Class: SzymanskisMutex

Inherits:
Object
  • Object
show all
Defined in:
lib/szymanskis_mutex.rb

Overview

Based on the Szymanski’s Mutual Exclusion Algorithm

Constant Summary collapse

SZYMANSKIS_SLEEP =

Larger seconds mean less cycles/second but may result in lower completion

0.05
@@flags = 
{}
@@counter = 
{}

Class Method Summary collapse

Class Method Details

.mutual_exclusion(concern) ⇒ Object

Provide a MutEx lock Provide the critical section as a block to this method Different concerns will prevent unrelated code to wait on each other Returns the result of the critical code or nil if something fails



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# File 'lib/szymanskis_mutex.rb', line 41

def mutual_exclusion(concern)
  @@counter[concern] ||= 0
  @@flags[concern] ||= {}

  # Suppose @@counter += 1 is an atomic function
  my_id = @@counter[concern] += 1

  entry_protocol(concern, my_id)
  begin
    result = yield
  ensure
    # If something fails in the critical section release the resource
    exit_protocol(concern, my_id)
    result
  end
end