SocketServer.pyCreating network servers.contentsSocketServer.pycontentsfile headBaseServerBaseServer.serve_foreverBaseServer.shutdownBaseServer.handle_requestBaseServer.handle_request_noblockBaseServer Overridden functionsTCPServerUDPServerForkingMixInThreadingMixInBaseRequestHandlerStreamRequestHandlerDatagramRequestHandler版权file head__version_ = “0.4"import socketimport selectimport sysimport osimport errnotry: import threadingexcept ImportError: import dummy_threading as threading__all__ = [“TCPServer”,“UDPServer”,“ForkingUDPServer”,“ForkingTCPServer”, “ThreadingUDPServer”,“ThreadingTCPServer”,“BaseRequestHandler”, “StreamRequestHandler”,“DatagramRequestHandler”, “ThreadingMixIn”, “ForkingMixIn”]if hasattr(socket, “AF_UNIX”): all.extend([“UnixStreamServer”,“UnixDatagramServer”, “ThreadingUnixStreamServer”, “ThreadingUnixDatagramServer”])# 出现 EINTR 则重新调用def _eintr_retry(func, *args): “““restart a system call interrupted by EINTR””” while True: try: return func(*args) except (OSError, select.error) as e: if e.args[0] != errno.EINTR: raiseBaseServerRequestHandlerClass 注册 handle 函数。 finish_request 中实例化，调用用户定义的 handle 函数class BaseServer: timeout = None def init(self, server_address, RequestHandlerClass): “““Constructor. May be extended, do not override.””” self.server_address = server_address self.RequestHandlerClass = RequestHandlerClass self.__is_shut_down = threading.Event() self.__shutdown_request = False def server_activate(self): “““Called by constructor to activate the server. May be overridden. "”” passBaseServer.serve_forever服务循环监听端口处理请求 def serve_forever(self, poll_interval=0.5): “““Handle one request at a time until shutdown. Polls for shutdown every poll_interval seconds. Ignores self.timeout. If you need to do periodic tasks, do them in another thread. "”” self.__is_shut_down.clear() try: while not self.__shutdown_request: # 调用 select 监视请求，处理 EINTR 异常 r, w, e = _eintr_retry(select.select, [self], [], [], poll_interval) # 有请求进来 if self in r: self._handle_request_noblock() finally: self.__shutdown_request = False self.__is_shut_down.set()BaseServer.shutdown停止 serve_forever 循环. __is_shut_down 通知外部，循环已经退出 注意 threading.Event() 的用法，只设置一次，避免使用 Event 进行频繁的设置/清除。需要在与 serve_forever 不同的线程中调用. 因为调用 shutdown 后需要 wait 信号量，程序会 block，block 后 serve_forever 无法执行 serve_forever 收到请求后才能退出设置信号量注意 self.__shutdown_request 的读写操作，属于原子操作，在多线程中使用是安全的 def shutdown(self): “““Stops the serve_forever loop. Blocks until the loop has finished. This must be called while serve_forever() is running in another thread, or it will deadlock. "”” self.__shutdown_request = True self.__is_shut_down.wait()BaseServer.handle_request和 serve_forever 并列的函数如果不调用 server_forever, 在外面循环调用 handle_request # The distinction between handling, getting, processing and # finishing a request is fairly arbitrary. Remember: # # - handle_request() is the top-level call. It calls # select, get_request(), verify_request() and process_request() # - get_request() is different for stream or datagram sockets # - process_request() is the place that may fork a new process # or create a new thread to finish the request # - finish_request() instantiates the request handler class; # this constructor will handle the request all by itself def handle_request(self): “““Handle one request, possibly blocking. Respects self.timeout. "”” # Support people who used socket.settimeout() to escape # handle_request before self.timeout was available. # 如果用户使用 socket.settimeout() 设置了超时时间，则选取一个小的 timeout = self.socket.gettimeout() if timeout is None: timeout = self.timeout elif self.timeout is not None: timeout = min(timeout, self.timeout) # select,监听连接，会阻塞直到超时 fd_sets = _eintr_retry(select.select, [self], [], [], timeout) if not fd_sets[0]: self.handle_timeout() return # 处理请求 self._handle_request_noblock()BaseServer._handle_request_noblock真正的请求处理函数get_request: 接收请求 acceptverify_request: 验证，做一些验证工作，比如 ip 过滤process_request: 处理请求，子类重写该方法后，需要 调用 SocketServer.BaseServer.process_request,BaseServer.process_request 中有 BaseRequestHandler 的回调动作,实例化用户定义的 handler, init 中完成对 handle() 的调用shutdown_reques: 关闭连接 def _handle_request_noblock(self): “““Handle one request, without blocking. I assume that select.