epoll

The epoll API

epoll System Calls

Three system calls:

epoll_create()
epoll_ctl()
epoll_wait()

epollfd = epoll_create(int size)

Create an epoll file descriptor.

size is an estimate of the number of file descriptors to be placed in interest list.

epoll_ctl(int epollfd, int op, int fd,
struct epoll_event ev)

Manipulate the interest list of epollfd.

op selects one of the following:

add fd to the interest list (EPOLL_CTL_ADD);

modify interest list associated with fd (EPOLL_CTL_MOD);

remove fd from the interest list (EPOLL_CTL_DEL).

ev specifies "event mask" and "data" to be associated with fd.
struct epoll_event {
    uint32_t     events;    /* Epoll events (bit mask) */
    epoll_data_t data;      /* User data (union) */
};


typedef union epoll_data {
    void        *ptr;       /* Pointer to user-defined data */
    int          fd;        /* File descriptor */
    uint32_t     u32;       /* 32-bit integer */
    uint64_t     u64;       /* 64-bit integer */
} epoll_data_t;

nready = epoll_wait(int epollfd,
struct epoll_event *evlist, int maxevents,
int millisec_timeout)

Fetch up to maxevents items from the ready list associated with epollfd and place them into evlist.