77 lines
2.7 KiB
Plaintext
77 lines
2.7 KiB
Plaintext
m4_comment([$Id: memp_set_fileid.so,v 10.14 2005/04/14 13:08:06 sue Exp $])
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define(M4PAGELOCAL, [memp_set_fileid, memp_get_fileid])
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include(m4/m4.seealso)
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m4_pf_header(m4_ref(memp_set_fileid),
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ifelse(M4API, C_API, [dnl
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int
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DB_MPOOLFILE-__GT__set_fileid(DB_MPOOLFILE *mpf, u_int8_t *fileid);
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m4_blank
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int
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DB_MPOOLFILE-__GT__get_fileid(DB_MPOOLFILE *mpf, u_int8_t *fileid);
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])
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ifelse(M4API, CXX_API, [dnl
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int
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DbMpoolFile::set(u_int8_t *fileid);
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m4_blank
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int DbMpoolFile::get_fileid(u_int8_t *fileid);
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]))
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m4_p([dnl
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The m4_refT(memp_set_fileid) specifies a unique identifier for the file.
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(The shared memory buffer pool functions must be able to uniquely
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identify files in order that multiple processes wanting to share a file
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will correctly identify it in the pool.)])
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m4_p([dnl
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On most UNIX/POSIX systems, the m4_arg(fileid) field will not need to
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be set, and the memory pool functions will use the file's device and
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inode numbers for this purpose. On Windows systems, the memory pool
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functions use the values returned by GetFileInformationByHandle() by
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default -- these values are known to be constant between processes and
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over reboot in the case of NTFS (in which they are the NTFS MFT
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indices).])
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m4_p([dnl
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On other filesystems (for example, FAT or NFS), these default values
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are not necessarily unique between processes or across system reboots.
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m4_bold([Applications wanting to maintain a shared memory buffer pool
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between processes or across system reboots, in which the pool contains
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pages from files stored on such filesystems, must specify a unique file
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identifier using the m4_refT(memp_set_fileid), and each process opening
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the file must provide the same unique identifier.])])
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m4_p([dnl
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This call should not be necessary for most applications. Specifically,
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it is not necessary if the memory pool is not shared between processes
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and is reinstantiated after each system reboot, if the application is
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using the m4_db access methods instead of calling the pool functions
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explicitly, or if the files in the memory pool are stored on filesystems
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in which the default values as described previously are invariant
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between process and across system reboots.])
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m4_scope_mpf(memp_set_fileid)
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m4_when_mpfopen(memp_set_fileid)
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m4_return(memp_set_fileid, std)
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m4_parambegin
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m4_param(fileid, [dnl
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The m4_arg(fileid) parameter is the unique identifier for the file.
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Unique file identifiers must be a DB_FILE_ID_LEN length array of bytes.])
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m4_paramend
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m4_pf_description(m4_ref(memp_get_fileid))
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m4_p([dnl
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The m4_refT(memp_get_fileid) copies the file's identifier into the
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memory location referenced by m4_arg(fileid).])
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m4_return(memp_get_fileid, std)
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m4_when_any(memp_get_fileid)
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m4_seealso(DbMpool)
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m4_page_footer
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