/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 2001 by Sun Microsystems, Inc.
 * All rights reserved.
 */

#ifndef _NISDB_RW_H
#define _NISDB_RW_H

#include <pthread.h>
#include <thread.h>
#include <synch.h>
#include <stdlib.h>
#include <malloc.h>
#include <sys/errno.h>

#ifdef  __cplusplus
extern "C" {
#endif

#define INV_PTHREAD_ID  0

/*
 * DEFAULTNISDBRWLOCK_RW is the default initializer that does _not_
 * force read lock requests to write locks, while DEFAULTNISDBRWLOCK_W
 * does force all locks to be exclusive.
 *
 * Locks should be initialized DEFAULTNISDBRWLOCK_W until it's been
 * determined that non-exclusive locking can be safely used; see
 * comments in __nisdb_rwinit() in nisdb_rw.c.
 */
#define DEFAULTNISDBRWLOCK_RW   {DEFAULTMUTEX, DEFAULTCV, 0, 0, \
                                        0, {INV_PTHREAD_ID, 0, 0, 0}, \
                                        0, 0, {INV_PTHREAD_ID, 0, 0, 0}}

#define DEFAULTNISDBRWLOCK_W    {DEFAULTMUTEX, DEFAULTCV, 0, 1, \
                                        0, {INV_PTHREAD_ID, 0, 0, 0}, \
                                        0, 0, {INV_PTHREAD_ID, 0, 0, 0}}

#define DEFAULTNISDBRWLOCK      DEFAULTNISDBRWLOCK_W

/*
 * The value used for the 'force_write' field initialization in
 * __nisdb_rwinit(). Should be one unless it's been determined that
 * read locks can safely be used in for _all_ locks initialized
 * by __nisdb_rwinit().
 */
#define NISDB_FORCE_WRITE       1

#ifdef  NISDB_MT_DEBUG

#define DECLMUTEXLOCK(var)      pthread_mutex_t var ## _pmutex = \
                                        PTHREAD_MUTEX_INITIALIZER; \
                                pthread_t var ## _owner = INV_PTHREAD_ID
#define USEMUTEXLOCK(var)       extern pthread_mutex_t var ## _pmutex; \
                                extern pthread_t var ## _owner
#define STRUCTMUTEXLOCK(var)    pthread_mutex_t var ## _pmutex; \
                                pthread_t var ## _owner
#define INITMUTEX(var)          (void) pthread_mutex_init(&var ## _pmutex, 0)
#define MUTEXLOCK(var, msg)     if (var ## _owner != pthread_self()) { \
                                        pthread_mutex_lock(&var ## _pmutex); \
                                        var ## _owner = pthread_self(); \
                                } else \
                                        abort();
#define MUTEXUNLOCK(var, msg)   if (var ## _owner == pthread_self()) { \
                                        var ## _owner = INV_PTHREAD_ID; \
                                        pthread_mutex_unlock(&var ## _pmutex);\
                                } else \
                                        abort();
#define ASSERTMUTEXHELD(var)    if (var ## _owner != pthread_self()) \
                                        abort();

#define DECLRWLOCK(var)         __nisdb_rwlock_t var ## _rwlock = \
                                                DEFAULTNISDBRWLOCK
#define USERWLOCK(var)          extern __nisdb_rwlock_t var ## _rwlock
#define STRUCTRWLOCK(var)       __nisdb_rwlock_t var ## _rwlock
#define INITRW(var)             (void) __nisdb_rwinit(&var ## _rwlock)
#define READLOCKOK(var)         (void) __nisdb_rw_readlock_ok(&var ## _rwlock)
#define RLOCK(var)              __nisdb_rlock(&var ## _rwlock)
#define WLOCK(var)              __nisdb_wlock(&var ## _rwlock)
#define TRYWLOCK(var)           __nisdb_wlock_trylock(&var ## _rwlock, 1)
#define RULOCK(var)             __nisdb_rulock(&var ## _rwlock)
#define WULOCK(var)             __nisdb_wulock(&var ## _rwlock)
#define DESTROYRW(var)          __nisdb_destroy_lock(&var ## _rwlock)
#define ASSERTWHELD(var)        if (__nisdb_assert_wheld(&var ## _rwlock) \
                                        != 0) \
                                        abort();
#define ASSERTRHELD(var)        if (__nisdb_assert_rheld(&var ## _rwlock) \
                                        != 0) \
                                        abort();

