如何在龙卷风的 BaseIOStream 类对象中设置 max_write_buffer_size？答案

【问题标题】：how to set max_write_buffer_size in BaseIOStream class object in tornado?如何在龙卷风的 BaseIOStream 类对象中设置 max_write_buffer_size？
【发布时间】：2017-01-24 09:15:10
【问题描述】：

在 tornado 网络服务器代码中，SSLIOStream 继承自 IOStream 并继承 BaseIOStream 类。 BaseIOStream 具有 max_write_buffer_size 从我们启动龙卷风服务器的位置。我没有找到要设置的环境变量的任何用法，它必须作为构造函数参数传递。

【问题讨论】：

标签： tornado

【解决方案1】：

从source code 有人可以观察到max_write_buffer_size 不是私有变量。因此，您可以从BaseIOStream 对象或从BaseIOStream 继承的SSLIOStream 和IOStream 类的任何对象访问它。

例如：

import socket
import tornado.ioloop
import tornado.iostream
import tornado.options

# def connect_baseiostream():
#    sock = socket.socket()
#    stream = tornado.iostream.BaseIOStream(sock)
#    stream.max_write_buffer_size = 10000 # Set max_write_buffer_size

def connect_iostream():
    sock = socket.socket()
    stream = tornado.iostream.IOStream(sock)
    stream.max_write_buffer_size = 10000 # Set max_write_buffer_size
    stream.connect(host, port) # Defined host and port

def main():
    tornado.options.parse_command_line()
    tornado.ioloop.IOLoop.instance().add_callback(connect_iostream)
    tornado.ioloop.IOLoop.instance().start()

if __name__ == "__main__":
    main()

【讨论】：

【解决方案2】：

这个参数没有暴露在 HTTP 服务器中，因为它的使用是有限的，并且可能默认值是正确的（无限制）。当然，您可以为此创建一个问题并在github 上讨论它。另一种解决方案是使用自己的TCPServer's handle_connection 实现子类tornado.httpserver.HTTPServer（请记住它是私有的_ 方法）。

from tornado.httpserver import HTTPServer

max_write_buffer_size = 65535

class CustomHTTPServer(HTTPServer):

    def _handle_connection(self, connection, address):
    # https://github.com/tornadoweb/tornado/blob/master/tornado/tcpserver.py#L257
           if self.ssl_options is not None:
               assert ssl, "Python 2.6+ and OpenSSL required for SSL"
               try:
                   connection = ssl_wrap_socket(connection,
                                                self.ssl_options,
                                                server_side=True,
                                                do_handshake_on_connect=False)
               except ssl.SSLError as err:
                   if err.args[0] == ssl.SSL_ERROR_EOF:
                       return connection.close()
                   else:
                       raise
               except socket.error as err:
                   if errno_from_exception(err) in (errno.ECONNABORTED, errno.EINVAL):
                       return connection.close()
                   else:
                       raise
           try:
               if self.ssl_options is not None:
                   stream = SSLIOStream(connection, io_loop=self.io_loop,
                                        max_buffer_size=self.max_buffer_size,
                                        read_chunk_size=self.read_chunk_size,
                                        max_write_buffer_size=max_write_buffer_size)
               else:
                   stream = IOStream(connection, io_loop=self.io_loop,
                                     max_buffer_size=self.max_buffer_size,
                                     read_chunk_size=self.read_chunk_size,
                                     max_write_buffer_size=max_write_buffer_size)

               future = self.handle_stream(stream, address)
               if future is not None:
                   self.io_loop.add_future(gen.convert_yielded(future),
                                           lambda f: f.result())
           except Exception:
               app_log.error("Error in connection callback", exc_info=True)

并使用自定义服务器：

    application = web.Application([
        (r"/", MainPageHandler),
    ])
    http_server = CustomHTTPServer(application)
    http_server.listen(8080)
    ioloop.IOLoop.current().start()

【讨论】：