tornado.netutil — Miscellaneous network utilities

Miscellaneous network utility code.

class tornado.netutil.TCPServer(io_loop=None, ssl_options=None)[source]

A non-blocking, single-threaded TCP server.

To use TCPServer, define a subclass which overrides the handle_stream method.

TCPServer can serve SSL traffic with Python 2.6+ and OpenSSL. To make this server serve SSL traffic, send the ssl_options dictionary argument with the arguments required for the ssl.wrap_socket method, including “certfile” and “keyfile”:

TCPServer(ssl_options={
    "certfile": os.path.join(data_dir, "mydomain.crt"),
    "keyfile": os.path.join(data_dir, "mydomain.key"),
})

TCPServer initialization follows one of three patterns:

  1. listen: simple single-process:

    server = TCPServer()
    server.listen(8888)
    IOLoop.instance().start()
    
  2. bind/start: simple multi-process:

    server = TCPServer()
    server.bind(8888)
    server.start(0)  # Forks multiple sub-processes
    IOLoop.instance().start()
    

    When using this interface, an IOLoop must not be passed to the TCPServer constructor. start will always start the server on the default singleton IOLoop.

  3. add_sockets: advanced multi-process:

    sockets = bind_sockets(8888)
    tornado.process.fork_processes(0)
    server = TCPServer()
    server.add_sockets(sockets)
    IOLoop.instance().start()
    

    The add_sockets interface is more complicated, but it can be used with tornado.process.fork_processes to give you more flexibility in when the fork happens. add_sockets can also be used in single-process servers if you want to create your listening sockets in some way other than bind_sockets.

listen(port, address='')[source]

Starts accepting connections on the given port.

This method may be called more than once to listen on multiple ports. listen takes effect immediately; it is not necessary to call TCPServer.start afterwards. It is, however, necessary to start the IOLoop.

add_sockets(sockets)[source]

Makes this server start accepting connections on the given sockets.

The sockets parameter is a list of socket objects such as those returned by bind_sockets. add_sockets is typically used in combination with that method and tornado.process.fork_processes to provide greater control over the initialization of a multi-process server.

add_socket(socket)[source]

Singular version of add_sockets. Takes a single socket object.

bind(port, address=None, family=0, backlog=128)[source]

Binds this server to the given port on the given address.

To start the server, call start. If you want to run this server in a single process, you can call listen as a shortcut to the sequence of bind and start calls.

Address may be either an IP address or hostname. If it’s a hostname, the server will listen on all IP addresses associated with the name. Address may be an empty string or None to listen on all available interfaces. Family may be set to either socket.AF_INET or socket.AF_INET6 to restrict to ipv4 or ipv6 addresses, otherwise both will be used if available.

The backlog argument has the same meaning as for socket.listen.

This method may be called multiple times prior to start to listen on multiple ports or interfaces.

start(num_processes=1)[source]

Starts this server in the IOLoop.

By default, we run the server in this process and do not fork any additional child process.

If num_processes is None or <= 0, we detect the number of cores available on this machine and fork that number of child processes. If num_processes is given and > 1, we fork that specific number of sub-processes.

Since we use processes and not threads, there is no shared memory between any server code.

Note that multiple processes are not compatible with the autoreload module (or the debug=True option to tornado.web.Application). When using multiple processes, no IOLoops can be created or referenced until after the call to TCPServer.start(n).

stop()[source]

Stops listening for new connections.

Requests currently in progress may still continue after the server is stopped.

handle_stream(stream, address)[source]

Override to handle a new IOStream from an incoming connection.

tornado.netutil.bind_sockets(port, address=None, family=0, backlog=128)[source]

Creates listening sockets bound to the given port and address.

Returns a list of socket objects (multiple sockets are returned if the given address maps to multiple IP addresses, which is most common for mixed IPv4 and IPv6 use).

Address may be either an IP address or hostname. If it’s a hostname, the server will listen on all IP addresses associated with the name. Address may be an empty string or None to listen on all available interfaces. Family may be set to either socket.AF_INET or socket.AF_INET6 to restrict to ipv4 or ipv6 addresses, otherwise both will be used if available.

The backlog argument has the same meaning as for socket.listen().

tornado.netutil.bind_unix_socket(file, mode=384, backlog=128)[source]

Creates a listening unix socket.

If a socket with the given name already exists, it will be deleted. If any other file with that name exists, an exception will be raised.

Returns a socket object (not a list of socket objects like bind_sockets)

tornado.netutil.add_accept_handler(sock, callback, io_loop=None)[source]

Adds an IOLoop event handler to accept new connections on sock.

When a connection is accepted, callback(connection, address) will be run (connection is a socket object, and address is the address of the other end of the connection). Note that this signature is different from the callback(fd, events) signature used for IOLoop handlers.

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