Apache::SharedMem version 0.07 =============================== This module make it easer to share data between Apache children processes trough the shared memory. This module internal working is a lot inspired by IPC::SharedCache, but without any cache managment. The share memory segment key is automatically deduced by the caller package name, that's mine 2 modules can use same keys (variable's name) without be concerned about namespace clash. INSTALLATION To install this module type the following: perl Makefile.PL make make test make install DEPENDENCIES This module requires these other modules and libraries: IPC::ShareLite IPC::SysV Storable Data::Dumper CHANGES 0.07 Mon August 27, 2001 18:36:52 - Implement a more efficient IPC key generation for the root segment, using the system ftok() function provied by IPC::SysV module - Pod documentation - Default IPC mode is now 0600 - We now keep ipc_mode and ipc_segment_size in the root map for calling IPC::ShareLite with same values. - Add "readonly" parameter to constructor - Feature enhancement, add "dump" and "dump_map" methods - Data::Dumper is now autoused - Feature enhancement, release method now release root map when it go empty - Feature enhancement, add a "destroy" method, that call "release" method on all root-map's namespaces. Usefull for cleaning shared memory on Apache shutdown. - Adding tools to package for debuging purpose - Bugfix in delete method, for problem on root map cleanup - Better support of mod_perl - Minor bugfix in _init_namespace method - Misc bugfixes 0.06 Mon August 20, 2001 15:55:50 - Correction of an "undefined value" bug when lock method was called without arguments. - Forcing default lock to LOCK_EX 0.05 Tue Jully 03, 2001 17:41:30 - Implementation of timeout in lock method and integration of it in all public methods - Bug fix, mispelling of DESCRIPTION section in documentation (make warning with make) - Bug fix, timeout in delete method (delete call 'exists' method without his timeout value) - use of bitwise operators in smartlock 0.04 Wen Junary 27, 2001 08:58:54 - Bug fix, smartlock bug with set method - Bug fix, major bug in delete method - Bug fix, dupplicated entries in EXPORT_TAGS 0.03 Tue Junary 26, 2001 21:09:46 - Major bug fix 0.02 Tue Junary 26, 2001 14:20:02 - Documentation updates - Add of :all export tag - Implementation of multi-level debug 0.01 Thu Junary 21, 2001 23:37:46 - Original version based on IPC::SharedCache but rewritten from scratch. Very experimental code, don't use it for production purpose ! - Implementation of automated unique namespace based on package caller - Implementation of smartlock mechanisme (see documentation) NAME Apache::SharedMem - Share data between Apache children processes through the shared memory SYNOPSIS use Apache::SharedMem qw(:lock :wait :status); my $share = new Apache::SharedMem || die($Apache::SharedMem::ERROR); $share->set(key=>'some data'); # ...in another process my $var = $share->get(key, NOWAIT); die("can't get key: ", $self->error) unless($share->status eq SUCCESS); $share->delete(key); $share->clear if($share->size > $max_size); my $lock_timeout = 40; # seconds if($share->lock(LOCK_EX, $lock_timeout)) { my $data... ...some traitement... $share->set(key=>$data); warn(...) if($share->status eq FAILURE); $share->unlock; } $share->release; DESCRIPTION This module make it easier to share data between Apache children processes through shared memory. This module internal functionment is much inspired from IPC::SharedCache, but without any cache management. The share memory segment key is automatically deduced by the caller package, which means that 2 modules can use same keys without being concerned about namespace clash. An additionnal namespace is used per application, which means that the same module, with the same namespace used in two applications doesn't clash too. Application distinction is made on two things : the process' UID and DOCUMENT_ROOT (for http applications) or current working directory. This module handles all shared memory interaction via the IPC::SharedLite and all data serialization with Storable. See the IPC::ShareLite manpage and the Storable manpage for details. USAGE If you are running under mod_perl, you should put this line in your httpd.conf: # must be a valid path PerlAddVar PROJECT_DOCUMENT_ROOT /path/to/your/projects/root and in your startup.pl: use Apache::SharedMem; This allow Apache::SharedMem to determine a unique rootkey for all virtual hosts, and to cleanup this rootkey on Apache stop. PROJECT_DOCUMENT_ROOT is used instead of a per virtal host's DOCUMENT_ROOT for generating the rootkey. METHODS new (namespace => 