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irc-bot/epoll_wrapper.c

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/** OCaml poll() interface
*
* Time-stamp: <2008-03-11 17:44:00 neale>
*
* Copyright (C) 2008 Neale Pickett
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or (at
* your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <caml/mlvalues.h>
#include <caml/fail.h>
#include <caml/custom.h>
#include <caml/memory.h>
#include <caml/alloc.h>
#ifdef __linux
# include <sys/epoll.h>
# define EPOLL
#else
# include <poll.h>
# undef EPOLL
# define EPOLLIN POLLIN
# define EPOLLPRI POLLPRI
# define EPOLLOUT POLLOUT
# define EPOLLERR POLLERR
# define EPOLLHUP POLLHUP
#endif
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#define puke() \
{ \
char errstr[512]; \
snprintf(errstr, sizeof(errstr), "%s: %s", __FUNCTION__, strerror(errno)); \
caml_failwith(errstr); \
}
enum {
caml_POLLIN,
caml_POLLPRI,
caml_POLLOUT,
caml_POLLERR,
caml_POLLHUP
};
enum {
caml_POLL_ADD,
caml_POLL_MOD,
caml_POLL_DEL
};
static int
list_length(value list)
{
CAMLparam1(list);
CAMLlocal1(l);
int len = 0;
for (l = list; l != Val_int(0); l = Field(l, 1)) {
len += 1;
}
CAMLreturn(len);
}
static int
int_of_event_list(value list)
{
CAMLparam1(list);
CAMLlocal1(l);
int acc = 0;
for (l = list; l != Val_int(0); l = Field(l, 1)) {
switch (Int_val(Field(l, 0))) {
case caml_POLLIN:
acc |= EPOLLIN;
break;
case caml_POLLPRI:
acc |= EPOLLPRI;
break;
case caml_POLLOUT:
acc |= EPOLLOUT;
break;
case caml_POLLERR:
acc |= EPOLLERR;
break;
case caml_POLLHUP:
acc |= EPOLLHUP;
break;
}
}
CAMLreturn(acc);
}
static value
cons(value item, value list)
{
CAMLparam2(item, list);
CAMLlocal1(new);
new = alloc_small(2, 0);
Field(new, 0) = item;
Field(new, 1) = list;
CAMLreturn(new);
}
static value
event_list_of_int(int events)
{
CAMLparam0();
CAMLlocal1(result);
result = Val_int(0);
/* Do these in reverse order since we're prepending to the list */
if (events & EPOLLHUP) {
result = cons(Val_int(caml_POLLHUP), result);
}
if (events & EPOLLERR) {
result = cons(Val_int(caml_POLLERR), result);
}
if (events & EPOLLOUT) {
result = cons(Val_int(caml_POLLOUT), result);
}
if (events & EPOLLPRI) {
result = cons(Val_int(caml_POLLPRI), result);
}
if (events & EPOLLIN) {
result = cons(Val_int(caml_POLLIN), result);
}
CAMLreturn(result);
}
#ifdef EPOLL
/********************************************************************************
*
* epoll()
*
********************************************************************************/
CAMLprim value
ocaml_epoll_create(value size)
{
CAMLparam1(size);
CAMLlocal1(result);
int ret;
ret = epoll_create(Int_val(size));
if (-1 == ret) {
puke();
}
result = Val_int(ret);
CAMLreturn(result);
}
CAMLprim value
ocaml_epoll_destroy(value t)
{
CAMLparam1(t);
int ret;
ret = close(Int_val(t));
if (-1 == ret) {
puke();
}
CAMLreturn(Val_unit);
}
/* There are three reasons why I can't store a continuation or any other
* complex type in evt.data:
*
* 1. GC might blow them away
* 2. Heap compaction might move them
* 3. The kernel can remove events from its internal table without
* telling us (this is why there's no EPOLLNVAL)
*
* 1 and 2 can be solved by calling caml_register_global_root for each
* continuation, but this does not solve 3. So you get file
* descriptors. You can make a nice record type and wrap a Set around
* it. */
CAMLprim value
ocaml_epoll_ctl(value t, value op, value what)
{
CAMLparam3(t, op, what);
int op_;
int fd;
struct epoll_event evt;
int ret;
switch (Int_val(op)) {
case caml_POLL_ADD:
op_ = EPOLL_CTL_ADD;
break;
case caml_POLL_MOD:
op_ = EPOLL_CTL_MOD;
break;
case caml_POLL_DEL:
op_ = EPOLL_CTL_DEL;
break;
}
fd = Int_val(Field(what, 0));
evt.events = int_of_event_list(Field(what, 1));
evt.data.fd = fd;
ret = epoll_ctl(Int_val(t), op_, fd, &evt);
if (-1 == ret) {
puke();
}
CAMLreturn(Val_unit);
}
CAMLprim value
ocaml_epoll_wait(value t, value maxevents, value timeout)
{
CAMLparam2(t, timeout);
CAMLlocal2(result, item);
int maxevents_ = Int_val(maxevents);
struct epoll_event events[maxevents_];
int i;
int ret;
caml_enter_blocking_section();
ret = epoll_wait(Int_val(t), events, maxevents_, Int_val(timeout));
caml_leave_blocking_section();
if (-1 == ret) {
puke();
}
result = Val_int(0);
for (i = 0; i < ret; i += 1) {
item = alloc_small(2,0);
Field(item, 0) = Val_int(events[i].data.fd);
Field(item, 1) = event_list_of_int(events[i].events);
result = cons(item, result);
}
CAMLreturn(result);
}
#else
/********************************************************************************
*
* poll() compatibility
*
********************************************************************************/
#warn "The poll() compatibility routines have not been tested, nay compiled."
