go与python做web_粗读web框架之go gin和python django

为什么引入web框架

web应用的本质

浏览器发送一个HTTP请求；

服务器收到请求，生成一个HTML文档；

服务器把HTML文档作为HTTP响应的Body发送给浏览器；

浏览器收到HTTP响应，从HTTP Body取出HTML文档并显示；

涉及的问题

解析http请求

找到对应的处理函数

生成并发送http响应

web框架工作流程

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​

中间件

中间件是请求或者应用开始和结束时注入代码的机制

常见的web中间件： 鉴权、打印log、session、统计信息、处理数据库连接 等等

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​

golang http 服务端编程

golang 的net/http包提供了http编程的相关接口，封装了内部TCP连接和报文解析的复杂琐碎的细节

go c.serve(ctx)最终会启动goroutine处理请求

使用者只需要和http.request 和 http.ResponseWriter 两个对象交互就行(也就是一个struct 实现net/http包中的Handler interface中的 ServeHttp方法 )

//E:\Go\src\net\http\server.go +82

type Handler interface {

ServeHTTP(ResponseWriter, *Request)

}

//纯 net.http包的server方法

package main

import (

"io"

"net/http"

)

type helloHandler struct{}

func (h *helloHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {

w.Write([]byte("Hello, world!"))

}

func main() {

http.Handle("/", &helloHandler{})

http.ListenAndServe(":12345", nil)

}

//

import (

"net/http"

)

type Handle struct{}

func (h Handle) ServeHTTP(response http.ResponseWriter, request *http.Request) {

switch request.URL.Path {

case "/info":

response.Write([]byte("info"))

default:

}

}

func main() {

http.ListenAndServe(":8888", Handle{})

}

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net/http 的另外一个重要的概念 ，ServeMux (多路传输)：ServeMux 可以注册多了 URL 和 handler 的对应关系，并自动把请求转发到对应的 handler 进行处理

// 下面看一个带路由的http server

package main

import (

"io"

"net/http"

)

func helloHandler(w http.ResponseWriter, r *http.Request) {

io.WriteString(w, "Hello, world!\n")

}

func echoHandler(w http.ResponseWriter, r *http.Request) {

io.WriteString(w, r.URL.Path)

}

func main() {

mux := http.NewServeMux()

mux.HandleFunc("/hello", helloHandler)

mux.HandleFunc("/", echoHandler)

http.ListenAndServe(":12345", mux)

}

// 其实ServeMux 也实现了Handler的ServeHTTP方法所以也是Handler接口

//E:\Go\src\net\http\server.go 2382

func (mux *ServeMux) ServeHTTP(w ResponseWriter, r *Request) {

if r.RequestURI == "*" {

if r.ProtoAtLeast(1, 1) {

w.Header().Set("Connection", "close")

}

w.WriteHeader(StatusBadRequest)

return

}

h, _ := mux.Handler(r)

h.ServeHTTP(w, r)

}

// E:\Go\src\net\http\server.go +2219可以看到 net/http包中的 基于map 路由查找

// Find a handler on a handler map given a path string.

// Most-specific (longest) pattern wins.

func (mux *ServeMux) match(path string) (h Handler, pattern string) {

// Check for exact match first.

v, ok := mux.m[path]

if ok {

return v.h, v.pattern

}

// Check for longest valid match.

var n = 0

for k, v := range mux.m {

if !pathMatch(k, path) {

continue

}

if h == nil || len(k) > n {

n = len(k)

h = v.h

pattern = v.pattern

}

}

return

}

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golang web框架 GIN golang gin web框架

//gin框架初始化的流程

1.初始化engine

2.注册中间件

3.注册路由

//响应流程

1.路由，找到handle

2.将请求和响应用Context包装起来供业务代码使用

3.依次调用中间件和处理函数

4.输出结果

//gin 里面最重要的两个数据结构

//1.Context在中间件中传递本次请求的各种数据、管理流程，进行响应

//2.Engine gin 引擎，是框架的实例，它包含多路复用器，中间件和配置设置

// 下面看下open-falcon-api中的实际应用

//open-falcon-api里面注册路由和中间件

//E:\go_path\src\github.com\open-falcon\falcon-plus\modules\api\app\controller\graph\graph_routes.go

