:
  /// A do nothing constructor.
  ACE_Asynch_Accept (void);

  /// Destructor.
  virtual ~ACE_Asynch_Accept (void);

  /**
   * Initializes the factory with information which will be used with
   * each asynchronous call. If (<handle> == ACE_INVALID_HANDLE),
   * <ACE_Handler::handle> will be called on the <handler> to get the
   * correct handle.
   */
  int open (ACE_Handler &handler,
            ACE_HANDLE handle = ACE_INVALID_HANDLE,
            const void *completion_key = 0,
            ACE_Proactor *proactor = 0);

  /**
   * This starts off an asynchronous accept.  The asynchronous accept
   * call also allows any initial data to be returned to the
   * <handler>.  Upto <bytes_to_read> will be read and stored in the
   * <message_block>.  The <accept_handle> will be used for the
   * <accept> call.  If (<accept_handle> == INVALID_HANDLE), a new
   * handle will be created. Priority of the
   * operation is specified by <priority>. On POSIX4-Unix, this is
   * supported. Works like <nice> in Unix. Negative values are not
   * allowed. 0 means priority of the operation same as the process
   * priority. 1 means priority of the operation is one less than
   * process. And so forth. On Win32, this is a no-op.
   *
   * <message_block> must be specified. This is because the address of
   * the new connection is placed at the end of this buffer.
   * <signal_number> is the POSIX4 real-time signal number to be used
   * for the operation. <signal_number> ranges from ACE_SIGRTMIN to
   * ACE_SIGRTMAX. This argument is a no-op on non-POSIX4 systems.
   */
  int accept (ACE_Message_Block &message_block,
              u_long bytes_to_read,
              ACE_HANDLE accept_handle = ACE_INVALID_HANDLE,
              const void *act = 0,
              int priority = 0,
              int signal_number = ACE_SIGRTMIN);

  /// Return the underlying implementation class.
  ACE_Asynch_Accept_Impl *implementation (void) const;

protected:
  /// Set the implementation class.
  void implementation (ACE_Asynch_Accept_Impl *implementation);

  /// Delegation/implementation class that all methods will be
  /// forwarded to.
  ACE_Asynch_Accept_Impl *implementation_;

public:
/**
 * @class Result
 *
 * @brief This is that class which will be passed back to the
 * <handler> when the asynchronous accept completes.
 *
 * This class has all the information necessary for the
 * <handler> to uniquiely identify the completion of the
 * asynchronous accept.
 */
  class ACE_Export Result : public ACE_Asynch_Result
  {

    /// The concrete implementation result classes only construct this
    /// class.
    friend class ACE_POSIX_Asynch_Accept_Result;
    friend class ACE_WIN32_Asynch_Accept_Result;

  public:
    /// The number of bytes which were requested at the start of the
    /// asynchronous accept.
    u_long bytes_to_read (void) const;

    /// Message block which contains the read data.
    ACE_Message_Block &message_block (void) const;

    /// I/O handle used for accepting new connections.
    ACE_HANDLE listen_handle (void) const;

    /// I/O handle for the new connection.
    ACE_HANDLE accept_handle (void) const;

    /// Get the implementation.
    ACE_Asynch_Accept_Result_Impl *implementation (void) const;

  protected:
    /// Contructor. Implementation will not be deleted.
    Result (ACE_Asynch_Accept_Result_Impl *implementation);

    /// Destructor.
    virtual ~Result (void);

    /// Impelmentation class.
    ACE_Asynch_Accept_Result_Impl *implementation_;
  };
};

// Forward declarations
class ACE_Asynch_Transmit_File_Result_Impl;
class ACE_Asynch_Transmit_File_Impl;

/**
 * @class ACE_Asynch_Transmit_File
 *
 * @brief This class is a factory for starting off asynchronous
 * transmit files on a stream.
 *
 * Once <open> is called, multiple asynchronous <transmit_file>s
 * can started using this class.  A
 * ACE_Asynch_Transmit_File::Result will be passed back to the
 * <handler> when the asynchronous transmit file completes
 * through the <ACE_Handler::handle_transmit_file> callback.
 * The transmit_file function transmits file data over a
 * connected network connection. The function uses the operating
 * system's cache manager to retrieve the file data. This
 * function provides high-performance file data transfer over
 * network connections.  This function would be of great use in
 * a Web Server, Image Server, etc.
 */
class ACE_Export ACE_Asynch_Transmit_File : public ACE_Asynch_Operation
{

public:
  // Forward declarations
  class Header_And_Trailer;

