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event_select.c
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event_select.c
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/*
event_select.c -- select(2) support
Copyright (C) 2012-2022 Guus Sliepen <[email protected]>
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 2 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, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "system.h"
#include "event.h"
#include "utils.h"
static bool running = false;
static fd_set readfds;
static fd_set writefds;
void io_add(io_t *io, io_cb_t cb, void *data, int fd, int flags) {
if(io->cb) {
return;
}
io->fd = fd;
io->cb = cb;
io->data = data;
io->node.data = io;
io_set(io, flags);
if(!splay_insert_node(&io_tree, &io->node)) {
abort();
}
}
void io_set(io_t *io, int flags) {
if(flags == io->flags) {
return;
}
io->flags = flags;
if(io->fd == -1) {
return;
}
if(flags & IO_READ) {
FD_SET(io->fd, &readfds);
} else {
FD_CLR(io->fd, &readfds);
}
if(flags & IO_WRITE) {
FD_SET(io->fd, &writefds);
} else {
FD_CLR(io->fd, &writefds);
}
}
void io_del(io_t *io) {
if(io->cb) {
io_set(io, 0);
splay_unlink_node(&io_tree, &io->node);
io->cb = NULL;
}
}
bool event_loop(void) {
running = true;
fd_set readable;
fd_set writable;
while(running) {
struct timeval diff;
struct timeval *tv = timeout_execute(&diff);
memcpy(&readable, &readfds, sizeof(readable));
memcpy(&writable, &writefds, sizeof(writable));
int maxfds = 0;
if(io_tree.tail) {
io_t *last = io_tree.tail->data;
maxfds = last->fd + 1;
}
int n = select(maxfds, &readable, &writable, NULL, tv);
if(n < 0) {
if(sockwouldblock(sockerrno)) {
continue;
} else {
return false;
}
}
if(!n) {
continue;
}
unsigned int curgen = io_tree.generation;
for splay_each(io_t, io, &io_tree) {
if(FD_ISSET(io->fd, &writable)) {
io->cb(io->data, IO_WRITE);
} else if(FD_ISSET(io->fd, &readable)) {
io->cb(io->data, IO_READ);
} else {
continue;
}
/*
There are scenarios in which the callback will remove another io_t from the tree
(e.g. closing a double connection). Since splay_each does not support that, we
need to exit the loop if that happens. That's okay, since any remaining events will
get picked up by the next select() call.
*/
if(curgen != io_tree.generation) {
break;
}
}
}
return true;
}
void event_exit(void) {
running = false;
}