// 首先注册/api/v1/开头的path的路由组

// 然后Use 一个auth的中间件 ，作用是检查token

// 这个组后面的所有path 都使用这个中间件

// 也就是访问 /graph/endpoint 时会过 3个中间件(log recovery auth )+一个EndpointRegexpQuery处理函数

//

func Routes(r *gin.Engine) {

db = config.Con()

authapi := r.Group("/api/v1")

authapi.Use(utils.AuthSessionMidd)

authapi.GET("/graph/endpointobj", EndpointObjGet)

authapi.GET("/graph/endpoint", EndpointRegexpQuery)

authapi.GET("/graph/endpoint_counter", EndpointCounterRegexpQuery)

authapi.POST("/graph/history", QueryGraphDrawData)

authapi.POST("/graph/lastpoint", QueryGraphLastPoint)

authapi.POST("/graph/info", QueryGraphItemPosition)

authapi.DELETE("/graph/endpoint", DeleteGraphEndpoint)

authapi.DELETE("/graph/counter", DeleteGraphCounter)

grfanaapi := r.Group("/api")

grfanaapi.GET("/v1/grafana", GrafanaMainQuery)

grfanaapi.GET("/v1/grafana/metrics/find", GrafanaMainQuery)

grfanaapi.POST("/v1/grafana/render", GrafanaRender)

grfanaapi.GET("/v1/grafana/render", GrafanaRender)

}

func AuthSessionMidd(c *gin.Context) {

auth, err := h.SessionChecking(c)

if !viper.GetBool("skip_auth") {

if err != nil || auth != true {

log.Debugf("error: %v, auth: %v", err, auth)

c.Set("auth", auth)

h.JSONR(c, http.StatusUnauthorized, err)

c.Abort()

return

}

}

c.Set("auth", auth)

}

// E:\go_path\src\github.com\open-falcon\falcon-plus\vendor\github.com\gin-gonic\gin\context.go +715 最后会调用这里的Render方法

// Render writes the response headers and calls render.Render to render data.

func (c *Context) Render(code int, r render.Render) {

c.Status(code)

if !bodyAllowedForStatus(code) {

r.WriteContentType(c.Writer)

c.Writer.WriteHeaderNow()

return

}

if err := r.Render(c.Writer); err != nil {

panic(err)

}

}

// 可以看到这里的bind 是在gin在解析请求payload是否和函数中要求的struct一致

// E:\go_path\src\github.com\open-falcon\falcon-plus\vendor\github.com\gin-gonic\gin\context.go +504

// bind会根据请求中的Content-Type header判断是json 还是xml

// 并且根据struct中的tag通过反射解析payload

// Bind checks the Content-Type to select a binding engine automatically,

// Depending the "Content-Type" header different bindings are used:

// "application/json" --> JSON binding

// "application/xml" --> XML binding

// otherwise --> returns an error.

// It parses the request's body as JSON if Content-Type == "application/json" using JSON or XML as a JSON input.

// It decodes the json payload into the struct specified as a pointer.

// It writes a 400 error and sets Content-Type header "text/plain" in the response if input is not valid.

func (c *Context) Bind(obj interface{}) error {

b := binding.Default(c.Request.Method, c.ContentType())

return c.MustBindWith(obj, b)

}

type APIEndpointObjGetInputs struct {

Endpoints []string `json:"endpoints" form:"endpoints"`

Deadline int64 `json:"deadline" form:"deadline"`

}

func EndpointObjGet(c *gin.Context) {

inputs := APIEndpointObjGetInputs{

Deadline: 0,

}

if err := c.Bind(&inputs); err != nil {

h.JSONR(c, badstatus, err)

return

}

if len(inputs.Endpoints) == 0 {

h.JSONR(c, http.StatusBadRequest, "endpoints missing")

return

}

var result []m.Endpoint = []m.Endpoint{}

dt := db.Graph.Table("endpoint").

Where("endpoint in (?) and ts >= ?", inputs.Endpoints, inputs.Deadline).

Scan(&result)

if dt.Error != nil {

h.JSONR(c, http.StatusBadRequest, dt.Error)

return

}

endpoints := []map[string]interface{}{}

for _, r := range result {

endpoints = append(endpoints, map[string]interface{}{"id": r.ID, "endpoint": r.Endpoint, "ts": r.Ts})

}

h.JSONR(c, endpoints)

}

//E:\go_path\src\github.com\open-falcon\falcon-plus\modules\api\main.go +78

//初始化gin

routes := gin.Default()

//E:\go_path\src\github.com\open-falcon\falcon-plus\vendor\github.com\gin-gonic\gin\gin.go +148

// Default returns an Engine instance with the Logger and Recovery middleware already attached.

