[svn-r13745] Description:

    Take further advantage of the readers/writer locking in the metadata cache
and push the locking of the local heap up to the routines which call B-tree
routines, which should drastically lower the number of metadata cache protect/
unprotect calls.

Tested on:
    Mac OS X/32 10.4.9 (amazon)
    Linux/32 2.6 (chicago)
    Linux/64 2.6 (chicago2)

1 files changed, 146 insertions, 90 deletions

diff --git a/src/H5Gstab.c b/src/H5Gstab.c
index 7bb07aa..22d90a7 100644
--- a/src/H5Gstab.c
+++ b/src/H5Gstab.c
@@ -30,50 +30,47 @@
 #include "H5MMprivate.h"	/* Memory management			*/
 
 /* Private typedefs */
-/* User data for finding a name in the link messages */
+/* User data for finding link information from B-tree */
 typedef struct {
     /* downward */
-    H5F_t      *f;              /* Pointer to file for insertion */
+    H5F_t      *file;           /* Pointer to file for query */
     const char *name;           /* Name to search for */
+    H5HL_t     *heap;           /* Local heap for group */
 
     /* upward */
-    H5G_entry_t *ent;           /* Entry to update when match found */
-} H5G_stab_ud1_t;
+    H5O_link_t *lnk;            /* Caller's link location */
+} H5G_stab_fnd_ud_t;
 
-/* User data for finding object info from B-tree */
-typedef struct {
+/* Data passed through B-tree iteration for looking up a name by index */
+typedef struct H5G_bt_it_gnbi_t {
     /* downward */
-    H5O_loc_t *grp_oloc;        /* Object location of group */
-    hid_t       dxpl_id;        /* DXPL during operation */
-    haddr_t     heap_addr;      /* Local heap address for group */
+    H5G_bt_it_idx_common_t common; /* Common information for "by index" lookup  */
+    H5HL_t      *heap;          /*symbol table heap 			     */
 
     /* upward */
-    H5G_stat_t *statbuf;        /* Caller's statbuf */
-} H5G_stab_fnd_ud1_t;
+    char         *name;         /*member name to be returned                 */
+} H5G_bt_it_gnbi_t;
 
-/* User data for finding link information from B-tree */
-typedef struct {
+/* Data passed through B-tree iteration for looking up a type by index */
+typedef struct H5G_bt_it_gtbi_t {
     /* downward */
-    H5F_t      *file;           /* Pointer to file for query */
-    hid_t       dxpl_id;        /* DXPL during operation */
-    const char *name;           /* Name to search for */
-    haddr_t     heap_addr;      /* Local heap address for group */
+    H5G_bt_it_idx_common_t common; /* Common information for "by index" lookup  */
+    hid_t       dxpl_id;        /* DXPL for operation */
 
     /* upward */
-    H5O_link_t *lnk;            /* Caller's link location */
-} H5G_stab_fnd_ud2_t;
+    H5G_obj_t    type;          /*member type to be returned                 */
+} H5G_bt_it_gtbi_t;
 
-/* User data for finding object location from B-tree */
-typedef struct {
+/* Data passed through B-tree iteration for looking up a link by index */
+typedef struct H5G_bt_it_lbi_t {
     /* downward */
-    H5F_t      *file;           /* Pointer to file for query */
-    size_t      size;           /* Buffer size for link value */
-    haddr_t     heap_addr;      /* Local heap address for group */
-    hid_t       dxpl_id;        /* DXPL during operation */
+    H5G_bt_it_idx_common_t common; /* Common information for "by index" lookup  */
+    H5HL_t      *heap;          /*symbol table heap 			     */
 
     /* upward */
-    char *buf;                  /* Buffer to fill with link value */
-} H5G_stab_fnd_ud3_t;
+    H5O_link_t *lnk;            /*link to be returned                        */
+    hbool_t     found;      	/*whether we found the link                  */
+} H5G_bt_it_lbi_t;
 
