path: root/db/lock/lock_list.c

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996,2007 Oracle.  All rights reserved.
 *
 * $Id: lock_list.c,v 12.12 2007/05/17 15:15:43 bostic Exp $
 */

#include "db_config.h"

#include "db_int.h"
#include "dbinc/lock.h"
#include "dbinc/log.h"

static int __lock_sort_cmp __P((const void *, const void *));

/*
 * Lock list routines.
 *	The list is composed of a 32-bit count of locks followed by
 * each lock.  A lock is represented by a 16-bit page-count, a lock
 * object and a page list.  A lock object consists of a 16-bit size
 * and the object itself.   In a pseudo BNF notation, you get:
 *
 * LIST = COUNT32 LOCK*
 * LOCK = COUNT16 LOCKOBJ PAGELIST
 * LOCKOBJ = COUNT16 OBJ
 * PAGELIST = COUNT32*
 *
 * (Recall that X* means "0 or more X's")
 *
 * In most cases, the OBJ is a struct __db_ilock and the page list is
 * a series of (32-bit) page numbers that should get written into the
 * pgno field of the __db_ilock.  So, the actual number of pages locked
 * is the number of items in the PAGELIST plus 1. If this is an application-
 * specific lock, then we cannot interpret obj and the pagelist must
 * be empty.
 *
 * Consider a lock list for: File A, pages 1&2, File B pages 3-5, Applock
 * This would be represented as:
 *	5 1 [fid=A;page=1] 2 2 [fid=B;page=3] 4 5 0 APPLOCK
 *        ------------------ -------------------- ---------
 *         LOCK for file A    LOCK for file B     application-specific lock
 */

#define	MAX_PGNOS	0xffff

/*
 * These macros are bigger than one might expect because some compilers say a
 * cast does not return an lvalue, so constructs like *(u_int32_t*)dp = count;
 * generate warnings.
 */
#define	RET_SIZE(size, count)  ((size) +				\
     sizeof(u_int32_t) + (count) * 2 * sizeof(u_int16_t))

#define	PUT_COUNT(dp, count)	do {	u_int32_t *ip = (u_int32_t *)dp;\
					*ip = count;			\
					dp = (u_int8_t *)dp +		\
					     sizeof(u_int32_t);		\
				} while (0)
#define	PUT_PCOUNT(dp, count)	do {	u_int16_t *ip = (u_int16_t *)dp;\
					*ip = count;			\
					dp = (u_int8_t *)dp +		\
					    sizeof(u_int16_t);		\
				} while (0)
#define	PUT_SIZE(dp, size)	do {	u_int16_t *ip = (u_int16_t *)dp;\
					*ip = size;			\
					dp = (u_int8_t *)dp +		\
					    sizeof(u_int16_t);		\
				} while (0)
#define	PUT_PGNO(dp, pgno)	do {	db_pgno_t *ip = (db_pgno_t *)dp;\
					*ip = pgno;			\
					dp = (u_int8_t *)dp +		\
					    sizeof(db_pgno_t);		\
				} while (0)
#define	COPY_OBJ(dp, obj)	do {					\
					memcpy(dp,			\
					    (obj)->data, (obj)->size);  \
					dp = (u_int8_t *)dp +		\
					     DB_ALIGN((obj)->size,	\
					     sizeof(u_int32_t));	\
				} while (0)
#define	GET_COUNT(dp, count)	do {					\
					(count) = *(u_int32_t *)dp;	\
					dp = (u_int8_t *)dp +		\
					     sizeof(u_int32_t);	\
				} while (0)
#define	GET_PCOUNT(dp, count)	do {					\
					(count) = *(u_int16_t *)dp;	\
					dp = (u_int8_t *)dp +		\
					     sizeof(u_int16_t);	\
				} while (0)
#define	GET_SIZE(dp, size)	do {					\
					(size) = *(u_int16_t *)dp;	\
					dp = (u_int8_t *)dp +		\
					     sizeof(u_int16_t);	\
				} while (0)
#define	GET_PGNO(dp, pgno)	do {					\
					(pgno) = *(db_pgno_t *)dp;	\
					dp = (u_int8_t *)dp +		\
					     sizeof(db_pgno_t);	\
				} while (0)