func Default() *Engine {

debugPrintWARNINGDefault()

engine := New()

engine.Use(Logger(), Recovery())

return engine

}

//E:\go_path\src\github.com\open-falcon\falcon-plus\vendor\github.com\gin-gonic\gin\gin.go +119

// new方法 返回一个不带中间件的 单例engine ，并且把context 放在池中

func New() *Engine {

debugPrintWARNINGNew()

engine := &Engine{

RouterGroup: RouterGroup{

Handlers: nil,

basePath: "/",

root: true,

},

FuncMap: template.FuncMap{},

RedirectTrailingSlash: true,

RedirectFixedPath: false,

HandleMethodNotAllowed: false,

ForwardedByClientIP: true,

AppEngine: defaultAppEngine,

UseRawPath: false,

UnescapePathValues: true,

MaxMultipartMemory: defaultMultipartMemory,

trees: make(methodTrees, 0, 9),

delims: render.Delims{Left: "{{", Right: "}}"},

secureJsonPrefix: "while(1);",

}

engine.RouterGroup.engine = engine

engine.pool.New = func() interface{} {

return engine.allocateContext()

}

return engine

}

//E:\go_path\src\github.com\open-falcon\falcon-plus\modules\api\app\controller\routes.go

//r.Run(port) 最后调用的是 net.http.ListenAndServe

func (engine *Engine) Run(addr ...string) (err error) {

defer func() { debugPrintError(err) }()

address := resolveAddress(addr)

debugPrint("Listening and serving HTTP on %s\n", address)

err = http.ListenAndServe(address, engine)

return

}

//E:\Go\src\net\http\server.go +2686

func (sh serverHandler) ServeHTTP(rw ResponseWriter, req *Request) {

handler := sh.srv.Handler

if handler == nil {

handler = DefaultServeMux

}

if req.RequestURI == "*" && req.Method == "OPTIONS" {

handler = globalOptionsHandler{}

}

handler.ServeHTTP(rw, req)

}

//E:\go_path\src\github.com\open-falcon\falcon-plus\vendor\github.com\gin-gonic\gin\gin.go +321

//我们可以看到 在gin中实现了ServeHTTP方法 net.http.Handler

// ServeHTTP conforms to the http.Handler interface.

// 这里使用sync.pool cache context数据结构，避免频繁GC，每次使用都初始化

//一个struct实现了 interface中的方法 就说明这个struct是这个类型

func (engine *Engine) ServeHTTP(w http.ResponseWriter, req *http.Request) {

c := engine.pool.Get().(*Context)

c.writermem.reset(w)

c.Request = req

c.reset()

engine.handleHTTPRequest(c)

engine.pool.Put(c)

}

// gin 里面处理请求的核心方法

// 根据一些配置去 压缩前缀树 radix.tree中找到对应的handleChain 然后执行

// 注意这句handlers, params, tsr := root.getValue(path, c.Params, unescape)

// 路由查找的过程是 从基数树的根节点一直匹配到和请求一致的节点找到对应的handlerchain

// 注册路由 E:\go_path\src\github.com\open-falcon\falcon-plus\vendor\github.com\gin-gonic\gin\gin.go +243

// 从下面的addRoute方法中可以看到gin 为每个HttpMethod GET POST PUT DELETE都注册了一颗tree

// 并且有priority 即最长的路径优先匹配

/*

func (engine *Engine) addRoute(method, path string, handlers HandlersChain) {

assert1(path[0] == '/', "path must begin with '/'")

assert1(method != "", "HTTP method can not be empty")

assert1(len(handlers) > 0, "there must be at least one handler")

debugPrintRoute(method, path, handlers)

root := engine.trees.get(method)

if root == nil {

root = new(node)

engine.trees = append(engine.trees, methodTree{method: method, root: root})

}

root.addRoute(path, handlers)

}

*/

func (engine *Engine) handleHTTPRequest(c *Context) {

httpMethod := c.Request.Method

path := c.Request.URL.Path

unescape := false

if engine.UseRawPath && len(c.Request.URL.RawPath) > 0 {

path = c.Request.URL.RawPath

unescape = engine.UnescapePathValues

}

// Find root of the tree for the given HTTP method

t := engine.trees

for i, tl := 0, len(t); i < tl; i++ {

if t[i].method != httpMethod {

continue

}

root := t[i].root

// Find route in tree

handlers, params, tsr := root.getValue(path, c.Params, unescape)

if handlers != nil {

c.handlers = handlers

c.Params = params

c.Next()

c.writermem.WriteHeaderNow()

