php - 非阻塞套接字 : Are messages queued?

Question

据我所知，可以创建一个 nonblocking网络socket在 PHP 5.x 中。

但是，如果脚本使用如下相同的非阻塞套接字发送多条长消息，会发生什么情况:

socket_write($socket, $string1, $length);
socket_write($socket, $string2, $length);
socket_write($socket, $string3, $length);
socket_write($socket, $string4, $length);

这些消息是否排队(在发送方/接收方一侧？)或者接收方是否可能因为“并行”发送而获得不同消息的部分？

例如:接收方是否有可能获得 10 个字节的 $string1，然后是 30 个字节的 $string2，然后是另外 25 个字节的 $string1 ... 依此类推...

Answer 1

这取决于套接字使用的协议(protocol)。参见 socket_create对于可能的套接字类型。主要类型有UDP和TCP:

udp The User Datagram Protocol is a connectionless, unreliable, protocol with fixed record lengths. Due to these aspects, UDP requires a minimum amount of protocol overhead.

tcp The Transmission Control Protocol is a reliable, connection based, stream oriented, full duplex protocol. TCP guarantees that all data packets will be received in the order in which they were sent. If any packet is somehow lost during communication, TCP will automatically retransmit the packet until the destination host acknowledges that packet. For reliability and performance reasons, the TCP implementation itself decides the appropriate octet boundaries of the underlying datagram communication layer. Therefore, TCP applications must allow for the possibility of partial record transmission.

直接回答您的问题，TCP 套接字将保证按顺序传递，而 UDP 套接字则不会。