io_getcookie (3)

#include <io.h>

void* io_getcookie(int64 fd);

io_getcookie retrieves a cookie (pointer to some anonymous data structure you associated with this descriptor).

Use io_setcookie(3) to associate a cookie with a descriptor.

If you did not associate a cookie with this descriptor, io_getcookie returns NULL.

The idea is that you put the state associated with a TCP connection you serve in a common struct. Then you do not need to have your own data structure to retrieve the state for a connection, you can just use the data structure io_wait already maintains. The lookup works in constant time and should not cause any cache misses.

io_wait(3), io_setcookie(3)