return

}

if httpMethod != "CONNECT" && path != "/" {

if tsr && engine.RedirectTrailingSlash {

redirectTrailingSlash(c)

return

}

if engine.RedirectFixedPath && redirectFixedPath(c, root, engine.RedirectFixedPath) {

return

}

}

break

}

if engine.HandleMethodNotAllowed {

for _, tree := range engine.trees {

if tree.method == httpMethod {

continue

}

if handlers, _, _ := tree.root.getValue(path, nil, unescape); handlers != nil {

c.handlers = engine.allNoMethod

serveError(c, http.StatusMethodNotAllowed, default405Body)

return

}

}

}

c.handlers = engine.allNoRoute

serveError(c, http.StatusNotFound, default404Body)

}

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python django (django框架复杂，先简单看一下)

# 入口文件

def execute_from_command_line(argv=None):

"""

A simple method that runs a ManagementUtility.

"""

utility = ManagementUtility(argv)

utility.execute()

def execute(self):

"""

Given the command-line arguments, figure out which subcommand is being

run, create a parser appropriate to that command, and run it.

"""

try:

subcommand = self.argv[1]

except IndexError:

subcommand = 'help' # Display help if no arguments were given.

# Preprocess options to extract --settings and --pythonpath.

# These options could affect the commands that are available, so they

# must be processed early.

parser = CommandParser(usage='%(prog)s subcommand [options] [args]', add_help=False, allow_abbrev=False)

parser.add_argument('--settings')

parser.add_argument('--pythonpath')

parser.add_argument('args', nargs='*') # catch-all

try:

options, args = parser.parse_known_args(self.argv[2:])

handle_default_options(options)

except CommandError:

pass # Ignore any option errors at this point.

try:

settings.INSTALLED_APPS

except ImproperlyConfigured as exc:

self.settings_exception = exc

except ImportError as exc:

self.settings_exception = exc

if settings.configured:

# Start the auto-reloading dev server even if the code is broken.

# The hardcoded condition is a code smell but we can't rely on a

# flag on the command class because we haven't located it yet.

if subcommand == 'runserver' and '--noreload' not in self.argv:

try:

autoreload.check_errors(django.setup)()

except Exception:

# The exception will be raised later in the child process

# started by the autoreloader. Pretend it didn't happen by

# loading an empty list of applications.

apps.all_models = defaultdict(OrderedDict)

apps.app_configs = OrderedDict()

apps.apps_ready = apps.models_ready = apps.ready = True

# Remove options not compatible with the built-in runserver

# (e.g. options for the contrib.staticfiles' runserver).

# Changes here require manually testing as described in

# #27522.

_parser = self.fetch_command('runserver').create_parser('django', 'runserver')

_options, _args = _parser.parse_known_args(self.argv[2:])

for _arg in _args:

self.argv.remove(_arg)

# In all other cases, django.setup() is required to succeed.

else:

django.setup()

self.autocomplete()

if subcommand == 'help':

if '--commands' in args:

sys.stdout.write(self.main_help_text(commands_only=True) + '\n')

elif not options.args:

sys.stdout.write(self.main_help_text() + '\n')

else:

self.fetch_command(options.args[0]).print_help(self.prog_name, options.args[0])

# Special-cases: We want 'django-admin --version' and

# 'django-admin --help' to work, for backwards compatibility.

elif subcommand == 'version' or self.argv[1:] == ['--version']:

sys.stdout.write(django.get_version() + '\n')

elif self.argv[1:] in (['--help'], ['-h']):

sys.stdout.write(self.main_help_text() + '\n')

else:

self.fetch_command(subcommand).run_from_argv(self.argv)

#C:\Users\Administrator\AppData\Local\Programs\Python\Python37\Lib\site-packages\django\core\management\__init__.py +301

'''

#1.fetch_command 最终会调用C:\Users\Administrator\AppData\Local\Programs\Python\Python37\Lib\site-packages\django\core\management\__init__.py 的find_commands()

最终会找到 django\core\management\commands 下面的所有的command

check

compilemessages

createcachetable

dbshell

diffsettings

dumpdata

flush

inspectdb

loaddata

makemessages

makemigrations

migrate

runserver

sendtestemail

shell

showmigrations

sqlflush

sqlmigrate

sqlsequencereset

squashmigrations

startapp

startproject

test

testserver

2\. run_from_argv 调 execute() 再调用handle()

'''

# 最常用的runserver

#C:\Users\Administrator\AppData\Local\Programs\Python\Python37\Lib\site-packages\django\core\management\commands\runserver.py +

