shm_mmap.h

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#ifndef SHM_MMAP_H
#define SHM_MMAP_H 1

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <sys/mman.h>
#include <pthread.h>

#define MAPSIZE (size_t)(1024 * 1024)
#define FORKS 20
#define PARENT_FILE "/dev/zero"
#define FORKED_FILE "/opt/local/data/fork%d"
#define FORKED_SIZE 32

class shm_mmap
{
 public:
  shm_mmap( char * file ) :
    size(MAPSIZE),
    rights(PROT_WRITE | PROT_READ),
    publication(MAP_SHARED)    
    {
      if ( 0 == prepareFile( file )  ) {
    base = mmapIntArray( file );
      }
    };

  int * mmapIntArray( char * file );
  int prepareFile( char * file );
  int * initMap( void );


 private:
  long long id;
  char * file;
  void * base;
  size_t size;
  int rights;
  int publication;
  int last_errno;


};

int * 
shm_mmap::mmapIntArray( char * file ) 
{
  int *mmap_mp;
  int mmap_fd;
  /* open file */
  if (( mmap_fd = open( file, O_RDWR, 0644 ) ) == -1 ) {
    perror( "data file open fails" );
    return (int *) MAP_FAILED;
  } else {
    fprintf( stdout, "%d : file opened %d. \n", id, mmap_fd ) ;
    fflush( stdout );
  }
  /* mmap in file memory */
  if ((mmap_mp = (int *) mmap( (void *) 0, (size_t) MAPSIZE,
                PROT_WRITE | PROT_READ, 
                MAP_SHARED,
                mmap_fd, 0 ) ) == MAP_FAILED) {
    perror("mmap failed");
  }else {
    fprintf( stdout, "%d : memory mapped %p. \n", id, mmap_mp ) ;
    fflush( stdout );
  }
  return mmap_mp;
}


int 
shm_mmap::prepareFile( char * file ) 
{
  char zero = '\0';
  int count = 0;
  int fd;
  FILE *stream;
  /* open file */
  if (( fd = open( file, O_RDWR|O_CREAT, 0644 ) ) == -1 ) {
    perror( "data file open fails" );
    return count;
  } else {
    fprintf( stdout, "%d : file opened %d. \n", id, fd ) ;
    fflush( stdout );
  }
  if (( stream = fdopen( fd, "w" ) ) == NULL ) {
    perror( "data stream open fails" );
    return count;
  } else {
    fprintf( stdout, "%d : stream opened %d. \n", id, fd ) ;
    fflush( stdout );
  }
  count = (int) fwrite( &zero, (size_t) 1, (size_t) MAPSIZE, stream);
  close( fd );
  return count;
}



int *
shm_mmap::initMap( void ) 
{
  char fileNameBuffer[FORKED_SIZE];
  snprintf( fileNameBuffer, (size_t) FORKED_SIZE, FORKED_FILE, id );
  fprintf( stdout, "%d : file name : %s constructed.\n", id, fileNameBuffer );
  fflush( stdout );
  if ( 0 == prepareFile( fileNameBuffer ) ) {
    fprintf( stdout, "%d : file name : %s not prepared.\n", id, fileNameBuffer );
    fflush( stdout );
  } else {
    fprintf( stdout, "%d : file name : %s prepared.\n", id, fileNameBuffer );
    fflush( stdout );
  }
  return mmapIntArray( fileNameBuffer );
}


#endif

/*
 * $Log: shm_mmap.h,v $
 * Revision 1.1.1.1  2006/08/30 12:14:48  oommoo
 * Initial checkin of project library
 *
 * Revision 1.1  2004/11/19 20:54:15  vic
 * initial version of memory mapped file backing for shared memory segments
 *
 */

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