extra-dependencies/debian/htdig/htdig-3.2.0b6/db/lock.h

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996, 1997, 1998, 1999
 *	Sleepycat Software.  All rights reserved.
 *
 *	@(#)lock.h	11.5 (Sleepycat) 10/27/99
 */

#ifndef DB_LOCK_DEFAULT_N
#define DB_LOCK_DEFAULT_N	1000	/* Default # of locks in region. */
#endif

/*
 * Out of band value for a lock.  Locks contain an offset into a lock region,
 * so we use an invalid region offset to indicate an invalid or unset lock.
 */
#define	LOCK_INVALID	INVALID_ROFF

/*
 * The locker id space is divided between the transaction manager and the lock
 * manager.  Lock IDs start at 0 and go to DB_LOCK_MAXID.  Txn IDs start at
 * DB_LOCK_MAXID + 1 and go up to TXN_INVALID.
 */
#define DB_LOCK_MAXID		0x7fffffff

/*
 * DB_LOCKREGION --
 *	The lock shared region.
 */
typedef struct __db_lockregion {
	u_int32_t	id;		/* unique id generator */
	u_int32_t	need_dd;	/* flag for deadlock detector */
	u_int32_t	detect;		/* run dd on every conflict */
					/* free lock header */
	SH_TAILQ_HEAD(__flock) free_locks;
					/* free obj header */
	SH_TAILQ_HEAD(__fobj) free_objs;
					/* free locker header */
	SH_TAILQ_HEAD(__flocker) free_lockers;
	u_int32_t	maxlocks;	/* maximum number of locks in table */
	u_int32_t	table_size;	/* size of hash table */
	u_int32_t	nmodes;		/* number of lock modes */
	u_int32_t	nlockers;	/* number of lockers */
	u_int32_t	maxnlockers;	/* maximum number of lockers */
	roff_t		memlock_off;	/* offset of memory mutex */
	roff_t		conf_off;	/* offset of conflicts array */
	roff_t		obj_off;	/* offset of object hash table */
	roff_t		osynch_off;	/* offset of the object mutex table */
	roff_t		locker_off;	/* offset of locker hash table */
	roff_t		lsynch_off;	/* offset of the locker mutex table */
	u_int32_t	nconflicts;	/* number of lock conflicts */
	u_int32_t	nrequests;	/* number of lock gets */
	u_int32_t	nreleases;	/* number of lock puts */
	u_int32_t	ndeadlocks;	/* number of deadlocks */
} DB_LOCKREGION;

/*
 * Since we will store DBTs in shared memory, we need the equivalent of a
 * DBT that will work in shared memory.
 */
typedef struct __sh_dbt {
	u_int32_t size;			/* Byte length. */
	ssize_t   off;			/* Region offset. */
} SH_DBT;

#define SH_DBT_PTR(p)	((void *)(((u_int8_t *)(p)) + (p)->off))

/*
 * Object structures;  these live in the object hash table.
 */
typedef struct __db_lockobj {
	SH_DBT	lockobj;		/* Identifies object locked. */
	SH_TAILQ_ENTRY links;		/* Links for free list. */
	SH_TAILQ_HEAD(__wait) waiters;	/* List of waiting locks. */
	SH_TAILQ_HEAD(__hold) holders;	/* List of held locks. */
					/* Declare room in the object to hold
					 * typical DB lock structures so that
					 * we do not have to allocate them from
					 * shalloc at run-time. */
	u_int8_t objdata[sizeof(struct __db_ilock)];
} DB_LOCKOBJ;

