/*-
 * Copyright (c) 1999 Michael Smith <msmith@freebsd.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD: src/sys/sys/eventhandler.h,v 1.33.2.1 2006/05/16 07:27:49 ps Exp $
 */
#ifndef SYS_EVENTHANDLER_H
#define SYS_EVENTHANDLER_H

#include <sys/lock.h>
#include <sys/ktr.h>
#include <sys/mutex.h>
#include <sys/queue.h>

struct eventhandler_entry {
        TAILQ_ENTRY(eventhandler_entry) ee_link;
        int                             ee_priority;
#define EHE_DEAD_PRIORITY       (-1)
        void                            *ee_arg;
};

struct eventhandler_list {
        char                            *el_name;
        int                             el_flags;
#define EHL_INITTED     (1<<0)
        u_int                           el_runcount;
        struct mtx                      el_lock;
        TAILQ_ENTRY(eventhandler_list)  el_link;
        TAILQ_HEAD(,eventhandler_entry) el_entries;
};

typedef struct eventhandler_entry       *eventhandler_tag;

#define EHL_LOCK(p)             mtx_lock(&(p)->el_lock)
#define EHL_UNLOCK(p)           mtx_unlock(&(p)->el_lock)
#define EHL_LOCK_ASSERT(p, x)   mtx_assert(&(p)->el_lock, x)

/*
 * Macro to invoke the handlers for a given event.
 */
#define _EVENTHANDLER_INVOKE(name, list, ...) do {                      \
        struct eventhandler_entry *_ep;                                 \
        struct eventhandler_entry_ ## name *_t;                         \
                                                                        \
        KASSERT((list)->el_flags & EHL_INITTED,                         \
           ("eventhandler_invoke: running non-inited list"));           \
        EHL_LOCK_ASSERT((list), MA_OWNED);                              \
        (list)->el_runcount++;                                          \
        KASSERT((list)->el_runcount > 0,                                \
            ("eventhandler_invoke: runcount overflow"));                \
        CTR0(KTR_EVH, "eventhandler_invoke(\"" __STRING(name) "\")");   \
        TAILQ_FOREACH(_ep, &((list)->el_entries), ee_link) {            \
                if (_ep->ee_priority != EHE_DEAD_PRIORITY) {            \
                        EHL_UNLOCK((list));                             \
                        _t = (struct eventhandler_entry_ ## name *)_ep; \
                        CTR1(KTR_EVH, "eventhandler_invoke: executing %p", \
                            (void *)_t->eh_func);                       \
                        _t->eh_func(_ep->ee_arg , ## __VA_ARGS__);      \
                        EHL_LOCK((list));                               \
                }                                                       \
        }                                                               \
        KASSERT((list)->el_runcount > 0,                                \
            ("eventhandler_invoke: runcount underflow"));               \
        (list)->el_runcount--;                                          \
        if ((list)->el_runcount == 0)                                   \
                eventhandler_prune_list(list);                          \
        EHL_UNLOCK((list));                                             \
} while (0)

/*
 * Slow handlers are entirely dynamic; lists are created
 * when entries are added to them, and thus have no concept of "owner",
 *
 * Slow handlers need to be declared, but do not need to be defined. The
 * declaration must be in scope wherever the handler is to be invoked.
 */
#define EVENTHANDLER_DECLARE(name, type)                                \
struct eventhandler_entry_ ## name                                      \
{                                                                       \
        struct eventhandler_entry       ee;                             \
        type                            eh_func;                        \
};                                                                      \
struct __hack

#define EVENTHANDLER_INVOKE(name, ...)                                  \
do {                                                                    \
        struct eventhandler_list *_el;                                  \
                                                                        \
        if ((_el = eventhandler_find_list(#name)) != NULL)              \
                _EVENTHANDLER_INVOKE(name, _el , ## __VA_ARGS__);       \
} while (0)

#define EVENTHANDLER_REGISTER(name, func, arg, priority)                \
        eventhandler_register(NULL, #name, func, arg, priority)

#define EVENTHANDLER_DEREGISTER(name, tag)                              \
do {                                                                    \
        struct eventhandler_list *_el;                                  \
                                                                        \
        if ((_el = eventhandler_find_list(#name)) != NULL)              \
                eventhandler_deregister(_el, tag);                      \
} while(0)
        

eventhandler_tag eventhandler_register(struct eventhandler_list *list, 
            const char *name, void *func, void *arg, int priority);
void    eventhandler_deregister(struct eventhandler_list *list,
            eventhandler_tag tag);
struct eventhandler_list *eventhandler_find_list(const char *name);
void    eventhandler_prune_list(struct eventhandler_list *list);

/*
 * Standard system event queues.
 */

/* Generic priority levels */
#define EVENTHANDLER_PRI_FIRST  0
#define EVENTHANDLER_PRI_ANY    10000
#define EVENTHANDLER_PRI_LAST   20000

/* Shutdown events */
typedef void (*shutdown_fn)(void *, int);

#define SHUTDOWN_PRI_FIRST      EVENTHANDLER_PRI_FIRST
#define SHUTDOWN_PRI_DEFAULT    EVENTHANDLER_PRI_ANY
#define SHUTDOWN_PRI_LAST       EVENTHANDLER_PRI_LAST

EVENTHANDLER_DECLARE(shutdown_pre_sync, shutdown_fn);   /* before fs sync */
EVENTHANDLER_DECLARE(shutdown_post_sync, shutdown_fn);  /* after fs sync */
EVENTHANDLER_DECLARE(shutdown_final, shutdown_fn);

/* Low memory event */
typedef void (*vm_lowmem_handler_t)(void *, int);
#define LOWMEM_PRI_DEFAULT      EVENTHANDLER_PRI_FIRST
EVENTHANDLER_DECLARE(vm_lowmem, vm_lowmem_handler_t);

/*
 * Process events
 * process_fork and exit handlers are called without Giant.
 * exec handlers are called with Giant, but that is by accident.
 */
struct proc;

typedef void (*exitlist_fn)(void *, struct proc *);
typedef void (*forklist_fn)(void *, struct proc *, struct proc *, int);
typedef void (*execlist_fn)(void *, struct proc *);

EVENTHANDLER_DECLARE(process_exit, exitlist_fn);
EVENTHANDLER_DECLARE(process_fork, forklist_fn);
EVENTHANDLER_DECLARE(process_exec, execlist_fn);

typedef void (*uma_zone_chfn)(void *);
EVENTHANDLER_DECLARE(nmbclusters_change, uma_zone_chfn);
EVENTHANDLER_DECLARE(maxsockets_change, uma_zone_chfn);
#endif /* SYS_EVENTHANDLER_H */