path: root/src/H5B.c

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright by the Board of Trustees of the University of Illinois.         *
 * All rights reserved.                                                      *
 *                                                                           *
 * This file is part of HDF5.  The full HDF5 copyright notice, including     *
 * terms governing use, modification, and redistribution, is contained in    *
 * the files COPYING and Copyright.html.  COPYING can be found at the root   *
 * of the source code distribution tree; Copyright.html can be found at the  *
 * root level of an installed copy of the electronic HDF5 document set and   *
 * is linked from the top-level documents page.  It can also be found at     *
 * http://hdf.ncsa.uiuc.edu/HDF5/doc/Copyright.html.  If you do not have     *
 * access to either file, you may request a copy from hdfhelp@ncsa.uiuc.edu. *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/*-------------------------------------------------------------------------
 *
 * Created:		hdf5btree.c
 *			Jul 10 1997
 *			Robb Matzke <matzke@llnl.gov>
 *
 * Purpose:		Implements balanced, sibling-linked, N-ary trees
 *			capable of storing any type of data with unique key
 *			values.
 *
 *			A B-link-tree is a balanced tree where each node has
 *			a pointer to its left and right siblings.  A
 *			B-link-tree is a rooted tree having the following
 *			properties:
 *
 *			1. Every node, x, has the following fields:
 *
 *			   a. level[x], the level in the tree at which node
 *			      x appears.  Leaf nodes are at level zero.
 *
 *			   b. n[x], the number of children pointed to by the
 *			      node.  Internal nodes point to subtrees while
 *			      leaf nodes point to arbitrary data.
 *
 *			   c. The child pointers themselves, child[x,i] such
 *			      that 0 <= i < n[x].
 *
 *			   d. n[x]+1 key values stored in increasing
 *			      order:
 *
 *				key[x,0] < key[x,1] < ... < key[x,n[x]].
 *
 *			   e. left[x] is a pointer to the node's left sibling
 *			      or the null pointer if this is the left-most
 *			      node at this level in the tree.
 *			      
 *			   f. right[x] is a pointer to the node's right
 *			      sibling or the null pointer if this is the
 *			      right-most node at this level in the tree.
 *
 *			3. The keys key[x,i] partition the key spaces of the
 *			   children of x:
 *
 *			      key[x,i] <= key[child[x,i],j] <= key[x,i+1]
 *
 *			   for any valid combination of i and j.
 *
 *			4. There are lower and upper bounds on the number of
 *			   child pointers a node can contain.  These bounds
 *			   can be expressed in terms of a fixed integer k>=2
 *			   called the `minimum degree' of the B-tree.
 *
 *			   a. Every node other than the root must have at least
 *			      k child pointers and k+1 keys.  If the tree is
 *			      nonempty, the root must have at least one child
 *			      pointer and two keys.
 *
 *			   b. Every node can contain at most 2k child pointers
 *			      and 2k+1 keys.  A node is `full' if it contains
 *			      exactly 2k child pointers and 2k+1 keys.
 *
 *			5. When searching for a particular value, V, and
 *			   key[V] = key[x,i] for some node x and entry i,
 *			   then:
 *
 *			   a. If i=0 the child[0] is followed.
 *
 *			   b. If i=n[x] the child[n[x]-1] is followed.
 *
 *			   c. Otherwise, the child that is followed
 *			      (either child[x,i-1] or child[x,i]) is
 *			      determined by the type of object to which the
 *			      leaf nodes of the tree point and is controlled
 *			      by the key comparison function registered for
 *			      that type of B-tree.
 *
 *
 * Modifications:
 *
 *	Robb Matzke, 4 Aug 1997
 *	Added calls to H5E.
 *
 *-------------------------------------------------------------------------
 */

#define H5B_PACKAGE		/*suppress error about including H5Bpkg	  */
#define H5F_PACKAGE		/*suppress error about including H5Fpkg	  */

/* Pablo information */
/* (Put before include files to avoid problems with inline functions) */
#define PABLO_MASK	H5B_mask

/* private headers */
#include "H5private.h"		/* Generic Functions			*/
#include "H5ACprivate.h"	/* Metadata cache			*/
#include "H5Bpkg.h"		/* B-link trees				*/
#include "H5Eprivate.h"		/* Error handling		  	*/
#include "H5Fpkg.h"		/* File access				*/
#include "H5FLprivate.h"	/* Free Lists                           */
#include "H5Iprivate.h"		/* IDs			  		*/
#include "H5MFprivate.h"	/* File memory management		*/
#include "H5MMprivate.h"	/* Memory management			*/

/* Local macros */
#define H5B_SIZEOF_HDR(F)						      \
   (H5B_SIZEOF_MAGIC +		/*magic number				  */  \
    4 +				/*type, level, num entries		  */  \
    2*H5F_SIZEOF_ADDR(F))	/*left and right sibling addresses	  */

/* Local typedefs */

/* PRIVATE PROTOTYPES */
static H5B_ins_t H5B_insert_helper(H5F_t *f, hid_t dxpl_id, haddr_t addr,
				   const H5B_class_t *type,
				   const double split_ratios[],
				   uint8_t *lt_key,
				   hbool_t *lt_key_changed,
				   uint8_t *md_key, void *udata,
				   uint8_t *rt_key,
				   hbool_t *rt_key_changed,
				   haddr_t *retval);
static herr_t H5B_insert_child(const H5F_t *f, const H5B_class_t *type,
			       H5B_t *bt, unsigned idx, haddr_t child,
			       H5B_ins_t anchor, const void *md_key);
static herr_t H5B_decode_key(H5F_t *f, H5B_t *bt, unsigned idx);
static herr_t H5B_decode_keys(H5F_t *f, H5B_t *bt, unsigned idx);
static size_t H5B_nodesize(const H5F_t *f, const H5B_class_t *type,
			   size_t *total_nkey_size, size_t sizeof_rkey);
static herr_t H5B_split(H5F_t *f, hid_t dxpl_id, const H5B_class_t *type, H5B_t *old_bt,
			haddr_t old_addr, unsigned idx,
			const double split_ratios[], void *udata,
			haddr_t *new_addr/*out*/);
static H5B_t * H5B_copy(const H5F_t *f, const H5B_t *old_bt);
#ifdef H5B_DEBUG
static herr_t H5B_assert(H5F_t *f, hid_t dxpl_id, haddr_t addr, const H5B_class_t *type,
			 void *udata);
#endif

/* Metadata cache callbacks */
static H5B_t *H5B_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void *_type, void *udata);
static herr_t H5B_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5B_t *b);
static herr_t H5B_dest(H5F_t *f, H5B_t *b);
static herr_t H5B_clear(H5F_t *f, H5B_t *b, hbool_t destroy);

/* H5B inherits cache-like properties from H5AC */
static const H5AC_class_t H5AC_BT[1] = {{
    H5AC_BT_ID,
    (H5AC_load_func_t)H5B_load,
    (H5AC_flush_func_t)H5B_flush,
    (H5AC_dest_func_t)H5B_dest,
    (H5AC_clear_func_t)H5B_clear,
}};

/* Interface initialization? */
#define INTERFACE_INIT NULL
static int interface_initialize_g = 0;

/* Declare a free list to manage the page information */
H5FL_BLK_DEFINE_STATIC(page);

/* Declare a PQ free list to manage the native block information */
H5FL_BLK_DEFINE_STATIC(native_block);

/* Declare a free list to manage the H5B_key_t array information */
H5FL_ARR_DEFINE_STATIC(H5B_key_t,-1);

/* Declare a free list to manage the haddr_t array information */
H5FL_ARR_DEFINE_STATIC(haddr_t,-1);

/* Declare a free list to manage the H5B_t struct */
H5FL_DEFINE_STATIC(H5B_t);


/*-------------------------------------------------------------------------
 * Function:	H5B_create
 *
 * Purpose:	Creates a new empty B-tree leaf node.  The UDATA pointer is
 *		passed as an argument to the sizeof_rkey() method for the
 *		B-tree.
 *
 * Return:	Success:	Non-negative, and the address of new node is
 *				returned through the ADDR_P argument.
 *
 * 		Failure:	Negative
 *
 * Programmer:	Robb Matzke
 *		matzke@llnl.gov
 *		Jun 23 1997
 *
 * Modifications:
 *		Robb Matzke, 1999-07-28
 *		Changed the name of the ADDR argument to ADDR_P to make it
 *		obvious that the address is passed by reference unlike most
 *		other functions that take addresses.
 *-------------------------------------------------------------------------
 */
herr_t
H5B_create(H5F_t *f, hid_t dxpl_id, const H5B_class_t *type, void *udata,
	   haddr_t *addr_p/*out*/)
{
    H5B_t		*bt = NULL;
    size_t		sizeof_rkey;
    size_t		size=0;
    size_t		total_native_keysize;
    size_t		offset;
    unsigned		u;
    herr_t		ret_value = SUCCEED;

    FUNC_ENTER_NOAPI(H5B_create, FAIL)

    /*
     * Check arguments.
     */
    assert(f);
    assert(type);
    assert(addr_p);

    /*
     * Allocate file and memory data structures.
     */
    sizeof_rkey = (type->get_sizeof_rkey) (f, udata);
    size = H5B_nodesize(f, type, &total_native_keysize, sizeof_rkey);
    H5_CHECK_OVERFLOW(size,size_t,hsize_t);
    if (HADDR_UNDEF==(*addr_p=H5MF_alloc(f, H5FD_MEM_BTREE, dxpl_id, (hsize_t)size)))
	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "file allocation failed for B-tree root node")
    if (NULL==(bt = H5FL_CALLOC(H5B_t)))
	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for B-tree root node")
    bt->type = type;
    bt->sizeof_rkey = sizeof_rkey;
    bt->cache_info.dirty = TRUE;
    bt->ndirty = 0;
    bt->level = 0;
    bt->left = HADDR_UNDEF;
    bt->right = HADDR_UNDEF;
    bt->nchildren = 0;
    if (NULL==(bt->page=H5FL_BLK_CALLOC(page,size)) ||
            NULL==(bt->native=H5FL_BLK_MALLOC(native_block,total_native_keysize)) ||
            NULL==(bt->child=H5FL_ARR_MALLOC(haddr_t,(size_t)(2*H5F_KVALUE(f,type)))) ||
            NULL==(bt->key=H5FL_ARR_MALLOC(H5B_key_t,(size_t)(2*H5F_KVALUE(f,type)+1))))
	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for B-tree root node")

    /*
     * Initialize each entry's raw child and key pointers to point into the
     * `page' buffer.  Each native key pointer should be null until the key is
     * translated to native format.
     */
    for (u = 0, offset = H5B_SIZEOF_HDR(f);
            u < 2 * H5F_KVALUE(f, type);
            u++, offset += bt->sizeof_rkey + H5F_SIZEOF_ADDR(f)) {

	bt->key[u].dirty = FALSE;
	bt->key[u].rkey = bt->page + offset;
	bt->key[u].nkey = NULL;
	bt->child[u] = HADDR_UNDEF;
    }

    /*
     * The last possible key...
     */
    bt->key[2 * H5F_KVALUE(f, type)].dirty = FALSE;
    bt->key[2 * H5F_KVALUE(f, type)].rkey = bt->page + offset;
    bt->key[2 * H5F_KVALUE(f, type)].nkey = NULL;

    /*
     * Cache the new B-tree node.
     */
    if (H5AC_set(f, dxpl_id, H5AC_BT, *addr_p, bt) < 0)
	HGOTO_ERROR(H5E_BTREE, H5E_CANTINIT, FAIL, "can't add B-tree root node to cache")
#ifdef H5B_DEBUG
    H5B_assert(f, dxpl_id, *addr_p, type, udata);
#endif
    
done:
    if (ret_value<0) {
        if(size>0) {
            H5_CHECK_OVERFLOW(size,size_t,hsize_t);
            (void)H5MF_xfree(f, H5FD_MEM_BTREE, dxpl_id, *addr_p, (hsize_t)size);
        } /* end if */
	if (bt)
            (void)H5B_dest(f,bt);
    }
    
    FUNC_LEAVE_NOAPI(ret_value)
} /*lint !e818 Can't make udata a pointer to const */


