Feature #17059
Updated by dsh0416 (Delton Ding) over 4 years ago
Current Ruby's `IO.select` method calls POSIX `select` API directly. With the new non-blocking scheduler, this may be the bottleneck of the I/O scheduling. For keeping the backward compatibilty of the current `IO.select` methods, a proposal may be to create a "duck" `select` which uses the `epoll_wait` as the backend.
One tricky part is that the `fd_set` described in POSIX is write-only, which means it is impossible to iterate for generating the `epoll_event` argument for `epoll_wait`. But similar to the large-size select situation, we could define our own `rb_fdset_t` struct in this case, and implement the following APIs.
```
void rb_fd_init(rb_fdset_t *);
void rb_fd_term(rb_fdset_t *);
void rb_fd_zero(rb_fdset_t *);
void rb_fd_set(int, rb_fdset_t *);
void rb_fd_clr(int, rb_fdset_t *);
int rb_fd_isset(int, const rb_fdset_t *);
void rb_fd_copy(rb_fdset_t *, const fd_set *, int);
void rb_fd_dup(rb_fdset_t *dst, const rb_fdset_t *src);
int rb_fd_select(int, rb_fdset_t *, rb_fdset_t *, rb_fdset_t *, struct timeval *);
```
TODO:
1. Implement the fd_set with dynamic allocated fds.
2. Implement the epoll with select API.
3. Edit io.c to use the customized fd_set struct.
I'm trying to work on a branch for this. Any suggestions for this?