  /// A do nothing constructor.
  ACE_Asynch_Transmit_File (void);

  /// Destructor.
  virtual ~ACE_Asynch_Transmit_File (void);

  /**
   * Initializes the factory with information which will be used with
   * each asynchronous call. If (<handle> == ACE_INVALID_HANDLE),
   * <ACE_Handler::handle> will be called on the <handler> to get the
   * correct handle.
   */
  int open (ACE_Handler &handler,
            ACE_HANDLE handle = ACE_INVALID_HANDLE,
            const void *completion_key = 0,
            ACE_Proactor *proactor = 0);

  /**
   * This starts off an asynchronous transmit file.  The <file> is a
   * handle to an open file.  <header_and_trailer> is a pointer to a
   * data structure that contains pointers to data to send before and
   * after the file data is sent.  Set this parameter to 0 if you only
   * want to transmit the file data.  Upto <bytes_to_write> will be
   * written to the <socket>.  If you want to send the entire file,
   * let <bytes_to_write> = 0.  <bytes_per_send> is the size of each
   * block of data sent per send operation.  Please read the Win32
   * documentation on what the flags should be. Priority of the
   * operation is specified by <priority>. On POSIX4-Unix, this is
   * supported. Works like <nice> in Unix. Negative values are not
   * allowed. 0 means priority of the operation same as the process
   * priority. 1 means priority of the operation is one less than
   * process. And so forth. On Win32, this is a no-op.
   * <signal_number> is the POSIX4 real-time signal number to be used
   * for the operation. <signal_number> ranges from ACE_SIGRTMIN to
   * ACE_SIGRTMAX. This argument is a no-op on non-POSIX4 systems.
   */
  int transmit_file (ACE_HANDLE file,
                     Header_And_Trailer *header_and_trailer = 0,
                     u_long bytes_to_write = 0,
                     u_long offset = 0,
                     u_long offset_high = 0,
                     u_long bytes_per_send = 0,
                     u_long flags = 0,
                     const void *act = 0,
                     int priority = 0,
                     int signal_number = ACE_SIGRTMIN);

  /// Return the underlying implementation class.
  ACE_Asynch_Transmit_File_Impl *implementation (void) const;

protected:
  /// Set the implementation.
  void implementation (ACE_Asynch_Transmit_File_Impl *);

  /// The implementation class.
  ACE_Asynch_Transmit_File_Impl *implementation_;

public:
/**
 * @class Result
 *
 * @brief This is that class which will be passed back to the
 * <handler> when the asynchronous transmit file completes.
 *
 * This class has all the information necessary for the
 * <handler> to uniquiely identify the completion of the
 * asynchronous transmit file.
 */
  class ACE_Export Result : public ACE_Asynch_Result
  {

    /// The concrete implementation result classes only construct this
    /// class.
    friend class ACE_POSIX_Asynch_Transmit_File_Result;
    friend class ACE_WIN32_Asynch_Transmit_File_Result;

  public:
    /// Socket used for transmitting the file.
    ACE_HANDLE socket (void) const;

    /// File from which the data is read.
    ACE_HANDLE file (void) const;

    /// Header and trailer data associated with this transmit file.
    Header_And_Trailer *header_and_trailer (void) const;

    /// The number of bytes which were requested at the start of the
    /// asynchronous transmit file.
    u_long bytes_to_write (void) const;

    /// Number of bytes per send requested at the start of the transmit
    /// file.
    u_long bytes_per_send (void) const;

    /// Flags which were passed into transmit file.
    u_long flags (void) const;

    /// Get the implementation class.
    ACE_Asynch_Transmit_File_Result_Impl *implementation (void) const;

  protected:
    /// Constructor.
    Result (ACE_Asynch_Transmit_File_Result_Impl *implementation);

