idl.c

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/* idl.c - ldap id list handling routines */
/* $OpenLDAP: pkg/ldap/servers/slapd/back-ldbm/idl.c,v 1.29.2.8 2001/10/01 19:20:30 kurt Exp $ */
/*
 * Copyright 1998-2000 The OpenLDAP Foundation, All Rights Reserved.
 * COPYING RESTRICTIONS APPLY, see COPYRIGHT file
 */

#include "portable.h"

#include <stdio.h>

#include <ac/string.h>
#include <ac/socket.h>

#include "slap.h"
#include "back-ldbm.h"

static ID_BLOCK* idl_dup( ID_BLOCK *idl );

static void cont_alloc( Datum *cont, Datum *key )
{
	ldbm_datum_init( *cont );
	cont->dsize = 1 + sizeof(ID) + key->dsize;
	cont->dptr = ch_malloc( cont->dsize );

	* (unsigned char *) cont->dptr = SLAP_INDEX_CONT_PREFIX;

	AC_MEMCPY( &((unsigned char *)cont->dptr)[1 + sizeof(ID)],
		key->dptr, key->dsize );
}

static void cont_id( Datum *cont, ID id )
{
	int i;

	for( i=1; i <= sizeof(id); i++) {
		((unsigned char *)cont->dptr)[i] = (unsigned char)(id & 0xFF);
		id >>= 8;
	}

}

static void cont_free( Datum *cont )
{
	ch_free( cont->dptr );
}

#ifdef LDBM_DEBUG_IDL
static void idl_check(ID_BLOCK *idl)
{
	int i;
	ID_BLOCK last;

	if( ID_BLOCK_INDIRECT(idl) || ID_BLOCK_ALLIDS(idl)
		|| ID_BLOCK_NIDS(idl) <= 1 )
	{
		return;
	}

	for( last = ID_BLOCK_ID(idl, 0), i = 1;
		i < ID_BLOCK_NIDS(idl);
		last = ID_BLOCK_ID(idl, i), i++ )
	{
		assert (last < ID_BLOCK_ID(idl, i) );
	}
}
#endif

/* Allocate an ID_BLOCK with room for nids ids */
ID_BLOCK *
idl_alloc( unsigned int nids )
{
	ID_BLOCK	*new;

	/* nmax + nids + space for the ids */
	new = (ID_BLOCK *) ch_calloc( (ID_BLOCK_IDS_OFFSET + nids), sizeof(ID) );
	ID_BLOCK_NMAX(new) = nids;
	ID_BLOCK_NIDS(new) = 0;

	return( new );
}


/* Allocate an empty ALLIDS ID_BLOCK */
ID_BLOCK	*
idl_allids( Backend *be )
{
	ID_BLOCK	*idl;
	ID		id;

	idl = idl_alloc( 0 );
	ID_BLOCK_NMAX(idl) = ID_BLOCK_ALLIDS_VALUE;
	if ( next_id_get( be, &id ) ) {
		return NULL;
	}
	ID_BLOCK_NIDS(idl) = id;

	return( idl );
}

/* Free an ID_BLOCK */
void
idl_free( ID_BLOCK *idl )
{
	if ( idl == NULL ) {
		Debug( LDAP_DEBUG_TRACE,
			"idl_free: called with NULL pointer\n",
			0, 0, 0 );
		return;
	}

	free( (char *) idl );
}


/* Fetch an single ID_BLOCK from the cache */
static ID_BLOCK *
idl_fetch_one(
    Backend		*be,
    DBCache	*db,
    Datum		key
)
{
	Datum	data;
	ID_BLOCK	*idl;

	/* Debug( LDAP_DEBUG_TRACE, "=> idl_fetch_one\n", 0, 0, 0 ); */

	data = ldbm_cache_fetch( db, key );

	if( data.dptr == NULL ) {
		return NULL;
	}

	idl = idl_dup((ID_BLOCK *) data.dptr);

	ldbm_datum_free( db->dbc_db, data );

	return idl;
}


/* Fetch a set of ID_BLOCKs from the cache
 *	if not INDIRECT
 * 		if block return is an ALLIDS block,
 *			return an new ALLIDS block
 * 		otherwise
 *			return block
 *	construct super block from all blocks referenced by INDIRECT block
 *	return super block
 */
ID_BLOCK *
idl_fetch(
    Backend		*be,
    DBCache	*db,
    Datum		key
)
{
	Datum	data;
	ID_BLOCK	*idl;
	ID_BLOCK	**tmp;
	int	i, nids;

	idl = idl_fetch_one( be, db, key );

	if ( idl == NULL ) {
		return NULL;
	}

	if ( ID_BLOCK_ALLIDS(idl) ) {
		/* all ids block */
		/* make sure we have the current value of highest id */
		idl_free( idl );
		idl = idl_allids( be );

		return( idl );
	}

	if ( ! ID_BLOCK_INDIRECT( idl ) ) {
		/* regular block */
		return( idl );
	}

	/*
	 * this is an indirect block which points to other blocks.
	 * we need to read in all the blocks it points to and construct
	 * a big id list containing all the ids, which we will return.
	 */