/*-------------------------------------------------------------------------
 * Function:	H5B_load
 *
 * Purpose:	Loads a B-tree node from the disk.
 *
 * Return:	Success:	Pointer to a new B-tree node.
 *
 *		Failure:	NULL
 *
 * Programmer:	Robb Matzke
 *		matzke@llnl.gov
 *		Jun 23 1997
 *
 * Modifications:
 *		Robb Matzke, 1999-07-28
 *		The ADDR argument is passed by value.
 *
 *	Quincey Koziol, 2002-7-180
 *	Added dxpl parameter to allow more control over I/O from metadata
 *      cache.
 *-------------------------------------------------------------------------
 */
static H5B_t *
H5B_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void *_type, void *udata)
{
    const H5B_class_t	*type = (const H5B_class_t *) _type;
    size_t		total_nkey_size;
    size_t		size;
    H5B_t		*bt = NULL;
    uint8_t		*p;
    unsigned		u;              /* Local index variable */
    H5B_t		*ret_value;

    FUNC_ENTER_NOAPI(H5B_load, NULL)

    /* Check arguments */
    assert(f);
    assert(H5F_addr_defined(addr));
    assert(type);
    assert(type->get_sizeof_rkey);

    if (NULL==(bt = H5FL_CALLOC(H5B_t)))
	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
    bt->sizeof_rkey = (type->get_sizeof_rkey) (f, udata);
    size = H5B_nodesize(f, type, &total_nkey_size, bt->sizeof_rkey);
    bt->type = type;
    bt->cache_info.dirty = FALSE;
    bt->ndirty = 0;
    if (NULL==(bt->page=H5FL_BLK_MALLOC(page,size)) ||
            NULL==(bt->native=H5FL_BLK_MALLOC(native_block,total_nkey_size)) ||
            NULL==(bt->key=H5FL_ARR_MALLOC(H5B_key_t,(size_t)(2*H5F_KVALUE(f,type)+1))) ||
            NULL==(bt->child=H5FL_ARR_MALLOC(haddr_t,(size_t)(2*H5F_KVALUE(f,type)))))
	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
    if (H5F_block_read(f, H5FD_MEM_BTREE, addr, size, dxpl_id, bt->page)<0)
	HGOTO_ERROR(H5E_BTREE, H5E_READERROR, NULL, "can't read B-tree node")
    p = bt->page;

    /* magic number */
    if (HDmemcmp(p, H5B_MAGIC, H5B_SIZEOF_MAGIC))
	HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, NULL, "wrong B-tree signature")
    p += 4;

    /* node type and level */
    if (*p++ != type->id)
	HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, NULL, "incorrect B-tree node level")
    bt->level = *p++;

    /* entries used */
    UINT16DECODE(p, bt->nchildren);

    /* sibling pointers */
    H5F_addr_decode(f, (const uint8_t **) &p, &(bt->left));
    H5F_addr_decode(f, (const uint8_t **) &p, &(bt->right));

    /* the child/key pairs */
    for (u = 0; u < 2 * H5F_KVALUE(f, type); u++) {

	bt->key[u].dirty = FALSE;
	bt->key[u].rkey = p;
	p += bt->sizeof_rkey;
	bt->key[u].nkey = NULL;

	if (u < bt->nchildren) {
	    H5F_addr_decode(f, (const uint8_t **) &p, bt->child + u);
	} else {
	    bt->child[u] = HADDR_UNDEF;
	    p += H5F_SIZEOF_ADDR(f);
	}
    }

    bt->key[2 * H5F_KVALUE(f, type)].dirty = FALSE;
    bt->key[2 * H5F_KVALUE(f, type)].rkey = p;
    bt->key[2 * H5F_KVALUE(f, type)].nkey = NULL;

    /* Set return value */
    ret_value = bt;

done:
    if (!ret_value && bt)
        (void)H5B_dest(f,bt);
    FUNC_LEAVE_NOAPI(ret_value)
} /*lint !e818 Can't make udata a pointer to const */


/*-------------------------------------------------------------------------
 * Function:	H5B_flush
 *
 * Purpose:	Flushes a dirty B-tree node to disk.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Robb Matzke
 *		matzke@llnl.gov
 *		Jun 23 1997
 *
 * Modifications:
 *              rky 980828
 *		Only p0 writes metadata to disk.
 *
 * 		Robb Matzke, 1999-07-28
 *		The ADDR argument is passed by value.
 *
 *	Quincey Koziol, 2002-7-180
 *	Added dxpl parameter to allow more control over I/O from metadata
 *      cache.
 *-------------------------------------------------------------------------
 */
static herr_t
H5B_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5B_t *bt)
{
    size_t	size = 0;
    uint8_t	*p = bt->page;
    unsigned	u;                      /* Local index variable */
    herr_t      ret_value=SUCCEED;      /* Return value */

    FUNC_ENTER_NOAPI(H5B_flush, FAIL)

    /*
     * Check arguments.
     */
    assert(f);
    assert(H5F_addr_defined(addr));
    assert(bt);
    assert(bt->type);
    assert(bt->type->encode);

    size = H5B_nodesize(f, bt->type, NULL, bt->sizeof_rkey);

    if (bt->cache_info.dirty) {

	/* magic number */
	HDmemcpy(p, H5B_MAGIC, H5B_SIZEOF_MAGIC);
	p += 4;

	/* node type and level */
	*p++ = bt->type->id;
        H5_CHECK_OVERFLOW(bt->level,int,uint8_t);
	*p++ = (uint8_t)bt->level;

	/* entries used */
	UINT16ENCODE(p, bt->nchildren);

	/* sibling pointers */
	H5F_addr_encode(f, &p, bt->left);
	H5F_addr_encode(f, &p, bt->right);

	/* child keys and pointers */
	for (u=0; u<=bt->nchildren; u++) {

	    /* encode the key */
	    assert(bt->key[u].rkey == p);
	    if (bt->key[u].dirty) {
		if (bt->key[u].nkey) {
		    if ((bt->type->encode) (f, bt, bt->key[u].rkey, bt->key[u].nkey) < 0)
			HGOTO_ERROR(H5E_BTREE, H5E_CANTENCODE, FAIL, "unable to encode B-tree key")
		}
		bt->key[u].dirty = FALSE;
	    }
	    p += bt->sizeof_rkey;

	    /* encode the child address */
	    if (u < bt->ndirty) {
		H5F_addr_encode(f, &p, bt->child[u]);
	    } else {
		p += H5F_SIZEOF_ADDR(f);
	    }
	}

	/*
	 * Write the disk page.	 We always write the header, but we don't
	 * bother writing data for the child entries that don't exist or
	 * for the final unchanged children.
	 */
	if (H5F_block_write(f, H5FD_MEM_BTREE, addr, size, dxpl_id, bt->page)<0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTFLUSH, FAIL, "unable to save B-tree node to disk")
	bt->cache_info.dirty = FALSE;
	bt->ndirty = 0;
    }
    if (destroy) {
        if(H5B_dest(f,bt)<0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTFREE, FAIL, "unable to destroy B-tree node")
    }

done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:	H5B_dest
 *
 * Purpose:	Destroys a B-tree node in memory.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Jan 15 2003
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
/* ARGSUSED */
static herr_t
H5B_dest(H5F_t UNUSED *f, H5B_t *bt)
{
    FUNC_ENTER_NOINIT(H5B_dest)

    /*
     * Check arguments.
     */
    assert(bt);

    /* Verify that node is clean */
    assert(bt->cache_info.dirty==0);

    H5FL_ARR_FREE(haddr_t,bt->child);
    H5FL_ARR_FREE(H5B_key_t,bt->key);
    H5FL_BLK_FREE(page,bt->page);
    H5FL_BLK_FREE(native_block,bt->native);
    H5FL_FREE(H5B_t,bt);

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5B_dest() */


/*-------------------------------------------------------------------------
 * Function:	H5B_clear
 *
 * Purpose:	Mark a B-tree node in memory as non-dirty.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Mar 20 2003
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5B_clear(H5F_t *f, H5B_t *bt, hbool_t destroy)
{
    unsigned	u;      /* Local index variable */
    herr_t ret_value = SUCCEED;

    FUNC_ENTER_NOINIT(H5B_clear)

    /*
     * Check arguments.
     */
    assert(bt);

    /* Look for dirty keys and reset the dirty flag.  */
    for (u=0; u<=bt->nchildren; u++)
        bt->key[u].dirty = FALSE;
    bt->cache_info.dirty = FALSE;
 
    if (destroy)
        if (H5B_dest(f, bt) < 0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTFREE, FAIL, "unable to destroy B-tree node");

done:
    FUNC_LEAVE_NOAPI(ret_value);
} /* end H5B_clear() */


/*-------------------------------------------------------------------------
 * Function:	H5B_find
 *
 * Purpose:	Locate the specified information in a B-tree and return
 *		that information by filling in fields of the caller-supplied
 *		UDATA pointer depending on the type of leaf node
 *		requested.  The UDATA can point to additional data passed
 *		to the key comparison function.
 *
 * Note:	This function does not follow the left/right sibling
 *		pointers since it assumes that all nodes can be reached
 *		from the parent node.
 *
 * Return:	Non-negative on success (if found, values returned through the
 *              UDATA argument). Negative on failure (if not found, UDATA is
 *              undefined).
 *
 * Programmer:	Robb Matzke
 *		matzke@llnl.gov
 *		Jun 23 1997
 *
 * Modifications:
 *		Robb Matzke, 1999-07-28
 *		The ADDR argument is passed by value.
 *-------------------------------------------------------------------------
 */
herr_t
H5B_find(H5F_t *f, hid_t dxpl_id, const H5B_class_t *type, haddr_t addr, void *udata)
{
    H5B_t	*bt = NULL;
    unsigned    idx=0, lt = 0, rt;        /* Final, left & right key indices */
    int	        cmp = 1;                /* Key comparison value */
    int         level;                  /* Level of B-tree node */
    haddr_t     child;                  /* Address of child to recurse to */
    void       *nkey1, *nkey2;          /* Native keys of child */
    int		ret_value = SUCCEED;    /* Return value */

    FUNC_ENTER_NOAPI(H5B_find, FAIL)

    /*
     * Check arguments.
     */
    assert(f);
    assert(type);
    assert(type->decode);
    assert(type->cmp3);
    assert(type->found);
    assert(H5F_addr_defined(addr));

    /*
     * Perform a binary search to locate the child which contains
     * the thing for which we're searching.
     */
    if (NULL == (bt = H5AC_protect(f, dxpl_id, H5AC_BT, addr, type, udata, H5AC_READ)))
	HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load B-tree node")
    rt = bt->nchildren;

    while (lt < rt && cmp) {
	idx = (lt + rt) / 2;
	if (H5B_decode_keys(f, bt, idx) < 0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTDECODE, FAIL, "unable to decode B-tree key(s)")
	/* compare */
	if ((cmp = (type->cmp3) (f, dxpl_id, bt->key[idx].nkey, udata,
				 bt->key[idx+1].nkey)) < 0) {
	    rt = idx;
	} else {
	    lt = idx+1;
	}
    }
    if (cmp)
	HGOTO_ERROR(H5E_BTREE, H5E_NOTFOUND, FAIL, "B-tree key not found")
    
    /*
     * Follow the link to the subtree or to the data node.
     */
    assert(idx < bt->nchildren);

    /* Retrieve the rest of the B-tree information, so we can unlock it before recursing */
    level = bt->level;
    child = bt->child[idx];
    nkey1=bt->key[idx].nkey;
    nkey2=bt->key[idx+1].nkey;

    if (H5AC_unprotect(f, dxpl_id, H5AC_BT, addr, bt, FALSE) < 0)
        HGOTO_ERROR(H5E_BTREE, H5E_PROTECT, FAIL, "unable to release B-tree node")

    bt = NULL;  /* Make certain future references will be caught */

    if (level > 0) {
	if (H5B_find(f, dxpl_id, type, child, udata) < 0)
	    HGOTO_ERROR(H5E_BTREE, H5E_NOTFOUND, FAIL, "key not found in subtree")
    } else {
	if ((type->found) (f, dxpl_id, child, nkey1, udata, nkey2) < 0)
	    HGOTO_ERROR(H5E_BTREE, H5E_NOTFOUND, FAIL, "key not found in leaf node")
    }

done:
    if (bt && H5AC_unprotect(f, dxpl_id, H5AC_BT, addr, bt, FALSE) < 0)
	HDONE_ERROR(H5E_BTREE, H5E_PROTECT, FAIL, "unable to release node")

