ruby - 方法闭包似乎在 therubyracer 中不起作用

Question

一旦我将一个方法存储在 V8::Context 中，该方法的所有后续实例都以任何名称存储在任何上下文中，其行为与初始实例一样(即，就好像原始实例已再次存储一样)。

我尝试通过以下方式隔离/演示问题:

require 'V8'

class TestClass
  def test_method
    self.inspect
  end
end

(1..2).each do |cxt_i|
  cxt = V8::Context.new
  [:test_method, :test_method2].each_with_index do |method_name, method_i|
    method = TestClass.new.method(:test_method)
    cxt[method_name.to_s] = method
    script = method_name.to_s+'()'
    puts "Context #{cxt_i}, method #{method_i+1} result is #{method.call}, V8 returns #{cxt.eval(script)}"
  end
end

产生以下输出:

Context 1, method 1 result is #<TestClass:0x007fce2419cdb0>, V8 returns #<TestClass:0x007fce2419cdb0>
Context 1, method 2 result is #<TestClass:0x007fce2419b780>, V8 returns #<TestClass:0x007fce2419cdb0>
Context 2, method 1 result is #<TestClass:0x007fce2419abc8>, V8 returns #<TestClass:0x007fce2419cdb0>
Context 2, method 2 result is #<TestClass:0x007fce24199a98>, V8 returns #<TestClass:0x007fce2419cdb0>

Answer 1

这是一个弱引用问题。通过在内循环中插入 GC.start，我们强制对 V8 上下文中的弱引用进行垃圾回收。但是会大大减慢速度。

require 'v8'

class TestClass
  def test_method
    self.inspect
  end
end

(1..2).each do |cxt_i|
  cxt = V8::Context.new
  [:test_method, :test_method2].each_with_index do |method_name, method_i|
    method = TestClass.new.method(:test_method)
    cxt[method_name.to_s] = method
    script = method_name.to_s+'()'
    puts "Context #{cxt_i}, method #{method_i+1} result is #{method.call}, V8 returns #{cxt.eval(script)}"
    GC.start # <<<<=========
  end
end

输出:

Context 1, method 1 result is #<TestClass:0x007f8f13a26cd8>, V8 returns #<TestClass:0x007f8f13a26cd8>
Context 1, method 2 result is #<TestClass:0x007f8f135cca48>, V8 returns #<TestClass:0x007f8f135cca48>
Context 2, method 1 result is #<TestClass:0x007f8f135ceac8>, V8 returns #<TestClass:0x007f8f135ceac8>
Context 2, method 2 result is #<TestClass:0x007f8f135cdbf0>, V8 returns #<TestClass:0x007f8f135cdbf0>

ruby -v 是 ruby 2.0.0p195 (2013-05-14 revision 40734) [x86_64-linux]，libv8 是 3.11.8.17 x86_64-linux/p>