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Ruby TCPSocket：找出有多少数据可用

发布于 2024-09-28 13:11:55 字数 62 浏览 5 评论 0原文

有没有办法找出 Ruby 中的 TCPSocket 上有多少字节的数据可用？即有多少字节可以准备好而不会阻塞？

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Smile简单爱 2024-10-05 13:11:55

标准库 io/wait 在这里可能有用。要求它为基于流的 I/O（套接字和管道）提供了一些新方法，其中准备好了吗？。根据文档，准备好了吗？如果有可用字节而不阻塞，则返回非零。碰巧它返回的非零值是 MRI 中可用的字节数。

这是一个创建一个愚蠢的小套接字服务器，然后使用客户端连接到它的示例。服务器只发送“foo”，然后关闭连接。客户端稍等一下，给服务器时间发送，然后打印有多少字节可供读取。对您来说有趣的事情是在客户端：

require 'socket'
require 'io/wait'

# Server

server_socket = TCPServer.new('localhost', 0)
port = server_socket.addr[1]
Thread.new do
  session = server_socket.accept
  sleep 0.5
  session.puts "foo"
  session.close
end

# Client

client_socket = TCPSocket.new('localhost', port)
puts client_socket.ready?    # => nil
sleep 1
puts client_socket.ready?    # => 4

不要在任何实际的事情中使用该服务器代码。为了使示例简单，它故意很短。

注意：根据 Pickaxe 书，io/wait 仅在“ioctl(2) 中的 FIONREAD 功能”（在 Linux 中）时可用。我不了解 Windows 和 Windows其他的。

The standard library io/wait might be useful here. Requiring it gives stream-based I/O (sockets and pipes) some new methods, among which is ready?. According to the documentation, ready? returns non-nil if there are bytes available without blocking. It just so happens that the non-nil value it returns it the number of bytes that are available in MRI.

Here's an example which creates a dumb little socket server, and then connects to it with a client. The server just sends "foo" and then closes the connection. The client waits a little bit to give the server time to send, and then prints how many bytes are available for reading. The interesting stuff for you is in the client:

require 'socket'
require 'io/wait'

# Server

server_socket = TCPServer.new('localhost', 0)
port = server_socket.addr[1]
Thread.new do
  session = server_socket.accept
  sleep 0.5
  session.puts "foo"
  session.close
end

# Client

client_socket = TCPSocket.new('localhost', port)
puts client_socket.ready?    # => nil
sleep 1
puts client_socket.ready?    # => 4

Don't use that server code in anything real. It's deliberately short in order to keep the example simple.

Note: According to the Pickaxe book, io/wait is only available if "FIONREAD feature in ioctl(2)", which it is in Linux. I don't know about Windows & others.

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