mirror of https://gerrit.osmocom.org/libosmocore
273 lines
7.3 KiB
C
273 lines
7.3 KiB
C
/*! \file it_q.c
|
|
* Osmocom Inter-Thread queue implementation */
|
|
/* (C) 2019 by Harald Welte <laforge@gnumonks.org>
|
|
* All Rights Reserved.
|
|
*
|
|
* SPDX-License-Identifier: GPL-2.0+
|
|
*
|
|
* 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.
|
|
*/
|
|
|
|
/*! \addtogroup it_q
|
|
* @{
|
|
* Inter-Thread Message Queue.
|
|
*
|
|
* This implements a general-purpose queue between threads. It uses
|
|
* user-provided data types (containing a llist_head as initial member)
|
|
* as elements in the queue and an eventfd-based notification mechanism.
|
|
* Hence, it can be used for pretty much anything, including but not
|
|
* limited to msgbs, including msgb-wrapped osmo_prim.
|
|
*
|
|
* The idea is that the sending thread simply calls osmo_it_q_enqueue().
|
|
* The receiving thread is woken up from its osmo_select_main() loop by eventfd,
|
|
* and a general osmo_fd callback function for the eventfd will dequeue each item
|
|
* and call a queue-specific callback function.
|
|
*/
|
|
|
|
#include "../config.h"
|
|
|
|
#ifdef HAVE_SYS_EVENTFD_H
|
|
|
|
#include <pthread.h>
|
|
#include <unistd.h>
|
|
#include <string.h>
|
|
#include <errno.h>
|
|
#include <sys/eventfd.h>
|
|
|
|
#include <osmocom/core/linuxlist.h>
|
|
#include <osmocom/core/talloc.h>
|
|
#include <osmocom/core/utils.h>
|
|
#include <osmocom/core/it_q.h>
|
|
|
|
/* "increment" the eventfd by specified 'inc' */
|
|
static int eventfd_increment(int fd, uint64_t inc)
|
|
{
|
|
int rc;
|
|
|
|
rc = write(fd, &inc, sizeof(inc));
|
|
if (rc != sizeof(inc))
|
|
return -1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* global (for all threads) list of message queues in a program + associated lock */
|
|
static LLIST_HEAD(it_queues);
|
|
static pthread_rwlock_t it_queues_rwlock = PTHREAD_RWLOCK_INITIALIZER;
|
|
|
|
/* resolve it-queue by its [globally unique] name; must be called with rwlock held */
|
|
static struct osmo_it_q *_osmo_it_q_by_name(const char *name)
|
|
{
|
|
struct osmo_it_q *q;
|
|
llist_for_each_entry(q, &it_queues, entry) {
|
|
if (!strcmp(q->name, name))
|
|
return q;
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
/*! resolve it-queue by its [globally unique] name */
|
|
struct osmo_it_q *osmo_it_q_by_name(const char *name)
|
|
{
|
|
struct osmo_it_q *q;
|
|
pthread_rwlock_rdlock(&it_queues_rwlock);
|
|
q = _osmo_it_q_by_name(name);
|
|
pthread_rwlock_unlock(&it_queues_rwlock);
|
|
return q;
|
|
}
|
|
|
|
/* osmo_fd call-back when eventfd is readable */
|
|
static int osmo_it_q_fd_cb(struct osmo_fd *ofd, unsigned int what)
|
|
{
|
|
struct osmo_it_q *q = (struct osmo_it_q *) ofd->data;
|
|
uint64_t val;
|
|
int i, rc;
|
|
|
|
if (!(what & OSMO_FD_READ))
|
|
return 0;
|
|
|
|
rc = read(ofd->fd, &val, sizeof(val));
|
|
if (rc < sizeof(val))
|
|
return rc;
|
|
|
|
for (i = 0; i < val; i++) {
|
|
struct llist_head *item = _osmo_it_q_dequeue(q);
|
|
/* in case the user might have called osmo_it_q_flush() we may
|
|
* end up in the eventfd-dispatch but without any messages left in the queue,
|
|
* otherwise I'd have loved to OSMO_ASSERT(msg) here. */
|
|
if (!item)
|
|
break;
|
|
q->read_cb(q, item);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*! Allocate a new inter-thread message queue.
|
|
* \param[in] ctx talloc context from which to allocate the queue
|
|
* \param[in] name human-readable string name of the queue; function creates a copy.
|
|
* \param[in] read_cb call-back function to be called for each de-queued message; may be
|
|
* NULL in case you don't want eventfd/osmo_select integration and
|
|
* will manually take care of noticing if and when to dequeue.