    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:	H5B_split
 *
 * Purpose:	Split a single node into two nodes.  The old node will
 *		contain the left children and the new node will contain the
 *		right children.
 *
 *		The UDATA pointer is passed to the sizeof_rkey() method but is
 *		otherwise unused.
 *
 *		The OLD_BT argument is a pointer to a protected B-tree
 *		node.
 *
 * Return:	Non-negative on success (The address of the new node is
 *              returned through the NEW_ADDR argument). Negative on failure.
 *
 * Programmer:	Robb Matzke
 *		matzke@llnl.gov
 *		Jul  3 1997
 *
 * Modifications:
 *		Robb Matzke, 1999-07-28
 *		The OLD_ADDR argument is passed by value. The NEW_ADDR
 *		argument has been renamed to NEW_ADDR_P
 *-------------------------------------------------------------------------
 */
static herr_t
H5B_split(H5F_t *f, hid_t dxpl_id, const H5B_class_t *type, H5B_t *old_bt, haddr_t old_addr,
	  unsigned idx, const double split_ratios[], void *udata,
	  haddr_t *new_addr_p/*out*/)
{
    H5B_t	*new_bt = NULL, *tmp_bt = NULL;
    unsigned	k;                      /* B-tree 'K' value for the maximum number of entries in node */
    unsigned	nleft, nright;          /* Number of keys in left & right halves */
    size_t	recsize = 0;
    unsigned	u;                      /* Local index variable */
    herr_t	ret_value = SUCCEED;    /* Return value */

    FUNC_ENTER_NOINIT(H5B_split)

    /*
     * Check arguments.
     */
    assert(f);
    assert(type);
    assert(H5F_addr_defined(old_addr));

    /*
     * Initialize variables.
     */
    assert(old_bt->nchildren == 2 * H5F_KVALUE(f, type));
    recsize = old_bt->sizeof_rkey + H5F_SIZEOF_ADDR(f);
    k = H5F_KVALUE(f, type);

#ifdef H5B_DEBUG
    if (H5DEBUG(B)) {
	const char *side;
	if (!H5F_addr_defined(old_bt->left) &&
	    !H5F_addr_defined(old_bt->right)) {
	    side = "ONLY";
	} else if (!H5F_addr_defined(old_bt->right)) {
	    side = "RIGHT";
	} else if (!H5F_addr_defined(old_bt->left)) {
	    side = "LEFT";
	} else {
	    side = "MIDDLE";
	}
	fprintf(H5DEBUG(B), "H5B_split: %3u {%5.3f,%5.3f,%5.3f} %6s",
		2*k, split_ratios[0], split_ratios[1], split_ratios[2], side);
    }
#endif

    /*
     * Decide how to split the children of the old node among the old node
     * and the new node.
     */
    if (!H5F_addr_defined(old_bt->right)) {
	nleft = (unsigned)(2 * (double)k * split_ratios[2]);	/*right*/
    } else if (!H5F_addr_defined(old_bt->left)) {
	nleft = (unsigned)(2 * (double)k * split_ratios[0]);	/*left*/
    } else {
	nleft = (unsigned)(2 * (double)k * split_ratios[1]);	/*middle*/
    }

    /*
     * Keep the new child in the same node as the child that split.  This can
     * result in nodes that have an unused child when data is written
     * sequentially, but it simplifies stuff below.
     */
    if (idx<nleft && nleft==2*k) {
	--nleft;
    } else if (idx>=nleft && 0==nleft) {
	nleft++;
    }
    nright = 2*k - nleft;
#ifdef H5B_DEBUG
    if (H5DEBUG(B))
	fprintf(H5DEBUG(B), " split %3d/%-3d\n", nleft, nright);
#endif
    
    /*
     * Create the new B-tree node.
     */
    if (H5B_create(f, dxpl_id, type, udata, new_addr_p/*out*/) < 0)
	HGOTO_ERROR(H5E_BTREE, H5E_CANTINIT, FAIL, "unable to create B-tree")
    if (NULL==(new_bt=H5AC_protect(f, dxpl_id, H5AC_BT, *new_addr_p, type, udata, H5AC_WRITE)))
	HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to protect B-tree")
    new_bt->level = old_bt->level;

    /*
     * Copy data from the old node to the new node.
     */
    HDmemcpy(new_bt->page + H5B_SIZEOF_HDR(f),
	     old_bt->page + H5B_SIZEOF_HDR(f) + nleft * recsize,
	     nright * recsize + new_bt->sizeof_rkey);
    HDmemcpy(new_bt->native,
	     old_bt->native + nleft * type->sizeof_nkey,
	     (nright+1) * type->sizeof_nkey);

    for (u=0; u<=nright; u++) {
	/* key */
	new_bt->key[u].dirty = old_bt->key[nleft+u].dirty;
	if (old_bt->key[nleft+u].nkey)
	    new_bt->key[u].nkey = new_bt->native + u * type->sizeof_nkey;

	/* child */
	if (u < nright)
	    new_bt->child[u] = old_bt->child[nleft+u];
    }
    new_bt->ndirty = new_bt->nchildren = nright;

    /*
     * Truncate the old node.
     */
    old_bt->cache_info.dirty = TRUE;
    old_bt->nchildren = nleft;
    old_bt->ndirty = MIN(old_bt->ndirty, old_bt->nchildren);
    
    /*
     * Update sibling pointers.
     */
    new_bt->left = old_addr;
    new_bt->right = old_bt->right;

    if (H5F_addr_defined(old_bt->right)) {
	if (NULL == (tmp_bt = H5AC_protect(f, dxpl_id, H5AC_BT, old_bt->right, type, udata, H5AC_WRITE)))
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load right sibling")

	tmp_bt->cache_info.dirty = TRUE;
	tmp_bt->left = *new_addr_p;

        if (H5AC_unprotect(f, dxpl_id, H5AC_BT, old_bt->right, tmp_bt, FALSE) != SUCCEED)
            HGOTO_ERROR(H5E_BTREE, H5E_PROTECT, FAIL, "unable to release B-tree node")
        tmp_bt=NULL;    /* Make certain future references will be caught */
    }

    old_bt->right = *new_addr_p;

done:
    if (new_bt && H5AC_unprotect(f, dxpl_id, H5AC_BT, *new_addr_p, new_bt, FALSE) < 0)
        HDONE_ERROR(H5E_BTREE, H5E_PROTECT, FAIL, "unable to release B-tree node")

    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:	H5B_decode_key
 *
 * Purpose:	Decode the specified key into native format.  Do not call
 *		this function if the key is already decoded since it my
 *		decode a stale raw key into the native key.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Robb Matzke
 *		matzke@llnl.gov
 *		Jul  8 1997
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5B_decode_key(H5F_t *f, H5B_t *bt, unsigned idx)
{
    herr_t      ret_value=SUCCEED;       /* Return value */

    FUNC_ENTER_NOINIT(H5B_decode_key)

    assert(bt->key[idx].dirty==0);

    bt->key[idx].nkey = bt->native + idx * bt->type->sizeof_nkey;
    if ((bt->type->decode) (f, bt, bt->key[idx].rkey, bt->key[idx].nkey) < 0)
	HGOTO_ERROR(H5E_BTREE, H5E_CANTDECODE, FAIL, "unable to decode key")

done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:	H5B_decode_keys
 *
 * Purpose:	Decode keys on either side of the specified branch.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Robb Matzke
 *		Tuesday, October 14, 1997
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5B_decode_keys(H5F_t *f, H5B_t *bt, unsigned idx)
{
    herr_t      ret_value=SUCCEED;       /* Return value */

    FUNC_ENTER_NOINIT(H5B_decode_keys)

    assert(f);
    assert(bt);
    assert(idx < bt->nchildren);

    if (!bt->key[idx].nkey && H5B_decode_key(f, bt, idx) < 0)
	HGOTO_ERROR(H5E_BTREE, H5E_CANTDECODE, FAIL, "unable to decode key")
    if (!bt->key[idx+1].nkey && H5B_decode_key(f, bt, idx+1) < 0)
	HGOTO_ERROR(H5E_BTREE, H5E_CANTDECODE, FAIL, "unable to decode key")

done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:	H5B_insert
 *
 * Purpose:	Adds a new item to the B-tree.	If the root node of
 *		the B-tree splits then the B-tree gets a new address.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Robb Matzke
 *		matzke@llnl.gov
 *		Jun 23 1997
 *
 * Modifications:
 * 	Robb Matzke, 28 Sep 1998
 *	The optional SPLIT_RATIOS[] indicates what percent of the child
 *	pointers should go in the left node when a node splits.  There are
 *	three possibilities and a separate split ratio can be specified for
 *	each: [0] The node that split is the left-most node at its level of
 *	the tree, [1] the node that split has left and right siblings, [2]
 *	the node that split is the right-most node at its level of the tree.
 *	When a node is an only node at its level then we use the right-most
 *	rule.  If SPLIT_RATIOS is null then default values are used.
 *
 * 	Robb Matzke, 1999-07-28
 *	The ADDR argument is passed by value.
 *-------------------------------------------------------------------------
 */
herr_t
H5B_insert(H5F_t *f, hid_t dxpl_id, const H5B_class_t *type, haddr_t addr,
	   const double split_ratios[], void *udata)
{
    /*
     * These are defined this way to satisfy alignment constraints.
     */
    uint64_t	_lt_key[128], _md_key[128], _rt_key[128];
    uint8_t	*lt_key=(uint8_t*)_lt_key;
    uint8_t	*md_key=(uint8_t*)_md_key;
    uint8_t	*rt_key=(uint8_t*)_rt_key;

    hbool_t	lt_key_changed = FALSE, rt_key_changed = FALSE;
    haddr_t	child, old_root;
    int	level;
    H5B_t	*bt;
    H5B_t	*new_bt;        /* Copy of B-tree info */
    hsize_t	size;
    H5B_ins_t	my_ins = H5B_INS_ERROR;
    herr_t	ret_value = SUCCEED;

    FUNC_ENTER_NOAPI(H5B_insert, FAIL)

    /*
     * Check arguments.
     */
    assert(f);
    assert(type);
    assert(type->sizeof_nkey <= sizeof _lt_key);
    assert(H5F_addr_defined(addr));

    if ((my_ins = H5B_insert_helper(f, dxpl_id, addr, type, split_ratios, lt_key,
            &lt_key_changed, md_key, udata, rt_key, &rt_key_changed, &child/*out*/))<0 ||
            my_ins<0)
	HGOTO_ERROR(H5E_BTREE, H5E_CANTINIT, FAIL, "unable to insert key")
    if (H5B_INS_NOOP == my_ins)
        HGOTO_DONE(SUCCEED)
    assert(H5B_INS_RIGHT == my_ins);

    /* the current root */
    if (NULL == (bt = H5AC_protect(f, dxpl_id, H5AC_BT, addr, type, udata, H5AC_READ)))
	HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to locate root of B-tree")

    level = bt->level;

    if (!lt_key_changed) {
	if (!bt->key[0].nkey && H5B_decode_key(f, bt, 0) < 0) {
            /* We want the actual error to show up but also want to
             * execute the "H5AC_unprotect" call. So we use the
             * "HCOMMON_ERROR" macro. */
            HCOMMON_ERROR(H5E_BTREE, H5E_CANTDECODE, "unable to decode key");

            if (H5AC_unprotect(f, dxpl_id, H5AC_BT, addr, bt, FALSE) != SUCCEED)
                HGOTO_ERROR(H5E_BTREE, H5E_PROTECT, FAIL, "unable to release new child")

