third_party_alsa-utils/axfer/waiter-epoll.c
Takashi Sakamoto 3f652d3caa axfer: add an implementation of waiter for epoll(7)
This commit adds support of waiter for Linux specific epoll(7) system call.
For portability to the other Unix-like systems such as xBSD, modification
of Makefile.am may be required for conditional build, but this commit
includes no changes for it.

Below lines are examples to use this option:
$ axfer transfer --waiter-type=epoll -M -P -d 2 -D hw:0,3 /dev/urandom -f dat -vvv
$ axfer transfer --waiter-type=epoll -M -C -d 2 -D hw:1,0 /dev/null -r 48000 -vvv

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2018-11-13 12:04:51 +01:00

108 lines
2.3 KiB
C

// SPDX-License-Identifier: GPL-2.0
//
// waiter-epoll.c - Waiter for event notification by epoll(7).
//
// Copyright (c) 2018 Takashi Sakamoto <o-takashi@sakamocchi.jp>
//
// Licensed under the terms of the GNU General Public License, version 2.
#include "waiter.h"
#include "misc.h"
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/epoll.h>
struct epoll_state {
int epfd;
struct epoll_event *events;
unsigned int ev_count;
};
static int epoll_prepare(struct waiter_context *waiter)
{
struct epoll_state *state = waiter->private_data;
int i;
state->ev_count = waiter->pfd_count;
state->events = calloc(state->ev_count, sizeof(*state->events));
if (state->events == NULL)
return -ENOMEM;
state->epfd = epoll_create(1);
if (state->epfd < 0)
return -errno;
for (i = 0; i < waiter->pfd_count; ++i) {
struct epoll_event ev = {
.data.fd = waiter->pfds[i].fd,
.events = waiter->pfds[i].events,
};
if (epoll_ctl(state->epfd, EPOLL_CTL_ADD, ev.data.fd, &ev) < 0)
return -errno;
}
return 0;
}
static int epoll_wait_event(struct waiter_context *waiter, int timeout_msec)
{
struct epoll_state *state = waiter->private_data;
unsigned int ev_count;
int i, j;
int err;
memset(state->events, 0, state->ev_count * sizeof(*state->events));
err = epoll_wait(state->epfd, state->events, state->ev_count,
timeout_msec);
if (err < 0)
return -errno;
ev_count = (unsigned int)err;
if (ev_count > 0) {
// Reconstruct data of pollfd structure.
for (i = 0; i < ev_count; ++i) {
struct epoll_event *ev = &state->events[i];
for (j = 0; j < waiter->pfd_count; ++j) {
if (waiter->pfds[i].fd == ev->data.fd) {
waiter->pfds[i].revents = ev->events;
break;
}
}
}
}
return ev_count;
}
static void epoll_release(struct waiter_context *waiter)
{
struct epoll_state *state = waiter->private_data;
int i;
for (i = 0; i < waiter->pfd_count; ++i) {
int fd = waiter->pfds[i].fd;
epoll_ctl(state->epfd, EPOLL_CTL_DEL, fd, NULL);
}
free(state->events);
state->events = NULL;
close(state->epfd);
state->ev_count = 0;
state->epfd = 0;
}
const struct waiter_data waiter_epoll = {
.ops = {
.prepare = epoll_prepare,
.wait_event = epoll_wait_event,
.release = epoll_release,
},
.private_size = sizeof(struct epoll_state),
};