* hook_register_arg (some_update_event, event_handler, addonptr);
*
* (addonptr isn't typesafe, but that should be manageable.)
+ *
+ * Hooks also support a "priority" value for ordering registered calls
+ * relative to each other. The priority is a signed integer where lower
+ * values are called earlier. There is also "Koohs", which is hooks with
+ * reverse priority ordering (for cleanup/deinit hooks, so you can use the
+ * same priority value).
+ *
+ * Recommended priority value ranges are:
+ *
+ * -999 ... 0 ... 999 - main executable / daemon, or library
+ * -1999 ... -1000 - modules registering calls that should run before
+ * the daemon's bits
+ * 1000 ... 1999 - modules calls that should run after daemon's
+ *
+ * Note: the default value is 1000, based on the following 2 expectations:
+ * - most hook_register() usage will be in loadable modules
+ * - usage of hook_register() in the daemon itself may need relative ordering
+ * to itself, making an explicit value the expected case
+ *
+ * The priority value is passed as extra argument on hook_register_prio() /
+ * hook_register_arg_prio(). Whether a hook runs in reverse is determined
+ * solely by the code defining / calling the hook. (DECLARE_KOOH is actually
+ * the same thing as DECLARE_HOOK, it's just there to make it obvious.)
*/
/* TODO:
struct hookent {
struct hookent *next;
- void *hookfn; /* actually a function pointer */
+ void *hookfn; /* actually a function pointer */
void *hookarg;
bool has_arg;
+ int priority;
struct frrmod_runtime *module;
const char *fnname;
};
struct hook {
const char *name;
struct hookent *entries;
+ bool reverse;
};
+#define HOOK_DEFAULT_PRIORITY 1000
+
/* subscribe/add callback function to a hook
*
* always use hook_register(), which uses the static inline helper from
*/
extern void _hook_register(struct hook *hook, void *funcptr, void *arg,
bool has_arg, struct frrmod_runtime *module,
- const char *funcname);
-#define hook_register(hookname, func) \
- _hook_register(&_hook_ ## hookname, \
- _hook_typecheck_ ## hookname (func), \
- NULL, false, THIS_MODULE, #func)
-#define hook_register_arg(hookname, func, arg) \
- _hook_register(&_hook_ ## hookname, \
- _hook_typecheck_arg_ ## hookname (func), \
- arg, true, THIS_MODULE, #func)
+ const char *funcname, int priority);
+#define hook_register(hookname, func) \
+ _hook_register(&_hook_##hookname, _hook_typecheck_##hookname(func), \
+ NULL, false, THIS_MODULE, #func, HOOK_DEFAULT_PRIORITY)
+#define hook_register_arg(hookname, func, arg) \
+ _hook_register(&_hook_##hookname, \
+ _hook_typecheck_arg_##hookname(func), arg, true, \
+ THIS_MODULE, #func, HOOK_DEFAULT_PRIORITY)
+#define hook_register_prio(hookname, prio, func) \
+ _hook_register(&_hook_##hookname, _hook_typecheck_##hookname(func), \
+ NULL, false, THIS_MODULE, #func, prio)
+#define hook_register_arg_prio(hookname, prio, func, arg) \
+ _hook_register(&_hook_##hookname, \
+ _hook_typecheck_arg_##hookname(func), arg, true, \
+ THIS_MODULE, #func, prio)
extern void _hook_unregister(struct hook *hook, void *funcptr, void *arg,
bool has_arg);
-#define hook_unregister(hookname, func) \
- _hook_unregister(&_hook_ ## hookname, \
- _hook_typecheck_ ## hookname (func), NULL, false)
-#define hook_unregister_arg(hookname, func, arg) \
- _hook_unregister(&_hook_ ## hookname, \
- _hook_typecheck_arg_ ## hookname (func), arg, true)
+#define hook_unregister(hookname, func) \
+ _hook_unregister(&_hook_##hookname, _hook_typecheck_##hookname(func), \
+ NULL, false)
+#define hook_unregister_arg(hookname, func, arg) \
+ _hook_unregister(&_hook_##hookname, \
+ _hook_typecheck_arg_##hookname(func), arg, true)
/* invoke hooks
* this is private (static) to the file that has the DEFINE_HOOK statement
*/
-#define hook_call(hookname, ...) \
- hook_call_ ## hookname (__VA_ARGS__)
+#define hook_call(hookname, ...) hook_call_##hookname(__VA_ARGS__)
/* helpers to add the void * arg */
#define HOOK_ADDDEF(...) (void *hookarg , ## __VA_ARGS__)
* theoretically passlist is not neccessary, but let's keep things simple and
* use exact same args on DECLARE and DEFINE.