            HGOTO_DONE(FAIL)
        }

	HDmemcpy(lt_key, bt->key[0].nkey, type->sizeof_nkey);
    }

    if (H5AC_unprotect(f, dxpl_id, H5AC_BT, addr, bt, FALSE) != SUCCEED)
        HGOTO_ERROR(H5E_BTREE, H5E_PROTECT, FAIL, "unable to release new child")

    bt = NULL;
    
    /* the new node */
    if (NULL == (bt = H5AC_protect(f, dxpl_id, H5AC_BT, child, type, udata, H5AC_READ)))
	HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load new node")

    if (!rt_key_changed) {
	if (!bt->key[bt->nchildren].nkey &&
                H5B_decode_key(f, bt, bt->nchildren) < 0) {
            HCOMMON_ERROR(H5E_BTREE, H5E_CANTDECODE, "unable to decode key");

            if (H5AC_unprotect(f, dxpl_id, H5AC_BT, child, bt, FALSE) != SUCCEED)
                HGOTO_ERROR(H5E_BTREE, H5E_PROTECT, FAIL, "unable to release new child")

            HGOTO_DONE(FAIL)
        }

	HDmemcpy(rt_key, bt->key[bt->nchildren].nkey, type->sizeof_nkey);
    }
    
    /*
     * Copy the old root node to some other file location and make the new
     * root at the old root's previous address.	 This prevents the B-tree
     * from "moving".
     */
    size = H5B_nodesize(f, type, NULL, bt->sizeof_rkey);

    if (H5AC_unprotect(f, dxpl_id, H5AC_BT, child, bt, FALSE) != SUCCEED)
        HGOTO_ERROR(H5E_BTREE, H5E_PROTECT, FAIL, "unable to release new child")

    bt = NULL;

    if (HADDR_UNDEF==(old_root=H5MF_alloc(f, H5FD_MEM_BTREE, dxpl_id, size)))
        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "unable to allocate file space to move root")

    /* update the new child's left pointer */
    if (NULL == (bt = H5AC_protect(f, dxpl_id, H5AC_BT, child, type, udata, H5AC_WRITE)))
        HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load new child")

    bt->cache_info.dirty = TRUE;
    bt->left = old_root;

    if (H5AC_unprotect(f, dxpl_id, H5AC_BT, child, bt, FALSE) != SUCCEED)
        HGOTO_ERROR(H5E_BTREE, H5E_PROTECT, FAIL, "unable to release new child")

    bt=NULL;    /* Make certain future references will be caught */

    /*
     * Move the node to the new location by checking it out & checking it in
     * at the new location -QAK
     */
    /* Bring the old root into the cache if it's not already */
    if (NULL == (bt = H5AC_protect(f, dxpl_id, H5AC_BT, addr, type, udata, H5AC_WRITE)))
        HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load new child")

    /* Make certain the old root info is marked as dirty before moving it, */
    /* so it is certain to be written out at the new location */
    bt->cache_info.dirty = TRUE;

    /* Make a copy of the old root information */
    if (NULL == (new_bt = H5B_copy(f, bt))) {
        HCOMMON_ERROR(H5E_BTREE, H5E_CANTLOAD, "unable to copy old root");

        if (H5AC_unprotect(f, dxpl_id, H5AC_BT, addr, bt, FALSE) != SUCCEED)
            HGOTO_ERROR(H5E_BTREE, H5E_PROTECT, FAIL, "unable to release new child")

        HGOTO_DONE(FAIL)
    }

    if (H5AC_unprotect(f, dxpl_id, H5AC_BT, addr, bt, FALSE) != SUCCEED)
        HGOTO_ERROR(H5E_BTREE, H5E_PROTECT, FAIL, "unable to release new child")

    bt=NULL;    /* Make certain future references will be caught */

    /* Move the location of the old root on the disk */
    if (H5AC_rename(f, dxpl_id, H5AC_BT, addr, old_root) < 0)
        HGOTO_ERROR(H5E_BTREE, H5E_CANTSPLIT, FAIL, "unable to move B-tree root node")

    /* clear the old root info at the old address (we already copied it) */
    new_bt->cache_info.dirty = TRUE;
    new_bt->left = HADDR_UNDEF;
    new_bt->right = HADDR_UNDEF;

    /* Set the new information for the copy */
    new_bt->ndirty = 2;
    new_bt->level = level + 1;
    new_bt->nchildren = 2;

    new_bt->child[0] = old_root;
    new_bt->key[0].dirty = TRUE;
    new_bt->key[0].nkey = new_bt->native;
    HDmemcpy(new_bt->key[0].nkey, lt_key, type->sizeof_nkey);

    new_bt->child[1] = child;
    new_bt->key[1].dirty = TRUE;
    new_bt->key[1].nkey = new_bt->native + type->sizeof_nkey;
    HDmemcpy(new_bt->key[1].nkey, md_key, type->sizeof_nkey);

    new_bt->key[2].dirty = TRUE;
    new_bt->key[2].nkey = new_bt->native + 2 * type->sizeof_nkey;
    HDmemcpy(new_bt->key[2].nkey, rt_key, type->sizeof_nkey);

    /* Insert the modified copy of the old root into the file again */
    if (H5AC_set(f, dxpl_id, H5AC_BT, addr, new_bt) < 0)
        HGOTO_ERROR(H5E_BTREE, H5E_CANTFLUSH, FAIL, "unable to flush old B-tree root node")

#ifdef H5B_DEBUG
    H5B_assert(f, dxpl_id, addr, type, udata);
#endif
    
done:
    FUNC_LEAVE_NOAPI(ret_value)
}
    

/*-------------------------------------------------------------------------
 * Function:	H5B_insert_child
 *
 * Purpose:	Insert a child to the left or right of child[IDX] depending
 *		on whether ANCHOR is H5B_INS_LEFT or H5B_INS_RIGHT. The BT
 *		argument is a pointer to a protected B-tree node.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Robb Matzke
 *		matzke@llnl.gov
 *		Jul  8 1997
 *
 * Modifications:
 *		Robb Matzke, 1999-07-28
 *		The CHILD argument is passed by value.
 *-------------------------------------------------------------------------
 */
static herr_t
H5B_insert_child(const H5F_t *f, const H5B_class_t *type, H5B_t *bt,
		 unsigned idx, haddr_t child, H5B_ins_t anchor, const void *md_key)
{
    size_t	recsize;
    unsigned	u;              /* Local index variable */

    FUNC_ENTER_NOINIT(H5B_insert_child)

    assert(bt);
    assert(bt->nchildren<2*H5F_KVALUE(f, type));

    bt->cache_info.dirty = TRUE;
    recsize = bt->sizeof_rkey + H5F_SIZEOF_ADDR(f);

    if (H5B_INS_RIGHT == anchor) {
	/*
	 * The MD_KEY is the left key of the new node.
	 */
	idx++;
	
	HDmemmove(bt->page + H5B_SIZEOF_HDR(f) + (idx+1) * recsize,
		  bt->page + H5B_SIZEOF_HDR(f) + idx * recsize,
		  (bt->nchildren - idx) * recsize + bt->sizeof_rkey);

	HDmemmove(bt->native + (idx+1) * type->sizeof_nkey,
		  bt->native + idx * type->sizeof_nkey,
		  ((bt->nchildren - idx) + 1) * type->sizeof_nkey);

	for (u=bt->nchildren; u>=idx; --u) {
	    bt->key[u+1].dirty = bt->key[u].dirty;
	    if (bt->key[u].nkey) {
		bt->key[u+1].nkey = bt->native + (u+1) * type->sizeof_nkey;
	    } else {
		bt->key[u+1].nkey = NULL;
	    }
	}
	bt->key[idx].dirty = TRUE;
	bt->key[idx].nkey = bt->native + idx * type->sizeof_nkey;
	HDmemcpy(bt->key[idx].nkey, md_key, type->sizeof_nkey);

    } else {
	/*
	 * The MD_KEY is the right key of the new node.
	 */
	HDmemmove(bt->page + (H5B_SIZEOF_HDR(f) +
			      (idx+1) * recsize + bt->sizeof_rkey),
		  bt->page + (H5B_SIZEOF_HDR(f) +
			      idx * recsize + bt->sizeof_rkey),
		  (bt->nchildren - idx) * recsize);

	HDmemmove(bt->native + (idx+2) * type->sizeof_nkey,
		  bt->native + (idx+1) * type->sizeof_nkey,
		  (bt->nchildren - idx) * type->sizeof_nkey);

	for (u = bt->nchildren; u > idx; --u) {
	    bt->key[u+1].dirty = bt->key[u].dirty;
	    if (bt->key[u].nkey) {
		bt->key[u+1].nkey = bt->native + (u+1) * type->sizeof_nkey;
	    } else {
		bt->key[u+1].nkey = NULL;
	    }
	}
	bt->key[idx+1].dirty = TRUE;
	bt->key[idx+1].nkey = bt->native + (idx+1) * type->sizeof_nkey;
	HDmemcpy(bt->key[idx+1].nkey, md_key, type->sizeof_nkey);
    }

    HDmemmove(bt->child + idx + 1,
	      bt->child + idx,
	      (bt->nchildren - idx) * sizeof(haddr_t));

    bt->child[idx] = child;
    bt->nchildren += 1;
    bt->ndirty = bt->nchildren;

    FUNC_LEAVE_NOAPI(SUCCEED)
}


/*-------------------------------------------------------------------------
 * Function:	H5B_insert_helper
 *
 * Purpose:	Inserts the item UDATA into the tree rooted at ADDR and having
 *		the specified type.
 *
 *		On return, if LT_KEY_CHANGED is non-zero, then LT_KEY is
 *		the new native left key.  Similarily for RT_KEY_CHANGED
 *		and RT_KEY.
 *
 *		If the node splits, then MD_KEY contains the key that
 *		was split between the two nodes (that is, the key that
 *		appears as the max key in the left node and the min key
 *		in the right node).
 *
 * Return:	Success:	A B-tree operation.  The address of the new
 *				node, if the node splits, is returned through
 *				the NEW_NODE_P argument. The new node is always
 *				to the right of the previous node.  This
 *				function is called recursively and the return
 *				value influences the behavior of the caller.
 *				See also, declaration of H5B_ins_t.
 *
 *		Failure:	H5B_INS_ERROR
 *
 * Programmer:	Robb Matzke
 *		matzke@llnl.gov
 *		Jul  9 1997
 *
 * Modifications:
 *
 * 	Robb Matzke, 28 Sep 1998
 *	The optional SPLIT_RATIOS[] indicates what percent of the child
 *	pointers should go in the left node when a node splits.  There are
 *	three possibilities and a separate split ratio can be specified for
 *	each: [0] The node that split is the left-most node at its level of
 *	the tree, [1] the node that split has left and right siblings, [2]
 *	the node that split is the right-most node at its level of the tree.
 *	When a node is an only node at its level then we use the right-most
 *	rule.  If SPLIT_RATIOS is null then default values are used.
 *
 * 	Robb Matzke, 1999-07-28
 *	The ADDR argument is passed by value. The NEW_NODE argument is
 *	renamed NEW_NODE_P
 *-------------------------------------------------------------------------
 */
static H5B_ins_t
H5B_insert_helper(H5F_t *f, hid_t dxpl_id, haddr_t addr, const H5B_class_t *type,
		  const double split_ratios[], uint8_t *lt_key,
		  hbool_t *lt_key_changed, uint8_t *md_key, void *udata,
		  uint8_t *rt_key, hbool_t *rt_key_changed,
		  haddr_t *new_node_p/*out*/)
{
    H5B_t	*bt = NULL, *twin = NULL;
    unsigned	lt = 0, idx = 0, rt;    /* Left, final & right index values */
    int         cmp = -1;               /* Key comparison value */
    haddr_t	child_addr = HADDR_UNDEF;
    H5B_ins_t	my_ins = H5B_INS_ERROR;
    H5B_ins_t	ret_value = H5B_INS_ERROR;      /* Return value */

    FUNC_ENTER_NOINIT(H5B_insert_helper)

    /*
     * Check arguments
     */
    assert(f);
    assert(H5F_addr_defined(addr));
    assert(type);
    assert(type->decode);
    assert(type->cmp3);
    assert(type->new_node);
    assert(lt_key);
    assert(lt_key_changed);
    assert(rt_key);
    assert(rt_key_changed);
    assert(new_node_p);

