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   "source": [
    "async def opt_comm_exec(reader, writer, query, db_name, flag):\n",
    "    \n",
    "    if reader is None or writer is None:\n",
    "        print(\"Connection Error!\")\n",
    "        return None\n",
    "    else:\n",
    "        \n",
    "        #execute query\n",
    "        if flag:\n",
    "            writer.write(b'<execute>\\n')\n",
    "        \n",
    "        #optimize query\n",
    "        else: \n",
    "            writer.write(b'<optimize>\\n')\n",
    "    \n",
    "        writer.write(b'<database>\\n')\n",
    "        db_name += \"\\n\"\n",
    "        writer.write(db_name.encode())\n",
    "    \n",
    "        writer.write(b'</database>\\n')\n",
    "    \n",
    "        writer.write(b'<query>\\n')\n",
    "        query += \"\\n\"\n",
    "        writer.write(query.encode())\n",
    "    \n",
    "        writer.write(b'</query>\\n')\n",
    "    \n",
    "        if flag:\n",
    "            writer.write(b'</execute>\\n')\n",
    "        \n",
    "        else: \n",
    "            writer.write(b'</optimize>\\n')\n",
    "    \n",
    "        await writer.drain()\n",
    "    \n",
    "        res = await reader.readline()\n",
    "        res = res.decode()\n",
    "        print(\"first response from OptServer: \")\n",
    "        print(res)\n",
    "        if not res:\n",
    "            print(\"Connection to Optimizer is broken!\")\n",
    "            return None\n",
    "        if res != \"<answer>\\n\":\n",
    "            print(\"Protocol Error!\")\n",
    "            return None\n",
    "        #res = await optrdr.readuntil(b'</answer>')\n",
    "        res = await reader.readline()\n",
    "        print(\"second response from OptServer: \")\n",
    "        print(res)\n",
    "        res = res.decode()\n",
    "        if not res:\n",
    "            print(\"Connection to Optimizer is broken!\")\n",
    "            return None\n",
    "        opt_res = \"\"\n",
    "        count = 3\n",
    "        while res != \"</answer>\\n\":\n",
    "            if flag:\n",
    "                opt_res += res\n",
    "            else:\n",
    "                opt_res += res.replace(\" \\n\", \"\")\n",
    "            res = await reader.readline()\n",
    "            print(str(count) + \"th response from OptServer: \")\n",
    "            print(res)\n",
    "            res = res.decode()\n",
    "            count += 1\n",
    "            if not res:\n",
    "                print(\"Connection to Optimizer is broken!\")\n",
    "                return None\n",
    "    \n",
    "        if opt_res == \"\":\n",
    "            print(\"Optimization failed!\")\n",
    "            return None\n",
    "        print(opt_res)\n",
    "        return opt_res"
   ]
  }
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