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Diffstat (limited to 'src/evmgr.c')
| -rw-r--r-- | src/evmgr.c | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/src/evmgr.c b/src/evmgr.c new file mode 100644 index 00000000..2dc35e42 --- /dev/null +++ b/src/evmgr.c @@ -0,0 +1,220 @@ +/* + * Copyright (C) 2016-2019 "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 + +/** + * 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) { + ERROR("can't make eventfd for events"); + rc = -errno; + goto error1; + } + /* create the systemd event loop */ + evmgr->sdev = systemd_get_event_loop(); + if (!evmgr->sdev) { + 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; +} + |