覆盖worker

多亏了暴露给插件的”worker”钩子，你可以覆盖每个uWSGI worker运行的代码。

目前，python插件是唯一一个暴露它的插件：

[uwsgi]
; create a bunch of sockets
socket = 127.0.0.1:3031
socket = 127.0.0.1:3032
; spawn the master
master = true
; spawn 4 processes
processes = 4
; load a python script as the worker code
python-worker-override = aioserver.py

该python脚本可以访问uwsgi模块，因此它可以控制/改变内部逻辑。

下面的例子展示了aiohttp的使用 (需要python 3.5)

import asyncio
from aiohttp import web

import uwsgi
import socket
import sys
import signal

async def handle(request):
   name = request.match_info.get('name', "Anonymous")
   text = "Hello, " + name
   return web.Response(body=text.encode('utf-8'))

async def wshandler(request):
   ws = web.WebSocketResponse()
   await ws.prepare(request)

   async for msg in ws:
     if msg.tp == web.MsgType.text:
         ws.send_str("Hello, {}".format(msg.data))
     elif msg.tp == web.MsgType.binary:
         ws.send_bytes(msg.data)
     elif msg.tp == web.MsgType.close:
         break

   return ws

 async def init(loop, fd):
    app = web.Application(loop=loop)
    app.router.add_route('GET', '/echo', wshandler)
    app.router.add_route('GET', '/{name}', handle)

    srv = await loop.create_server(app.make_handler(),
                                   sock=socket.fromfd(fd, socket.AF_INET, socket.SOCK_STREAM))
    print("asyncio server started on uWSGI {0}".format(uwsgi.version))
    return srv

def destroy():
   print("destroy worker {0}".format(uwsgi.worker_id()))
   sys.exit(0)

def graceful_reload():
   print("graceful reload for worker {0}".format(uwsgi.worker_id()))
   # TODO do somethign meaningful
   sys.exit(0)

loop = asyncio.get_event_loop()
loop.add_signal_handler(signal.SIGINT, destroy)
loop.add_signal_handler(signal.SIGHUP, graceful_reload)
# spawn a handler for every uWSGI socket
for fd in uwsgi.sockets:
   loop.run_until_complete(init(loop, fd))
uwsgi.accepting()
loop.run_forever()

在这个例子中 (来自官方的aiohttp文档)，我们看到uwsgi.sockets列表 (保存uWSGI socket文件描述符列表)，以及对SIGINT和SIGHUP的覆盖，以支持重新加载 (SIGHUP应该调整以支持等待所有的入队请求)

调用 uwsgi.accepting() 以通知master，worker正在接收请求，这对于touch-chain-reload正常工作是必须的。

应该扩展该脚本，在每个请求后调用uwsgi.log(...)，以及（最后）更新一些度量