{
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   "cell_type": "markdown",
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   "source": [
    "## 5-10 Fiber\n",
    "### 5-10-1 基本的な振る舞い"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Hello, Fiber\n",
      "Hello (again)\n"
     ]
    },
    {
     "ename": "FiberError",
     "evalue": "dead fiber called",
     "output_type": "error",
     "traceback": [
      "\u001b[31mFiberError\u001b[0m: dead fiber called",
      "\u001b[37m<main>:10:in `resume'\u001b[0m",
      "\u001b[37m<main>:10:in `<main>'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/iruby-0.3/lib/iruby/backend.rb:44:in `eval'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/iruby-0.3/lib/iruby/backend.rb:44:in `eval'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/iruby-0.3/lib/iruby/backend.rb:12:in `eval'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/iruby-0.3/lib/iruby/kernel.rb:87:in `execute_request'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/iruby-0.3/lib/iruby/kernel.rb:47:in `dispatch'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/iruby-0.3/lib/iruby/kernel.rb:37:in `run'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/iruby-0.3/lib/iruby/command.rb:70:in `run_kernel'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/iruby-0.3/lib/iruby/command.rb:34:in `run'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.5.1/lib/ruby/gems/2.5.0/gems/iruby-0.3/bin/iruby:5:in `<top (required)>'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.5.1/bin/iruby:23:in `load'\u001b[0m",
      "\u001b[37m/Users/ariga/.rbenv/versions/2.5.1/bin/iruby:23:in `<main>'\u001b[0m"
     ]
    }
   ],
   "source": [
    "fiber = Fiber.new {\n",
    "  puts 'Hello, Fiber'\n",
    "  Fiber.yield\n",
    "  puts 'Hello (again)'\n",
    "}\n",
    "\n",
    "fiber.resume\n",
    "\n",
    "fiber.resume\n",
    "\n",
    "fiber.resume"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 5-10-2 引数と戻り値"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "hello\n",
      "goodbye\n",
      "hello (again)\n",
      "goodbye (again)\n"
     ]
    }
   ],
   "source": [
    "fiber = Fiber.new { |first|\n",
    "  puts first\n",
    "  \n",
    "  second = Fiber.yield('goodbye')\n",
    "  \n",
    "  puts second\n",
    "  \n",
    "  'goodbye (again)'\n",
    "}\n",
    "\n",
    "puts fiber.resume('hello')\n",
    "puts fiber.resume('hello (again)')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 5-10-3 ジェネレータ"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "[1, 1, 2, 3, 5, 8, 13, 21, 34, 55]\n",
      "89\n",
      "144\n"
     ]
    }
   ],
   "source": [
    "fib = Fiber.new {\n",
    "  a, b = 0, 1\n",
    "  \n",
    "  loop do\n",
    "    a, b = b, a+b\n",
    "    \n",
    "    Fiber.yield(a)\n",
    "  end\n",
    "}\n",
    "\n",
    "puts 10.times.map { fib.resume }\n",
    "puts fib.resume\n",
    "puts fib.resume"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "233"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "fib.resume"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "- `Proc` との差異は？\n",
    "- @kishima: `Fiber` はmrubyのコンパイル時に並列で処理するのに使っている。並列処理はOSでやって、待ちをFiberでやっている。なお、Cygwinではこのビルドが壊れている。"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 5-10-4 スレッドと組み合わせた場合の制限"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "#<Thread:0x00007fa5898e4ff0@<main>:4 run> terminated with exception (report_on_exception is true):\n",
      "<main>:5:in `resume': fiber called across threads (FiberError)\n",
      "\tfrom <main>:5:in `block in <main>'\n"
     ]
    },
    {
     "ename": "FiberError",
     "evalue": "fiber called across threads",
     "output_type": "error",
     "traceback": [
      "\u001b[31mFiberError\u001b[0m: fiber called across threads",
      "\u001b[37m<main>:5:in `resume'\u001b[0m",
      "\u001b[37m<main>:5:in `block in <main>'\u001b[0m"
     ]
    }
   ],
   "source": [
    "fiber = Fiber.new {\n",
    "  puts 'OMG'\n",
    "}\n",
    "\n",
    "Thread.fork {\n",
    "  fiber.resume\n",
    "}.join"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "#<Thread:0x00007fa58a91e330@<main>:1 run> terminated with exception (report_on_exception is true):\n",
      "<main>:2:in `yield': can't yield from root fiber (FiberError)\n",
      "\tfrom <main>:2:in `block (2 levels) in <main>'\n"
     ]
    },
    {
     "ename": "FiberError",
     "evalue": "can't yield from root fiber",
     "output_type": "error",
     "traceback": [
      "\u001b[31mFiberError\u001b[0m: can't yield from root fiber",
      "\u001b[37m<main>:2:in `yield'\u001b[0m",
      "\u001b[37m<main>:2:in `block (2 levels) in <main>'\u001b[0m"
     ]
    }
   ],
   "source": [
    "fiber = Fiber.new {\n",
    "  Thread.fork {\n",
    "    Fiber.yield\n",
    "  }.join\n",
    "}\n",
    "\n",
    "fiber.resume"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "次回は、「5-11 Process」から"
   ]
  }
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