/*-
 * 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 1.5 2000/01/16 06:11:33 bde Exp $
 */

#ifndef _SYS_EVENTHANDLER_H_
#define _SYS_EVENTHANDLER_H_

#if !defined(_KERNEL) && !defined(_KERNEL_STRUCTURES)

#error "This file should not be included by userland programs."

#else

#include <sys/queue.h>

struct eventhandler_entry 
{
    TAILQ_ENTRY(eventhandler_entry)     ee_link;
    int                                 ee_priority;
    void                                *ee_arg;
};

struct eventhandler_list 
{
    TAILQ_ENTRY(eventhandler_list)      el_link;
    char                                *el_name;
    int                                 el_flags;
#define EHE_INITTED     (1<<0)
    TAILQ_HEAD(,eventhandler_entry)     el_entries;
};

typedef struct eventhandler_entry       *eventhandler_tag;

/* 
 * Fast handler lists require the eventhandler list be present
 * at link time.  They don't allow addition of entries to
 * unknown eventhandler lists, ie. each list must have an 
 * "owner".
 *
 * Fast handler lists must be defined once by the owner 
 * of the eventhandler list, and the declaration must be in 
 * scope at any point the list is manipulated.
 */
#define EVENTHANDLER_FAST_DECLARE(name, type)                   \
extern struct eventhandler_list Xeventhandler_list_ ## name ;   \
struct eventhandler_entry_ ## name                              \
{                                                               \
    struct eventhandler_entry   ee;                             \
    type                eh_func;                                \
};                                                              \
struct __hack

#define EVENTHANDLER_FAST_DEFINE(name, type)                            \
struct eventhandler_list Xeventhandler_list_ ## name = { #name };       \
struct __hack

#define EVENTHANDLER_FAST_INVOKE(name, args...)                         \
do {                                                                    \
    struct eventhandler_list *_el = &Xeventhandler_list_ ## name ;      \
    struct eventhandler_entry *_ep = TAILQ_FIRST(&(_el->el_entries));   \
                                                                        \
    while (_ep != NULL) {                                               \
        ((struct eventhandler_entry_ ## name *)_ep)->eh_func(_ep->ee_arg , ## args); \
        _ep = TAILQ_NEXT(_ep, ee_link);                                 \
    }                                                                   \
} while (0)

#define EVENTHANDLER_FAST_REGISTER(name, func, arg, priority) \
    eventhandler_register(Xeventhandler_list_ ## name, #name, func, arg, priority)

#define EVENTHANDLER_FAST_DEREGISTER(name, tag) \
    eventhandler_deregister(Xeventhandler_list ## name, tag)


/*
 * 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, args...)                              \
do {                                                                    \
    struct eventhandler_list *_el;                                      \
    struct eventhandler_entry *_ep;                                     \
                                                                        \
    if ((_el = eventhandler_find_list(#name)) != NULL) {                \
        for (_ep = TAILQ_FIRST(&(_el->el_entries));                     \
             _ep != NULL;                                               \
             _ep = TAILQ_NEXT(_ep, ee_link)) {                          \
            ((struct eventhandler_entry_ ## name *)_ep)->eh_func(_ep->ee_arg , ## 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)


#ifdef _KERNEL
eventhandler_tag        eventhandler_register(struct eventhandler_list *,
                                              const char *, void *, void *,
                                              int);
void                    eventhandler_deregister(struct eventhandler_list *,
                                                eventhandler_tag);
struct eventhandler_list *eventhandler_find_list(const char *);
#endif /* _KERNEL */

/*
 * Standard system event queues.
 */

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

struct image_params;
struct proc;

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

#define SHUTDOWN_PRI_FIRST      EVENTHANDLER_PRI_FIRST
#define SHUTDOWN_PRI_SECOND     (EVENTHANDLER_PRI_FIRST + 1)
#define SHUTDOWN_PRI_THIRD      (EVENTHANDLER_PRI_FIRST + 2)
#define SHUTDOWN_PRI_DEFAULT    EVENTHANDLER_PRI_ANY
#define SHUTDOWN_PRI_DRIVER     (EVENTHANDLER_PRI_ANY + 5000)
#define SHUTDOWN_PRI_LAST       EVENTHANDLER_PRI_LAST
typedef void (*execlist_fn)(void *, struct image_params *);
typedef void (*exit_list_fn)(void *, struct proc *);

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);

#endif  /* _KERNEL || _KERNEL_STRUCTURES */
#endif  /* !_SYS_EVENTHANDLER_H_ */