/*
 * Locker structures; these live in the locker hash table.
 */
typedef struct __db_locker {
	u_int32_t id;			/* Locker id. */
	u_int32_t dd_id;		/* Deadlock detector id. */
	size_t master_locker; 		/* Locker of master transaction. */
	size_t parent_locker;		/* Parent of this child. */
        SH_LIST_HEAD(_child) child_locker; 	/* List of descendant txns;
						   only used in a "master"
						   txn. */
        SH_LIST_ENTRY child_link; 	/* Links transactions in the family;
					   elements of the child_locker
					   list. */
	SH_TAILQ_ENTRY links;		/* Links for free list. */
	SH_LIST_HEAD(_held) heldby;	/* Locks held by this locker. */

#define DB_LOCKER_DELETED	0x0001
	u_int32_t flags;
} DB_LOCKER;

/*
 * Lockers can be freed if they are not poart of a transaction
 * family.  Members of a family either point at the master
 * transaction or are the master transaction and have
 * children lockers.
 */
#define LOCKER_FREEABLE(lp)	((lp)->master_locker 			\
			 == TXN_INVALID_ID && 			\
			SH_LIST_FIRST(&(lp)->child_locker, __db_locker) \
			 == NULL)

/*
 * DB_LOCKTAB --
 *	The primary library lock data structure (i.e., the one referenced
 * by the environment, as opposed to the internal one laid out in the region.)
 */
typedef struct __db_locktab {
	DB_ENV		*dbenv;		/* Environment. */
	REGINFO		 reginfo;	/* Region information. */
	MUTEX		*memlock;	/* Mutex to protect memory alloc. */
	u_int8_t 	*conflicts;	/* Pointer to conflict matrix. */
	DB_HASHTAB 	*obj_tab; 	/* Beginning of object hash table. */
	MUTEX		*osynch_tab;	/* Object mutex table. */
	DB_HASHTAB 	*locker_tab; 	/* Beginning of locker hash table. */
	MUTEX		*lsynch_tab;	/* Locker mutex table. */
} DB_LOCKTAB;

/* Test for conflicts. */
#define CONFLICTS(T, R, HELD, WANTED) \
	(T)->conflicts[(HELD) * (R)->nmodes + (WANTED)]

#define OBJ_LINKS_VALID(L) ((L)->links.stqe_prev != -1)

struct __db_lock {
	/*
	 * Wait on mutex to wait on lock.  You reference your own mutex with
	 * ID 0 and others reference your mutex with ID 1.
	 */
	MUTEX		mutex;

	u_int32_t	holder;		/* Who holds this lock. */
	u_int32_t	gen;		/* Generation count. */
	SH_TAILQ_ENTRY	links;		/* Free or holder/waiter list. */
	SH_LIST_ENTRY	locker_links;	/* List of locks held by a locker. */
	u_int32_t	refcount;	/* Reference count the lock. */
	db_lockmode_t	mode;		/* What sort of lock. */
	ssize_t		obj;		/* Relative offset of object struct. */
	roff_t		txnoff;		/* Offset of holding transaction. */
	db_status_t	status;		/* Status of this lock. */
};

/*
 * This is a serious layering violation.  To support nested transactions, we
 * need to be able to tell that a lock is held by a transaction (as opposed to
 * some other locker) and to be able to traverse the parent/descendent chain.
 * In order to do this, each lock held by a transaction maintains a reference
 * to the shared memory transaction structure so it can be accessed during lock
 * promotion.  As the structure is in shared memory, we cannot store a pointer
 * to it, so we use the offset within the region.  An invalid region offset is
 * used to indicate that there is no transaction associated with the current
 * lock.
 */
#define TXN_IS_HOLDING(L)	((L)->txnoff != INVALID_ROFF)

/*
 * Flag values for CDB___lock_put_internal:
 * DB_LOCK_DOALL:     Unlock all references in this lock (instead of only 1).
 * DB_LOCK_FREE:      Free the lock (used in checklocker).
 * DB_LOCK_IGNOREDEL: Remove from the locker hash table even if already
		      deleted (used in checklocker).
 * DB_LOCK_NOPROMOTE: Don't bother running promotion when releasing locks
 *		      (used by CDB___lock_put_internal).
 * DB_LOCK_UNLINK:    Remove from the locker links (used in checklocker).
 */
#define	DB_LOCK_DOALL		0x001
#define	DB_LOCK_FREE		0x002
#define	DB_LOCK_IGNOREDEL	0x004
#define	DB_LOCK_NOPROMOTE	0x008
#define	DB_LOCK_UNLINK		0x010