#else   /* NISDB_MT_DEBUG */

#define DECLMUTEXLOCK(var)      pthread_mutex_t var ## _pmutex = \
                                        PTHREAD_MUTEX_INITIALIZER
#define USEMUTEXLOCK(var)       extern pthread_mutex_t var ## _pmutex
#define STRUCTMUTEXLOCK(var)    pthread_mutex_t var ## _pmutex
#define INITMUTEX(var)          (void) pthread_mutex_init(&var ## _pmutex, 0)
#define MUTEXLOCK(var, msg)     pthread_mutex_lock(&var ## _pmutex)
#define MUTEXUNLOCK(var, msg)   pthread_mutex_unlock(&var ## _pmutex)

#define DECLRWLOCK(var)         __nisdb_rwlock_t var ## _rwlock = \
                                                DEFAULTNISDBRWLOCK
#define USERWLOCK(var)          extern __nisdb_rwlock_t var ## _rwlock
#define STRUCTRWLOCK(var)       __nisdb_rwlock_t var ## _rwlock
#define INITRW(var)             (void) __nisdb_rwinit(&var ## _rwlock)
#define READLOCKOK(var)         (void) __nisdb_rw_readlock_ok(&var ## _rwlock)
#define RLOCK(var)              __nisdb_rlock(&var ## _rwlock)
#define WLOCK(var)              __nisdb_wlock(&var ## _rwlock)
#define TRYWLOCK(var)           __nisdb_wlock_trylock(&var ## _rwlock, 1)
#define RULOCK(var)             __nisdb_rulock(&var ## _rwlock)
#define WULOCK(var)             __nisdb_wulock(&var ## _rwlock)
#define DESTROYRW(var)          __nisdb_destroy_lock(&var ## _rwlock)
#define ASSERTMUTEXHELD(var)
#define ASSERTWHELD(var)
#define ASSERTRHELD(var)

#endif  /* NISDB_MT_DEBUG */

/* Nesting-safe RW locking */
typedef struct __nisdb_rwlock {
        pthread_t               id;     /* Which thread */
        uint32_t                count;  /* Lock depth for thread */
        uint32_t                wait;   /* Blocked on mutex */
        struct __nisdb_rwlock   *next;  /* Next reader record */
} __nisdb_rl_t;

typedef struct {
        mutex_t         mutex;          /* Exclusive access to structure */
        cond_t          cv;             /* CV for signaling */
        uint32_t        destroyed;      /* Set if lock has been destroyed */
        uint32_t        force_write;    /* Set if read locks forced to write */
        uint32_t        writer_count;   /* Number of writer threads [0, 1] */
        __nisdb_rl_t    writer;         /* Writer record */
        uint32_t        reader_count;   /* # of reader threads [0, N] */
        uint32_t        reader_blocked; /* # of readers blocked on mutex */
        __nisdb_rl_t    reader;         /* List of reader records */
} __nisdb_rwlock_t;

extern int              __nisdb_rwinit(__nisdb_rwlock_t *);
extern int              __nisdb_rw_readlock_ok(__nisdb_rwlock_t *rw);
extern int              __nisdb_rw_force_writelock(__nisdb_rwlock_t *rw);
extern int              __nisdb_wlock(__nisdb_rwlock_t *);
extern int              __nisdb_wlock_trylock(__nisdb_rwlock_t *, int);
extern int              __nisdb_rlock(__nisdb_rwlock_t *);
extern int              __nisdb_wulock(__nisdb_rwlock_t *);
extern int              __nisdb_rulock(__nisdb_rwlock_t *);
extern int              __nisdb_assert_wheld(__nisdb_rwlock_t *);
extern int              __nisdb_assert_rheld(__nisdb_rwlock_t *);
extern int              __nisdb_destroy_lock(__nisdb_rwlock_t *);
extern void             __nisdb_lock_report(__nisdb_rwlock_t *rw);

#ifdef  __cplusplus
}
#endif

#endif  /* _NISDB_RW_H */