207 lines
6.3 KiB
Python
207 lines
6.3 KiB
Python
{
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"cells": [
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"This notebook was prepared by [Donne Martin](https://github.com/donnemartin). Source and license info is on [GitHub](https://github.com/donnemartin/system-design-primer-primer)."
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"# Design a call center"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Constraints and assumptions\n",
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"\n",
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"* What levels of employees are in the call center?\n",
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" * Operator, supervisor, director\n",
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"* Can we assume operators always get the initial calls?\n",
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" * Yes\n",
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"* If there is no free operators or the operator can't handle the call, does the call go to the supervisors?\n",
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" * Yes\n",
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"* If there is no free supervisors or the supervisor can't handle the call, does the call go to the directors?\n",
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" * Yes\n",
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"* Can we assume the directors can handle all calls?\n",
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" * Yes\n",
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"* What happens if nobody can answer the call?\n",
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" * It gets queued\n",
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"* Do we need to handle 'VIP' calls where we put someone to the front of the line?\n",
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" * No\n",
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"* Can we assume inputs are valid or do we have to validate them?\n",
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" * Assume they're valid"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Solution"
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]
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},
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{
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"cell_type": "code",
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"execution_count": 1,
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"metadata": {
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"collapsed": false
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"Overwriting call_center.py\n"
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]
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}
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],
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"source": [
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"%%writefile call_center.py\n",
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"from abc import ABCMeta, abstractmethod\n",
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"from collections import deque\n",
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"from enum import Enum\n",
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"\n",
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"\n",
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"class Rank(Enum):\n",
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"\n",
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" OPERATOR = 0\n",
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" SUPERVISOR = 1\n",
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" DIRECTOR = 2\n",
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"\n",
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"\n",
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"class Employee(metaclass=ABCMeta):\n",
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"\n",
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" def __init__(self, employee_id, name, rank, call_center):\n",
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" self.employee_id = employee_id\n",
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" self.name = name\n",
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" self.rank = rank\n",
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" self.call = None\n",
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" self.call_center = call_center\n",
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"\n",
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" def take_call(self, call):\n",
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" \"\"\"Assume the employee will always successfully take the call.\"\"\"\n",
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" self.call = call\n",
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" self.call.employee = self\n",
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" self.call.state = CallState.IN_PROGRESS\n",
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"\n",
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" def complete_call(self):\n",
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" self.call.state = CallState.COMPLETE\n",
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" self.call_center.notify_call_completed(self.call)\n",
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"\n",
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" @abstractmethod\n",
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" def escalate_call(self):\n",
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" pass\n",
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"\n",
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" def _escalate_call(self):\n",
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" self.call.state = CallState.READY\n",
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" call = self.call\n",
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" self.call = None\n",
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" self.call_center.notify_call_escalated(call)\n",
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"\n",
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"\n",
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"class Operator(Employee):\n",
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"\n",
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" def __init__(self, employee_id, name):\n",
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" super(Operator, self).__init__(employee_id, name, Rank.OPERATOR)\n",
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"\n",
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" def escalate_call(self):\n",
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" self.call.level = Rank.SUPERVISOR\n",
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" self._escalate_call()\n",
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"\n",
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"\n",
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"class Supervisor(Employee):\n",
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"\n",
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" def __init__(self, employee_id, name):\n",
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" super(Operator, self).__init__(employee_id, name, Rank.SUPERVISOR)\n",
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"\n",
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" def escalate_call(self):\n",
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" self.call.level = Rank.DIRECTOR\n",
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" self._escalate_call()\n",
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"\n",
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"\n",
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"class Director(Employee):\n",
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"\n",
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" def __init__(self, employee_id, name):\n",
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" super(Operator, self).__init__(employee_id, name, Rank.DIRECTOR)\n",
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"\n",
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" def escalate_call(self):\n",
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" raise NotImplemented('Directors must be able to handle any call')\n",
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"\n",
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"\n",
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"class CallState(Enum):\n",
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"\n",
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" READY = 0\n",
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" IN_PROGRESS = 1\n",
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" COMPLETE = 2\n",
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"\n",
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"\n",
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"class Call(object):\n",
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"\n",
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" def __init__(self, rank):\n",
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" self.state = CallState.READY\n",
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" self.rank = rank\n",
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" self.employee = None\n",
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"\n",
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"\n",
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"class CallCenter(object):\n",
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"\n",
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" def __init__(self, operators, supervisors, directors):\n",
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" self.operators = operators\n",
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" self.supervisors = supervisors\n",
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" self.directors = directors\n",
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" self.queued_calls = deque()\n",
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"\n",
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" def dispatch_call(self, call):\n",
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" if call.rank not in (Rank.OPERATOR, Rank.SUPERVISOR, Rank.DIRECTOR):\n",
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" raise ValueError('Invalid call rank: {}'.format(call.rank))\n",
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" employee = None\n",
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" if call.rank == Rank.OPERATOR:\n",
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" employee = self._dispatch_call(call, self.operators)\n",
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" if call.rank == Rank.SUPERVISOR or employee is None:\n",
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" employee = self._dispatch_call(call, self.supervisors)\n",
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" if call.rank == Rank.DIRECTOR or employee is None:\n",
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" employee = self._dispatch_call(call, self.directors)\n",
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" if employee is None:\n",
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" self.queued_calls.append(call)\n",
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"\n",
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" def _dispatch_call(self, call, employees):\n",
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" for employee in employees:\n",
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" if employee.call is None:\n",
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" employee.take_call(call)\n",
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" return employee\n",
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" return None\n",
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"\n",
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" def notify_call_escalated(self, call): # ...\n",
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" def notify_call_completed(self, call): # ...\n",
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" def dispatch_queued_call_to_newly_freed_employee(self, call, employee): # ..."
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]
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}
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],
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"metadata": {
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"kernelspec": {
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"display_name": "Python 3",
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"language": "python",
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"name": "python3"
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"file_extension": ".py",
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