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/*
* Copyright (C) 2015, 2016, 2017 "IoT.bzh"
* Author "Fulup Ar Foll"
* 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 <string.h>
#include <assert.h>
#include <errno.h>
#include <pthread.h>
#include <json-c/json.h>
#include <afb/afb-event-itf.h>
#include "afb-evt.h"
#include "afb-hook.h"
#include "verbose.h"
struct afb_evt_watch;
/*
* Structure for event listeners
*/
struct afb_evt_listener {
/* chaining listeners */
struct afb_evt_listener *next;
/* interface for callbacks */
const struct afb_evt_itf *itf;
/* closure for the callback */
void *closure;
/* head of the list of events listened */
struct afb_evt_watch *watchs;
/* mutex of the listener */
pthread_mutex_t mutex;
/* count of reference to the listener */
int refcount;
};
/*
* Structure for describing events
*/
struct afb_evt_event {
/* next event */
struct afb_evt_event *next;
/* head of the list of listeners watching the event */
struct afb_evt_watch *watchs;
/* id of the event */
int id;
/* hooking */
int hookflags;
/* mutex of the event */
pthread_mutex_t mutex;
/* name of the event */
char name[1];
};
/*
* Structure for associating events and listeners
*/
struct afb_evt_watch {
/* the event */
struct afb_evt_event *event;
/* link to the next listener for the same event */
struct afb_evt_watch *next_by_event;
/* the listener */
struct afb_evt_listener *listener;
/* link to the next event for the same listener */
struct afb_evt_watch *next_by_listener;
/* activity */
unsigned activity;
};
/* declare functions */
static int evt_broadcast(struct afb_evt_event *evt, struct json_object *obj);
static int evt_push(struct afb_evt_event *evt, struct json_object *obj);
static void evt_destroy(struct afb_evt_event *evt);
static const char *evt_name(struct afb_evt_event *evt);
/* the interface for events */
static struct afb_event_itf afb_evt_event_itf = {
.broadcast = (void*)evt_broadcast,
.push = (void*)evt_push,
.drop = (void*)evt_destroy,
.name = (void*)evt_name
};
/* head of the list of listeners */
static pthread_mutex_t listeners_mutex = PTHREAD_MUTEX_INITIALIZER;
static struct afb_evt_listener *listeners = NULL;
/* handling id of events */
static pthread_mutex_t events_mutex = PTHREAD_MUTEX_INITIALIZER;
static struct afb_evt_event *events = NULL;
static int event_id_counter = 0;
static int event_id_wrapped = 0;
/*
* Broadcasts the 'event' of 'id' with its 'obj'
* 'obj' is released (like json_object_put)
* calls hooks if hookflags isn't 0
* Returns the count of listener having receive the event.
*/
static int broadcast(const char *event, struct json_object *obj, int id, int hookflags)
{
int result;
struct afb_evt_listener *listener;
if (hookflags & afb_hook_flag_evt_broadcast_before)
afb_hook_evt_broadcast_before(event, id, obj);
result = 0;
pthread_mutex_lock(&listeners_mutex);
listener = listeners;
while(listener) {
if (listener->itf->broadcast != NULL) {
listener->itf->broadcast(listener->closure, event, id, json_object_get(obj));
result++;
}
listener = listener->next;
}
pthread_mutex_unlock(&listeners_mutex);
if (hookflags & afb_hook_flag_evt_broadcast_after)
afb_hook_evt_broadcast_after(event, id, obj, result);
json_object_put(obj);
return result;
}
/*
* Broadcasts the event 'evt' with its 'object'
* 'object' is released (like json_object_put)
* Returns the count of listener that received the event.
*/
static int evt_broadcast(struct afb_evt_event *evt, struct json_object *object)
{
return broadcast(evt->name, object, evt->id, evt->hookflags);
}
/*
* Broadcasts the 'event' with its 'object'
* 'object' is released (like json_object_put)
* Returns the count of listener having receive the event.
*/
int afb_evt_broadcast(const char *event, struct json_object *object)
{
return broadcast(event, object, 0, -1);
}
/*
* Pushes the event 'evt' with 'obj' to its listeners
* 'obj' is released (like json_object_put)
* calls hooks if hookflags isn't 0
* Returns the count of listener taht received the event.
*/
static int push(struct afb_evt_event *evt, struct json_object *obj, int hookflags)
{
int result;
struct afb_evt_watch *watch;
struct afb_evt_listener *listener;
result = 0;
pthread_mutex_lock(&evt->mutex);
if (hookflags & afb_hook_flag_evt_push_before)
afb_hook_evt_push_before(evt->name, evt->id, obj);
watch = evt->watchs;
while(watch) {
listener = watch->listener;
assert(listener->itf->push != NULL);
if (watch->activity != 0) {
listener->itf->push(listener->closure, evt->name, evt->id, json_object_get(obj));
result++;
}
watch = watch->next_by_event;
}
if (hookflags & afb_hook_flag_evt_push_after)
afb_hook_evt_push_after(evt->name, evt->id, obj, result);
pthread_mutex_unlock(&evt->mutex);
json_object_put(obj);
return result;
}
/*
* Pushes the event 'evt' with 'obj' to its listeners
* 'obj' is released (like json_object_put)
* Returns the count of listener taht received the event.