|
|
* \returns a newly-allocated inter-thread message queue; NULL in case of error */
|
|
struct osmo_it_q *osmo_it_q_alloc(void *ctx, const char *name, unsigned int max_length,
|
|
void (*read_cb)(struct osmo_it_q *q, struct llist_head *item),
|
|
void *data)
|
|
{
|
|
struct osmo_it_q *q;
|
|
int fd;
|
|
|
|
q = talloc_zero(ctx, struct osmo_it_q);
|
|
if (!q)
|
|
return NULL;
|
|
q->data = data;
|
|
q->name = talloc_strdup(q, name);
|
|
q->current_length = 0;
|
|
q->max_length = max_length;
|
|
q->read_cb = read_cb;
|
|
INIT_LLIST_HEAD(&q->list);
|
|
pthread_mutex_init(&q->mutex, NULL);
|
|
q->event_ofd.fd = -1;
|
|
|
|
if (q->read_cb) {
|
|
/* create eventfd *if* the user has provided a read_cb function */
|
|
fd = eventfd(0, 0);
|
|
if (fd < 0) {
|
|
talloc_free(q);
|
|
return NULL;
|
|
}
|
|
|
|
/* initialize BUT NOT REGISTER the osmo_fd. The receiving thread must
|
|
* take are to select/poll/read/... on it */
|
|
osmo_fd_setup(&q->event_ofd, fd, OSMO_FD_READ, osmo_it_q_fd_cb, q, 0);
|
|
}
|
|
|
|
/* add to global list of queues, checking for duplicate names */
|
|
pthread_rwlock_wrlock(&it_queues_rwlock);
|
|
if (_osmo_it_q_by_name(q->name)) {
|
|
pthread_rwlock_unlock(&it_queues_rwlock);
|
|
if (q->event_ofd.fd >= 0)
|
|
osmo_fd_close(&q->event_ofd);
|
|
talloc_free(q);
|
|
return NULL;
|
|
}
|
|
llist_add_tail(&q->entry, &it_queues);
|
|
pthread_rwlock_unlock(&it_queues_rwlock);
|
|
|
|
return q;
|
|
}
|
|
|
|
static void *item_dequeue(struct llist_head *queue)
|
|
{
|
|
struct llist_head *lh;
|
|
|
|
if (llist_empty(queue))
|
|
return NULL;
|
|
|
|
lh = queue->next;
|
|
if (lh) {
|
|
llist_del(lh);
|
|
return lh;
|
|
} else
|
|
return NULL;
|
|
}
|
|
|
|
/*! Flush all messages currently present in queue */
|
|
static void _osmo_it_q_flush(struct osmo_it_q *q)
|
|
{
|
|
void *item;
|
|
while ((item = item_dequeue(&q->list))) {
|
|
talloc_free(item);
|
|
}
|
|
q->current_length = 0;
|
|
}
|
|
|
|
/*! Flush all messages currently present in queue */
|
|
void osmo_it_q_flush(struct osmo_it_q *q)
|
|
{
|
|
OSMO_ASSERT(q);
|
|
|
|
pthread_mutex_lock(&q->mutex);
|
|
_osmo_it_q_flush(q);
|
|
pthread_mutex_unlock(&q->mutex);
|
|
}
|
|
|
|
/*! Destroy a message queue */
|
|
void osmo_it_q_destroy(struct osmo_it_q *q)
|
|
{
|
|
OSMO_ASSERT(q);
|
|
|
|
/* first remove from global list of queues */
|
|
pthread_rwlock_wrlock(&it_queues_rwlock);
|
|
llist_del(&q->entry);
|
|
pthread_rwlock_unlock(&it_queues_rwlock);
|
|
/* next, close the eventfd */
|
|
if (q->event_ofd.fd >= 0)
|
|
osmo_fd_close(&q->event_ofd);
|
|
/* flush all messages still present */
|
|
osmo_it_q_flush(q);
|
|
pthread_mutex_destroy(&q->mutex);
|
|
/* and finally release memory */
|
|
talloc_free(q);
|
|
}
|
|
|
|
/*! Thread-safe en-queue to an inter-thread message queue.
|
|
* \param[in] queue Inter-thread queue on which to enqueue
|
|
* \param[in] item Item to enqueue. Must have llist_head as first member!
|
|
* \returns 0 on success; negative on error */
|
|
int _osmo_it_q_enqueue(struct osmo_it_q *queue, struct llist_head *item)
|
|
{
|
|
OSMO_ASSERT(queue);
|
|
OSMO_ASSERT(item);
|
|
|
|
pthread_mutex_lock(&queue->mutex);
|
|
if (queue->current_length+1 > queue->max_length) {
|
|
pthread_mutex_unlock(&queue->mutex);
|
|
return -ENOSPC;
|
|
}
|
|
llist_add_tail(item, &queue->list);
|
|
queue->current_length++;
|
|
pthread_mutex_unlock(&queue->mutex);
|
|
/* increment eventfd counter by one */
|
|
if (queue->event_ofd.fd >= 0)
|
|
eventfd_increment(queue->event_ofd.fd, 1);
|
|
return 0;
|
|
}
|
|
|
|
|
|
/*! Thread-safe de-queue from an inter-thread message queue.
|
|
* \param[in] queue Inter-thread queue from which to dequeue
|
|
* \returns dequeued message buffer; NULL if none available
|
|
*/
|
|
struct llist_head *_osmo_it_q_dequeue(struct osmo_it_q *queue)
|
|
{
|
|
struct llist_head *l;
|
|
OSMO_ASSERT(queue);
|
|
|
|
pthread_mutex_lock(&queue->mutex);
|
|
|
|
if (llist_empty(&queue->list))
|
|
l = NULL;
|
|
l = queue->list.next;
|
|
OSMO_ASSERT(l);
|
|
llist_del(l);
|
|
queue->current_length--;
|
|
|
|
pthread_mutex_unlock(&queue->mutex);
|
|
|
|
return l;
|
|
}
|
|
|
|
|
|
#endif /* HAVE_SYS_EVENTFD_H */
|
|
|
|
/*! @} */
|