App::ResourceLocker::IPCSemaphore - locking shared resources using IPC::Locker
use App; $context = App->context(); $srs = $context->service("ResourceLocker"); # or ... $srs = $context->shared_resource_set();
A ResourceLocker service represents a collection of "advisory" (or "cooperative") resource locks. The IPCSemaphore implementation uses the IPC::Locker distribution available on CPAN. Locking is implemented by a Locker Daemon (lockerd), so that locking may be effectively achieved across an entire network.
A ResourceLocker service represents a collection of "advisory" (or "cooperative") resource locks. These can be used to synchronize access to and modification of shared resources such as are stored in a SharedDatastore.
* Throws: App::Exception::ResourceLocker * Since: 0.01
Generally speaking, this module only works on Unix platforms, because they support the System V semaphore API on which the IPC::Semaphore module is built.
The ResourceLocker may be configured with the following parameters, which govern all locks accessed in the ResourceLocker (as per IPC::Semaphore).
semkey an 8-digit hex key (i.e. 0x1234FA78) uniquely identifying the semaphore set (or may be "private", not shared with any other processes, useful only for multi-threaded applications). If the ResourceLocker needs more than one semaphore set, it will allocation additional sets with keys incremented by 1 from this semkey. default: 0x95EE10CC nsems number of semaphores to get (limited by kernel settings) in each semaphore set default: 100 create boolean whether to create the semaphore set if it does not exist already default: 1 mode permissions mode with which to create the semaphore set default: 0600
The constructor is inherited from App::Service.
App::Service
* Signature: $resource_name = $srs->lock($resource_pool); * Signature: $resource_name = $srs->lock($resource_set); * Signature: $resource_name = $srs->lock($named); * Param: $resource_pool string * Param: $resource_set [] * Param: resourcePool string * Param: nonBlocking boolean * Param: nonExclusive boolean * Param: maxWaitTimeMS integer * Return: $resource_name string * Throws: App::Exception::ResourceLocker * Since: 0.01 Sample Usage: $context = App->context(); $srs = $context->service("ResourceLocker"); $srs->lock("shmem01");
The lock() method on a ResourceLocker is for the purposes of cooperative resource locking.
The "nonBlocking" option works in this implementation. However, all locks are exclusive (the nonExclusive option is ignored). The "maxWaitTimeMS" option is not yet implemented.
* Signature: $srs->unlock($resource_name); * Param: $resource_name string * Return: void * Throws: App::Exception::ResourceLocker * Since: 0.01 Sample Usage: $context = App->context(); $srs = $context->service("ResourceLocker"); $srs->unlock("shmem01");
* Signature: $self->_init(); * Param: void * Return: void * Throws: App::Exception::ResourceLocker * Since: 0.01 Sample Usage: $self->_init();
The _init() method is called from within the constructor to allow the class to customize itself.
* Signature: ($semset, $semnum) = $self->allocate($resource_name); * Param: $resource_name string * Return: $semset IPC::Semaphore * Return: $semnum integer * Throws: App::Exception::ResourceLocker * Since: 0.01 Sample Usage: ($semset, $semnum) = $self->allocate($resource_name);
The allocate() method is called when $self->{semset}{$resource_name} is not defined in order to allocate an appropriate ($semset, $semnum) pair for a $resource_name.
* Signature: $self->free($resource_name); * Param: $resource_name string * Return: void * Throws: App::Exception::ResourceLocker * Since: 0.01 Sample Usage: $self->free($resource_name);
The free() method frees up a resource name so that its physical semaphore may be reused for some other resource.
* Author: Stephen Adkins <spadkins@gmail.com> * License: This is free software. It is licensed under the same terms as Perl itself.
App::ResourceLocker, App::Context, App::Service
App::ResourceLocker
App::Context
To install App::Context, copy and paste the appropriate command in to your terminal.
cpanm
cpanm App::Context
CPAN shell
perl -MCPAN -e shell install App::Context
For more information on module installation, please visit the detailed CPAN module installation guide.