*/
static int evt_push(struct afb_evt_event *evt, struct json_object *obj)
{
return push(evt, obj, evt->hookflags);
}
/*
* Returns the name associated to the event 'evt'.
*/
static const char *evt_name(struct afb_evt_event *evt)
{
const char *name = strchr(evt->name, '/');
name = name ? name + 1 : evt->name;
if (evt->hookflags & afb_hook_flag_evt_name)
afb_hook_evt_name(evt->name, evt->id);
return name;
}
/*
* remove the 'watch'
*/
static void remove_watch(struct afb_evt_watch *watch)
{
struct afb_evt_watch **prv;
struct afb_evt_event *evt;
struct afb_evt_listener *listener;
/* notify listener if needed */
evt = watch->event;
listener = watch->listener;
if (watch->activity != 0 && listener->itf->remove != NULL)
listener->itf->remove(listener->closure, evt->name, evt->id);
/* unlink the watch for its event */
prv = &evt->watchs;
while(*prv != watch)
prv = &(*prv)->next_by_event;
*prv = watch->next_by_event;
/* unlink the watch for its listener */
prv = &listener->watchs;
while(*prv != watch)
prv = &(*prv)->next_by_listener;
*prv = watch->next_by_listener;
/* recycle memory */
free(watch);
}
/*
* Destroys the event 'evt'
*/
static void evt_destroy(struct afb_evt_event *evt)
{
int found;
struct afb_evt_event **prv;
struct afb_evt_listener *listener;
if (evt != NULL) {
/* unlinks the event if valid! */
pthread_mutex_lock(&events_mutex);
found = 0;
prv = &events;
while (*prv && !(found = (*prv == evt)))
prv = &(*prv)->next;
if (found)
*prv = evt->next;
pthread_mutex_unlock(&events_mutex);
/* destroys the event */
if (found) {
/* removes all watchers */
while(evt->watchs != NULL) {
listener = evt->watchs->listener;
pthread_mutex_lock(&listener->mutex);
pthread_mutex_lock(&evt->mutex);
remove_watch(evt->watchs);
pthread_mutex_unlock(&evt->mutex);
pthread_mutex_unlock(&listener->mutex);
}
/* hook */
if (evt->hookflags & afb_hook_flag_evt_drop)
afb_hook_evt_drop(evt->name, evt->id);
/* free */
pthread_mutex_destroy(&evt->mutex);
free(evt);
}
}
}
/*
* Creates an event of 'name' and returns it.
* Returns an event with closure==NULL in case of error.
*/
struct afb_event afb_evt_create_event(const char *name)
{
size_t len;
struct afb_evt_event *evt, *oevt;
/* allocates the event */
len = strlen(name);
evt = malloc(len + sizeof * evt);
if (evt == NULL)
goto error;
/* allocates the id */
pthread_mutex_lock(&events_mutex);
do {
if (++event_id_counter < 0) {
event_id_wrapped = 1;
event_id_counter = 1024; /* heuristic: small numbers are not destroyed */
}
if (!event_id_wrapped)
break;
oevt = events;
while(oevt != NULL && oevt->id != event_id_counter)
oevt = oevt->next;
} while (oevt != NULL);
/* initialize the event */
memcpy(evt->name, name, len + 1);
evt->next = events;
evt->watchs = NULL;
evt->id = event_id_counter;
pthread_mutex_init(&evt->mutex, NULL);
events = evt;
evt->hookflags = afb_hook_flags_evt(evt->name);
if (evt->hookflags & afb_hook_flag_evt_create)
afb_hook_evt_create(evt->name, evt->id);
pthread_mutex_unlock(&events_mutex);
/* returns the event */
return (struct afb_event){ .itf = &afb_evt_event_itf, .closure = evt };
error:
return (struct afb_event){ .itf = NULL, .closure = NULL };
}
/*
* Returns the name of the 'event'
*/
const char *afb_evt_event_name(struct afb_event event)
{
return (event.itf != &afb_evt_event_itf) ? NULL : ((struct afb_evt_event *)event.closure)->name;
}
/*
* Returns the id of the 'event'
*/
int afb_evt_event_id(struct afb_event event)
{
return (event.itf != &afb_evt_event_itf) ? 0 : ((struct afb_evt_event *)event.closure)->id;
}
/*
* Returns an instance of the listener defined by the 'send' callback
* and the 'closure'.
* Returns NULL in case of memory depletion.