 /* Private prototypes */
 
@@ -100,6 +97,7 @@ typedef struct {
 herr_t
 H5G_stab_create_components(H5F_t *f, H5O_stab_t *stab, size_t size_hint, hid_t dxpl_id)
 {
+    H5HL_t      *heap = NULL;           /* Pointer to local heap */
     size_t	name_offset;	        /* Offset of "" name	*/
     herr_t      ret_value = SUCCEED;    /* Return value */
 
@@ -119,9 +117,14 @@ H5G_stab_create_components(H5F_t *f, H5O_stab_t *stab, size_t size_hint, hid_t d
     /* Create symbol table private heap */
     if(H5HL_create(f, dxpl_id, size_hint, &(stab->heap_addr)/*out*/) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "can't create heap")
-    name_offset = H5HL_insert(f, dxpl_id, stab->heap_addr, (size_t)1, "");
-    if((size_t)(-1) == name_offset)
-	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "can't initialize heap")
+
+    /* Pin the heap down in memory */
+    if(NULL == (heap = H5HL_protect(f, dxpl_id, stab->heap_addr, H5AC_WRITE)))
+        HGOTO_ERROR(H5E_SYM, H5E_PROTECT, FAIL, "unable to protect symbol table heap")
+
+    /* Insert name into the heap */
+    if((size_t)(-1) == (name_offset = H5HL_insert(f, dxpl_id, heap, (size_t)1, "")))
+	HGOTO_ERROR(H5E_SYM, H5E_CANTINSERT, FAIL, "can't insert name into heap")
 
     /*
      * B-tree's won't work if the first name isn't at the beginning
@@ -130,6 +133,10 @@ H5G_stab_create_components(H5F_t *f, H5O_stab_t *stab, size_t size_hint, hid_t d
     HDassert(0 == name_offset);
 
 done:
+    /* Release resources */
+    if(heap && H5HL_unprotect(f, dxpl_id, heap, stab->heap_addr) < 0)
+        HDONE_ERROR(H5E_SYM, H5E_PROTECT, FAIL, "unable to unprotect symbol table heap")
+
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5G_stab_create_components() */
 
@@ -214,6 +221,7 @@ herr_t
 H5G_stab_insert_real(H5F_t *f, H5O_stab_t *stab, const char *name,
     H5O_link_t *obj_lnk, hid_t dxpl_id)
 {
+    H5HL_t      *heap = NULL;           /* Pointer to local heap */
     H5G_bt_ins_t	udata;		/* Data to pass through B-tree	*/
     herr_t              ret_value = SUCCEED;       /* Return value */
 
@@ -225,9 +233,13 @@ H5G_stab_insert_real(H5F_t *f, H5O_stab_t *stab, const char *name,
     HDassert(name && *name);
     HDassert(obj_lnk);
 
+    /* Pin the heap down in memory */
+    if(NULL == (heap = H5HL_protect(f, dxpl_id, stab->heap_addr, H5AC_WRITE)))
+        HGOTO_ERROR(H5E_SYM, H5E_PROTECT, FAIL, "unable to protect symbol table heap")
+
     /* Initialize data to pass through B-tree */
     udata.common.name = name;
-    udata.common.heap_addr = stab->heap_addr;
+    udata.common.heap = heap;
     udata.lnk = obj_lnk;
 
     /* Insert into symbol table */
@@ -235,6 +247,10 @@ H5G_stab_insert_real(H5F_t *f, H5O_stab_t *stab, const char *name,
         HGOTO_ERROR(H5E_SYM, H5E_CANTINSERT, FAIL, "unable to insert entry")
 
 done:
+    /* Release resources */
+    if(heap && H5HL_unprotect(f, dxpl_id, heap, stab->heap_addr) < 0)
+        HDONE_ERROR(H5E_SYM, H5E_PROTECT, FAIL, "unable to unprotect symbol table heap")
+
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5G_stab_insert_real() */
 