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: # 接收请求 # get_request 由子类实现，一般为接收请求，返回 socket request, client_address = self.get_request() except socket.error: return if self.verify_request(request, client_address): try: self.process_request(request, client_address) except: self.handle_error(request, client_address) self.shutdown_request(request) else: self.shutdown_request(request)BaseServer Overridden functions def handle_timeout(self): “““Called if no new request arrives within self.timeout. Overridden by ForkingMixIn. "”” pass def verify_request(self, request, client_address): “““Verify the request. May be overridden. Return True if we should proceed with this request. "”” return True 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) def server_close(self): “““Called to clean-up the server. May be overridden. "”” pass def finish_request(self, request, client_address): “““Finish one request by instantiating RequestHandlerClass.””” self.RequestHandlerClass(request, client_address, self) def shutdown_request(self, request): “““Called to shutdown and close an individual request.””” self.close_request(request) def close_request(self, request): “““Called to clean up an individual request.””” pass def handle_error(self, request, client_address): “““Handle an error gracefully. May be overridden. The default is to print a traceback and continue. "”” print ‘-’*40 print ‘Exception happened during processing of request from’, print client_address import traceback traceback.print_exc() # XXX But this goes to stderr! print ‘-’*40TCPServershutdown_request 先调用 socket.shutdown 后调用 socket.closeclose()releases the resource associated with a connection but does not necessarily close the connection immediately. If you want to close the connection in a timely fashion, callshutdown() beforeclose().Shut down one or both halves of the connection. If how is SHUT_RD, further receives are disallowed. If how is SHUT_WR, further sends are disallowed. Ifhow is SHUT_RDWR, further sends and receives are disallowed. Depending on the platform, shutting down one half of the connection can also close the opposite half (e.g. on Mac OS X, shutdown(SHUT_WR) does not allow further reads on the other end of the connection).class TCPServer(BaseServer): address_family = socket.AF_INET socket_type = socket.SOCK_STREAM request_queue_size = 5 allow_reuse_address = False def init(self, server_address, RequestHandlerClass, bind_and_activate=True): “““Constructor. May be extended, do not override.””” BaseServer.init(self, server_address, RequestHandlerClass) self.socket = socket.socket(self.address_family, self.socket_type) if bind_and_activate: try: self.server_bind() self.server_activate() except: self.server_close() raise def server_bind(self): “““Called by constructor to bind the socket. May be overridden. "”” if self.allow_reuse_address: self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) self.socket.bind(self.server_address) self.server_address = self.socket.getsockname() def server_activate(self): “““Called by constructor to activate the server. May be overridden. "”” self.socket.listen(self.request_queue_size) def server_close(self): “““Called to clean-up the server. May be overridden. "”” self.socket.close() def fileno(self): “““Return socket file number. Interface required by select(). "”” return self.socket.fileno() def get_request(self): “““Get the request and client address from the socket. May be overridden. "”” return self.socket.accept() # 调用 shutdown 后调用 close，立即关闭并释放资源 def shutdown_request(self, request): “““Called to shutdown and close an individual request.””” try: #explicitly shutdown. socket.close() merely releases #the socket and waits for GC to perform the actual close. request.shutdown(socket.SHUT_WR) except socket.error: pass #some platforms may raise ENOTCONN here self.close_request(request) def close_request(self, request): “““Called to clean up an individual request.””” request.close()UDPServerUDPServer get_request 返回的是一个 (data, socket) 的 tuple，而 TCPServer 返回的是 socket handle 中要区分处理msg, sock = self.request msg 已经获取，无需额外 recv对于数据的传送， 你应该使用 socket 的 sendto() 和 recvfrom() 方法。 尽管传统的 send() 和 recv() 也可以达到同样的效果， 但是前面的两个方法对于 UDP 连接而言更普遍。 from python3-cookbookfrom SocketServer import BaseRequestHandler, UDPServerimport timeclass TimeHandler(BaseRequestHandler): def handle(self): print(‘Got connection from’, self.client_address) # Get message and client socket msg, sock = self.request resp = time.ctime() sock.sendto(resp.encode(‘ascii’), self.client_address)if name == ‘main’: serv = UDPServer((’’, 20000), TimeHandler) serv.serve_forever()#—————————–>>> from socket import socket, AF_INET, SOCK_DGRAM>>> s = socket(AF_INET, SOCK_DGRAM)>>> s.sendto(b’’, (’localhost’, 20000))0>>> s.recvfrom(8192)(‘Thu Dec 20 10:01:01 2018’, (‘127.0.0.1’, 20000))class UDPServer(TCPServer): “““UDP server class.””” allow_reuse_address = False socket_type = socket.SOCK_DGRAM max_packet_size = 8192 def get_request(self): data, client_addr = self.socket.recvfrom(self.max_packet_size) return (data, self.socket), client_addr def server_activate(self): # No need to call listen() for UDP. pass def shutdown_request(self, request): # No need to shutdown anything. self.close_request(request) def close_request(self, request): # No need to close anything. passForkingMixIn典型的 fork 使用，这里我们能看到 fork 多进程的典型使用限定最大进程数，保证系统资源不至于耗尽父进程 wait defunct 进程fork 后父进程返回子进程处理请求后 _exit()class ForkingMixIn: “““Mix-in class to handle each request in a new process.””” timeout = 300 active_children = None max_children = 