'Namespace', ipc_mode => 0666, ipc_segment_size => 1_000, debug => 1) "rootkey" (optional) integer: Changes the root segment key. It must be an unsigned integer. Don't use this option unless you really know what you are doing. This key allows Apache::SharedMem to find the root map of all namespaces (see below) owned by your application. The rootkey is automatically generated using the "ftok" provided by IPC::SysV. Process' UID and DOCUMENT_ROOT (or current working directory) are given to "ftok" so as to guarantee an unique key as far as possible. Note, if you are using mod_perl, and you'v load mod_perl via startup.pl (see USAGE section for more details), the rootkey is generated once at the apache start, based on the supplied PROJECT_DOCUMENT_ROOT and Apache's uid. "namespace" (optional) string: Setup manually the namespace. To share same datas, your program must use the same namespace. This namespace is set by default to the caller's package name. In most cases the default value is a good choice. But you may setup manually this value if, for example, you want to share the same datas between two or more modules. "ipc_mode" (optional) octal: Setup manually the segment mode (see the IPC::ShareLite manpage) for more details (default: 0600). Warning: this value _must_ be octal, see chmod documentation in perlfunc manpage for more details. "ipc_segment_size" (optional) integer: Setup manually the segment size (see the IPC::ShareLite manpage) for more details (default: 65_536). "debug" (optional) boolean: Turn on/off the debug mode (default: 0) In most case, you don't need to give any arguments to the constructor. "ipc_mode" and "ipc_segment_size" are used only on the first namespace initialisation. Using different values on an existing key (in shared memory) has no effect. Note that "ipc_segment_size" is default value of IPC::ShareLite, see the IPC::ShareLite manpage get (key, [wait, [timeout]]) my $var = $object->get('mykey', WAIT, 50); if($object->status eq FAILURE) { die("can't get key 'mykey´: " . $object->error); } key (required) string: This is the name of elemenet that you want get from the shared namespace. It can be any string that perl support for hash's key. wait (optional): Defined the locking status of the request. If you must get the value, and can't continue without it, set this argument to constant WAIT, unless you can set it to NOWAIT. If the key is locked when you are tring to get the value, NOWAIT return status FAILURE, and WAIT hangup until the value is unlocked. An alternative is to setup a WAIT timeout, see below. NOTE: you needs :wait tag import: use Apache::SharedMem qw(:wait) timeout (optional) integer: if WAIT is on, timeout setup the number of seconds to wait for a blocking lock, usefull for preventing dead locks. Following status can be set: SUCCESS FAILURE set (key, value, [wait, [timeout]]) my $rv = $object->set('mykey' => 'somevalue'); if($object->status eq FAILURE) { die("can't set key 'mykey´: " . $object->error); } key (required): key to set value (required): store a value in key wait (optional): WAIT or NOWAIT (default WAIT) make or not a blocking shared lock (need :wait tag import). timeout (optional): if WAIT is on, timeout setup the number of seconds to wait for a blocking lock (usefull for preventing dead locks) Try to set element "key" to "value" from the shared segment. In case of failure, this methode return "undef()". status: SUCCESS FAILURE delete (key, [wait, [timeout]]) exists (key, [wait, [timeout]]) firstkey ([wait, [timeout]]) nextkey (lastkey, [wait, [timeout]]) clear ([wait, [timeout]]) return 0 on error release [namespace] Release share memory space taken by the given namespace or object's namespace. Root map will be release too if empty. destroy Destroy all namespace found in the root map, and root map itself. size ([wait, [timeout]]) namespaces Debug method, return the list of all namespace in the root map. (devel only) lock ([lock_type, [timeout]]) lock_type (optional): type of lock (LOCK_EX, LOCK_SH, LOCK_NB, LOCK_UN) timeout (optional): time to wait for an exclusive lock before aborting get a lock on the share segment. It returns "undef()" if failed, 1 if successed. unlock freeing a lock error return the last error message that happened. AUTHOR Olivier Poitrey LICENCE This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with the program; if not, write to the Free Software Foundation, Inc. : 59 Temple Place, Suite 330, Boston, MA 02111-1307 COPYRIGHT Copyright (C) 2001 - Fininfo http://www.fininfo.fr PREREQUISITES Apache::SharedMem needs IPC::ShareLite, Storable both available from the CPAN. SEE ALSO the IPC::ShareLite manpage, shmget, ftok