/* I just coded up how it more or less ought to go. I haven't debugged
* it at all. I haven't even tried to compile it. */
struct t {
int nfds;
int size;
struct pollfd *fds;
}
CAMLprim value
ocaml_epoll_create(value size)
{
CAMLparam1(size);
CAMLlocal1(result);
struct t *t_;
t_ = (struct t *)malloc(sizeof(struct t));
t_->nfds = 0;
t_->size = size;
t_->fds = (struct pollfd *)calloc(size, sizeof(struct pollfd));
result = caml_alloc(1, Abstract_tag);
Field(result, 0) = (value)t_;
CAMLreturn(result);
}
CAMLprim value
ocaml_epoll_destroy(value t)
{
CAMLparam1(t);
struct t *t_ = Field(t, 0);
free(t_->fds);
free(t_);
CAMLreturn(Val_unit);
}
CAMLprim value
ocaml_epoll_ctl(value t, value op, value what)
{
CAMLparam3(t, op, what);
struct t *t_ = Field(t, 0);
int op_ = Int_val(op);
struct pollfd pfd;
int i;
pfd.fd = Int_val(Field(what, 0));
pfd.events = int_of_event_list(Field(what, 1));
/* Find this fd in our list */
for (i == 0; i < t_->nfds; i += 1) {
struct pollfd *p = &(t_->fds[i]);
if (p->fd == pfd.fd) {
break;
}
}
switch (op_) {
case caml_POLL_ADD:
if (i < t_->nfds) {
caml_failwith("file descriptor already present");
}
if (i >= t->size) {
struct pollfd *newfds;
int newsize;
newsize = t_->size + 20;
new = (struct pollfd *)realloc(t_, (sizeof struct pollfd) * newsize);
if (! new) {
caml_failwith("out of memory");
}
t_->size = newsize;
t_->fds = newfds;
}
t_->nfds += 1;
t_->fds[i] = pfd;
break;
case caml_POLL_MOD:
t_->fds[i] = pdf;
break;
case caml_POLL_DEL:
if (i == t_->nfds) {
caml_failwith("file descriptor not present");
}
t_->nfds -= 1;
for(; i < t_->nfds; i += 1) {
t_->fds[i] = t_->fds[i+1];
}
break;
}
}
CAMLprim value
ocaml_epoll_wait(value t, value maxevents, value timeout)
{
CAMLparam3(t, maxevents, caml_timeout);
CAMLlocal2(result, l, v);
struct t *t_ = Field(t, 0);
int maxevents_ = Int_val(maxevents);
int i;
int j;
int ret;
/* Call poll */
caml_enter_blocking_section();
ret = poll(t_->fds, t_->nfds, Int_val(timeout));
caml_leave_blocking_section();
if (-1 == ret) {
puke();
}
result = Val_int(0);
j = 0;
for (i=0; ((i < t_->nfds) && (i < maxevents_)); i += 1) {
struct pollfd *p = &(t_->fds[i]);
if (p->revents & POLLNVAL) {
/* Don't let j increment: remove this item */
continue;
} else if (p->revents) {
v = alloc_small(2, 0);
Field(v, 0) = Val_int(p->fd);
Field(v, 1) = event_list_of_int(p->revents);
result = cons(v, result);
}
if (i != j) {
t_->fds[i] = t_->fds[j];
}
j += i;
}
t_->nfds = j;
CAMLreturn(result);
}
#endif
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