import asyncio

import aiofiles

import aiohttp

import json

from django.http import HttpResponse

HASH_TABLE_FILE_PATH = 'hash_table.json'

async def read_hash_table_from_file(file_path):

async with aiofiles.open(file_path, mode='r') as f:

content = await f.read()

hash_table = json.loads(content)

return hash_table

async def update_hash_table_to_file(file_path, hash_table):

async with aiofiles.open(file_path, mode='w') as f:

content = json.dumps(hash_table)

await f.write(content)

def get_client_ip_port(request):

# 获取客户端IP

x_forwarded_for = request.META.get('HTTP_X_FORWARDED_FOR')

if x_forwarded_for:

ip = x_forwarded_for.split(',')[0]

else:

ip = request.META.get('REMOTE_ADDR')

# 获取客户端端口

port = request.META.get('REMOTE_PORT')

return ip, port

async def handle_client_request(request):

# 获取客户端IP和端口

client_ip, client_port = get_client_ip_port(request)

# 先从哈希表中查询是否已有记录，如果有则直接转发到对应服务器，否则需要进行服务端的轮询

backend_server = hash_table.get((client_ip, client_port))

if backend_server:

# 直接转发请求到对应的服务器

response = await try_forward_request(request, backend_server, update=False)

else:

# 进行服务端轮询

for server in backend_servers:

response = await try_forward_request(request, server)

if response.status == 200:

#TODO 判断是否选择此服务端 依据是返回的json中包含一定的状态值

# 转发请求成功，更新哈希表

hash_table[(client_ip, client_port)] = server

update_hash_table_to_file(HASH_TABLE_FILE_PATH,hash_table)

break

# 将后端服务器返回的响应原样返回给客户端

content = await response.content.read()

return HttpResponse(content=content, status=response.status, content_type=response.headers.get('Content-Type', 'text/plain'))

async def try_forward_request(request, server, update=True):

url = f"http://{server['ip']}:{server['port']}{request.path}"

async with aiohttp.ClientSession() as session:

headers = request.headers.copy()

headers.pop('Host', None)

headers.pop('Content-Length', None)

async with session.request(request.method, url, headers=headers, data=await request.content.read()) as response:

if response.status == 200:

if update:

# 转发请求成功，更新哈希表

hash_table[(client_ip, client_port)] = server

return response