	/* count the number of blocks & allocate space for pointers to them */
	for ( i = 0; !ID_BLOCK_NOID(idl, i); i++ )
		;	/* NULL */
	tmp = (ID_BLOCK **) ch_malloc( (i + 1) * sizeof(ID_BLOCK *) );

	/* read in all the blocks */
	cont_alloc( &data, &key );
	nids = 0;
	for ( i = 0; !ID_BLOCK_NOID(idl, i); i++ ) {
		cont_id( &data, ID_BLOCK_ID(idl, i) );

		if ( (tmp[i] = idl_fetch_one( be, db, data )) == NULL ) {
			Debug( LDAP_DEBUG_ANY,
			    "idl_fetch: one returned NULL\n", 0, 0, 0 );
			continue;
		}

		nids += ID_BLOCK_NIDS(tmp[i]);
	}
	tmp[i] = NULL;
	cont_free( &data );
	idl_free( idl );

	/* allocate space for the big block */
	idl = idl_alloc( nids );
	ID_BLOCK_NIDS(idl) = nids;
	nids = 0;

	/* copy in all the ids from the component blocks */
	for ( i = 0; tmp[i] != NULL; i++ ) {
		if ( tmp[i] == NULL ) {
			continue;
		}

		AC_MEMCPY(
			(char *) &ID_BLOCK_ID(idl, nids),
			(char *) &ID_BLOCK_ID(tmp[i], 0),
			ID_BLOCK_NIDS(tmp[i]) * sizeof(ID) );
		nids += ID_BLOCK_NIDS(tmp[i]);

		idl_free( tmp[i] );
	}
	free( (char *) tmp );

#ifdef LDBM_DEBUG_IDL
	idl_check(idl);
#endif

	Debug( LDAP_DEBUG_TRACE, "<= idl_fetch %ld ids (%ld max)\n",
	       ID_BLOCK_NIDS(idl), ID_BLOCK_NMAX(idl), 0 );
	return( idl );
}


/* store a single block */
static int
idl_store(
    Backend		*be,
    DBCache	*db,
    Datum		key, 
    ID_BLOCK		*idl
)
{
	int	rc, flags;
	Datum	data;
	struct ldbminfo *li = (struct ldbminfo *) be->be_private;

#ifdef LDBM_DEBUG_IDL
	idl_check(idl);
#endif

	ldbm_datum_init( data );

	/* Debug( LDAP_DEBUG_TRACE, "=> idl_store\n", 0, 0, 0 ); */

	data.dptr = (char *) idl;
	data.dsize = (ID_BLOCK_IDS_OFFSET + ID_BLOCK_NMAX(idl)) * sizeof(ID);
	
#ifdef LDBM_DEBUG
	Statslog( LDAP_DEBUG_STATS, "<= idl_store(): rc=%d\n",
		rc, 0, 0, 0, 0 );
#endif

	flags = LDBM_REPLACE;
	rc = ldbm_cache_store( db, key, data, flags );

	/* Debug( LDAP_DEBUG_TRACE, "<= idl_store %d\n", rc, 0, 0 ); */
	return( rc );
}

/* split the block at id 
 *	locate ID greater than or equal to id.
 */
static void
idl_split_block(
    ID_BLOCK	*b,
    ID		id,
    ID_BLOCK	**right,
    ID_BLOCK	**left
)
{
	unsigned int	nr, nl;

	/* find where to split the block *//* XXX linear search XXX */
	for ( nr = 0; nr < ID_BLOCK_NIDS(b) && id > ID_BLOCK_ID(b, nr); nr++ )
		;	/* NULL */

	nl = ID_BLOCK_NIDS(b) - nr;

	*right = idl_alloc( nr == 0 ? 1 : nr );
	*left = idl_alloc( nl + (nr == 0 ? 0 : 1));

