wepoll

Windows epoll wrapper based on wepoll

Installation

nimble install wepoll

API

Docs from https://github.com/piscisaureus/wepoll

General remarks

• The epoll port is a EpollHandle, not a file descriptor.
• All functions set both errno and GetLastError() on failure.
• For more extensive documentation, see the epoll(7) man page, and the per-function man pages that are linked below.

epoll_create/epoll_create1

proc epoll_create*(size: cint): EpollHandle
proc epoll_create1*(flags: cint): EpollHandle

• Create a new epoll instance (port).
• size is ignored but most be greater than zero.
• flags must be zero as there are no supported flags.
• Returns NULL on failure.
• Linux man page

epoll_close

proc epoll_close*(ephnd: EpollHandle): cint

• Close an epoll port.
• Do not attempt to close the epoll port with close(), CloseHandle() or closesocket().

epoll_ctl

proc epoll_ctl*(ephnd: EpollHandle, op: cint, 
                sock: EpollSocket, event: ptr EpollEvent): cint {.wepoll.}

• Control which socket events are monitored by an epoll port.
• ephnd must be a EpollHandle created by epoll_create() or epoll_create1().
• op must be one of EPOLL_CTL_ADD, EPOLL_CTL_MOD, EPOLL_CTL_DEL.
• sock must be a valid socket created by socket(), WSASocket(), or accept().
• event should be a pointer to a EpollEvent.
  If op is EPOLL_CTL_DEL then the event parameter is ignored, and it may be NULL.
• Returns 0 on success, -1 on failure.
• It is recommended to always explicitly remove a socket from its epoll set using EPOLL_CTL_DEL before closing it.
  As on Linux, closed sockets are automatically removed from the epoll set, but wepoll may not be able to detect that a socket was closed until the next call to epoll_wait().
• Linux man page

epoll_wait

proc epoll_wait*(ephnd: EpollHandle, events: ptr EpollEvent, 
                 maxevents: cint, timeout: cint): cint {.wepoll.}

• Receive socket events from an epoll port.
• events should point to a caller-allocated array of EpollEvent object, which will receive the reported events.
• maxevents is the maximum number of events that will be written to the events array, and must be greater than zero.
• timeout specifies whether to block when no events are immediately available.
  • <0 block indefinitely
  • 0 report any events that are already waiting, but don't block
  • ≥1 block for at most N milliseconds
• Return value:
  • -1 an error occurred
  • 0 timed out without any events to report
  • ≥1 the number of events stored in the events buffer
• Linux man page

object EpollEvent

type
  EpollHandle* = pointer

  EpollSocket* = culonglong

type
  EpollData* {.bycopy, union.} = object
    p*: pointer
    fd*: cint
    u32*: uint32
    u64*: uint64
    sock*: EpollSocket         ##  Windows specific
    hnd*: EpollHandle          ##  Windows specific

type
  EpollEvent* {.bycopy.} = object
    events*: uint32          ##  Epoll events and flags
    data*: EpollData         ##  User data variable

• The events field is a bit mask containing the events being monitored/reported, and optional flags.
  Flags are accepted by epoll_ctl(), but they are not reported back by epoll_wait().
• The data field can be used to associate application-specific information with a socket; its value will be returned unmodified by epoll_wait().
• Linux man page

Event	Description
EPOLLIN	incoming data available, or incoming connection ready to be accepted
EPOLLOUT	ready to send data, or outgoing connection successfully established
EPOLLRDHUP	remote peer initiated graceful socket shutdown
EPOLLPRI	out-of-band data available for reading
EPOLLERR	socket error1
EPOLLHUP	socket hang-up1
EPOLLRDNORM	same as EPOLLIN
EPOLLRDBAND	same as EPOLLPRI
EPOLLWRNORM	same as EPOLLOUT
EPOLLWRBAND	same as EPOLLOUT
EPOLLMSG	never reported

Flag	Description
EPOLLONESHOT	report event(s) only once
EPOLLET	not supported by wepoll
EPOLLEXCLUSIVE	not supported by wepoll
EPOLLWAKEUP	not supported by wepoll

¹: the EPOLLERR and EPOLLHUP events may always be reported by epoll_wait(), regardless of the event mask that was passed to epoll_ctl().