40 def collect_children(self): “““Internal routine to wait for children that have exited.””” if self.active_children is None: return while len(self.active_children) >= self.max_children: try: pid, _ = os.waitpid(-1, 0) self.active_children.discard(pid) except OSError as e: if e.errno == errno.ECHILD: # we don’t have any children, we’re done self.active_children.clear() elif e.errno != errno.EINTR: break # Now reap all defunct children. for pid in self.active_children.copy(): try: pid, _ = os.waitpid(pid, os.WNOHANG) # if the child hasn’t exited yet, pid will be 0 and ignored by # discard() below self.active_children.discard(pid) except OSError as e: if e.errno == errno.ECHILD: # someone else reaped it self.active_children.discard(pid) def handle_timeout(self): “““Wait for zombies after self.timeout seconds of inactivity. May be extended, do not override. "”” self.collect_children() def process_request(self, request, client_address): “““Fork a new subprocess to process the request.””” self.collect_children() pid = os.fork() if pid: # Parent process if self.active_children is None: self.active_children = set() self.active_children.add(pid) self.close_request(request) #close handle in parent process return else: # Child process. # This must never return, hence os._exit()! try: self.finish_request(request, client_address) self.shutdown_request(request) os._exit(0) except: try: self.handle_error(request, client_address) self.shutdown_request(request) finally: os._exit(1)ThreadingMixInThreadingMixIn 重载了 process_request 函数创建一个线程在线程中处理请求启动线程class ThreadingMixIn: “““Mix-in class to handle each request in a new thread.””” # Decides how threads will act upon termination of the # main process daemon_threads = False def process_request_thread(self, request, client_address): “““Same as in BaseServer but as a thread. In addition, exception handling is done here. "”” try: self.finish_request(request, client_address) self.shutdown_request(request) except: self.handle_error(request, client_address) self.shutdown_request(request) def process_request(self, request, client_address): “““Start a new thread to process the request.””” t = threading.Thread(target = self.process_request_thread, args = (request, client_address)) t.daemon = self.daemon_threads t.start()class ForkingUDPServer(ForkingMixIn, UDPServer): passclass ForkingTCPServer(ForkingMixIn, TCPServer): passclass ThreadingUDPServer(ThreadingMixIn, UDPServer): passclass ThreadingTCPServer(ThreadingMixIn, TCPServer): passif hasattr(socket, ‘AF_UNIX’): class UnixStreamServer(TCPServer): address_family = socket.AF_UNIX class UnixDatagramServer(UDPServer): address_family = socket.AF_UNIX class ThreadingUnixStreamServer(ThreadingMixIn, UnixStreamServer): pass class ThreadingUnixDatagramServer(ThreadingMixIn, UnixDatagramServer): passBaseRequestHandler基础请求类，对外提供三个接口setup()handle()finish()使用时继承该类，通过 BaseServer 注册 BaseServer.finish_request 中实例化 BaseRequestHandler 类，在 __init__函数调用中完成继承类重载的 handle() 接口的调用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() def setup(self): pass def handle(self): pass def finish(self): passStreamRequestHandler提供文件操作接口class StreamRequestHandler(BaseRequestHandler): “““Define self.rfile and self.wfile for stream sockets.””” # Default buffer sizes for rfile, wfile. # We default rfile to buffered because otherwise it could be # really slow for large data (a getc() call per byte); we make # wfile unbuffered because (a) often after a write() we want to # read and we need to flush the line; (b) big writes to unbuffered # files are typically optimized by stdio even when big reads # aren’t. rbufsize = -1 wbufsize = 0 # A timeout to apply to the request socket, if not None. timeout = None # Disable nagle algorithm for this socket, if True. # Use only when wbufsize != 0, to avoid small packets. disable_nagle_algorithm = False def setup(self): self.connection = self.request if self.timeout is not None: self.connection.settimeout(self.timeout) if self.disable_nagle_algorithm: self.connection.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, True) self.rfile = self.connection.makefile(‘rb’, self.rbufsize) self.wfile = self.connection.makefile(‘wb’, self.wbufsize) def finish(self): if not self.wfile.closed: try: self.wfile.flush() except socket.error: # A final socket error may have occurred here, such as # the local error ECONNABORTED. pass self.wfile.close() self.rfile.close()DatagramRequestHandlerclass DatagramRequestHandler(BaseRequestHandler): “““Define self.rfile and self.wfile for datagram sockets.””” def setup(self): try: from cStringIO import StringIO except ImportError: from StringIO import StringIO self.packet, self.socket = self.request self.rfile = StringIO(self.packet) self.wfile = StringIO() def finish(self): self.socket.sendto(self.wfile.getvalue(), self.client_address)版权作者：bigfish 许可协议：许可协议 知识共享署名-非商业性使用 4.0 国际许可协议