    /// Destructor.
    virtual ~Result (void);

    /// The implementation class.
    ACE_Asynch_Transmit_File_Result_Impl *implementation_;
  };

/**
 * @class Header_And_Trailer
 *
 * @brief The class defines a data structure that contains pointers
 * to data to send before and after the file data is sent.
 *
 * This class provides a wrapper over TRANSMIT_FILE_BUFFERS
 * and provided a consistent use of ACE_Message_Blocks.
 */
  class ACE_Export Header_And_Trailer
  {

  public:
    /// Constructor.
    Header_And_Trailer (ACE_Message_Block *header = 0,
                        u_long header_bytes = 0,
                        ACE_Message_Block *trailer = 0,
                        u_long trailer_bytes = 0);

    /// Destructor
    virtual ~Header_And_Trailer (void);

    /// This method allows all the member to be set in one fell swoop.
    void header_and_trailer (ACE_Message_Block *header = 0,
                             u_long header_bytes = 0,
                             ACE_Message_Block *trailer = 0,
                             u_long trailer_bytes = 0);

    /// Header which goes before the file data.
    ACE_Message_Block *header (void) const;
    void header (ACE_Message_Block *message_block);

    /// Size of the header data.
    u_long header_bytes (void) const;
    void header_bytes (u_long bytes);

    /// Trailer which goes after the file data.
    ACE_Message_Block *trailer (void) const;
    void trailer (ACE_Message_Block *message_block);

    /// Size of the trailer data.
    u_long trailer_bytes (void) const;
    void trailer_bytes (u_long bytes);

    /// Conversion routine.
    ACE_LPTRANSMIT_FILE_BUFFERS transmit_buffers (void);

  protected:
    /// Header data.
    ACE_Message_Block *header_;

    /// Size of header data.
    u_long header_bytes_;

    /// Trailer data.
    ACE_Message_Block *trailer_;

    /// Size of trailer data.
    u_long trailer_bytes_;

    /// Target data structure.
    ACE_TRANSMIT_FILE_BUFFERS transmit_buffers_;
  };
};


// Forward declarations
class ACE_Asynch_Read_Dgram_Result_Impl;
class ACE_Asynch_Read_Dgram_Impl;
class ACE_Addr;

/**
 * @class ACE_Asynch_Read_Dgram
 *
 * @brief This class is a factory for starting off asynchronous reads
 * on a UDP socket. This class forwards all methods to its
 * implementation class.
 *
 * Once <open> is called, multiple asynchronous <read>s can be
 * started using this class.  An ACE_Asynch_Read_Dgram::Result
 * will be passed back to the <handler> when the asynchronous
 * reads completes through the <ACE_Handler::handle_read_dgram>
 * callback.
 */
class ACE_Export ACE_Asynch_Read_Dgram : public ACE_Asynch_Operation
{

public:
  /// A do nothing constructor.
  ACE_Asynch_Read_Dgram (void);

  /// Destructor
  virtual ~ACE_Asynch_Read_Dgram (void);

  /**
   * Initializes the factory with information which will be used with
   * each asynchronous call. If (<handle> == ACE_INVALID_HANDLE),
   * <ACE_Handler::handle> will be called on the <handler> to get the
   * correct handle.
   */
  int open (ACE_Handler &handler,
            ACE_HANDLE handle = ACE_INVALID_HANDLE,
            const void *completion_key = 0,
            ACE_Proactor *proactor = 0);