# execute()-->handle()-->run()-->inner_run()-->get_wsgi_application() #WSGIHandler 在这里加载中间件

# C:\Users\Administrator\AppData\Local\Programs\Python\Python37\Lib\site-packages\django\core\handlers\wsgi.py

class WSGIHandler(base.BaseHandler):

request_class = WSGIRequest

def __init__(self, *args, **kwargs):

super().__init__(*args, **kwargs)

self.load_middleware()

def __call__(self, environ, start_response):

set_script_prefix(get_script_name(environ))

signals.request_started.send(sender=self.__class__, environ=environ)

request = self.request_class(environ)

response = self.get_response(request)

response._handler_class = self.__class__

status = '%d %s' % (response.status_code, response.reason_phrase)

response_headers = [

*response.items(),

*(('Set-Cookie', c.output(header='')) for c in response.cookies.values()),

]

start_response(status, response_headers)

if getattr(response, 'file_to_stream', None) is not None and environ.get('wsgi.file_wrapper'):

response = environ['wsgi.file_wrapper'](response.file_to_stream)

return response

def inner_run(self, *args, **options):

# If an exception was silenced in ManagementUtility.execute in order

# to be raised in the child process, raise it now.

autoreload.raise_last_exception()

threading = options['use_threading']

# 'shutdown_message' is a stealth option.

shutdown_message = options.get('shutdown_message', '')

quit_command = 'CTRL-BREAK' if sys.platform == 'win32' else 'CONTROL-C'

self.stdout.write("Performing system checks...\n\n")

self.check(display_num_errors=True)

# Need to check migrations here, so can't use the

# requires_migrations_check attribute.

self.check_migrations()

now = datetime.now().strftime('%B %d, %Y - %X')

self.stdout.write(now)

self.stdout.write((

"Django version %(version)s, using settings %(settings)r\n"

"Starting development server at %(protocol)s://%(addr)s:%(port)s/\n"

"Quit the server with %(quit_command)s.\n"

) % {

"version": self.get_version(),

"settings": settings.SETTINGS_MODULE,

"protocol": self.protocol,

"addr": '[%s]' % self.addr if self._raw_ipv6 else self.addr,

"port": self.port,

"quit_command": quit_command,

})

try:

handler = self.get_handler(*args, **options)

run(self.addr, int(self.port), handler,

ipv6=self.use_ipv6, threading=threading, server_cls=self.server_cls)

except socket.error as e:

# Use helpful error messages instead of ugly tracebacks.

ERRORS = {

errno.EACCES: "You don't have permission to access that port.",

errno.EADDRINUSE: "That port is already in use.",

errno.EADDRNOTAVAIL: "That IP address can't be assigned to.",

}

try:

error_text = ERRORS[e.errno]

except KeyError:

error_text = e

self.stderr.write("Error: %s" % error_text)

# Need to use an OS exit because sys.exit doesn't work in a thread

os._exit(1)

except KeyboardInterrupt:

if shutdown_message:

self.stdout.write(shutdown_message)

sys.exit(0)

# C:\Users\Administrator\AppData\Local\Programs\Python\Python37\Lib\site-packages\django\core\handlers\base.py

class BaseHandler:

_view_middleware = None

_template_response_middleware = None

_exception_middleware = None

_middleware_chain = None

def load_middleware(self):

"""

Populate middleware lists from settings.MIDDLEWARE.

Must be called after the environment is fixed (see __call__ in subclasses).

"""

self._view_middleware = []

self._template_response_middleware = []

self._exception_middleware = []

handler = convert_exception_to_response(self._get_response)

for middleware_path in reversed(settings.MIDDLEWARE):

middleware = import_string(middleware_path)

try:

mw_instance = middleware(handler)

except MiddlewareNotUsed as exc:

if settings.DEBUG:

if str(exc):

logger.debug('MiddlewareNotUsed(%r): %s', middleware_path, exc)

else:

logger.debug('MiddlewareNotUsed: %r', middleware_path)

continue

if mw_instance is None:

raise ImproperlyConfigured(

'Middleware factory %s returned None.' % middleware_path

)

if hasattr(mw_instance, 'process_view'):

self._view_middleware.insert(0, mw_instance.process_view)

if hasattr(mw_instance, 'process_template_response'):

self._template_response_middleware.append(mw_instance.process_template_response)

if hasattr(mw_instance, 'process_exception'):

self._exception_middleware.append(mw_instance.process_exception)

handler = convert_exception_to_response(mw_instance)