/*
 * __lock_fix_list --
 *
 * PUBLIC: int __lock_fix_list __P((DB_ENV *, DBT *, u_int32_t));
 */
int
__lock_fix_list(dbenv, list_dbt, nlocks)
	DB_ENV *dbenv;
	DBT *list_dbt;
	u_int32_t nlocks;
{
	DBT *obj;
	DB_LOCK_ILOCK *lock, *plock;
	u_int32_t i, j, nfid, npgno, size;
	u_int8_t *data, *dp;
	int ret;

	if ((size = list_dbt->size) == 0)
		return (0);

	obj = (DBT *)list_dbt->data;

	/*
	 * If necessary sort the list of locks so that locks on the same fileid
	 * are together.  We do not sort 1 or 2 locks because by definition if
	 * there are locks on the same fileid they will be together.  The sort
	 * will also move any locks that do not look like page locks to the end
	 * of the list so we can stop looking for locks we can combine when we
	 * hit one.
	 */
	switch (nlocks) {
	case 1:
		size = RET_SIZE(obj->size, 1);
		if ((ret = __os_malloc(dbenv, size, &data)) != 0)
			return (ret);

		dp = data;
		PUT_COUNT(dp, 1);
		PUT_PCOUNT(dp, 0);
		PUT_SIZE(dp, obj->size);
		COPY_OBJ(dp, obj);
		break;
	default:
		/* Sort so that all locks with same fileid are together. */
		qsort(list_dbt->data, nlocks, sizeof(DBT), __lock_sort_cmp);
		/* FALLTHROUGH */
	case 2:
		nfid = npgno = 0;
		i = 0;
		if (obj->size != sizeof(DB_LOCK_ILOCK))
			goto not_ilock;

		nfid = 1;
		plock = (DB_LOCK_ILOCK *)obj->data;

		/* We use ulen to keep track of the number of pages. */
		j = 0;
		obj[0].ulen = 0;
		for (i = 1; i < nlocks; i++) {
			if (obj[i].size != sizeof(DB_LOCK_ILOCK))
				break;
			lock = (DB_LOCK_ILOCK *)obj[i].data;
			if (obj[j].ulen < MAX_PGNOS &&
			     lock->type == plock->type &&
			     memcmp(lock->fileid,
			     plock->fileid, DB_FILE_ID_LEN) == 0) {
				obj[j].ulen++;
				npgno++;
			} else {
				nfid++;
				plock = lock;
				j = i;
				obj[j].ulen = 0;
			}
		}

not_ilock:	size = nfid * sizeof(DB_LOCK_ILOCK);
		size += npgno * sizeof(db_pgno_t);
		/* Add the number of nonstandard locks and get their size. */
		nfid += nlocks - i;
		for (; i < nlocks; i++) {
			size += obj[i].size;
			obj[i].ulen = 0;
		}

		size = RET_SIZE(size, nfid);
		if ((ret = __os_malloc(dbenv, size, &data)) != 0)
			return (ret);

		dp = data;
		PUT_COUNT(dp, nfid);

		for (i = 0; i < nlocks; i = j) {
			PUT_PCOUNT(dp, obj[i].ulen);
			PUT_SIZE(dp, obj[i].size);
			COPY_OBJ(dp, &obj[i]);
			lock = (DB_LOCK_ILOCK *)obj[i].data;
			for (j = i + 1; j <= i + obj[i].ulen; j++) {
				lock = (DB_LOCK_ILOCK *)obj[j].data;
				PUT_PGNO(dp, lock->pgno);
			}
		}
	}

	__os_free(dbenv, list_dbt->data);

	list_dbt->data = data;
	list_dbt->size = size;

	return (0);
}

/*
 * PUBLIC: int __lock_get_list __P((DB_ENV *, DB_LOCKER *, u_int32_t,
 * PUBLIC:	      db_lockmode_t, DBT *));
 */
int
__lock_get_list(dbenv, locker, flags, lock_mode, list)
	DB_ENV *dbenv;
	DB_LOCKER *locker;
	u_int32_t flags;
	db_lockmode_t lock_mode;
	DBT *list;
{
	DBT obj_dbt;
	DB_LOCK ret_lock;
	DB_LOCK_ILOCK *lock;
	DB_LOCKTAB *lt;
	db_pgno_t save_pgno;
	u_int16_t npgno, size;
	u_int32_t i, nlocks;
	int ret;
	void *data, *dp;

	if (list->size == 0)
		return (0);
	ret = 0;
	data = NULL;

	lt = dbenv->lk_handle;
	dp = list->data;

