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v/vlib/os/notify/backend_linux.c.v

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module notify
import time
import os
#include <sys/epoll.h>
struct C.epoll_event {
events u32
data C.epoll_data_t
}
[typedef]
union C.epoll_data_t {
ptr voidptr
fd int
u32 u32
u64 u64
}
fn C.epoll_create1(int) int
fn C.epoll_ctl(int, int, int, &C.epoll_event) int
fn C.epoll_wait(int, &C.epoll_event, int, int) int
// EpollNotifier provides methods that implement FdNotifier using the
// epoll I/O event notification facility (linux only)
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[noinit]
struct EpollNotifier {
epoll_fd int
}
// EpollEvent describes an event that occurred for a file descriptor in
// the watch list
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[noinit]
struct EpollEvent {
pub:
fd int
kind FdEventType
}
// new creates a new EpollNotifier
// The FdNotifier interface is returned to allow OS specific
// implementations without exposing the concrete type
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pub fn new() ?FdNotifier {
fd := C.epoll_create1(0) // 0 indicates default behavior
if fd == -1 {
return error(os.posix_get_error_msg(C.errno))
}
// Needed to circumvent V limitations
x := &EpollNotifier{
epoll_fd: fd
}
return x
}
const (
epoll_read = u32(C.EPOLLIN)
epoll_write = u32(C.EPOLLOUT)
epoll_peer_hangup = u32(C.EPOLLRDHUP)
epoll_exception = u32(C.EPOLLPRI)
epoll_error = u32(C.EPOLLERR)
epoll_hangup = u32(C.EPOLLHUP)
epoll_edge_trigger = u32(C.EPOLLET)
epoll_one_shot = u32(C.EPOLLONESHOT)
epoll_wake_up = u32(C.EPOLLWAKEUP)
epoll_exclusive = u32(C.EPOLLEXCLUSIVE)
)
// ctl is a helper method for add, modify, and remove
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fn (mut en EpollNotifier) ctl(fd int, op int, mask u32) ? {
event := C.epoll_event{
events: mask
data: C.epoll_data_t{
fd: fd
}
}
if C.epoll_ctl(en.epoll_fd, op, fd, &event) == -1 {
return error(os.posix_get_error_msg(C.errno))
}
}
// add adds a file descriptor to the watch list
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fn (mut en EpollNotifier) add(fd int, events FdEventType, conf ...FdConfigFlags) ? {
mask := flags_to_mask(events, ...conf)
en.ctl(fd, C.EPOLL_CTL_ADD, mask)?
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}
// modify sets an existing entry in the watch list to the provided events and configuration
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fn (mut en EpollNotifier) modify(fd int, events FdEventType, conf ...FdConfigFlags) ? {
mask := flags_to_mask(events, ...conf)
en.ctl(fd, C.EPOLL_CTL_MOD, mask)?
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}
// remove removes a file descriptor from the watch list
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fn (mut en EpollNotifier) remove(fd int) ? {
en.ctl(fd, C.EPOLL_CTL_DEL, 0)?
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}
// wait waits to be notified of events on the watch list,
// returns at most 512 events
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fn (mut en EpollNotifier) wait(timeout time.Duration) []FdEvent {
// arbitrary 512 limit; events will round robin on successive
// waits if the number exceeds this
// NOTE: we use a fixed size array here for stack allocation; this has
// the added bonus of making EpollNotifier thread safe
events := [512]C.epoll_event{}
// populate events with the new events
to := timeout.sys_milliseconds()
count := C.epoll_wait(en.epoll_fd, &events[0], events.len, to)
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if count > 0 {
mut arr := []FdEvent{cap: count}
for i := 0; i < count; i++ {
fd := unsafe { events[i].data.fd }
kind := event_mask_to_flag(events[i].events)
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if kind.is_empty() {
// NOTE: tcc only reports the first event for some
// reason, leaving subsequent structs in the array as 0
// (or possibly garbage)
panic('encountered an empty event kind; this is most likely due to using tcc')
}
arr << &EpollEvent{
fd: fd
kind: kind
}
}
return arr
}
return []
}
// close closes the EpollNotifier,
// any successive calls to add, modify, remove, and wait should fail
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fn (mut en EpollNotifier) close() ? {
if C.close(en.epoll_fd) == -1 {
return error(os.posix_get_error_msg(C.errno))
}
}
// event_mask_to_flag is a helper function that converts a bitmask
// returned by epoll_wait to FdEventType
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fn event_mask_to_flag(mask u32) FdEventType {
mut flags := FdEventType{}
if mask & notify.epoll_read != 0 {
flags.set(.read)
}
if mask & notify.epoll_write != 0 {
flags.set(.write)
}
if mask & notify.epoll_peer_hangup != 0 {
flags.set(.peer_hangup)
}
if mask & notify.epoll_exception != 0 {
flags.set(.exception)
}
if mask & notify.epoll_error != 0 {
flags.set(.error)
}
if mask & notify.epoll_hangup != 0 {
flags.set(.hangup)
}
return flags
}
// flags_to_mask is a helper function that converts FdEventType and
// FdConfigFlags to a bitmask used by the C functions
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fn flags_to_mask(events FdEventType, confs ...FdConfigFlags) u32 {
mut mask := u32(0)
if events.has(.read) {
mask |= notify.epoll_read
}
if events.has(.write) {
mask |= notify.epoll_write
}
if events.has(.peer_hangup) {
mask |= notify.epoll_peer_hangup
}
if events.has(.exception) {
mask |= notify.epoll_exception
}
if events.has(.error) {
mask |= notify.epoll_error
}
if events.has(.hangup) {
mask |= notify.epoll_hangup
}
for conf in confs {
if conf.has(.edge_trigger) {
mask |= notify.epoll_edge_trigger
}
if conf.has(.one_shot) {
mask |= notify.epoll_one_shot
}
if conf.has(.wake_up) {
mask |= notify.epoll_wake_up
}
if conf.has(.exclusive) {
mask |= notify.epoll_exclusive
}
}
return mask
}