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/*
* Copyright (C) 2015-2020 "IoT.bzh"
* Author José Bollo <jose.bollo@iot.bzh>
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define _GNU_SOURCE
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include <signal.h>
#include <string.h>
#include <time.h>
#include <sys/syscall.h>
#include <pthread.h>
#include <errno.h>
#include <assert.h>
#include <sys/eventfd.h>
#include <systemd/sd-event.h>
#include "evmgr.h"
#include "verbose.h"
#include "systemd.h"
/** Description of handled event loops */
struct evmgr
{
unsigned state; /**< encoded state */
int efd; /**< event notification */
void *holder; /**< holder of the evmgr */
struct sd_event *sdev; /**< the systemd event loop */
};
#define EVLOOP_STATE_WAIT 1U
#define EVLOOP_STATE_RUN 2U
/**
* prepare the evmgr to run
*/
void evmgr_prepare_run(struct evmgr *evmgr)
{
evmgr->state = EVLOOP_STATE_WAIT|EVLOOP_STATE_RUN;
}
/**
* Run the event loop is set.
*/
void evmgr_run(struct evmgr *evmgr)
{
int rc;
struct sd_event *se;
evmgr->state = EVLOOP_STATE_WAIT|EVLOOP_STATE_RUN;
se = evmgr->sdev;
rc = sd_event_prepare(se);
if (rc < 0) {
errno = -rc;
CRITICAL("sd_event_prepare returned an error (state: %d): %m", sd_event_get_state(se));
abort();
} else {
if (rc == 0) {
rc = sd_event_wait(se, (uint64_t)(int64_t)-1);
if (rc < 0) {
errno = -rc;
ERROR("sd_event_wait returned an error (state: %d): %m", sd_event_get_state(se));
}
}
evmgr->state = EVLOOP_STATE_RUN;
if (rc > 0) {
rc = sd_event_dispatch(se);
if (rc < 0) {
errno = -rc;
ERROR("sd_event_dispatch returned an error (state: %d): %m", sd_event_get_state(se));
}
}
}
evmgr->state = 0;
}
void evmgr_job_run(int signum, struct evmgr *evmgr)
{
if (signum)
evmgr->state = 0;
else
evmgr_run(evmgr);
}
int evmgr_can_run(struct evmgr *evmgr)
{
return !evmgr->state;
}
/**
* Internal callback for evmgr management.
* The effect of this function is hidden: it exits
* the waiting poll if any.
*/
static void evmgr_on_efd_event(struct evmgr *evmgr)
{
uint64_t x;
read(evmgr->efd, &x, sizeof x);
}
/**
* wakeup the event loop if needed by sending
* an event.
*/
void evmgr_wakeup(struct evmgr *evmgr)
{
uint64_t x;
if (evmgr->state & EVLOOP_STATE_WAIT) {
x = 1;
write(evmgr->efd, &x, sizeof x);
}
}
/**
*/
void *evmgr_holder(struct evmgr *evmgr)
{
return evmgr->holder;
}
/**
*/
int evmgr_release_if(struct evmgr *evmgr, void *holder)
{
if (evmgr->holder != holder)
return 0;
evmgr->holder = 0;
return 1;
}
/**
*/
int evmgr_try_hold(struct evmgr *evmgr, void *holder)
{
if (!evmgr->holder)
evmgr->holder = holder;
return evmgr->holder == holder;
}
/******************************************************************************/
/******************************************************************************/
/****** SYSTEM D ******/
/******************************************************************************/
/******************************************************************************/
/**
* Internal callback for evmgr management.
* The effect of this function is hidden: it exits
* the waiting poll if any. Then it wakes up a thread
* awaiting the evmgr using signal.
*/
static int on_evmgr_efd(sd_event_source *s, int fd, uint32_t revents, void *userdata)
{
struct evmgr *evmgr = userdata;
evmgr_on_efd_event(evmgr);
return 1;
}
/**
* Gets a sd_event item for the current thread.
* @return a sd_event or NULL in case of error
*/
int evmgr_create(struct evmgr **result)
{
int rc;
struct evmgr *evmgr;
/* creates the evmgr on need */
evmgr = malloc(sizeof *evmgr);
if (!evmgr) {
ERROR("out of memory");
rc = -ENOMEM;
goto error;
}
/* creates the eventfd for waking up polls */
evmgr->efd = eventfd(0, EFD_CLOEXEC|EFD_SEMAPHORE);
if (evmgr->efd < 0) {
rc = -errno;
ERROR("can't make eventfd for events");
goto error1;
}
/* create the systemd event loop */
evmgr->sdev = systemd_get_event_loop();
if (!evmgr->sdev) {
rc = -errno;
ERROR("can't make new event loop");
goto error2;
}
/* put the eventfd in the event loop */
rc = sd_event_add_io(evmgr->sdev, NULL, evmgr->efd, EPOLLIN, on_evmgr_efd, evmgr);
if (rc < 0) {
ERROR("can't register eventfd");
goto error2;
}
/* start the creation */
evmgr->state = 0;
evmgr->holder = 0;
*result = evmgr;
return 0;
error2:
close(evmgr->efd);
error1:
free(evmgr);
error:
*result = 0;
return rc;
}
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