dnl

dnl Definitions for using shared memory

dnl

dnl/*D

dnl PAC_ARG_SHARED_MEMORY - add --with-shared-memory=kind to configure

dnl

dnl Synopsis:

dnl PAC_ARG_SHARED_MEMORY

dnl

dnl Output effects:

dnl Adds '--with-shared-memory' to the command line. Checks for available

dnl shared memory functionality.

dnl

dnl Supported values of 'kind' include \:

dnl+    auto - default

dnl.    mmap - use mmap and munmap

dnl-    sysv - use sysv shared memory functions

dnl D*/

AC_DEFUN([PAC_ARG_SHARED_MEMORY],[

# check how to allocate shared memory

AC_ARG_WITH(shared-memory,

    AC_HELP_STRING([--with-shared-memory[=auto|sysv|mmap]], [create shared memory using sysv or mmap (default is auto)]),,

    with_shared_memory=auto)

if test "$with_shared_memory" = auto -o "$with_shared_memory" = mmap; then

    found_mmap_funcs=yes

    AC_CHECK_FUNCS(mmap munmap, , found_mmap_funcs=no)

    if test "$found_mmap_funcs" = yes ; then

        with_shared_memory=mmap

        AC_DEFINE(USE_MMAP_SHM,1,[Define if we have sysv shared memory])

        AC_MSG_NOTICE([Using a memory-mapped file for shared memory])

    elif test "$with_shared_memory" = mmap ; then

        AC_MSG_ERROR([cannot support shared memory:  mmap() or munmap() not found])

    fi

fi

if test "$with_shared_memory" = auto -o "$with_shared_memory" = sysv; then

    found_sysv_shm_funcs=yes

    AC_CHECK_FUNCS(shmget shmat shmctl shmdt, , found_sysv_shm_funcs=no)

    if test "$found_sysv_shm_funcs" = yes ; then

        with_shared_memory=sysv

        AC_DEFINE(USE_SYSV_SHM,1,[Define if we have sysv shared memory])

        AC_MSG_NOTICE([Using SYSV shared memory])

    elif test "$with_shared_memory" = sysv ; then

        AC_MSG_ERROR([cannot support shared memory:  sysv shared memory functions functions not found])

    fi

fi

])