Semaphore Readers Writers Pattern or Light switch

Synopsis

use Semaphore::ReadersWriters;

my Semaphore::ReadersWriters $rw .= new;
$rw.add-mutex-names('shv');
my $shared-var = 10;

# After creating threads ...
# Some writer thread
$rw.writer( 'shv', {$shared-var += 2});

# Some reader thread
say 'Shared var is ', $rw.reader( 'shv', {$shared-var;});

Documentation

The Markdown files in this package uses the atom plugin Markdown Preview Enhanced. E.g. the synopsis can be run by placing the cursor in the code and type `shift-enter' or, if not possible, look for the readme pdf in doc)

• README pdf
• ReadersWriters pdf

TODO

• Implement other variants of this pattern.
  • Readers priority variant.
  • No writer starvation variant.
  • Document return value restrictions. Only items, no List.

CHANGELOG

See semantic versioning. Please note point 4. on that page: Major version zero (0.y.z) is for initial development. Anything may change at any time. The public API should not be considered stable.

• 2024-02-15 0.2.7
  • Renamed extensions of raku source code files
• 0.2.6
  • Methods reader and writer returned a failure object when things are wrong. This poses a problem in some situations. Now it will throw an exception.
• 0.2.5
  • Changed last method into check-mutex-names() to test for more than one name.
• 0.2.4
  • Added convenience method check-mutex-name().
• 0.2.3
  • add-mutex-names throws an exception when keys are reused
• 0.2.2
  • Added $.debug to show messages about the actions. This will be deprecated later when I am confident enough that everything works well enough.
• 0.2.1
  • Removed debugging texts to publish class
• 0.2.0
  • Documentation
  • Bugfixes, hangups caused by overuse of same semaphores. Added more semaphores per critical section.
  • Preparations for other variations of this pattern
• 0.1.0 First tests
• 0.0.1 Setup

Other info

Perl6 version

Tested on the latest version of perl6 on moarvm

Install

Install package using zef

zef install Semaphore::ReadersWriters

Author

Marcel Timmerman

Contact

MARTIMM on github