Messages in this thread |  | | Date | Wed, 19 Sep 2001 19:28:04 -0700 (PDT) | From | Davide Libenzi <> | Subject | Re: [PATCH] /dev/epoll update ... |
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On 20-Sep-2001 Dan Kegel wrote: > Davide Libenzi wrote: >> 1) if (recv()/send() == FAIL) >> 2) ioctl(EP_POLL); > > A lot of people, including me, were under the mistaken impression > that /dev/epoll, like /dev/poll, provided an efficient way to > retrieve the current readiness state of fd's. I understand from your post > that /dev/epoll's purpose is to retrieve state changes; in other > words, it's exactly like F_SETSIG/F_SETOWN/O_ASYNC except that > the readiness change indications are picked up via an ioctl > rather than via a signal. > > A scorecard for the confused (Davide, correct me if I'm wrong): > > * API's that allow you to retrieve the current readiness state of > a set of fd's: poll(), select(), /dev/poll, kqueue(). > Buzzwords describing this kind of interface: level-triggered, multishot. > > * API's that allow you to retrieve *changes* to the readiness state of > a set of fd's: F_SETSIG/F_SETOWN/O_ASYNC + sigtimedwait(), /dev/epoll, kqueue(). > Buzzwords describing this kind of interface: edge-triggered, single-shot. > > (Note that kqueue is in both camps.) > > Er, I guess that means I'll rip up the /dev/epoll support I based on my > /dev/poll code, and replace it with some based on my O_ASYNC code...
Exactly :) Here are examples basic functions when used with coroutines :
int dph_connect(struct dph_conn *conn, const struct sockaddr *serv_addr, socklen_t addrlen) {
if (connect(conn->sfd, serv_addr, addrlen) == -1) { if (errno != EWOULDBLOCK && errno != EINPROGRESS) return -1; conn->events = POLLOUT | POLLERR | POLLHUP; co_resume(conn); if (conn->revents & (POLLERR | POLLHUP)) return -1; } return 0; }
int dph_read(struct dph_conn *conn, char *buf, int nbyte) { int n;
while ((n = read(conn->sfd, buf, nbyte)) < 0) { if (errno == EINTR) continue; if (errno != EAGAIN && errno != EWOULDBLOCK) return -1; conn->events = POLLIN | POLLERR | POLLHUP; co_resume(conn); } return n; }
int dph_write(struct dph_conn *conn, char const *buf, int nbyte) { int n;
while ((n = write(conn->sfd, buf, nbyte)) < 0) { if (errno == EINTR) continue; if (errno != EAGAIN && errno != EWOULDBLOCK) return -1; conn->events = POLLOUT | POLLERR | POLLHUP; co_resume(conn); } return n; }
int dph_accept(struct dph_conn *conn, struct sockaddr *addr, int *addrlen) { int sfd;
while ((sfd = accept(conn->sfd, addr, (socklen_t *) addrlen)) < 0) { if (errno == EINTR) continue; if (errno != EAGAIN && errno != EWOULDBLOCK) return -1; conn->events = POLLIN | POLLERR | POLLHUP; co_resume(conn); } return sfd; }
- Davide
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