Class: Cyc::Cache

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

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Cache

Returns a new instance of Cache.



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# File 'lib/cyc/cache.rb', line 6

def initialize
  @soft_references = Ref::SoftValueMap.new
  @hard_references = {}
  @in_progress = {}
  @lock = Mutex.new
end

Instance Method Details

#cached_value(key) ⇒ Object

Get cached value of a key or generate new one using given block



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# File 'lib/cyc/cache.rb', line 14

def cached_value(key)
  monitor = value = nil
  @lock.synchronize do
    if @hard_references.has_key?(key)
      return @hard_references[key]
    elsif (value = @soft_references[key])
      return value
    elsif (monitor = @in_progress[key])
      monitor.wait(@lock)
      return self[key]
    end
    @in_progress[key] = monitor = ConditionVariable.new
  end
  begin
    value = yield
    value_set = true
  ensure
    @lock.synchronize do
      self[key] = value if value_set
      @in_progress.delete key
      monitor.broadcast
    end
  end
  value
end

#clear ⇒ Object

Clear the cache.



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# File 'lib/cyc/cache.rb', line 41

def clear
  @lock.synchronize do
    @soft_references.clear
    @hard_references.clear
  end
end