    *lt_key_changed = FALSE;
    *rt_key_changed = FALSE;

    /*
     * Use a binary search to find the child that will receive the new
     * data.  When the search completes IDX points to the child that
     * should get the new data.
     */
    if (NULL == (bt = H5AC_protect(f, dxpl_id, H5AC_BT, addr, type, udata, H5AC_WRITE)))
	HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, H5B_INS_ERROR, "unable to load node")
    rt = bt->nchildren;

    while (lt < rt && cmp) {
	idx = (lt + rt) / 2;
	if (H5B_decode_keys(f, bt, idx) < 0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTDECODE, H5B_INS_ERROR, "unable to decode key")
	if ((cmp = (type->cmp3) (f, dxpl_id, bt->key[idx].nkey, udata,
				 bt->key[idx+1].nkey)) < 0) {
	    rt = idx;
	} else {
	    lt = idx + 1;
	}
    }

    if (0 == bt->nchildren) {
	/*
	 * The value being inserted will be the only value in this tree. We
	 * must necessarily be at level zero.
	 */
	assert(0 == bt->level);
	bt->key[0].nkey = bt->native;
	bt->key[1].nkey = bt->native + type->sizeof_nkey;
	if ((type->new_node)(f, dxpl_id, H5B_INS_FIRST, bt->key[0].nkey, udata,
			     bt->key[1].nkey, bt->child + 0/*out*/) < 0) {
	    bt->key[0].nkey = bt->key[1].nkey = NULL;
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTINIT, H5B_INS_ERROR, "unable to create leaf node")
	}
	bt->nchildren = 1;
	bt->cache_info.dirty = TRUE;
	bt->ndirty = 1;
	bt->key[0].dirty = TRUE;
	bt->key[1].dirty = TRUE;
	idx = 0;

	if (type->follow_min) {
	    if ((my_ins = (type->insert)(f, dxpl_id, bt->child[idx], bt->key[idx].nkey,
                     lt_key_changed, md_key, udata, bt->key[idx+1].nkey,
                     rt_key_changed, &child_addr/*out*/)) < 0)
		HGOTO_ERROR(H5E_BTREE, H5E_CANTINSERT, H5B_INS_ERROR, "unable to insert first leaf node")
	} else {
	    my_ins = H5B_INS_NOOP;
	}

    } else if (cmp < 0 && idx == 0 && bt->level > 0) {
	/*
	 * The value being inserted is less than any value in this tree.
	 * Follow the minimum branch out of this node to a subtree.
	 */
	if (H5B_decode_keys(f, bt, idx) < 0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTDECODE, H5B_INS_ERROR, "unable to decode key")
	if ((my_ins = H5B_insert_helper(f, dxpl_id, bt->child[idx], type, split_ratios,
                bt->key[idx].nkey, lt_key_changed, md_key,
                udata, bt->key[idx+1].nkey, rt_key_changed,
                &child_addr/*out*/))<0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTINSERT, H5B_INS_ERROR, "can't insert minimum subtree")
    } else if (cmp < 0 && idx == 0 && type->follow_min) {
	/*
	 * The value being inserted is less than any leaf node out of this
	 * current node.  Follow the minimum branch to a leaf node and let the
	 * subclass handle the problem.
	 */
	if (H5B_decode_keys(f, bt, idx) < 0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTDECODE, H5B_INS_ERROR, "unable to decode key")
	if ((my_ins = (type->insert)(f, dxpl_id, bt->child[idx], bt->key[idx].nkey,
                 lt_key_changed, md_key, udata, bt->key[idx+1].nkey,
                 rt_key_changed, &child_addr/*out*/)) < 0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTINSERT, H5B_INS_ERROR, "can't insert minimum leaf node")
    } else if (cmp < 0 && idx == 0) {
	/*
	 * The value being inserted is less than any leaf node out of the
	 * current node. Create a new minimum leaf node out of this B-tree
	 * node. This node is not empty (handled above).
	 */
	if (H5B_decode_keys(f, bt, idx) < 0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTDECODE, H5B_INS_ERROR, "unable to decode key")
	my_ins = H5B_INS_LEFT;
	HDmemcpy(md_key, bt->key[idx].nkey, type->sizeof_nkey);
	if ((type->new_node)(f, dxpl_id, H5B_INS_LEFT, bt->key[idx].nkey, udata,
			     md_key, &child_addr/*out*/) < 0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTINSERT, H5B_INS_ERROR, "can't insert minimum leaf node")
	*lt_key_changed = TRUE;

    } else if (cmp > 0 && idx + 1 >= bt->nchildren && bt->level > 0) {
	/*
	 * The value being inserted is larger than any value in this tree.
	 * Follow the maximum branch out of this node to a subtree.
	 */
	idx = bt->nchildren - 1;
	if (H5B_decode_keys(f, bt, idx) < 0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTDECODE, H5B_INS_ERROR, "unable to decode key")
	if ((my_ins = H5B_insert_helper(f, dxpl_id, bt->child[idx], type, split_ratios,
                bt->key[idx].nkey, lt_key_changed, md_key, udata,
                bt->key[idx+1].nkey, rt_key_changed, &child_addr/*out*/)) < 0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTINSERT, H5B_INS_ERROR, "can't insert maximum subtree")
    } else if (cmp > 0 && idx + 1 >= bt->nchildren && type->follow_max) {
	/*
	 * The value being inserted is larger than any leaf node out of the
	 * current node.  Follow the maximum branch to a leaf node and let the
	 * subclass handle the problem.
	 */
	idx = bt->nchildren - 1;
	if (H5B_decode_keys(f, bt, idx) < 0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTDECODE, H5B_INS_ERROR, "unable to decode key")
	if ((my_ins = (type->insert)(f, dxpl_id, bt->child[idx], bt->key[idx].nkey,
                 lt_key_changed, md_key, udata, bt->key[idx+1].nkey,
                 rt_key_changed, &child_addr/*out*/)) < 0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTINSERT, H5B_INS_ERROR, "can't insert maximum leaf node")
    } else if (cmp > 0 && idx + 1 >= bt->nchildren) {
	/*
	 * The value being inserted is larger than any leaf node out of the
	 * current node.  Create a new maximum leaf node out of this B-tree
	 * node.
	 */
	idx = bt->nchildren - 1;
	if (H5B_decode_keys(f, bt, idx) < 0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTDECODE, H5B_INS_ERROR, "unable to decode key")
	my_ins = H5B_INS_RIGHT;
	HDmemcpy(md_key, bt->key[idx+1].nkey, type->sizeof_nkey);
	if ((type->new_node)(f, dxpl_id, H5B_INS_RIGHT, md_key, udata,
			     bt->key[idx+1].nkey, &child_addr/*out*/) < 0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTINSERT, H5B_INS_ERROR, "can't insert maximum leaf node")
	*rt_key_changed = TRUE;

    } else if (cmp) {
	/*
	 * We couldn't figure out which branch to follow out of this node. THIS
	 * IS A MAJOR PROBLEM THAT NEEDS TO BE FIXED --rpm.
	 */
	assert("INTERNAL HDF5 ERROR (contact rpm)" && 0);
#ifdef NDEBUG
	HDabort();
#endif /* NDEBUG */
    } else if (bt->level > 0) {
	/*
	 * Follow a branch out of this node to another subtree.
	 */
	assert(idx < bt->nchildren);
	if ((my_ins = H5B_insert_helper(f, dxpl_id, bt->child[idx], type, split_ratios,
                bt->key[idx].nkey, lt_key_changed, md_key, udata,
                bt->key[idx+1].nkey, rt_key_changed, &child_addr/*out*/)) < 0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTINSERT, H5B_INS_ERROR, "can't insert subtree")
    } else {
	/*
	 * Follow a branch out of this node to a leaf node of some other type.
	 */
	assert(idx < bt->nchildren);
	if ((my_ins = (type->insert)(f, dxpl_id, bt->child[idx], bt->key[idx].nkey,
                  lt_key_changed, md_key, udata, bt->key[idx+1].nkey,
                  rt_key_changed, &child_addr/*out*/)) < 0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTINSERT, H5B_INS_ERROR, "can't insert leaf node")
    }
    assert(my_ins >= 0);

    /*
     * Update the left and right keys of the current node.
     */
    if (*lt_key_changed) {
	bt->cache_info.dirty = TRUE;
	bt->key[idx].dirty = TRUE;
	if (idx > 0) {
	    *lt_key_changed = FALSE;
	} else {
	    HDmemcpy(lt_key, bt->key[idx].nkey, type->sizeof_nkey);
	}
    }
    if (*rt_key_changed) {
	bt->cache_info.dirty = TRUE;
	bt->key[idx+1].dirty = TRUE;
	if (idx+1 < bt->nchildren) {
	    *rt_key_changed = FALSE;
	} else {
	    HDmemcpy(rt_key, bt->key[idx+1].nkey, type->sizeof_nkey);
	}
    }
    if (H5B_INS_CHANGE == my_ins) {
	/*
	 * The insertion simply changed the address for the child.
	 */
	bt->child[idx] = child_addr;
	bt->cache_info.dirty = TRUE;
	bt->ndirty = MAX(bt->ndirty, idx+1);
	ret_value = H5B_INS_NOOP;

    } else if (H5B_INS_LEFT == my_ins || H5B_INS_RIGHT == my_ins) {
        H5B_t	*tmp_bt;

	/*
	 * If this node is full then split it before inserting the new child.
	 */
	if (bt->nchildren == 2 * H5F_KVALUE(f, type)) {
	    if (H5B_split(f, dxpl_id, type, bt, addr, idx, split_ratios, udata, new_node_p/*out*/)<0)
		HGOTO_ERROR(H5E_BTREE, H5E_CANTSPLIT, H5B_INS_ERROR, "unable to split node")
	    if (NULL == (twin = H5AC_protect(f, dxpl_id, H5AC_BT, *new_node_p, type, udata, H5AC_WRITE)))
		HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, H5B_INS_ERROR, "unable to load node")
	    if (idx<bt->nchildren) {
		tmp_bt = bt;
	    } else {
		idx -= bt->nchildren;
		tmp_bt = twin;
	    }
	} else {
	    tmp_bt = bt;
	}

	/* Insert the child */
	if (H5B_insert_child(f, type, tmp_bt, idx, child_addr, my_ins, md_key) < 0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTINSERT, H5B_INS_ERROR, "can't insert child")
    }
    
    /*
     * If this node split, return the mid key (the one that is shared
     * by the left and right node).
     */
    if (twin) {
	if (!twin->key[0].nkey && H5B_decode_key(f, twin, 0) < 0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTDECODE, H5B_INS_ERROR, "unable to decode key")
	HDmemcpy(md_key, twin->key[0].nkey, type->sizeof_nkey);
	ret_value = H5B_INS_RIGHT;
#ifdef H5B_DEBUG
	/*
	 * The max key in the original left node must be equal to the min key
	 * in the new node.
	 */
	if (!bt->key[bt->nchildren].nkey) {
	    herr_t status = H5B_decode_key(f, bt, bt->nchildren);
	    assert(status >= 0);
	}
	cmp = (type->cmp2) (f, dxpl_id, bt->key[bt->nchildren].nkey, udata,
			    twin->key[0].nkey);
	assert(0 == cmp);
#endif
    } else {
	ret_value = H5B_INS_NOOP;
    }

done:
    {
	herr_t e1 = (bt && H5AC_unprotect(f, dxpl_id, H5AC_BT, addr, bt, FALSE) < 0);
	herr_t e2 = (twin && H5AC_unprotect(f, dxpl_id, H5AC_BT, *new_node_p, twin, FALSE)<0);
	if (e1 || e2)  /*use vars to prevent short-circuit of side effects */
	    HDONE_ERROR(H5E_BTREE, H5E_PROTECT, H5B_INS_ERROR, "unable to release node(s)")
    }

