ruby-on-rails - Ruby/Rails : Prepend, 将代码附加到所有方法

Question

我编写了一个小型基准测试类来测试我的开发代码。目前我必须将类添加到每个方法的开头和结尾。是否可以预先添加、动态添加，这样我就不必弄乱我的代码了？

class ApplicationController    
    before_filter :init_perf
    after_filter :write_perf_results_to_log!

    def init_perf
      @perf ||= Perf.new
    end

    def write_perf_results_to_log!
      @perf.results
    end
end

class Products < ApplicationsController    
    def foo      
      @perf.log(__methond__.to_s)
      caculation = 5 *4
      @perf.write! 
    end

    def bar      
      @perf.log(__methond__.to_s)
      caculation = 1 / 5
      @perf.write! 
    end
end

这是 Perf 类。它位于服务文件夹中。

class Perf
  def initialize
    @results = []
  end

  def log(note)
    @start = Time.now
    @note = note
  end

  def write!
    if @results.find {|h| h[:note] == @note } # Update :sec method exists in results 
      @results.select { |h| h["note"] == @note; h[":sec"] = (Time.now - @start).round(3) }
    else # Add new Hash to results
      @results << { :note => @note, :sec => (Time.now - @start).round(3) }
    end
  end

  def results
    content = "
    PERFORMANCE STATISTICS!
    "
    @results.each do |r|
      content += r[:note] + "   " + r[:sec].to_s + "
      "
    end
    content += "
    "
    Rails.logger.info content
  end
end

Answer 1

在一般计算术语中，您想要做的事情称为 code instrumentation .有几种方法可以实现这一点，但是这里有一个使用元编程的(粗略的)示例:

首先定义一个我们将用于注入(inject)检测代码的新方法:

class ApplicationController
  def self.instrument_methods(*methods)
    methods.each { |m|
      # Rename original method
      self.send(:alias_method, "#{m}_orig", m)

      # Redefine old method with instrumentation code added
      define_method m do
        puts "Perf log #{m}"
        self.send "#{m}_orig"
        puts "Perf write"
      end
    }
  end
end

使用方法:

class Product < ApplicationController
  def foo
    puts "Foo"
  end

  def bar
    puts "Bar"
  end

  # This has to be called last, once the original methods are defined
  instrument_methods :foo, :bar
end

然后:

p = Product.new
p.foo
p.bar

将输出:

Perf log foo
Foo
Perf write
Perf log bar
Bar
Perf write

以下是检测 ruby​​ 代码和衡量性能的一些其他方法:

http://ruby-prof.rubyforge.org/
http://www.igvita.com/2009/06/13/profiling-ruby-with-googles-perftools/