/*
 * Macros to get/release different types of mutexes.
 */
#define OBJECT_LOOKUP(lt, ndx, dbt, sh_obj)				\
	HASHLOOKUP((lt)->objtab,					\
	    ndx, __db_lockobj, links, dbt, sh_obj, CDB___lock_cmp);

#ifdef FINE_GRAIN
#define OBJECT_LOCK_NDX(lt, ndx)					\
	MUTEX_LOCK(&(lt)->osynch_tab[ndx], (lt)->dbenv->lockfhp)
#define OBJECT_LOCK(lt, reg, obj, ndx) 					\
	HASHACCESS((lt)->osynch_tab, obj,				\
	    (reg)->table_size, CDB___lock_ohash, ndx, (lt)->dbenv->lockfhp)
#define SHOBJECT_LOCK(lt, reg, shobj, ndx)				\
	HASHACCESS((lt)->osynch_tab, shobj,				\
	    (reg)->table_size, CDB___lock_lhash, ndx, (lt)->dbenv->lockfhp)
#define	OBJECT_UNLOCK(lt, ndx)						\
	MUTEX_UNLOCK(&(lt)->osynch_tab[ndx])
#else
#define	OBJECT_LOCK_NDX(lt, ndx)
#define OBJECT_LOCK(lt, reg, obj, ndx) 					\
	ndx = CDB___lock_ohash(obj) % (reg)->table_size
#define SHOBJECT_LOCK(lt, reg, shobj, ndx)				\
	ndx = CDB___lock_lhash(shobj) % (reg)->table_size
#define	OBJECT_UNLOCK(lt, ndx)
#endif

#define LOCKER_LOOKUP(lt, ndx, locker, sh_locker)			\
	HASHLOOKUP((lt)->lockertab,					\
	    ndx, __db_locker, links, locker, sh_locker, CDB___lock_locker_cmp);

#ifdef FINE_GRAIN
#define	LOCKER_LOCK_NDX(lt, ndx)					\
	MUTEX_LOCK(&(lt)->lsynch_tab[ndx], (lt)->dbenv->lockfhp)
#define	LOCKER_LOCK(lt, reg, locker, ndx)				\
	HASHACCESS((lt)->lsynch_tab, locker,				\
	    reg->table_size, CDB___lock_locker_hash, ndx, (lt)->dbenv->lockfhp)
#define	LOCKER_UNLOCK(lt, ndx)						\
	MUTEX_UNLOCK(&(lt)->lsynch_tab[ndx])

#define MEMORY_LOCK(lt)							\
	MUTEX_LOCK((lt)->memlock, (lt)->dbenv->lockfhp)
#define MEMORY_UNLOCK(lt)						\
	MUTEX_UNLOCK((lt)->memlock)
#else
#define	LOCKER_LOCK_NDX(lt, ndx)
#define	LOCKER_LOCK(lt, reg, locker, ndx)				\
	ndx = CDB___lock_locker_hash(locker) % (reg)->table_size
#define	LOCKER_UNLOCK(lt, ndx)
#define MEMORY_LOCK(lt)
#define MEMORY_UNLOCK(lt)
#endif

#ifdef FINE_GRAIN
#define	LOCKREGION(dbenv, lt)
#define	UNLOCKREGION(dbenv, lt)
#else
#define	LOCKREGION(dbenv, lt)  R_LOCK((dbenv), &(lt)->reginfo)
#define	UNLOCKREGION(dbenv, lt)  R_UNLOCK((dbenv), &(lt)->reginfo)
#endif
#include "lock_ext.h"