  /** This starts off an asynchronous read.  Upto
   * <message_block->total_size()> will be read and stored in the
   * <message_block>.  <message_block>'s <wr_ptr> will be updated to reflect
   * the added bytes if the read operation is successfully completed.
   * Return code of 1 means immediate success and <number_of_bytes_recvd>
   * will contain number of bytes read.  The <ACE_Handler::handle_read_dgram>
   * method will still be called.  Return code of 0 means the IO will
   * complete proactively.  Return code of -1 means there was an error, use
   * errno to get the error code.
   *
   * Scatter/gather is supported on WIN32 by using the <message_block->cont()>
   * method.  Up to ACE_IOV_MAX <message_block>'s are supported.  Upto 
   * <message_block->size()> bytes will be read into each <message block> for
   * a total of <message_block->total_size()> bytes.  All <message_block>'s
   * <wr_ptr>'s will be updated to reflect the added bytes for each 
   * <message_block>
   *
   * Priority of the operation is specified by <priority>. On POSIX4-Unix,
   * this is supported. Works like <nice> in Unix. Negative values are not
   * allowed. 0 means priority of the operation same as the process
   * priority. 1 means priority of the operation is one less than
   * process. And so forth. On Win32, <priority> is a no-op.
   * <signal_number> is the POSIX4 real-time signal number to be used
   * for the operation. <signal_number> ranges from ACE_SIGRTMIN to
   * ACE_SIGRTMAX. This argument is a no-op on non-POSIX4 systems.
   */
  ssize_t recv (ACE_Message_Block *message_block,
                size_t &number_of_bytes_recvd,
                int flags,
                int protocol_family = PF_INET,
                const void *act = 0,
                int priority = 0,
                int signal_number = ACE_SIGRTMIN);

  /// Return the underlying implementation class.
  ACE_Asynch_Read_Dgram_Impl *implementation (void) const;

protected:
  /// Set the implementation class.
  void implementation (ACE_Asynch_Read_Dgram_Impl *implementation);

  /// Implementation class that all methods will be forwarded to.
  ACE_Asynch_Read_Dgram_Impl *implementation_;

public:
/**
 * @class Result
 *
 * @brief This is the class which will be passed back to the
 * <handler> when the asynchronous read completes. This class
 * forwards all the methods to the implementation classes.
 *
 * This class has all the information necessary for the
 * <handler> to uniquiely identify the completion of the
 * asynchronous read.
 */
  class ACE_Export Result : public ACE_Asynch_Result
  {

    /// The concrete implementation result classes only construct this
    /// class.
    friend class ACE_POSIX_Asynch_Read_Dgram_Result;
    friend class ACE_WIN32_Asynch_Read_Dgram_Result;

  public:

    /// The number of bytes which were requested at the start of the
    /// asynchronous read.
    u_long bytes_to_read (void) const;

    /// Message block which contains the read data
    ACE_Message_Block *message_block (void) const;

    /// The flags used in the read
    int flags (void) const;

    /// The address of where the packet came from
    int remote_address (ACE_Addr& addr) const;

    /// I/O handle used for reading.
    ACE_HANDLE handle (void) const;

    /// Get the implementation class.
    ACE_Asynch_Read_Dgram_Result_Impl *implementation (void) const;

  protected:
    /// Constructor.
    Result (ACE_Asynch_Read_Dgram_Result_Impl *implementation);

    /// Destructor.
    virtual ~Result (void);

    /// The implementation class.
    ACE_Asynch_Read_Dgram_Result_Impl *implementation_;
  };
};

// Forward declarations
class ACE_Asynch_Write_Dgram_Impl;
class ACE_Asynch_Write_Dgram_Result_Impl;

/**
 * @class ACE_Asynch_Write_Dgram
 *
 * @brief This class is a factory for starting off asynchronous writes
 * on a UDP socket. This class forwards all methods to its
 * implementation class.
 *
 * Once <open> is called, multiple asynchronous <writes>s can
 * started using this class.  An ACE_Asynch_Write_Dgram::Result
 * will be passed back to the <handler> when the asynchronous
 * write completes through the
 * <ACE_Handler::handle_write_dgram> callback.
 */
class ACE_Export ACE_Asynch_Write_Dgram : public ACE_Asynch_Operation
{

public:
  /// A do nothing constructor.
  ACE_Asynch_Write_Dgram (void);

  /// Destructor.
  virtual ~ACE_Asynch_Write_Dgram (void);

  /**
   * Initializes the factory with information which will be used with
   * each asynchronous call. If (<handle> == ACE_INVALID_HANDLE),
   * <ACE_Handler::handle> will be called on the <handler> to get the
   * correct handle.
   */
  int open (ACE_Handler &handler,
            ACE_HANDLE handle = ACE_INVALID_HANDLE,
            const void *completion_key = 0,
            ACE_Proactor *proactor = 0);