	/*
	 * everything before the id being inserted in the first block
	 * unless there is nothing, in which case the id being inserted
	 * goes there.
	 */
	if ( nr == 0 ) {
		ID_BLOCK_NIDS(*right) = 1;
		ID_BLOCK_ID(*right, 0) = id;
	} else {
		AC_MEMCPY(
			(char *) &ID_BLOCK_ID(*right, 0),
			(char *) &ID_BLOCK_ID(b, 0),
			nr * sizeof(ID) );
		ID_BLOCK_NIDS(*right) = nr;
		ID_BLOCK_ID(*left, 0) = id;
	}

	/* the id being inserted & everything after in the second block */
	AC_MEMCPY(
		(char *) &ID_BLOCK_ID(*left, (nr == 0 ? 0 : 1)),
	    (char *) &ID_BLOCK_ID(b, nr),
		nl * sizeof(ID) );
	ID_BLOCK_NIDS(*left) = nl + (nr == 0 ? 0 : 1);

#ifdef LDBM_DEBUG_IDL
	idl_check(*right);
	idl_check(*left);
#endif
}


/*
 * idl_change_first - called when an indirect block's first key has
 * changed, meaning it needs to be stored under a new key, and the
 * header block pointing to it needs updating.
 */
static int
idl_change_first(
    Backend		*be,
    DBCache	*db,
    Datum		hkey,		/* header block key	*/
    ID_BLOCK		*h,		/* header block 	*/
    int			pos,		/* pos in h to update	*/
    Datum		bkey,		/* data block key	*/
    ID_BLOCK		*b		/* data block 		*/
)
{
	int	rc;

	/* Debug( LDAP_DEBUG_TRACE, "=> idl_change_first\n", 0, 0, 0 ); */

	/* delete old key block */
	if ( (rc = ldbm_cache_delete( db, bkey )) != 0 ) {
		Debug( LDAP_DEBUG_ANY,
		    "idl_change_first: ldbm_cache_delete returned %d\n",
			rc, 0, 0 );
		return( rc );
	}

	/* write block with new key */
	cont_id( &bkey, ID_BLOCK_ID(b, 0) );

	if ( (rc = idl_store( be, db, bkey, b )) != 0 ) {
		Debug( LDAP_DEBUG_ANY,
		    "idl_change_first: idl_store returned %d\n", rc, 0, 0 );
		return( rc );
	}

	/* update + write indirect header block */
	ID_BLOCK_ID(h, pos) = ID_BLOCK_ID(b, 0);
	if ( (rc = idl_store( be, db, hkey, h )) != 0 ) {
		Debug( LDAP_DEBUG_ANY,
		    "idl_change_first: idl_store returned %d\n", rc, 0, 0 );
		return( rc );
	}

	return( 0 );
}


int
idl_insert_key(
    Backend		*be,
    DBCache	*db,
    Datum		key,
    ID			id
)
{
	int	i, j, first, rc;
	ID_BLOCK	*idl, *tmp, *tmp2, *tmp3;
	Datum	k2;

	if ( (idl = idl_fetch_one( be, db, key )) == NULL ) {
		idl = idl_alloc( 1 );
		ID_BLOCK_ID(idl, ID_BLOCK_NIDS(idl)++) = id;
		rc = idl_store( be, db, key, idl );

		idl_free( idl );
		return( rc );
	}

	if ( ID_BLOCK_ALLIDS( idl ) ) {
		/* ALLIDS */
		idl_free( idl );
		return 0;
	}

	if ( ! ID_BLOCK_INDIRECT( idl ) ) {
		/* regular block */
		switch ( idl_insert( &idl, id, db->dbc_maxids ) ) {
		case 0:		/* id inserted - store the updated block */
		case 1:
			rc = idl_store( be, db, key, idl );
			break;

		case 2:		/* id already there - nothing to do */
			rc = 0;
			break;

		case 3:		/* id not inserted - block must be split */
			/* check threshold for marking this an all-id block */
			if ( db->dbc_maxindirect < 2 ) {
				idl_free( idl );
				idl = idl_allids( be );
				rc = idl_store( be, db, key, idl );
				break;
			}

			idl_split_block( idl, id, &tmp, &tmp2 );
			idl_free( idl );

			/* create the header indirect block */
			idl = idl_alloc( 3 );
			ID_BLOCK_NMAX(idl) = 3;
			ID_BLOCK_NIDS(idl) = ID_BLOCK_INDIRECT_VALUE;
			ID_BLOCK_ID(idl, 0) = ID_BLOCK_ID(tmp, 0);
			ID_BLOCK_ID(idl, 1) = ID_BLOCK_ID(tmp2, 0);
			ID_BLOCK_ID(idl, 2) = NOID;

