| Name : perl-Sys-Mmap
| |
| Version : 0.17
| Vendor : obs://build_opensuse_org/home:ecsos
|
| Release : 2.1
| Date : 2016-01-25 13:54:42
|
| Group : Development/Libraries/Perl
| Source RPM : perl-Sys-Mmap-0.17-2.1.src.rpm
|
| Size : 0.05 MB
| |
| Packager : (none)
| |
| Summary : Uses mmap to map in a file as a Perl variable
|
Description :
The Mmap module uses the POSIX the mmap manpage call to map in a file as a
Perl variable. Memory access by mmap may be shared between threads or
forked processes, and may be a disc file that has been mapped into memory.
the Sys::Mmap manpage depends on your operating system supporting UNIX or
POSIX.1b mmap, of course.
*Note* that the PerlIO manpage now defines a \':mmap\' tag and presents
mmap\'d files as regular files, if that is your cup of joe.
Several processes may share one copy of the file or string, saving memory,
and concurrently making changes to portions of the file or string. When not
used with a file, it is an alternative to SysV shared memory. Unlike SysV
shared memory, there are no arbitrary size limits on the shared memory
area, and sparce memory usage is handled optimally on most modern UNIX
implementations.
Using the \'new()\' method provides a \'tie()\'\'d interface to \'mmap()\' that
allows you to use the variable as a normal variable. If a filename is
provided, the file is opened and mapped in. If the file is smaller than the
length provided, the file is grown to that length. If no filename is
provided, anonymous shared inheritable memory is used. Assigning to the
variable will replace a section in the file corresponding to the length of
the variable, leaving the remainder of the file intact and unmodified.
Using \'substr()\' allows you to access the file at an offset, and does not
place any requirements on the length argument to substr() or the length of
the variable being inserted, provided it does not exceed the length of the
memory region. This protects you from the pathological cases involved in
using \'mmap()\' directly, documented below.
When calling \'mmap()\' or \'hardwire()\' directly, you need to be careful how
you use the variable. Some programming constructs may create copies of a
string which, while unimportant for smallish strings, are far less welcome
if you\'re mapping in a file which is a few gigabytes big. If you use
PROT_WRITE and attempt to write to the file via the variable you need to be
even more careful. One of the few ways in which you can safely write to the
string in-place is by using \'substr()\' as an lvalue and ensuring that the
part of the string that you replace is exactly the same length. Other
functions will allocate other storage for the variable, and it will no
longer overlay the mapped in file.
* new Mmap VARIABLE, LENGTH, OPTIONALFILENAME
Maps LENGTH bytes of (the contents of) OPTIONALFILENAME if
OPTINALFILENAME is provided, otherwise uses anonymous, shared inheritable
memory. This memory region is inherited by any \'fork()\'ed children.
VARIABLE will now refer to the contents of that file. Any change to
VARIABLE will make an identical change to the file. If LENGTH is zero and
a file is specified, the current length of the file will be used. If
LENGTH is larger then the file, and OPTIONALFILENAME is provided, the
file is grown to that length before being mapped. This is the preferred
interface, as it requires much less caution in handling the variable.
VARIABLE will be tied into the \"Mmap\" package, and \'mmap()\' will be
called for you.
Assigning to VARIABLE will overwrite the beginning of the file for a
length of the value being assigned in. The rest of the file or memory
region after that point will be left intact. You may use substr() to
assign at a given position:
substr(VARIABLE, POSITION, LENGTH) = NEWVALUE
* mmap(VARIABLE, LENGTH, PROTECTION, FLAGS, FILEHANDLE, OFFSET)
Maps LENGTH bytes of (the underlying contents of) FILEHANDLE into your
address space, starting at offset OFFSET and makes VARIABLE refer to that
memory. The OFFSET argument can be omitted in which case it defaults to
zero. The LENGTH argument can be zero in which case a stat is done on
FILEHANDLE and the size of the underlying file is used instead.
The PROTECTION argument should be some ORed combination of the constants
PROT_READ, PROT_WRITE and PROT_EXEC or else PROT_NONE. The constants
PROT_EXEC and PROT_NONE are unlikely to be useful here but are included
for completeness.
The FLAGS argument must include either MAP_SHARED or MAP_PRIVATE (the
latter is unlikely to be useful here). If your platform supports it, you
may also use MAP_ANON or MAP_ANONYMOUS. If your platform supplies
MAP_FILE as a non-zero constant (necessarily non-POSIX) then you should
also include that in FLAGS. POSIX.1b does not specify MAP_FILE as a FLAG
argument and most if not all versions of Unix have MAP_FILE as zero.
mmap returns undef on failure, and the address in memory where the
variable was mapped to on success.
* munmap(VARIABLE)
Unmaps the part of your address space which was previously mapped in with
a call to \'mmap(VARIABLE, ...)\' and makes VARIABLE become undefined.
munmap returns 1 on success and undef on failure.
* hardwire(VARIABLE, ADDRESS, LENGTH)
Specifies the address in memory of a variable, possibly within a region
you\'ve \'mmap()\'ed another variable to. You must use the same percaustions
to keep the variable from being reallocated, and use \'substr()\' with an
exact length. If you \'munmap()\' a region that a \'hardwire()\'ed variable
lives in, the \'hardwire()\'ed variable will not automatically be
\'undef\'ed. You must do this manually.
* Constants
The Mmap module exports the following constants into your namespace
MAP_SHARED MAP_PRIVATE MAP_ANON MAP_ANONYMOUS MAP_FILE PROT_EXEC
PROT_NONE PROT_READ PROT_WRITE
Of the constants beginning MAP_, only MAP_SHARED and MAP_PRIVATE are
defined in POSIX.1b and only MAP_SHARED is likely to be useful.
|
RPM found in directory: /packages/linux-pbone/ftp5.gwdg.de/pub/opensuse/repositories/home:/ecsos:/server/openSUSE_13.2/x86_64 |
Hmm ... It's impossible ;-) This RPM doesn't exist on any FTP server
Provides :
Mmap.so()(64bit)
perl(Sys::Mmap)
perl-Sys-Mmap
perl-Sys-Mmap(x86-64)
Requires :
