Author: James CE Johnson

ACE Tutorial 020
Sharing your Memories with persistence

I wanted to show placement new again & prove that you can use it with a memory mapped file just as easily as with a shared memory segment.

Imagine if you had an object that contained an image & then you mapped that to a file... Instead of a bunch of jpg files laying around, you would actually have objects instead. Save the image? No problem, it's already there!

server2.cpp

    // page04.html,v 1.4 1999/04/03 21:56:34 jcej Exp

    #include "mmap.h"

    int
    main (int, char *[])
    {
        ACE_Shared_Memory_MM shm_server (SHM_KEY, sizeof(SharedData) );

        char *shm = (char *) shm_server.malloc ();

        ACE_DEBUG ((LM_INFO, "(%P|%t) Memory Mapped file is at 0x%x\n",
                    shm ));

        SharedData * sd = new(shm) SharedData;

        sd->set();
        sd->available(0);

        while ( ! sd->available() )
            ACE_OS::sleep (1);

        sd->show();

        if (shm_server.remove () < 0)
            ACE_ERROR ((LM_ERROR, "%p\n", "remove"));

        return 0;
    }

client2.cpp

    // page04.html,v 1.4 1999/04/03 21:56:34 jcej Exp

    #include "mmap.h"

    int main (int, char *[])
    {
        ACE_Shared_Memory_MM shm_client (SHM_KEY, sizeof(SharedData));

        char *shm = (char *) shm_client.malloc ();

        ACE_DEBUG ((LM_INFO, "(%P|%t) Memory Mapped file is at 0x%x\n",
                    shm ));

        SharedData * sd = new(shm) SharedData(0);

        sd->show();
        sd->set();
        sd->available(1);

        shm_client.close();

        return 0;
    }

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