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/*
* Copyright (c) 2023 Egor Tensin <egor@tensin.name>
* This file is part of the "cimple" project.
* For details, see https://github.com/egor-tensin/cimple.
* Distributed under the MIT License.
*/
#include "event_loop.h"
#include "log.h"
#include "string.h"
#include <poll.h>
#include <stddef.h>
#include <stdlib.h>
#include <sys/queue.h>
SIMPLEQ_HEAD(event_fd_queue, event_fd);
struct event_fd {
int fd;
short events;
event_handler handler;
void *arg;
int once;
SIMPLEQ_ENTRY(event_fd) entries;
};
static struct event_fd *event_fd_create(int fd, short events, event_handler handler, void *arg)
{
struct event_fd *res = calloc(1, sizeof(struct event_fd));
if (!res) {
log_errno("calloc");
return NULL;
}
res->fd = fd;
res->events = events;
res->handler = handler;
res->arg = arg;
res->once = 0;
return res;
}
static void event_fd_destroy(struct event_fd *entry)
{
free(entry);
}
static void event_fd_queue_create(struct event_fd_queue *queue)
{
SIMPLEQ_INIT(queue);
}
static void event_fd_queue_destroy(struct event_fd_queue *queue)
{
struct event_fd *entry1 = SIMPLEQ_FIRST(queue);
while (entry1) {
struct event_fd *entry2 = SIMPLEQ_NEXT(entry1, entries);
event_fd_destroy(entry1);
entry1 = entry2;
}
SIMPLEQ_INIT(queue);
}
struct event_loop {
nfds_t nfds;
struct event_fd_queue entries;
};
int event_loop_create(struct event_loop **_loop)
{
int ret = 0;
struct event_loop *loop = calloc(1, sizeof(struct event_loop));
if (!loop) {
log_errno("calloc");
return -1;
}
*_loop = loop;
event_fd_queue_create(&loop->entries);
return ret;
}
void event_loop_destroy(struct event_loop *loop)
{
event_fd_queue_destroy(&loop->entries);
free(loop);
}
static void event_loop_add_internal(struct event_loop *loop, struct event_fd *entry)
{
log_debug("Adding descriptor %d to event loop\n", entry->fd);
nfds_t nfds = loop->nfds + 1;
SIMPLEQ_INSERT_TAIL(&loop->entries, entry, entries);
loop->nfds = nfds;
}
int event_loop_add(struct event_loop *loop, int fd, short events, event_handler handler, void *arg)
{
struct event_fd *entry = event_fd_create(fd, events, handler, arg);
if (!entry)
return -1;
event_loop_add_internal(loop, entry);
return 0;
}
int event_loop_add_once(struct event_loop *loop, int fd, short events, event_handler handler,
void *arg)
{
struct event_fd *entry = event_fd_create(fd, events, handler, arg);
if (!entry)
return -1;
entry->once = 1;
event_loop_add_internal(loop, entry);
return 0;
}
static void event_loop_remove(struct event_loop *loop, struct event_fd *entry)
{
log_debug("Removing descriptor %d from event loop\n", entry->fd);
SIMPLEQ_REMOVE(&loop->entries, entry, event_fd, entries);
event_fd_destroy(entry);
--loop->nfds;
}
static char *append_event(char *buf, size_t sz, char *ptr, const char *event)
{
if (ptr > buf)
ptr = string_append(ptr, buf + sz, ",");
return string_append(ptr, buf + sz, event);
}
static char *events_to_string(short events)
{
const size_t sz = 128;
char *buf = calloc(1, sz);
if (!buf)
return NULL;
char *ptr = buf;
if (events & POLLNVAL)
ptr = append_event(buf, sz, ptr, "POLLNVAL");
if (events & POLLERR)
ptr = append_event(buf, sz, ptr, "POLLERR");
if (events & POLLHUP)
ptr = append_event(buf, sz, ptr, "POLLHUP");
if (events & POLLRDHUP)
ptr = append_event(buf, sz, ptr, "POLLRDHUP");
if (events & POLLPRI)
ptr = append_event(buf, sz, ptr, "POLLPRI");
if (events & POLLIN)
ptr = append_event(buf, sz, ptr, "POLLIN");
if (events & POLLOUT)
ptr = append_event(buf, sz, ptr, "POLLOUT");
return buf;
}
static struct pollfd *make_pollfds(const struct event_loop *loop)
{
struct pollfd *fds = calloc(loop->nfds, sizeof(struct pollfd));
if (!fds) {
log_errno("calloc");
return NULL;
}
struct event_fd *entry = SIMPLEQ_FIRST(&loop->entries);
for (nfds_t i = 0; i < loop->nfds; ++i, entry = SIMPLEQ_NEXT(entry, entries)) {
fds[i].fd = entry->fd;
fds[i].events = entry->events;
}
log_debug("Descriptors:\n");
for (nfds_t i = 0; i < loop->nfds; ++i) {
char *events = events_to_string(fds[i].events);
log_debug(" %d (%s)\n", fds[i].fd, events ? events : "");
free(events);
}
return fds;
}
int event_loop_run(struct event_loop *loop)
{
/* Cache the number of event descriptors so that event handlers can
* append new ones. */
const nfds_t nfds = loop->nfds;
struct pollfd *fds = make_pollfds(loop);
if (!fds)
return -1;
int ret = poll(fds, nfds, -1);
if (ret < 0) {
log_errno("poll");
return ret;
}
ret = 0;
struct event_fd *entry = SIMPLEQ_FIRST(&loop->entries);
for (nfds_t i = 0; i < nfds; ++i) {
struct event_fd *next = SIMPLEQ_NEXT(entry, entries);
if (!fds[i].revents)
goto next;
char *events = events_to_string(fds[i].revents);
log_debug("Descriptor %d is ready: %s\n", fds[i].fd, events ? events : "");
free(events);
/* Execute all handlers but notice if any of them fail. */
const int handler_ret = entry->handler(loop, fds[i].fd, fds[i].revents, entry->arg);
if (handler_ret < 0)
ret = handler_ret;
if (entry->once)
event_loop_remove(loop, entry);
next:
entry = next;
continue;
}
free(fds);
return ret;
}
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