m4_comment([$Id: memp_fopen.so,v 10.53 2006/08/08 05:24:05 mjc Exp $])

define(M4PAGELOCAL, [memp_fopen, DB_DIRECT, DB_ODDFILESIZE])
include(m4/m4.seealso)

m4_pf_header(m4_ref(memp_fopen),
ifelse(M4API, C_API, [dnl
int
DB_MPOOLFILE-__GT__open(DB_MPOOLFILE *mpf,
    char *file, u_int32_t flags, int mode, size_t pagesize);
])
ifelse(M4API, CXX_API, [dnl
int
DbMpoolFile::open(const char *file, u_int32_t flags, int mode, size_t pagesize);
]))

m4_p([dnl
The m4_refT(memp_fopen) opens a file in the shared memory buffer pool.])

m4_return(memp_fopen, std)

m4_parambegin

m4_param_utf8(file, [dnl
The m4_arg(file) parameter is the name of the file to be opened.  If
m4_arg(file) is NULL, a private temporary file is created that
cannot be shared with any other process (although it may be shared with
other threads of control in the same process).])

m4_param(flags, [dnl
m4_sf_or_may

m4_tagbegin
m4_tag(m4_idef(DB_CREATE), [dnl
Create any underlying files, as necessary.  If the files do not already
exist and the DB_CREATE flag is not specified, the call will
fail.])

m4_idefz([turn off system @buffering])
m4_tag(m4_idef(DB_DIRECT), [dnl
If set and supported by the system, turn off system buffering of the
file to avoid double caching.])

m4_tag(m4_idef(DB_MULTIVERSION), [dnl
Open the file with support for m4_link(M4RELDIR/ref/transapp/read,
multiversion concurrency control).  Calls to m4_ref(memp_fget) which
dirty pages will cause copies to be made in the cache.])

m4_tag(m4_idef(DB_NOMMAP), [dnl
Always copy this file into the local cache instead of potentially mapping
it into process memory (see the description of the
m4_refT(dbenv_set_mp_mmapsize) for further information).])

m4_tag(m4_idef(DB_ODDFILESIZE), [dnl
Attempts to open files which are not a multiple of the page size in
length will fail, by default.  If the m4_ref(DB_ODDFILESIZE) flag is
set, any partial page at the end of the file will be ignored and the
open will proceed.])

m4_tag(m4_idef(DB_RDONLY), [dnl
Open any underlying files for reading only.  Any attempt to write the file
using the pool functions will fail, regardless of the actual permissions
of the file.])
m4_tagend])

m4_param_filemode(m4_ref(memp_fopen))

m4_param(pagesize, [dnl
The m4_arg(pagesize) parameter is the size, in bytes, of the unit of
transfer between the application and the cache, although it is not
necessarily the unit of transfer between the cache and the underlying
filesystem.])

m4_paramend

m4_err(memp_fopen, einval,
[the file has already been entered into the pool, and the m4_arg(pagesize)
value is not the same as when the file was entered into the pool, or the
length of the file is not zero or a multiple of the m4_arg(pagesize);
the DB_RDONLY flag was specified for an in-memory pool],
memory, [maximum number of open files has been reached])

m4_seealso(DbMpool)
m4_page_footer