  /** This starts off an asynchronous send.  Upto
   * <message_block->total_length()> will be sent.  <message_block>'s 
   * <rd_ptr> will be updated to reflect the sent bytes if the send operation
   * is successfully completed.
   * Return code of 1 means immediate success and <number_of_bytes_sent>
   * is updated to number of bytes sent.  The <ACE_Handler::handle_write_dgram>
   * method will still be called.  Return code of 0 means the IO will
   * complete proactively.  Return code of -1 means there was an error, use
   * errno to get the error code.
   *
   * Scatter/gather is supported on WIN32 by using the <message_block->cont()>
   * method.  Up to ACE_IOV_MAX <message_block>'s are supported.  Upto 
   * <message_block->length()> bytes will be sent from each <message block>
   * for a total of <message_block->total_length()> bytes.  All
   * <message_block>'s <rd_ptr>'s will be updated to reflect the bytes sent
   * from each <message_block>.
   *
   * Priority of the operation is specified by <priority>. On POSIX4-Unix,
   * this is supported. Works like <nice> in Unix. Negative values are not
   * allowed. 0 means priority of the operation same as the process
   * priority. 1 means priority of the operation is one less than
   * process. And so forth. On Win32, this argument is a no-op.
   * <signal_number> is the POSIX4 real-time signal number to be used
   * for the operation. <signal_number> ranges from ACE_SIGRTMIN to
   * ACE_SIGRTMAX. This argument is a no-op on non-POSIX4 systems.
   */
  ssize_t send (ACE_Message_Block *message_block,
                size_t &number_of_bytes_sent,
                int flags,
                const ACE_Addr& remote_addr,
                const void *act = 0,
                int priority = 0,
                int signal_number = ACE_SIGRTMIN);

  /// Return the underlying implementation class.
  ACE_Asynch_Write_Dgram_Impl *implementation (void) const;

protected:
  /// Set the implementation class.
  void implementation (ACE_Asynch_Write_Dgram_Impl *implementation);

  /// Implementation class that all methods will be forwarded to.
  ACE_Asynch_Write_Dgram_Impl *implementation_;

public:
/**
 * @class
 *
 * @brief This is that class which will be passed back to the
 * <handler> when the asynchronous write completes. This class
 * forwards all the methods to the implementation class.
 *
 * This class has all the information necessary for the
 * <handler> to uniquiely identify the completion of the
 * asynchronous write.
 */
  class ACE_Export Result : public ACE_Asynch_Result
  {

    /// The concrete implementation result classes only construct this
    /// class.
    friend class ACE_POSIX_Asynch_Write_Dgram_Result;
    friend class ACE_WIN32_Asynch_Write_Dgram_Result;

  public:

    /// The number of bytes which were requested at the start of the
    /// asynchronous write.
    u_long bytes_to_write (void) const;

    /// Message block which contains the sent data
    ACE_Message_Block *message_block (void) const;

    /// The flags using in the write
    int flags (void) const;

    /// I/O handle used for writing.
    ACE_HANDLE handle (void) const;

    /// Get the implementation class.
    ACE_Asynch_Write_Dgram_Result_Impl *implementation (void) const;

  protected:
    /// Constrcutor.
    Result (ACE_Asynch_Write_Dgram_Result_Impl *implementation);

    /// Destructor.
    virtual ~Result (void);

    /// Implementation class.
    ACE_Asynch_Write_Dgram_Result_Impl *implementation_;
  };
};


/**
 * @class ACE_Handler
 *
 * @brief This base class defines the interface for receiving the
 * results of asynchronous operations.
 *
 * Subclasses of this class will fill in appropriate methods.
 */
class ACE_Export ACE_Handler
{
public:
  /// A do nothing constructor.
  ACE_Handler (void);

  /// A do nothing constructor which allows proactor to be set to <p>.
  ACE_Handler (ACE_Proactor *p);

  /// Virtual destruction.
  virtual ~ACE_Handler (void);

