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   "source": [
    "# Timer\n",
    "\n",
    "The code in this notebook helps with measuring time."
   ]
  },
  {
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   "source": [
    "**Prerequisites**\n",
    "\n",
    "* This notebook needs some understanding on advanced concepts in Python, notably \n",
    "    * classes\n",
    "    * the Python `with` statement\n",
    "    * measuring time"
   ]
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   "source": [
    "## Measuring Time\n",
    "\n",
    "The class `Timer` allows to measure the elapsed time during some code execution.  A typical usage looks as follows:\n",
    "\n",
    "```Python\n",
    "from Timer import Timer\n",
    "\n",
    "with Timer() as t:\n",
    "    function_that_is_supposed_to_be_timed()\n",
    "\n",
    "print(t.elapsed_time())\n",
    "```\n"
   ]
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   "outputs": [],
   "source": [
    "import fuzzingbook_utils"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
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   "source": [
    "import time"
   ]
  },
  {
   "cell_type": "code",
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   "source": [
    "def clock():\n",
    "    try:\n",
    "        return time.perf_counter()  # Python 3\n",
    "    except:\n",
    "        return time.clock()         # Python 2"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
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   "source": [
    "class Timer(object):\n",
    "    # Begin of `with` block\n",
    "    def __enter__(self):\n",
    "        self.start_time = clock()\n",
    "        self.end_time = None\n",
    "        return self\n",
    "\n",
    "    # End of `with` block\n",
    "    def __exit__(self, exc_type, exc_value, tb):\n",
    "        self.end_time = clock()\n",
    "\n",
    "    def elapsed_time(self):\n",
    "        \"\"\"Return elapsed time in seconds\"\"\"\n",
    "        if self.end_time is None:\n",
    "            # still running\n",
    "            return clock() - self.start_time\n",
    "        else:\n",
    "            return self.end_time - self.start_time"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
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    "run_control": {
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    },
    "slideshow": {
     "slide_type": "subslide"
    }
   },
   "source": [
    "Here's an example:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {
    "button": false,
    "new_sheet": false,
    "run_control": {
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    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [],
   "source": [
    "def some_long_running_function():\n",
    "    i = 1000000\n",
    "    while i > 0:\n",
    "        i -= 1"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {
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   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Stopping total time:\n",
      "0.06727509300071688\n"
     ]
    }
   ],
   "source": [
    "print(\"Stopping total time:\")\n",
    "with Timer() as t:\n",
    "    some_long_running_function()\n",
    "print(t.elapsed_time())"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
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   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Stopping time in between:\n",
      "4.9720001698005944e-06\n",
      "5.465600042953156e-05\n",
      "8.613899990450591e-05\n",
      "0.00011476500003482215\n",
      "0.00014296199879026972\n",
      "0.00017072300033760257\n",
      "0.00042000499888672493\n",
      "0.00047452599937969353\n",
      "0.0005045199995947769\n",
      "0.0005325679994712118\n"
     ]
    }
   ],
   "source": [
    "print(\"Stopping time in between:\")\n",
    "with Timer() as t:\n",
    "    for i in range(10):\n",
    "        print(t.elapsed_time())"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
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    }
   },
   "source": [
    "That's it, folks – enjoy!"
   ]
  }
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