*/
-#define DECLARE_HOOK(hookname, arglist, passlist) \
- extern struct hook _hook_ ## hookname; \
- __attribute__((unused)) \
- static void *_hook_typecheck_ ## hookname ( \
- int (*funcptr) arglist) { \
- return (void *)funcptr; } \
- __attribute__((unused)) \
- static void *_hook_typecheck_arg_ ## hookname ( \
- int (*funcptr) HOOK_ADDDEF arglist) { \
- return (void *)funcptr; }
+#define DECLARE_HOOK(hookname, arglist, passlist) \
+ extern struct hook _hook_##hookname; \
+ __attribute__((unused)) static void *_hook_typecheck_##hookname( \
+ int(*funcptr) arglist) \
+ { \
+ return (void *)funcptr; \
+ } \
+ __attribute__((unused)) static void *_hook_typecheck_arg_##hookname( \
+ int(*funcptr) HOOK_ADDDEF arglist) \
+ { \
+ return (void *)funcptr; \
+ }
+#define DECLARE_KOOH(hookname, arglist, passlist) \
+ DECLARE_HOOK(hookname, arglist, passlist)
/* use in source file - contains hook-related definitions.
*/
-#define DEFINE_HOOK(hookname, arglist, passlist) \
- struct hook _hook_ ## hookname = { \
- .name = #hookname, \
- .entries = NULL, \
- }; \
- static int hook_call_ ## hookname arglist { \
- int hooksum = 0; \
- struct hookent *he = _hook_ ## hookname .entries; \
- void *hookarg; \
- union { \
- void *voidptr; \
- int (*fptr) arglist; \
- int (*farg) HOOK_ADDDEF arglist; \
- } hookp; \
- for (; he; he = he->next) { \
- hookarg = he->hookarg; \
- hookp.voidptr = he->hookfn; \
- if (!he->has_arg) \
- hooksum += hookp.fptr passlist; \
- else \
- hooksum += hookp.farg HOOK_ADDARG passlist; \
- } \
- return hooksum; \
+#define DEFINE_HOOK_INT(hookname, arglist, passlist, rev) \
+ struct hook _hook_##hookname = { \
+ .name = #hookname, .entries = NULL, .reverse = rev, \
+ }; \
+ static int hook_call_##hookname arglist \
+ { \
+ int hooksum = 0; \
+ struct hookent *he = _hook_##hookname.entries; \
+ void *hookarg; \
+ union { \
+ void *voidptr; \
+ int(*fptr) arglist; \
+ int(*farg) HOOK_ADDDEF arglist; \
+ } hookp; \
+ for (; he; he = he->next) { \
+ hookarg = he->hookarg; \
+ hookp.voidptr = he->hookfn; \
+ if (!he->has_arg) \
+ hooksum += hookp.fptr passlist; \
+ else \
+ hooksum += hookp.farg HOOK_ADDARG passlist; \
+ } \
+ return hooksum; \
}
+#define DEFINE_HOOK(hookname, arglist, passlist) \
+ DEFINE_HOOK_INT(hookname, arglist, passlist, false)
+#define DEFINE_KOOH(hookname, arglist, passlist) \
+ DEFINE_HOOK_INT(hookname, arglist, passlist, true)
+
#endif /* _FRR_HOOK_H */
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