    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:	H5B_iterate
 *
 * Purpose:	Calls the list callback for each leaf node of the
 *		B-tree, passing it the UDATA structure.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Robb Matzke
 *		matzke@llnl.gov
 *		Jun 23 1997
 *
 * Modifications:
 * 		Robb Matzke, 1999-04-21
 *		The key values are passed to the function which is called.
 *
 * 		Robb Matzke, 1999-07-28
 *		The ADDR argument is passed by value.
 *
 *		Quincey Koziol, 2002-04-22
 *		Changed callback to function pointer from static function
 *-------------------------------------------------------------------------
 */
herr_t
H5B_iterate (H5F_t *f, hid_t dxpl_id, const H5B_class_t *type, H5B_operator_t op, haddr_t addr, void *udata)
{
    H5B_t		*bt = NULL;
    haddr_t		next_addr;
    haddr_t		cur_addr = HADDR_UNDEF;
    haddr_t		*child = NULL;
    uint8_t		*key = NULL;
    unsigned		nchildren;      /* Number of children of B-tree node */
    unsigned		u;              /* Local index variable */
    int                 level;
    haddr_t             left_child;
    herr_t		ret_value;
    
    FUNC_ENTER_NOAPI(H5B_iterate, FAIL)

    /*
     * Check arguments.
     */
    assert(f);
    assert(type);
    assert(op);
    assert(H5F_addr_defined(addr));
    assert(udata);

    if (NULL == (bt = H5AC_protect(f, dxpl_id, H5AC_BT, addr, type, udata, H5AC_READ)))
	HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load B-tree node")

    level = bt->level;
    left_child = bt->child[0];

    if (H5AC_unprotect(f, dxpl_id, H5AC_BT, addr, bt, FALSE) < 0)
        HGOTO_ERROR(H5E_BTREE, H5E_PROTECT, FAIL, "unable to release B-tree node")

    bt = NULL;  /* Make certain future references will be caught */

    if (level > 0) {
	/* Keep following the left-most child until we reach a leaf node. */
	if ((ret_value=H5B_iterate(f, dxpl_id, type, op, left_child, udata))<0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTLIST, FAIL, "unable to list B-tree node")
    } else {
	/*
	 * We've reached the left-most leaf.  Now follow the right-sibling
	 * pointer from leaf to leaf until we've processed all leaves.
	 */
	if (NULL==(child=H5FL_ARR_MALLOC(haddr_t,(size_t)(2*H5F_KVALUE(f,type)))) ||
                NULL==(key=H5MM_malloc((2*H5F_KVALUE(f, type)+1)*type->sizeof_nkey)))
	    HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")

	for (cur_addr=addr, ret_value=0; H5F_addr_defined(cur_addr) && !ret_value; cur_addr=next_addr) {
	    /*
	     * Save all the child addresses and native keys since we can't
	     * leave the B-tree node protected during an application
	     * callback.
	     */
	    if (NULL == (bt = H5AC_protect(f, dxpl_id, H5AC_BT, cur_addr, type, udata, H5AC_READ)))
		HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "B-tree node")

	    for (u=0; u<bt->nchildren; u++)
		child[u] = bt->child[u];

	    for (u=0; u<bt->nchildren+1; u++) {
		if (!bt->key[u].nkey) {
                    if (H5B_decode_key(f, bt, u) < 0) {
                        HCOMMON_ERROR(H5E_BTREE, H5E_CANTDECODE, "unable to decode key")

                        if (H5AC_unprotect(f, dxpl_id, H5AC_BT, cur_addr, bt, FALSE) < 0)
                            HGOTO_ERROR(H5E_BTREE, H5E_PROTECT, FAIL, "unable to release B-tree node")

                        HGOTO_DONE(FAIL)
                    }
                } /* end if */
		HDmemcpy(key+u*type->sizeof_nkey, bt->key[u].nkey, type->sizeof_nkey);
	    }

	    next_addr = bt->right;
	    nchildren = bt->nchildren;

            if (H5AC_unprotect(f, dxpl_id, H5AC_BT, cur_addr, bt, FALSE) < 0)
                HGOTO_ERROR(H5E_BTREE, H5E_PROTECT, FAIL, "unable to release B-tree node")

	    bt = NULL;

	    /*
	     * Perform the iteration operator, which might invoke an
	     * application callback.
	     */
	    for (u=0, ret_value=H5B_ITER_CONT; u<nchildren && !ret_value; u++) {
		ret_value = (*op)(f, dxpl_id, key+u*type->sizeof_nkey,
                         child[u], key+(u+1)*type->sizeof_nkey, udata);
		if (ret_value<0)
		    HGOTO_ERROR(H5E_BTREE, H5E_CANTINIT, FAIL, "iterator function failed")
	    } /* end for */
	} /* end for */
    } /* end else */

done:
    if(child!=NULL)
        H5FL_ARR_FREE(haddr_t,child);
    if(key!=NULL)
        H5MM_xfree(key);
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:	H5B_remove_helper
 *
 * Purpose:	The recursive part of removing an item from a B-tree.  The
 *		sub B-tree that is being considered is located at ADDR and
 *		the item to remove is described by UDATA.  If the removed
 *		item falls at the left or right end of the current level then
 *		it might be necessary to adjust the left and/or right keys
 *		(LT_KEY and/or RT_KEY) to to indicate that they changed by
 * 		setting LT_KEY_CHANGED and/or RT_KEY_CHANGED.
 *
 * Return:	Success:	A B-tree operation, see comments for
 *				H5B_ins_t declaration.  This function is
 *				called recursively and the return value
 *				influences the actions of the caller. It is
 *				also called by H5B_remove().
 *
 *		Failure:	H5B_INS_ERROR, a negative value.
 *
 * Programmer:	Robb Matzke
 *              Wednesday, September 16, 1998
 *
 * Modifications:
 *		Robb Matzke, 1999-07-28
 *		The ADDR argument is passed by value.
 *-------------------------------------------------------------------------
 */
static H5B_ins_t
H5B_remove_helper(H5F_t *f, hid_t dxpl_id, haddr_t addr, const H5B_class_t *type,
		  int level, uint8_t *lt_key/*out*/,
		  hbool_t *lt_key_changed/*out*/, void *udata,
		  uint8_t *rt_key/*out*/, hbool_t *rt_key_changed/*out*/)
{
    H5B_t	*bt = NULL, *sibling = NULL;
    H5B_ins_t	ret_value = H5B_INS_ERROR;
    unsigned    idx=0, lt=0, rt;        /* Final, left & right indices */
    int         cmp=1;                  /* Key comparison value */
    unsigned	u;                      /* Local index variable */
    size_t	sizeof_rkey, sizeof_rec;
    hsize_t	sizeof_node;
    
    FUNC_ENTER_NOAPI(H5B_remove_helper, H5B_INS_ERROR)

    assert(f);
    assert(H5F_addr_defined(addr));
    assert(type);
    assert(type->decode);
    assert(type->cmp3);
    assert(type->found);
    assert(lt_key && lt_key_changed);
    assert(udata);
    assert(rt_key && rt_key_changed);

    /*
     * Perform a binary search to locate the child which contains the thing
     * for which we're searching.
     */
    if (NULL==(bt=H5AC_protect(f, dxpl_id, H5AC_BT, addr, type, udata, H5AC_WRITE)))
	HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, H5B_INS_ERROR, "unable to load B-tree node")
    rt = bt->nchildren;
    while (lt<rt && cmp) {
	idx = (lt+rt)/2;
	if (H5B_decode_keys(f, bt, idx)<0)
	    HGOTO_ERROR(H5E_BTREE, H5E_CANTDECODE, H5B_INS_ERROR, "unable to decode B-tree key(s)")
	if ((cmp=(type->cmp3)(f, dxpl_id, bt->key[idx].nkey, udata,
			      bt->key[idx+1].nkey))<0) {
	    rt = idx;
	} else {
	    lt = idx+1;
	}
    }
    if (cmp)
	HGOTO_ERROR(H5E_BTREE, H5E_NOTFOUND, H5B_INS_ERROR, "B-tree key not found")

    /*
     * Follow the link to the subtree or to the data node.  The return value
     * will be one of H5B_INS_ERROR, H5B_INS_NOOP, or H5B_INS_REMOVE.
     */
    assert(idx<bt->nchildren);
    if (bt->level>0) {
	/* We're at an internal node -- call recursively */
	if ((ret_value=H5B_remove_helper(f, dxpl_id,
                 bt->child[idx], type, level+1, bt->key[idx].nkey/*out*/,
                 lt_key_changed/*out*/, udata, bt->key[idx+1].nkey/*out*/,
                 rt_key_changed/*out*/))<0)
	    HGOTO_ERROR(H5E_BTREE, H5E_NOTFOUND, H5B_INS_ERROR, "key not found in subtree")
    } else if (type->remove) {
	/*
	 * We're at a leaf node but the leaf node points to an object that
	 * has a removal method.  Pass the removal request to the pointed-to
	 * object and let it decide how to progress.
	 */
	if ((ret_value=(type->remove)(f, dxpl_id,
                  bt->child[idx], bt->key[idx].nkey, lt_key_changed, udata,
                  bt->key[idx+1].nkey, rt_key_changed))<0)
	    HGOTO_ERROR(H5E_BTREE, H5E_NOTFOUND, H5B_INS_ERROR, "key not found in leaf node")
    } else {
	/*
	 * We're at a leaf node which points to an object that has no removal
	 * method.  The best we can do is to leave the object alone but
	 * remove the B-tree reference to the object.
	 */
	*lt_key_changed = FALSE;
	*rt_key_changed = FALSE;
	ret_value = H5B_INS_REMOVE;
    }

    /*
     * Update left and right key dirty bits if the subtree indicates that they
     * have changed.  If the subtree's left key changed and the subtree is the
     * left-most child of the current node then we must update the key in our
     * parent and indicate that it changed.  Similarly, if the rigt subtree
     * key changed and it's the right most key of this node we must update
     * our right key and indicate that it changed.
     */
    if (*lt_key_changed) {
	bt->cache_info.dirty = TRUE;
	bt->key[idx].dirty = TRUE;
	if (idx>0) {
            /* Don't propagate change out of this B-tree node */
	    *lt_key_changed = FALSE;
	} else {
	    HDmemcpy(lt_key, bt->key[idx].nkey, type->sizeof_nkey);
	}
    }
    if (*rt_key_changed) {
	bt->cache_info.dirty = TRUE;
	bt->key[idx+1].dirty = TRUE;
	if (idx+1<bt->nchildren) {
            /* Don't propagate change out of this B-tree node */
	    *rt_key_changed = FALSE;
	} else {
	    HDmemcpy(rt_key, bt->key[idx+1].nkey, type->sizeof_nkey);
	}
    }

    /*
     * If the subtree returned H5B_INS_REMOVE then we should remove the
     * subtree entry from the current node.  There are four cases:
     */
    sizeof_rec = bt->sizeof_rkey + H5F_SIZEOF_ADDR(f);
    if (H5B_INS_REMOVE==ret_value && 1==bt->nchildren) {
	/*
	 * The subtree is the only child of this node.  Discard both
	 * keys and the subtree pointer. Free this node (unless it's the
	 * root node) and return H5B_INS_REMOVE.
	 */
	bt->cache_info.dirty = TRUE;
	bt->nchildren = 0;
	bt->ndirty = 0;
	if (level>0) {
	    if (H5F_addr_defined(bt->left)) {
		if (NULL == (sibling = H5AC_protect(f, dxpl_id, H5AC_BT, bt->left, type, udata, H5AC_WRITE)))
		    HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, H5B_INS_ERROR, "unable to load node from tree")

		sibling->right = bt->right;
		sibling->cache_info.dirty = TRUE;

                if (H5AC_unprotect(f, dxpl_id, H5AC_BT, bt->left, sibling, FALSE) != SUCCEED)
                    HGOTO_ERROR(H5E_BTREE, H5E_PROTECT, H5B_INS_ERROR, "unable to release node from tree")

                sibling=NULL;   /* Make certain future references will be caught */
	    }
	    if (H5F_addr_defined(bt->right)) {
		if (NULL == (sibling = H5AC_protect(f, dxpl_id, H5AC_BT, bt->right, type, udata, H5AC_WRITE)))
		    HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, H5B_INS_ERROR, "unable to unlink node from tree")

		sibling->left = bt->left;
		sibling->cache_info.dirty = TRUE;

                if (H5AC_unprotect(f, dxpl_id, H5AC_BT, bt->right, sibling, FALSE) != SUCCEED)
                    HGOTO_ERROR(H5E_BTREE, H5E_PROTECT, H5B_INS_ERROR, "unable to release node from tree")

                sibling=NULL;   /* Make certain future references will be caught */
	    }
	    bt->left = HADDR_UNDEF;
	    bt->right = HADDR_UNDEF;
	    sizeof_rkey = (type->get_sizeof_rkey)(f, udata);
	    sizeof_node = H5B_nodesize(f, type, NULL, sizeof_rkey);
	    if (H5MF_xfree(f, H5FD_MEM_BTREE, dxpl_id, addr, sizeof_node)<0
                    || H5AC_unprotect(f, dxpl_id, H5AC_BT, addr, bt, TRUE)<0) {
		bt = NULL;
		HGOTO_ERROR(H5E_BTREE, H5E_PROTECT, H5B_INS_ERROR, "unable to free B-tree node")
	    }
	    bt = NULL;
	}

