Class: Ref::SafeMonitor

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

Overview

The Monitor class in Ruby 1.8 has some bugs and also threads may not be available on all runtimes. This class provides a simple, safe re-entrant mutex as an alternative.

Instance Method Summary collapse

Constructor Details

#initialize ⇒ SafeMonitor

Returns a new instance of SafeMonitor.



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# File 'lib/ref/safe_monitor.rb', line 11

def initialize
  @owner = nil
  @count = 0
  @mutex = defined?(Mutex) ? Mutex.new : nil
end

Instance Method Details

#lock ⇒ Object

Acquire an exclusive lock.



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# File 'lib/ref/safe_monitor.rb', line 18

def lock
  if @mutex
    if @owner != Thread.current.object_id
      @mutex.lock
      @owner = Thread.current.object_id
    end
    @count += 1
  end
  true
end

#synchronize ⇒ Object

Run a block of code with an exclusive lock.



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# File 'lib/ref/safe_monitor.rb', line 43

def synchronize
  lock
  yield
ensure
  unlock
end

#unlock ⇒ Object

Release the exclusive lock.



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# File 'lib/ref/safe_monitor.rb', line 30

def unlock
  if @mutex
    if @owner == Thread.current.object_id
      @count -= 1
      if @count == 0
        @owner = nil
        @mutex.unlock
      end
    end
  end
end