# We only assign to this when initialization is complete as it is used

# as a flag for initialization being complete.

self._middleware_chain = handler

#get_handler 函数最终会返回一个 WSGIHandler 的实例。WSGIHandler 类只实现了 def __call__(self, environ, start_response) , 使它本身能够成为 WSGI 中的应用程序, 并且实现 __call__ 能让类的行为跟函数一样。

class WSGIHandler(base.BaseHandler):

request_class = WSGIRequest

def __init__(self, *args, **kwargs):

super().__init__(*args, **kwargs)

self.load_middleware()

def __call__(self, environ, start_response):

set_script_prefix(get_script_name(environ))

signals.request_started.send(sender=self.__class__, environ=environ)

request = self.request_class(environ)

response = self.get_response(request)

response._handler_class = self.__class__

status = '%d %s' % (response.status_code, response.reason_phrase)

response_headers = [

*response.items(),

*(('Set-Cookie', c.output(header='')) for c in response.cookies.values()),

]

start_response(status, response_headers)

if getattr(response, 'file_to_stream', None) is not None and environ.get('wsgi.file_wrapper'):

response = environ['wsgi.file_wrapper'](response.file_to_stream)

return response

# C:\Users\Administrator\AppData\Local\Programs\Python\Python37\Lib\socketserver.py + 215

def serve_forever(self, poll_interval=0.5):

"""

处理一个http请求直到关闭

"""

self.__is_shut_down.clear()

try:

# XXX: Consider using another file descriptor or connecting to the

# socket to wake this up instead of polling. Polling reduces our

# responsiveness to a shutdown request and wastes cpu at all other

# times.

with _ServerSelector() as selector:

selector.register(self, selectors.EVENT_READ)

while not self.__shutdown_request:

ready = selector.select(poll_interval)

if ready:

#如果 fd可用调用处理方法

self._handle_request_noblock()

self.service_actions()

finally:

self.__shutdown_request = False

self.__is_shut_down.set()

def _handle_request_noblock(self):

"""Handle one request, without blocking.

I assume that selector.select() has returned that the socket is

readable before this function was called, so there should be no risk of

blocking in get_request().

"""

try:

request, client_address = self.get_request()

except OSError:

return

if self.verify_request(request, client_address):

try:

#这里是真正处理请求的地方

self.process_request(request, client_address)

except Exception:

self.handle_error(request, client_address)

self.shutdown_request(request)

except:

self.shutdown_request(request)

raise

else:

self.shutdown_request(request)

def process_request(self, request, client_address):

"""Call finish_request.

Overridden by ForkingMixIn and ThreadingMixIn.

"""

self.finish_request(request, client_address)

self.shutdown_request(request)

#finish_request 最后调用这个BaseRequestHandler

class BaseRequestHandler:

'''

'''

def __init__(self, request, client_address, server):

self.request = request

self.client_address = client_address

self.server = server

self.setup()

try:

self.handle()

finally:

self.finish()

# C:\Users\Administrator\AppData\Local\Programs\Python\Python37\Lib\site-packages\django\core\servers\basehttp.py +156

def handle(self):

'''

这里对请求长度做限制

parse_request对http解包

'''

self.raw_requestline = self.rfile.readline(65537)

if len(self.raw_requestline) > 65536:

self.requestline = ''

self.request_version = ''

self.command = ''

self.send_error(414)

return

if not self.parse_request(): # An error code has been sent, just exit

return

handler = ServerHandler(

self.rfile, self.wfile, self.get_stderr(), self.get_environ()

)

handler.request_handler = self # backpointer for logging

handler.run(self.server.get_app())

#get_app 返回之前装配的WSGIAPP最终

class WSGIHandler(base.BaseHandler):

request_class = WSGIRequest

def __init__(self, *args, **kwargs):

super().__init__(*args, **kwargs)

self.load_middleware()

def __call__(self, environ, start_response):

set_script_prefix(get_script_name(environ))

signals.request_started.send(sender=self.__class__, environ=environ)

request = self.request_class(environ)

response = self.get_response(request)

response._handler_class = self.__class__

status = '%d %s' % (response.status_code, response.reason_phrase)

response_headers = [

*response.items(),

*(('Set-Cookie', c.output(header='')) for c in response.cookies.values()),

]

start_response(status, response_headers)

if getattr(response, 'file_to_stream', None) is not None and environ.get('wsgi.file_wrapper'):

response = environ['wsgi.file_wrapper'](response.file_to_stream)

return response

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