			/* store it */
			rc = idl_store( be, db, key, idl );

			cont_alloc( &k2, &key );
			cont_id( &k2, ID_BLOCK_ID(tmp, 0) );

			rc = idl_store( be, db, k2, tmp );

			cont_id( &k2, ID_BLOCK_ID(tmp2, 0) );
			rc = idl_store( be, db, k2, tmp2 );

			cont_free( &k2 );

			idl_free( tmp );
			idl_free( tmp2 );
			break;
		}

		idl_free( idl );
		return( rc );
	}

	/*
	 * this is an indirect block which points to other blocks.
	 * we need to read in the block into which the id should be
	 * inserted, then insert the id and store the block.  we might
	 * have to split the block if it is full, which means we also
	 * need to write a new "header" block.
	 */

	/* select the block to try inserting into *//* XXX linear search XXX */
	for ( i = 0; !ID_BLOCK_NOID(idl, i) && id > ID_BLOCK_ID(idl, i); i++ )
		;	/* NULL */

	if ( i != 0 ) {
		i--;
		first = 0;
	} else {
		first = 1;
	}

	/* get the block */
	cont_alloc( &k2, &key );
	cont_id( &k2, ID_BLOCK_ID(idl, i) );

	if ( (tmp = idl_fetch_one( be, db, k2 )) == NULL ) {
		Debug( LDAP_DEBUG_ANY, "idl_insert_key: nonexistent continuation block\n",
		    0, 0, 0 );
		cont_free( &k2 );
		idl_free( idl );
		return( -1 );
	}

	/* insert the id */
	switch ( idl_insert( &tmp, id, db->dbc_maxids ) ) {
	case 0:		/* id inserted ok */
		if ( (rc = idl_store( be, db, k2, tmp )) != 0 ) {
			Debug( LDAP_DEBUG_ANY,
			    "idl_insert_key: idl_store returned %d\n", rc, 0, 0 );
		}
		break;

	case 1:		/* id inserted - first id in block has changed */
		/*
		 * key for this block has changed, so we have to
		 * write the block under the new key, delete the
		 * old key block + update and write the indirect
		 * header block.
		 */

		rc = idl_change_first( be, db, key, idl, i, k2, tmp );
		break;

	case 2:		/* id not inserted - already there, do nothing */
		rc = 0;
		break;

	case 3:		/* id not inserted - block is full */
		/*
		 * first, see if it will fit in the next block,
		 * without splitting, unless we're trying to insert
		 * into the beginning of the first block.
		 */

		/* is there a next block? */
		if ( !first && !ID_BLOCK_NOID(idl, i + 1) ) {
			/* read it in */
			cont_alloc( &k2, &key );
			cont_id( &k2, ID_BLOCK_ID(idl, i) );
			if ( (tmp2 = idl_fetch_one( be, db, k2 )) == NULL ) {
				Debug( LDAP_DEBUG_ANY,
				    "idl_insert_key: idl_fetch_one returned NULL\n",
				    0, 0, 0 );
				/* split the original block */
				cont_free( &k2 );
				goto split;
			}

			/* If the new id is less than the last id in the
			 * current block, it must not be put into the next
			 * block. Push the last id of the current block
			 * into the next block instead.
			 */
			if (id < ID_BLOCK_ID(tmp, ID_BLOCK_NIDS(tmp) - 1)) {
			    ID id2 = ID_BLOCK_ID(tmp, ID_BLOCK_NIDS(tmp) - 1);
			    Datum k3;

			    ldbm_datum_init( k3 );

			    --ID_BLOCK_NIDS(tmp);
			    /* This must succeed since we just popped one
			     * ID off the end of it.
			     */
			    rc = idl_insert( &tmp, id, db->dbc_maxids );

				k3.dptr = ch_malloc(k2.dsize);
				k3.dsize = k2.dsize;
				AC_MEMCPY(k3.dptr, k2.dptr, k3.dsize);
			    if ( (rc = idl_store( be, db, k3, tmp )) != 0 ) {
				Debug( LDAP_DEBUG_ANY,
			    "idl_insert_key: idl_store returned %d\n", rc, 0, 0 );
			    }

				free( k3.dptr );

			    id = id2;
			    /* This new id will necessarily be inserted
			     * as the first id of the next block by the
			     * following switch() statement.
			     */
			}

			switch ( (rc = idl_insert( &tmp2, id,
			    db->dbc_maxids )) ) {
			case 1:		/* id inserted first in block */
				rc = idl_change_first( be, db, key, idl,
				    i + 1, k2, tmp2 );