ACE/apps/JAWS/clients/WebSTONE/src/nsapi-includes/base/shmem.h

   1 /*
   2  * Copyright (c) 1994, 1995.  Netscape Communications Corporation.  All
   3  * rights reserved.
   4  *
   5  * Use of this software is governed by the terms of the license agreement for
   6  * the Netscape Communications or Netscape Comemrce Server between the
   7  * parties.
   8  */
   9
  10
  11 /* ------------------------------------------------------------------------ */
  12
  13
  14 /*
  15  * shmem.h: Portable abstraction for memory shared among a server's workers
  16  *
  17  * Rob McCool
  18  */
  19
  20
  21 #ifndef _SHMEM_H
  22 #define _SHMEM_H
  23
  24 #include "netsite.h"
  25 #include "systems.h"
  26
  27
  28 /* --------------------------- Data structures ---------------------------- */
  29
  30
  31 #if defined (SHMEM_UNIX_MMAP) || defined (SHMEM_WIN32_MMAP)
  32 #include "file.h" /* SYS_FILE */
  33
  34 typedef struct {
  35     void *data;   /* the data */
  36 #ifdef SHMEM_WIN32_MMAP
  37     HANDLE fdmap;
  38 #endif /* SHMEM_WIN32_MMAP */
  39     int size;     /* the maximum length of the data */
  40
  41     char *name;   /* internal use: filename to unlink if exposed */
  42     SYS_FILE fd;  /* internal use: file descriptor for region */
  43 } shmem_s;
  44
  45
  46 /* ------------------------------ Prototypes ------------------------------ */
  47
  48
  49 /*
  50  * shmem_alloc allocates a region of shared memory of the given size, using
  51  * the given name to avoid conflicts between multiple regions within the
  52  * program. The region will not be automatically grown if its boundaries
  53  * are over-run, use shmem_realloc for that.
  54  *
  55  * If expose is non-zero and the underlying system supports it, the
  56  * file used to create the shared region will be visible to other processes
  57  * running on the system.
  58  *
  59  * name should be unique to the program which calls this routine, otherwise
  60  * conflicts will arise.
  61  *
  62  * Returns a new shared memory region, with the data element being a
  63  * pointer to the shared memory. This function must be called before any
  64  * daemon workers are spawned, in order for the handle to the shared region
  65  * to be inherited by the children.
  66  *
  67  * Because of the requirement that the region must be inherited by the
  68  * children, the region cannot be re-allocated with a larger size when
  69  * necessary.
  70  */
  71 shmem_s *shmem_alloc(char *name, int size, int expose);
  72
  73
  74 /*
  75  * shmem_free de-allocates the specified region of shared memory.
  76  */
  77 void shmem_free(shmem_s *region);
  78
  79 #endif  /* SHMEM_UNIX_MMAP || SHMEM_WIN32_MMAP */
  80
  81
  82 #endif