  /// This method will be called when an asynchronous read completes on
  /// a stream.
  virtual void handle_read_stream (const ACE_Asynch_Read_Stream::Result &result);

  /// This method will be called when an asynchronous write completes
  /// on a UDP socket.
  virtual void handle_write_dgram (const ACE_Asynch_Write_Dgram::Result &result);

  /// This method will be called when an asynchronous read completes on
  /// a UDP socket.
  virtual void handle_read_dgram (const ACE_Asynch_Read_Dgram::Result &result);

  /// This method will be called when an asynchronous write completes
  /// on a stream.
  virtual void handle_write_stream (const ACE_Asynch_Write_Stream::Result &result);

  /// This method will be called when an asynchronous read completes on
  /// a file.
  virtual void handle_read_file (const ACE_Asynch_Read_File::Result &result);

  /// This method will be called when an asynchronous write completes
  /// on a file.
  virtual void handle_write_file (const ACE_Asynch_Write_File::Result &result);

  /// This method will be called when an asynchronous accept completes.
  virtual void handle_accept (const ACE_Asynch_Accept::Result &result);

  /// This method will be called when an asynchronous transmit file
  /// completes.
  virtual void handle_transmit_file (const ACE_Asynch_Transmit_File::Result &result);

  /// Called when timer expires.  <tv> was the requested time value and
  /// <act> is the ACT passed when scheduling the timer.
  virtual void handle_time_out (const ACE_Time_Value &tv,
                                const void *act = 0);

  /**
   * This is method works with the <run_event_loop> of the
   * ACE_Proactor. A special <Wake_Up_Completion> is used to wake up
   * all the threads that are blocking for completions.
   */
  virtual void handle_wakeup (void);

  /// Get the proactor associated with this handler.
  ACE_Proactor *proactor (void);

  /// Set the proactor.
  void proactor (ACE_Proactor *p);

  /**
   * Get the I/O handle used by this <handler>. This method will be
   * called by the ACE_Asynch_* classes when an ACE_INVALID_HANDLE is
   * passed to <open>.
   */
  virtual ACE_HANDLE handle (void) const;

  /// Set the ACE_HANDLE value for this Handler.
  virtual void handle (ACE_HANDLE);

protected:
  /// The proactor associated with this handler.
  ACE_Proactor *proactor_;

  /// The ACE_HANDLE in use with this handler.
  ACE_HANDLE    handle_;
};

// Forward declarations
class ACE_INET_Addr;

// Forward declarations
template <class HANDLER>
class ACE_Asynch_Acceptor;

/**
 * @class ACE_Service_Handler
 *
 * @brief This base class defines the interface for the
 * ACE_Asynch_Acceptor to call into when new connection are
 * accepted.
 *
 * Subclasses of this class will fill in appropriate methods to
 * define application specific behavior.
 */
class ACE_Export ACE_Service_Handler : public ACE_Handler
{

  /// The Acceptor is the factory and therefore should have special
  /// privileges.
  friend class ACE_Asynch_Acceptor<ACE_Service_Handler>;

public:
  /// A do nothing constructor.
  ACE_Service_Handler (void);

  /// Virtual destruction.
  virtual ~ACE_Service_Handler (void);

  /**
   * <open> is called by ACE_Asynch_Acceptor to initialize a new
   * instance of ACE_Service_Handler that has been created after the a
   * new connection is accepted. The handle for the new connection is
   * passed along with an initial data that may have shown up.
   */
  virtual void open (ACE_HANDLE new_handle,
                     ACE_Message_Block &message_block);

  // protected:
  // This should be corrected after the correct semantics of the
  // friend has been figured out.

  /// Called by ACE_Asynch_Acceptor to pass the addresses of the new
  /// connections.
  virtual void addresses (const ACE_INET_Addr &remote_address,
                          const ACE_INET_Addr &local_address);

  /// Called by ACE_Asynch_Acceptor to pass the act.
  virtual void act (const void *);
};

#endif /* ACE_WIN32 || ACE_HAS_AIO_CALLS*/
#include "ace/post.h"
#endif /* ACE_ASYNCH_IO_H */