Module: When::Parts::MethodCash

Included in:
Coordinates::Temporal, Ephemeris::Formula
Defined in:
lib/when_exe/parts/method_cash.rb

Overview

メソッドの実行結果をキャッシュし処理の高速化を行う

fn というメソッドをキャッシュ化

* fn ではなく fn_ を定義しておく
* fn メソッドが呼ばれると fn_ を実行し、{引数=>戻り値} を Hash に記憶する
* 同じ引数で再度 fn メソッドが呼ばれると Hash から戻り値を取り出して返す

a_to_b と b_to_a という互いに逆関数のメソッドをキャッシュ化

* a_to_b ではなく a_to_b_ , b_to_a ではなく b_to_a_ を定義しておく
* a_to_b メソッドが呼ばれると a_to_b_ を実行し、{引数=>戻り値}, {戻り値=>引数}を Hash に記憶する
* 同じ引数で再度 a_to_b メソッドが呼ばれると Hash から戻り値を取り出して返す
* b_to_a メソッドが呼ばれ Hash に戻り値があれば Hash から戻り値を取り出して返す

特記事項

Argument identification

The eql? method of When::TM::(Temporal)Position is not overridden.
It seems that the cost of identification of the argument exceeds the merit of the method cash.
I do not recommend applying the methodcash to the method which takes
When::TM::(Temporal)Position as an argument.

Multi-thread critical situation

There is a problem in consistency of hash when this function is used in multi-thread environment.
If the initialize method sets Mutex in instance variable @_m_cash_lock_,
this function gives up use of hash in the critical situation.

class Foo
  include MethodCash

  def initialize
    ...
    @_m_cash_lock_ = Mutex.new
    ...
   end
end

参考 http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-list/47663

Instance Method Summary collapse

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(name, *args, &block) ⇒ void

This method returns an undefined value.

最初に発生する method_missing で、キャッシュ機能を登録する

Parameters:

  • name (Symbol) —

    メソッド名

  • args (Array) —

    メソッド引数

  • block (block) —

    ブロック(省略可)



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# File 'lib/when_exe/parts/method_cash.rb', line 65

def method_missing(name, *args, &block)

  return method_missing_(name, *args, &block) unless respond_to?("#{name}_", true)

  if ((name.to_s =~ /^(_*)(.+?)_to_(.+)$/) && respond_to?("#{$1}#{$3}_to_#{$2}_", true))
    prefix, from, to = $~[1..3]
    begin
      if (@_m_cash_lock_)
        return send("#{prefix}#{from}_to_#{to}_", *args, &block) unless @_m_cash_lock_.try_lock
        unlock = "ensure ; @_m_cash_lock_.locked? && @_m_cash_lock_.unlock"
      end
      [[from, to],[to, from]].each do |pair|
        a, b = pair
        lock = @_m_cash_lock_ ? "  return #{prefix}#{a}_to_#{b}_(*args) unless @_m_cash_lock_.try_lock" : ''
        instance_eval %Q{
          def #{prefix}#{a}_to_#{b}(*args)
            key = _key_simplefy(args)
            inv = @_m_cash_["#{prefix}#{a}_to_#{b}"][key]
            return inv if inv
            begin
            #{lock}
              inv = #{prefix}#{a}_to_#{b}_(*args)
              @_m_cash_["#{prefix}#{b}_to_#{a}"][_key_simplefy(inv)] = args
              @_m_cash_["#{prefix}#{a}_to_#{b}"][key] = inv
              return inv
            #{unlock}
            end
          end
        }
      end
      key = _key_simplefy(args)
      inv = send("#{prefix}#{from}_to_#{to}_", *args)
      @_m_cash_ ||= {}
      @_m_cash_["#{prefix}#{to}_to_#{from}"]    ||= {}
      @_m_cash_["#{prefix}#{from}_to_#{to}"]    ||= {}
      @_m_cash_["#{prefix}#{to}_to_#{from}"][_key_simplefy(inv)] = args
      @_m_cash_["#{prefix}#{from}_to_#{to}"][key] = inv
      return inv
    ensure
      @_m_cash_lock_ && @_m_cash_lock_.locked? && @_m_cash_lock_.unlock
    end

  else
    begin
      respond = respond_to?("#{name}_setup", true)
      setup   = respond ? "#{name}_setup(key, *args)" :
                          "(@_m_cash_[\"#{name}\"][key] = #{name}_(*args))"
      if (@_m_cash_lock_)
        return send("#{name}_", *args, &block) unless @_m_cash_lock_.try_lock
        lock   = "  return #{name}_(*args) unless @_m_cash_lock_.try_lock"
        unlock = "ensure ; @_m_cash_lock_.locked? && @_m_cash_lock_.unlock"
      end
      instance_eval %Q{
        def #{name}(*args)
          key = _key_simplefy(args)
          ret = @_m_cash_["#{name}"][key]
          return ret if ret
          begin
          #{lock}
            return #{setup}
          #{unlock}
          end
        end
      }
      key = _key_simplefy(args)
      @_m_cash_ ||= {}
      @_m_cash_["#{name}"] ||= {}
      if (respond)
        return send("#{name}_setup", key, *args)
      else
        return(@_m_cash_["#{name}"][key] ||= send("#{name}_", *args))
      end
    ensure
      @_m_cash_lock_ && @_m_cash_lock_.locked? && @_m_cash_lock_.unlock
    end
  end
end

Instance Method Details

#method_missing_ ⇒ Object 



54
 
# File 'lib/when_exe/parts/method_cash.rb', line 54

alias :method_missing_ :method_missing