*/
struct afb_evt_listener *afb_evt_listener_create(const struct afb_evt_itf *itf, void *closure)
{
struct afb_evt_listener *listener;
/* search if an instance already exists */
pthread_mutex_lock(&listeners_mutex);
listener = listeners;
while (listener != NULL) {
if (listener->itf == itf && listener->closure == closure) {
listener = afb_evt_listener_addref(listener);
goto found;
}
listener = listener->next;
}
/* allocates */
listener = calloc(1, sizeof *listener);
if (listener != NULL) {
/* init */
listener->itf = itf;
listener->closure = closure;
listener->watchs = NULL;
listener->refcount = 1;
pthread_mutex_init(&listener->mutex, NULL);
listener->next = listeners;
listeners = listener;
}
found:
pthread_mutex_unlock(&listeners_mutex);
return listener;
}
/*
* Increases the reference count of 'listener' and returns it
*/
struct afb_evt_listener *afb_evt_listener_addref(struct afb_evt_listener *listener)
{
__atomic_add_fetch(&listener->refcount, 1, __ATOMIC_RELAXED);
return listener;
}
/*
* Decreases the reference count of the 'listener' and destroys it
* when no more used.
*/
void afb_evt_listener_unref(struct afb_evt_listener *listener)
{
struct afb_evt_listener **prv;
struct afb_evt_event *evt;
if (!__atomic_sub_fetch(&listener->refcount, 1, __ATOMIC_RELAXED)) {
/* unlink the listener */
pthread_mutex_lock(&listeners_mutex);
prv = &listeners;
while (*prv != listener)
prv = &(*prv)->next;
*prv = listener->next;
pthread_mutex_unlock(&listeners_mutex);
/* remove the watchers */
pthread_mutex_lock(&listener->mutex);
while (listener->watchs != NULL) {
evt = listener->watchs->event;
pthread_mutex_lock(&evt->mutex);
remove_watch(listener->watchs);
pthread_mutex_unlock(&evt->mutex);
}
pthread_mutex_unlock(&listener->mutex);
/* free the listener */
pthread_mutex_destroy(&listener->mutex);
free(listener);
}
}
/*
* Makes the 'listener' watching 'event'
* Returns 0 in case of success or else -1.
*/
int afb_evt_add_watch(struct afb_evt_listener *listener, struct afb_event event)
{
struct afb_evt_watch *watch;
struct afb_evt_event *evt;
/* check parameter */
if (event.itf != &afb_evt_event_itf || listener->itf->push == NULL) {
errno = EINVAL;
return -1;
}
/* search the existing watch for the listener */
evt = event.closure;
pthread_mutex_lock(&listener->mutex);
watch = listener->watchs;
while(watch != NULL) {
if (watch->event == evt)
goto found;
watch = watch->next_by_listener;
}
/* not found, allocate a new */
watch = malloc(sizeof *watch);
if (watch == NULL) {
pthread_mutex_unlock(&listener->mutex);
errno = ENOMEM;
return -1;
}
/* initialise and link */
watch->event = evt;
watch->activity = 0;
watch->listener = listener;
watch->next_by_listener = listener->watchs;
listener->watchs = watch;
pthread_mutex_lock(&evt->mutex);
watch->next_by_event = evt->watchs;
evt->watchs = watch;
pthread_mutex_unlock(&evt->mutex);
found:
if (watch->activity == 0 && listener->itf->add != NULL)
listener->itf->add(listener->closure, evt->name, evt->id);
watch->activity++;
pthread_mutex_unlock(&listener->mutex);
return 0;
}
/*
* Avoids the 'listener' to watch 'event'
* Returns 0 in case of success or else -1.
*/
int afb_evt_remove_watch(struct afb_evt_listener *listener, struct afb_event event)
{
struct afb_evt_watch *watch;
struct afb_evt_event *evt;
/* check parameter */
if (event.itf != &afb_evt_event_itf) {
errno = EINVAL;
return -1;
}
/* search the existing watch */
evt = event.closure;
pthread_mutex_lock(&listener->mutex);
watch = listener->watchs;
while(watch != NULL) {
if (watch->event == evt) {
if (watch->activity != 0) {
watch->activity--;
if (watch->activity == 0 && listener->itf->remove != NULL)
listener->itf->remove(listener->closure, evt->name, evt->id);
}
pthread_mutex_unlock(&listener->mutex);
return 0;
}
watch = watch->next_by_listener;
}
pthread_mutex_unlock(&listener->mutex);
errno = ENOENT;
return -1;
}
/*
* update the hooks for events
*/
void afb_evt_update_hooks()
{
struct afb_evt_event *evt;
pthread_mutex_lock(&events_mutex);
for (evt = events ; evt ; evt = evt->next)
evt->hookflags = afb_hook_flags_evt(evt->name);
pthread_mutex_unlock(&events_mutex);
}
int afb_evt_push(struct afb_event event, struct json_object *object)
{
if (event.itf == &afb_evt_event_itf)
return evt_push((struct afb_evt_event *)event.closure, object);
json_object_put(object);
return 0;
}
int afb_evt_unhooked_push(struct afb_event event, struct json_object *object)
{
if (event.itf == &afb_evt_event_itf)
return push((struct afb_evt_event *)event.closure, object, 0);
json_object_put(object);
return 0;
}
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