ACE Tutorial 019
Sharing your Memories


Here's the mysterious shmem.h. I wanted to show it after the placement-new client and server so that the SharedData object would have some relevance.

shmem.h

// page05.html,v 1.7 2000/11/27 17:56:44 othman Exp

#ifndef SHMEM_H
#define SHMEM_H

// This is where you'll find the ACE_Shared_Memory_SV object
#include "ace/Shared_Memory_SV.h"

// SHMSZ is just enough for the alphabet and a null terminator
#define SHMSZ 27

// Play with this, pick a value you like that isn't used by something else.
#define SHM_KEY 4200

/*
  This is what we stuff into shared memory via placement new in the
  second client/server pair.  Notice that it is a very basic object
  with no virtual methods and only concrete data.
 */
class SharedData
{
public:
  // Construct the object and optionally initialize buf_.
  SharedData (int initialized = 1);

  // Put some data into buf_
  void set (void);

  // Show the data in buf_
  void show (void);

  // What is the value of available_
  int available (void);

  // Set the value of available_
  void available (int not_in_use);

protected:
  // Big enough for a simple message
  char buf_[128];
  // A cheap mutex
  int available_;
};

#endif /* SHMEM_H */

shmem.cpp

// page05.html,v 1.7 2000/11/27 17:56:44 othman Exp

#include "shmem.h"

#include "ace/Log_Msg.h"

#if ! defined (ACE_LACKS_SYSV_SHMEM)

/*
  Set the available_ flag to zero & optionally initialize the buf_
  area.
*/

SharedData::SharedData (int initialize)
  : available_ (0)
{
  if (initialize)
    ACE_OS::sprintf (buf_, "UNSET\n");
}

/*
  Write the process ID into the buffer.  This will prove to us that
  the data really is shared between the client and server.
*/
void SharedData::set (void)
{
  ACE_OS::sprintf (buf_,
                   "My PID is (%d)\n",
                   ACE_OS::getpid ());
}

/*
  Display the buffer to the user
*/
void SharedData::show(void)
{
  ACE_DEBUG ((LM_INFO,
              "(%P|%t) Shared Data text is (%s)\n",
              buf_));
}

// Show flag
int SharedData::available(void)
{
  return available_;
}

// Set flag
void SharedData::available(int a)
{
  available_ = a;
}

#endif /* ACE_LACKS_SYSV_SHMEM */


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