    } else if (H5B_INS_REMOVE==ret_value && 0==idx) {
	/*
	 * The subtree is the left-most child of this node. We discard the
	 * left-most key and the left-most child (the child has already been
	 * freed) and shift everything down by one.  We copy the new left-most
	 * key into lt_key and notify the caller that the left key has
	 * changed.  Return H5B_INS_NOOP.
	 */
	bt->cache_info.dirty = TRUE;
	bt->nchildren -= 1;
	bt->ndirty = bt->nchildren;
	
	HDmemmove(bt->page+H5B_SIZEOF_HDR(f),
		  bt->page+H5B_SIZEOF_HDR(f)+sizeof_rec,
		  bt->nchildren*sizeof_rec + bt->sizeof_rkey);
	HDmemmove(bt->native,
		  bt->native + type->sizeof_nkey,
		  (bt->nchildren+1) * type->sizeof_nkey);
	HDmemmove(bt->child,
		  bt->child+1,
		  bt->nchildren * sizeof(haddr_t));
	for (u=0; u<=bt->nchildren; u++) {
	    bt->key[u].dirty = bt->key[u+1].dirty;
	    if (bt->key[u+1].nkey) {
		bt->key[u].nkey = bt->native + u*type->sizeof_nkey;
	    } else {
		bt->key[u].nkey = NULL;
	    }
	}
	assert(bt->key[0].nkey);
	HDmemcpy(lt_key, bt->key[0].nkey, type->sizeof_nkey);
	*lt_key_changed = TRUE;
	ret_value = H5B_INS_NOOP;

    } else if (H5B_INS_REMOVE==ret_value && idx+1==bt->nchildren) {
	/*
	 * The subtree is the right-most child of this node.  We discard the
	 * right-most key and the right-most child (the child has already been
	 * freed).  We copy the new right-most key into rt_key and notify the
	 * caller that the right key has changed.  Return H5B_INS_NOOP.
	 */
	bt->cache_info.dirty = TRUE;
	bt->nchildren -= 1;
	bt->ndirty = MIN(bt->ndirty, bt->nchildren);
	assert(bt->key[bt->nchildren].nkey);
	HDmemcpy(rt_key, bt->key[bt->nchildren].nkey, type->sizeof_nkey);
	*rt_key_changed = TRUE;
	ret_value = H5B_INS_NOOP;

    } else if (H5B_INS_REMOVE==ret_value) {
	/*
	 * There are subtrees out of this node to both the left and right of
	 * the subtree being removed.  The key to the left of the subtree and
	 * the subtree are removed from this node and all keys and nodes to
	 * the right are shifted left by one place.  The subtree has already
	 * been freed). Return H5B_INS_NOOP.
	 */
	bt->cache_info.dirty = TRUE;
	bt->nchildren -= 1;
	bt->ndirty = bt->nchildren;
	
	HDmemmove(bt->page+H5B_SIZEOF_HDR(f)+idx*sizeof_rec,
		  bt->page+H5B_SIZEOF_HDR(f)+(idx+1)*sizeof_rec,
		  (bt->nchildren-idx)*sizeof_rec + bt->sizeof_rkey);
	HDmemmove(bt->native + idx * type->sizeof_nkey,
		  bt->native + (idx+1) * type->sizeof_nkey,
		  (bt->nchildren+1-idx) * type->sizeof_nkey);
	HDmemmove(bt->child+idx,
		  bt->child+idx+1,
		  (bt->nchildren-idx) * sizeof(haddr_t));
	for (u=idx; u<=bt->nchildren; u++) {
	    bt->key[u].dirty = bt->key[u+1].dirty;
	    if (bt->key[u+1].nkey) {
		bt->key[u].nkey = bt->native + u*type->sizeof_nkey;
	    } else {
		bt->key[u].nkey = NULL;
	    }
	}
	ret_value = H5B_INS_NOOP;
	
    } else {
	ret_value = H5B_INS_NOOP;
    }

done:
    if (bt && H5AC_unprotect(f, dxpl_id, H5AC_BT, addr, bt, FALSE)<0)
	HDONE_ERROR(H5E_BTREE, H5E_PROTECT, H5B_INS_ERROR, "unable to release node")

    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:	H5B_remove
 *
 * Purpose:	Removes an item from a B-tree.
 *
 * Note:	The current version does not attempt to rebalance the tree.
 *
 * Return:	Non-negative on success/Negative on failure (failure includes
 *		not being able to find the object which is to be removed).
 *
 * Programmer:	Robb Matzke
 *              Wednesday, September 16, 1998
 *
 * Modifications:
 *		Robb Matzke, 1999-07-28
 *		The ADDR argument is passed by value.
 *-------------------------------------------------------------------------
 */
herr_t
H5B_remove(H5F_t *f, hid_t dxpl_id, const H5B_class_t *type, haddr_t addr, void *udata)
{
    /* These are defined this way to satisfy alignment constraints */
    uint64_t	_lt_key[128], _rt_key[128];
    uint8_t	*lt_key = (uint8_t*)_lt_key;	/*left key*/
    uint8_t	*rt_key = (uint8_t*)_rt_key;	/*right key*/
    hbool_t	lt_key_changed = FALSE;		/*left key changed?*/
    hbool_t	rt_key_changed = FALSE;		/*right key changed?*/
    H5B_t	*bt = NULL;			/*btree node */
    herr_t      ret_value=SUCCEED;       /* Return value */
    
    FUNC_ENTER_NOAPI(H5B_remove, FAIL)

    /* Check args */
    assert(f);
    assert(type);
    assert(type->sizeof_nkey <= sizeof _lt_key);
    assert(H5F_addr_defined(addr));

    /* The actual removal */
    if (H5B_remove_helper(f, dxpl_id, addr, type, 0, lt_key, &lt_key_changed,
			  udata, rt_key, &rt_key_changed)==H5B_INS_ERROR)
	HGOTO_ERROR(H5E_BTREE, H5E_CANTINIT, FAIL, "unable to remove entry from B-tree")

    /*
     * If the B-tree is now empty then make sure we mark the root node as
     * being at level zero
     */
    if (NULL == (bt = H5AC_protect(f, dxpl_id, H5AC_BT, addr, type, udata, H5AC_WRITE)))
	HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load B-tree root node")

    if (0==bt->nchildren && 0!=bt->level) {
	bt->level = 0;
	bt->cache_info.dirty = TRUE;
    }
    
    if (H5AC_unprotect(f, dxpl_id, H5AC_BT, addr, bt, FALSE) != SUCCEED)
        HGOTO_ERROR(H5E_BTREE, H5E_PROTECT, FAIL, "unable to release node")

    bt=NULL;    /* Make certain future references will be caught */

#ifdef H5B_DEBUG
    H5B_assert(f, dxpl_id, addr, type, udata);
#endif
done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:	H5B_delete
 *
 * Purpose:	Deletes an entire B-tree from the file, calling the 'remove'
 *              callbacks for each node.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *              Thursday, March 20, 2003
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5B_delete(H5F_t *f, hid_t dxpl_id, const H5B_class_t *type, haddr_t addr, void *udata)
{
    H5B_t	*bt;                    /* B-tree node being operated on */
    size_t	sizeof_rkey;            /* Size of raw key */
    hsize_t	sizeof_node;            /* Size of B-tree node */
    unsigned    u;                      /* Local index variable */
    herr_t      ret_value=SUCCEED;      /* Return value */
    
    FUNC_ENTER_NOAPI(H5B_delete, FAIL)

    /* Check args */
    assert(f);
    assert(type);
    assert(H5F_addr_defined(addr));

    /* Lock this B-tree node into memory for now */
    if (NULL == (bt = H5AC_protect(f, dxpl_id, H5AC_BT, addr, type, udata, H5AC_WRITE)))
	HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load B-tree node")

    /* Iterate over all children in tree, deleting them */
    if (bt->level > 0) {
        /* Iterate over all children in node, deleting them */
        for (u=0; u<bt->nchildren; u++)
            if (H5B_delete(f, dxpl_id, type, bt->child[u], udata)<0)
                HGOTO_ERROR(H5E_BTREE, H5E_CANTLIST, FAIL, "unable to delete B-tree node")

    } else {
        hbool_t lt_key_changed, rt_key_changed; /* Whether key changed (unused here, just for callback) */

        /* Check for removal callback */
        if(type->remove) {
            /* Iterate over all entries in node, calling callback */
            for (u=0; u<bt->nchildren; u++) {
                /* Decode native keys */
                if (H5B_decode_keys(f, bt, u)<0)
                    HGOTO_ERROR(H5E_BTREE, H5E_CANTDECODE, FAIL, "unable to decode B-tree key(s)")

                /* Call user's callback for each entry */
                if ((type->remove)(f, dxpl_id,
                          bt->child[u], bt->key[u].nkey, &lt_key_changed, udata,
                          bt->key[u+1].nkey, &rt_key_changed)<0)
                    HGOTO_ERROR(H5E_BTREE, H5E_NOTFOUND, FAIL, "can't remove B-tree node")
            } /* end for */
        } /* end if */
    } /* end else */

    /* Delete this node from disk */
    sizeof_rkey = (type->get_sizeof_rkey)(f, udata);
    sizeof_node = H5B_nodesize(f, type, NULL, sizeof_rkey);
    if (H5MF_xfree(f, H5FD_MEM_BTREE, dxpl_id, addr, sizeof_node)<0)
        HGOTO_ERROR(H5E_BTREE, H5E_CANTFREE, FAIL, "unable to free B-tree node")
    
done:
    if (bt && H5AC_unprotect(f, dxpl_id, H5AC_BT, addr, bt, TRUE)<0)
        HDONE_ERROR(H5E_BTREE, H5E_PROTECT, FAIL, "unable to release B-tree node in cache")

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5B_delete() */


/*-------------------------------------------------------------------------
 * Function:	H5B_nodesize
 *
 * Purpose:	Returns the number of bytes needed for this type of
 *		B-tree node.  The size is the size of the header plus
 *		enough space for 2t child pointers and 2t+1 keys.
 *
 *		If TOTAL_NKEY_SIZE is non-null, what it points to will
 *		be initialized with the total number of bytes required to
 *		hold all the key values in native order.
 *
 * Return:	Success:	Size of node in file.
 *
 *		Failure:	0
 *
 * Programmer:	Robb Matzke
 *		matzke@llnl.gov
 *		Jul  3 1997
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
static size_t
H5B_nodesize(const H5F_t *f, const H5B_class_t *type,
	     size_t *total_nkey_size/*out*/, size_t sizeof_rkey)
{
    size_t	size;
    size_t ret_value;   /* Return value */

    FUNC_ENTER_NOAPI(H5B_nodesize, 0)

    /*
     * Check arguments.
     */
    assert(f);
    assert(type);
    assert(sizeof_rkey > 0);
    assert(H5F_KVALUE(f, type) > 0);

    /*
     * Total native key size.
     */
    if (total_nkey_size)
	*total_nkey_size = (2 * H5F_KVALUE(f, type) + 1) * type->sizeof_nkey;