	/*
	 * There is no assurance log records will be aligned.  If not, then
	 * copy the data to an aligned region so the rest of the code does
	 * not have to worry about it.
	 */
	if ((uintptr_t)dp != DB_ALIGN((uintptr_t)dp, sizeof(u_int32_t))) {
		if ((ret = __os_malloc(dbenv, list->size, &data)) != 0)
			return (ret);
		memcpy(data, list->data, list->size);
		dp = data;
	}

	GET_COUNT(dp, nlocks);
	LOCK_SYSTEM_LOCK(dbenv);

	for (i = 0; i < nlocks; i++) {
		GET_PCOUNT(dp, npgno);
		GET_SIZE(dp, size);
		lock = (DB_LOCK_ILOCK *) dp;
		save_pgno = lock->pgno;
		obj_dbt.data = dp;
		obj_dbt.size = size;
		dp = ((u_int8_t *)dp) + DB_ALIGN(size, sizeof(u_int32_t));
		do {
			if ((ret = __lock_get_internal(lt, locker,
			     flags, &obj_dbt, lock_mode, 0, &ret_lock)) != 0) {
			     lock->pgno = save_pgno;
			     goto err;
			}
			if (npgno != 0)
				GET_PGNO(dp, lock->pgno);
		} while (npgno-- != 0);
		lock->pgno = save_pgno;
	}

err:	LOCK_SYSTEM_UNLOCK(dbenv);
	if (data != NULL)
		__os_free(dbenv, data);
	return (ret);
}

#define	UINT32_CMP(A, B)	((A) == (B) ? 0 : ((A) > (B) ? 1 : -1))
static int
__lock_sort_cmp(a, b)
	const void *a, *b;
{
	const DBT *d1, *d2;
	DB_LOCK_ILOCK *l1, *l2;

	d1 = a;
	d2 = b;

	/* Force all non-standard locks to sort at end. */
	if (d1->size != sizeof(DB_LOCK_ILOCK)) {
		if (d2->size != sizeof(DB_LOCK_ILOCK))
			return (UINT32_CMP(d1->size, d2->size));
		else
			return (1);
	} else if (d2->size != sizeof(DB_LOCK_ILOCK))
		return (-1);

	l1 = d1->data;
	l2 = d2->data;
	if (l1->type != l2->type)
		return (UINT32_CMP(l1->type, l2->type));
	return (memcmp(l1->fileid, l2->fileid, DB_FILE_ID_LEN));
}

/*
 * PUBLIC: void __lock_list_print __P((DB_ENV *, DBT *));
 */
void
__lock_list_print(dbenv, list)
	DB_ENV *dbenv;
	DBT *list;
{
	DB_LOCK_ILOCK *lock;
	db_pgno_t pgno;
	u_int16_t npgno, size;
	u_int32_t i, nlocks;
	u_int8_t *fidp;
	char *namep;
	void *dp;

	if (list->size == 0)
		return;
	dp = list->data;

	GET_COUNT(dp, nlocks);

	for (i = 0; i < nlocks; i++) {
		GET_PCOUNT(dp, npgno);
		GET_SIZE(dp, size);
		lock = (DB_LOCK_ILOCK *) dp;
		fidp = lock->fileid;
		if (__dbreg_get_name(dbenv, fidp, &namep) != 0)
			namep = NULL;
		printf("\t");
		if (namep == NULL)
			printf("(%lx %lx %lx %lx %lx)",
			(u_long)fidp[0], (u_long)fidp[1], (u_long)fidp[2],
			(u_long)fidp[3], (u_long)fidp[4]);
		else
			printf("%-25s", namep);
		dp = ((u_int8_t *)dp) + DB_ALIGN(size, sizeof(u_int32_t));
		pgno = lock->pgno;
		do {
			printf(" %d", pgno);
			if (npgno != 0)
				GET_PGNO(dp, pgno);
		} while (npgno-- != 0);
		printf("\n");
	}
}