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Added functions to register callbacks to the param_sniffer() #49

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Added functions to register callbacks to the param_sniffer() #49

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49 changes: 49 additions & 0 deletions src/param_sniffer.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5,9 +5,12 @@
* Author: johan
*/

#include "param_sniffer.h"

#include <stdio.h>
#include <sys/time.h>
#include <pthread.h>
#include <sys/queue.h>
#include <param/param_server.h>
#include <param/param_queue.h>
#include <param/param_serializer.h>
Expand Down Expand Up @@ -141,6 +144,51 @@ int param_sniffer_crc(csp_packet_t * packet) {
return 0;
}

/* The intention here is to hide the `SLIST` usage behind the `register` and `unregister` API,
so we could change to a statically allocated array instead if desired. */
typedef struct param_sniffer_callback_s {
param_sniffer_callback_f callback;
void *context;
SLIST_ENTRY(param_sniffer_callback_s) next;
} param_sniffer_callback_t;
static SLIST_HEAD( sniffer_callbacks_head_s, param_sniffer_callback_s ) sniffer_callbacks_head = SLIST_HEAD_INITIALIZER(sniffer_callbacks_head);

int param_sniffer_register_callback(param_sniffer_callback_f callback, void * context) {

/* TODO Kevin: What about registering the same callback multiple times? What if it has different contexts? */
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@jeanbaptistelab jeanbaptistelab Nov 5, 2025

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What about that ? This is a way for users of this API to register things, we can't be responsible for what they actually register, can we ?

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@kivkiv12345 kivkiv12345 Nov 5, 2025

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I left that comment wondering how I should handle it in param_sniffer_UNregister_callback(). Do we unregister all callbacks to that function, or only the first match?
Do we error if that function is already registered?

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@jeanbaptistelab jeanbaptistelab Nov 5, 2025

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A solution would be to update the
int param_sniffer_unregister_callback(param_sniffer_callback_f callback)
to:
int param_sniffer_unregister_callback(param_sniffer_callback_f callback, void * context)
and then test for both the callbackand contextto find the correct element to unregister...

param_sniffer_callback_t * slist_entry = calloc(1, sizeof(*slist_entry));
slist_entry->callback = callback;
slist_entry->context = context;
SLIST_INSERT_HEAD(&sniffer_callbacks_head, slist_entry, next);

return 0;
}

int param_sniffer_unregister_callback(param_sniffer_callback_f callback) {

param_sniffer_callback_t *callback_entry = NULL;
param_sniffer_callback_t *prev_entry = (param_sniffer_callback_t*)&sniffer_callbacks_head;

SLIST_FOREACH(callback_entry, &sniffer_callbacks_head, next) {

if (callback_entry->callback == callback) {
//SLIST_REMOVE_PREVPTR(&prev_entry, callback_entry, next);
SLIST_REMOVE(&sniffer_callbacks_head, callback_entry, param_sniffer_callback_s, next);
}
prev_entry = callback_entry;
}

return 0;
}

static void param_sniffer_call_callbacks(param_t * param) {
param_sniffer_callback_t *callback_entry = NULL;

SLIST_FOREACH(callback_entry, &sniffer_callbacks_head, next) {
callback_entry->callback(param, callback_entry->context);
}
}

static void * param_sniffer(void * param) {
csp_promisc_enable(100);
while(1) {
Expand Down Expand Up @@ -200,6 +248,7 @@ static void * param_sniffer(void * param) {
param_t * param = param_list_find_id(node, id);
if (param) {
param_sniffer_log(NULL, &queue, param, offset, &reader, &timestamp);
param_sniffer_call_callbacks(param);
} else {
printf("Found unknown param node %d id %d\n", node, id);
mpack_discard(&reader);
Expand Down
14 changes: 14 additions & 0 deletions src/param_sniffer.h
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Original file line number Diff line number Diff line change
Expand Up @@ -9,9 +9,23 @@
#define SRC_PARAM_SNIFFER_H_

#include <csp/csp.h>
#include <param/param.h>
#include <param/param_queue.h>

int param_sniffer_crc(csp_packet_t * packet);
int param_sniffer_log(void * ctx, param_queue_t *queue, param_t *param, int offset, void *reader, csp_timestamp_t *timestamp);
void param_sniffer_init(int add_logfile);

/* TODO Kevin: We should probably pass along `*queue`, `offset` and `*timestamp` as well. */
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@jeanbaptistelab jeanbaptistelab Nov 5, 2025

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If we "probably should", why not do it ? :)

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@kivkiv12345 kivkiv12345 Nov 5, 2025

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I take it you agree then? I will do it!

typedef void (*param_sniffer_callback_f)(param_t * param, void * context);
/**
* @brief Register a function to be called when a parameter is sniffed and deserialized from the network.
*
* @param callback[in] Callback function to call whenever a decoding error is encountered.
* @param context[in] User-supplied context for the callback function. Must remain valid for as long as the function is registered (is not copied).
* @return int 0 OK, <0 ERROR
*/
int param_sniffer_register_callback(param_sniffer_callback_f callback, void * context);
int param_sniffer_unregister_callback(param_sniffer_callback_f callback);

#endif /* SRC_PARAM_SNIFFER_H_ */