    /*
     * Total node size.
     */
    size = (H5B_SIZEOF_HDR(f) + /*node header	*/
	    2 * H5F_KVALUE(f, type) * H5F_SIZEOF_ADDR(f) +	/*child pointers */
	    (2 * H5F_KVALUE(f, type) + 1) * sizeof_rkey);	/*keys		*/

    /* Set return value */
    ret_value=size;

done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:	H5B_copy
 *
 * Purpose:	Deep copies an existing H5B_t node.
 *
 * Return:	Success:	Pointer to H5B_t object.
 *
 * 		Failure:	NULL
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Apr 18 2000
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
static H5B_t *
H5B_copy(const H5F_t *f, const H5B_t *old_bt)
{
    H5B_t		*new_node = NULL;
    size_t		total_native_keysize;
    size_t		size;
    size_t              nkeys;
    size_t		u;
    H5B_t		*ret_value;

    FUNC_ENTER_NOAPI(H5B_copy, NULL)

    /*
     * Check arguments.
     */
    assert(f);
    assert(old_bt);

    /*
     * Get correct sizes 
     */
    size = H5B_nodesize(f, old_bt->type, &total_native_keysize, old_bt->sizeof_rkey);

    /* Allocate memory for the new H5B_t object */
    if (NULL==(new_node = H5FL_MALLOC(H5B_t)))
        HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for B-tree root node")

    /* Copy the main structure */
    HDmemcpy(new_node,old_bt,sizeof(H5B_t));

    /* Compute the number of keys in this node */
    nkeys=2*H5F_KVALUE(f,old_bt->type);

    if (NULL==(new_node->page=H5FL_BLK_MALLOC(page,size)) ||
            NULL==(new_node->native=H5FL_BLK_MALLOC(native_block,total_native_keysize)) ||
            NULL==(new_node->child=H5FL_ARR_MALLOC(haddr_t,nkeys)) ||
            NULL==(new_node->key=H5FL_ARR_MALLOC(H5B_key_t,(nkeys+1))))
        HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for B-tree root node")

    /* Copy the other structures */
    HDmemcpy(new_node->page,old_bt->page,(size_t)size);
    HDmemcpy(new_node->native,old_bt->native,(size_t)total_native_keysize);
    HDmemcpy(new_node->child,old_bt->child,(size_t)(sizeof(haddr_t)*nkeys));
    HDmemcpy(new_node->key,old_bt->key,(size_t)(sizeof(H5B_key_t)*(nkeys+1)));

    /*
     * Translate the keys from pointers into the old 'page' buffer into
     *  pointers into the new 'page' buffer.
     */
    for (u = 0; u < (nkeys+1); u++)
        new_node->key[u].rkey = (old_bt->key[u].rkey - old_bt->page) + new_node->page;

    /* Set return value */
    ret_value=new_node;

done:
    if(ret_value==NULL) {
        if(new_node) {
	    H5FL_BLK_FREE (page,new_node->page);
	    H5FL_BLK_FREE (native_block,new_node->native);
	    H5FL_ARR_FREE (haddr_t,new_node->child);
	    H5FL_ARR_FREE (H5B_key_t,new_node->key);
	    H5FL_FREE (H5B_t,new_node);
        } /* end if */
    } /* end if */

    FUNC_LEAVE_NOAPI(ret_value)
}   /* H5B_copy */


/*-------------------------------------------------------------------------
 * Function:	H5B_debug
 *
 * Purpose:	Prints debugging info about a B-tree.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Robb Matzke
 *		matzke@llnl.gov
 *		Aug  4 1997
 *
 * Modifications:
 *		Robb Matzke, 1999-07-28
 *		The ADDR argument is passed by value.
 *-------------------------------------------------------------------------
 */
herr_t
H5B_debug(H5F_t *f, hid_t dxpl_id, haddr_t addr, FILE *stream, int indent, int fwidth,
	  const H5B_class_t *type, void *udata)
{
    H5B_t	*bt = NULL;
    unsigned	u;                      /* Local index variable */
    herr_t      ret_value=SUCCEED;       /* Return value */

    FUNC_ENTER_NOAPI(H5B_debug, FAIL)

    /*
     * Check arguments.
     */
    assert(f);
    assert(H5F_addr_defined(addr));
    assert(stream);
    assert(indent >= 0);
    assert(fwidth >= 0);
    assert(type);

    /*
     * Load the tree node.
     */
    if (NULL == (bt = H5AC_protect(f, dxpl_id, H5AC_BT, addr, type, udata, H5AC_READ)))
	HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load B-tree node")

    /*
     * Print the values.
     */
    HDfprintf(stream, "%*s%-*s %s\n", indent, "", fwidth,
	      "Tree type ID:",
	      ((bt->type->id)==H5B_SNODE_ID ? "H5B_SNODE_ID" :
            ((bt->type->id)==H5B_ISTORE_ID ? "H5B_ISTORE_ID" : "Unknown!")));
    HDfprintf(stream, "%*s%-*s %lu\n", indent, "", fwidth,
	      "Size of node:",
	      (unsigned long) H5B_nodesize(f, bt->type, NULL, bt->sizeof_rkey));
    HDfprintf(stream, "%*s%-*s %lu\n", indent, "", fwidth,
	      "Size of raw (disk) key:",
	      (unsigned long) (bt->sizeof_rkey));
    HDfprintf(stream, "%*s%-*s %s\n", indent, "", fwidth,
	      "Dirty flag:",
	      bt->cache_info.dirty ? "True" : "False");
    HDfprintf(stream, "%*s%-*s %u\n", indent, "", fwidth,
	      "Number of initial dirty children:",
	      bt->ndirty);
    HDfprintf(stream, "%*s%-*s %d\n", indent, "", fwidth,
	      "Level:",
	      (int) (bt->level));

    HDfprintf(stream, "%*s%-*s %a\n", indent, "", fwidth,
	      "Address of left sibling:",
	      bt->left);

    HDfprintf(stream, "%*s%-*s %a\n", indent, "", fwidth,
	      "Address of right sibling:",
	      bt->right);

    HDfprintf(stream, "%*s%-*s %u (%u)\n", indent, "", fwidth,
	      "Number of children (max):",
	      bt->nchildren, (2 * H5F_KVALUE(f, type)));

    /*
     * Print the child addresses
     */
    for (u = 0; u < bt->nchildren; u++) {
	HDfprintf(stream, "%*sChild %d...\n", indent, "", u);
	HDfprintf(stream, "%*s%-*s %a\n", indent + 3, "", MAX(0, fwidth - 3),
		  "Address:", bt->child[u]);
	
        /* If there is a key debugging routine, use it to display the left & right keys */
	if (type->debug_key) {
            /* Decode the 'left' key & print it */
            HDfprintf(stream, "%*s%-*s\n", indent + 3, "", MAX(0, fwidth - 3),
                      "Left Key:");
            if(bt->key[u].nkey==NULL) {
                if(H5B_decode_key(f, bt, u)<0)
                    HGOTO_ERROR(H5E_BTREE, H5E_CANTDECODE, FAIL, "unable to decode B-tree key(s)")
            } /* end if */
	    (void)(type->debug_key)(stream, f, dxpl_id, indent+6, MAX (0, fwidth-6),
			      bt->key[u].nkey, udata);

            /* Decode the 'right' key & print it */
            HDfprintf(stream, "%*s%-*s\n", indent + 3, "", MAX(0, fwidth - 3),
                      "Right Key:");
            if(bt->key[u+1].nkey==NULL) {
                if(H5B_decode_key(f, bt, u+1)<0)
                    HGOTO_ERROR(H5E_BTREE, H5E_CANTDECODE, FAIL, "unable to decode B-tree key(s)")
            } /* end if */
	    (void)(type->debug_key)(stream, f, dxpl_id, indent+6, MAX (0, fwidth-6),
			      bt->key[u+1].nkey, udata);
	}
    }

done:
    if (bt && H5AC_unprotect(f, dxpl_id, H5AC_BT, addr, bt, FALSE) < 0)
        HDONE_ERROR(H5E_BTREE, H5E_PROTECT, FAIL, "unable to release B-tree node")

    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:	H5B_assert
 *
 * Purpose:	Verifies that the tree is structured correctly.
 *
 * Return:	Success:	SUCCEED
 *
 *		Failure:	aborts if something is wrong.
 *
 * Programmer:	Robb Matzke
 *		Tuesday, November  4, 1997
 *
 * Modifications:
 *		Robb Matzke, 1999-07-28
 *		The ADDR argument is passed by value.
 *-------------------------------------------------------------------------
 */
#ifdef H5B_DEBUG
static herr_t
H5B_assert(H5F_t *f, hid_t dxpl_id, haddr_t addr, const H5B_class_t *type, void *udata)
{
    H5B_t	*bt = NULL;
    int	i, ncell, cmp;
    static int	ncalls = 0;
    herr_t	status;
    herr_t      ret_value=SUCCEED;       /* Return value */

    /* A queue of child data */
    struct child_t {
	haddr_t			addr;
	int			level;
	struct child_t	       *next;
    } *head = NULL, *tail = NULL, *prev = NULL, *cur = NULL, *tmp = NULL;

    FUNC_ENTER_NOAPI(H5B_assert, FAIL)

    if (0==ncalls++) {
	if (H5DEBUG(B)) {
	    fprintf(H5DEBUG(B), "H5B: debugging B-trees (expensive)\n");
	}
    }
    /* Initialize the queue */
    bt = H5AC_protect(f, dxpl_id, H5AC_BT, addr, type, udata, H5AC_READ);
    assert(bt);
    cur = H5MM_calloc(sizeof(struct child_t));
    assert (cur);
    cur->addr = addr;
    cur->level = bt->level;
    head = tail = cur;

    status = H5AC_unprotect(f, dxpl_id, H5AC_BT, addr, bt, FALSE);
    assert(status >= 0);
    bt=NULL;    /* Make certain future references will be caught */

    /*
     * Do a breadth-first search of the tree.  New nodes are added to the end
     * of the queue as the `cur' pointer is advanced toward the end.  We don't
     * remove any nodes from the queue because we need them in the uniqueness
     * test.
     */
    for (ncell = 0; cur; ncell++) {
	bt = H5AC_protect(f, dxpl_id, H5AC_BT, cur->addr, type, udata, H5AC_READ);
	assert(bt);

	/* Check node header */
	assert(bt->ndirty <= bt->nchildren);
	assert(bt->level == cur->level);
	if (cur->next && cur->next->level == bt->level) {
	    assert(H5F_addr_eq(bt->right, cur->next->addr));
	} else {
	    assert(!H5F_addr_defined(bt->right));
	}
	if (prev && prev->level == bt->level) {
	    assert(H5F_addr_eq(bt->left, prev->addr));
	} else {
	    assert(!H5F_addr_defined(bt->left));
	}

	if (cur->level > 0) {
	    for (i = 0; i < bt->nchildren; i++) {

		/*
		 * Check that child nodes haven't already been seen.  If they
		 * have then the tree has a cycle.
		 */
		for (tmp = head; tmp; tmp = tmp->next) {
		    assert(H5F_addr_ne(tmp->addr, bt->child[i]));
		}

		/* Add the child node to the end of the queue */
		tmp = H5MM_calloc(sizeof(struct child_t));
		assert (tmp);
		tmp->addr = bt->child[i];
		tmp->level = bt->level - 1;
		tail->next = tmp;
		tail = tmp;

		/* Check that the keys are monotonically increasing */
		status = H5B_decode_keys(f, bt, i);
		assert(status >= 0);
		cmp = (type->cmp2) (f, dxpl_id, bt->key[i].nkey, udata,
				    bt->key[i+1].nkey);
		assert(cmp < 0);
	    }
	}
	/* Release node */
	status = H5AC_unprotect(f, dxpl_id, H5AC_BT, cur->addr, bt, FALSE);
	assert(status >= 0);
        bt=NULL;    /* Make certain future references will be caught */

	/* Advance current location in queue */
	prev = cur;
	cur = cur->next;
    }

    /* Free all entries from queue */
    while (head) {
	tmp = head->next;
	H5MM_xfree(head);
	head = tmp;
    }

done:
    FUNC_LEAVE_NOAPI(ret_value)
}
#endif /* H5B_DEBUG */