@@ -296,8 +312,9 @@ herr_t
 H5G_stab_remove(H5O_loc_t *loc, hid_t dxpl_id, H5RS_str_t *grp_full_path_r,
     const char *name)
 {
+    H5HL_t      *heap = NULL;           /* Pointer to local heap */
     H5O_stab_t		stab;		/*symbol table message		*/
-    H5G_bt_rm_t	udata;		/*data to pass through B-tree	*/
+    H5G_bt_rm_t		udata;		/*data to pass through B-tree	*/
     herr_t              ret_value = SUCCEED;       /* Return value */
 
     FUNC_ENTER_NOAPI(H5G_stab_remove, FAIL)
@@ -309,9 +326,13 @@ H5G_stab_remove(H5O_loc_t *loc, hid_t dxpl_id, H5RS_str_t *grp_full_path_r,
     if(NULL == H5O_msg_read(loc, H5O_STAB_ID, &stab, dxpl_id))
         HGOTO_ERROR(H5E_SYM, H5E_BADMESG, FAIL, "not a symbol table")
 
+    /* Pin the heap down in memory */
+    if(NULL == (heap = H5HL_protect(loc->file, dxpl_id, stab.heap_addr, H5AC_WRITE)))
+        HGOTO_ERROR(H5E_SYM, H5E_PROTECT, FAIL, "unable to protect symbol table heap")
+
     /* Initialize data to pass through B-tree */
     udata.common.name = name;
-    udata.common.heap_addr = stab.heap_addr;
+    udata.common.heap = heap;
     udata.grp_full_path_r = grp_full_path_r;
 
     /* Remove from symbol table */
@@ -319,6 +340,10 @@ H5G_stab_remove(H5O_loc_t *loc, hid_t dxpl_id, H5RS_str_t *grp_full_path_r,
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to remove entry")
 
 done:
+    /* Release resources */
+    if(heap && H5HL_unprotect(loc->file, dxpl_id, heap, stab.heap_addr) < 0)
+        HDONE_ERROR(H5E_SYM, H5E_PROTECT, FAIL, "unable to unprotect symbol table heap")
+
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5G_stab_remove() */
 
@@ -339,6 +364,7 @@ herr_t
 H5G_stab_remove_by_idx(H5O_loc_t *grp_oloc, hid_t dxpl_id, H5RS_str_t *grp_full_path_r,
     H5_iter_order_t order, hsize_t n)
 {
+    H5HL_t      *heap = NULL;           /* Pointer to local heap */
     H5O_stab_t		stab;		/* Symbol table message		*/
     H5G_bt_rm_t	udata;		/* Data to pass through B-tree	*/
     H5O_link_t          obj_lnk;        /* Object's link within group */
@@ -358,9 +384,13 @@ H5G_stab_remove_by_idx(H5O_loc_t *grp_oloc, hid_t dxpl_id, H5RS_str_t *grp_full_
     if(NULL == H5O_msg_read(grp_oloc, H5O_STAB_ID, &stab, dxpl_id))
         HGOTO_ERROR(H5E_SYM, H5E_BADMESG, FAIL, "not a symbol table")
 
+    /* Pin the heap down in memory */
+    if(NULL == (heap = H5HL_protect(grp_oloc->file, dxpl_id, stab.heap_addr, H5AC_WRITE)))
+        HGOTO_ERROR(H5E_SYM, H5E_PROTECT, FAIL, "unable to protect symbol table heap")
+
     /* Initialize data to pass through B-tree */
     udata.common.name = obj_lnk.name;
-    udata.common.heap_addr = stab.heap_addr;
+    udata.common.heap = heap;
     udata.grp_full_path_r = grp_full_path_r;
 
     /* Remove link from symbol table */
@@ -368,12 +398,16 @@ H5G_stab_remove_by_idx(H5O_loc_t *grp_oloc, hid_t dxpl_id, H5RS_str_t *grp_full_
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to remove entry")
 
 done:
+    /* Release resources */
+    if(heap && H5HL_unprotect(grp_oloc->file, dxpl_id, heap, stab.heap_addr) < 0)
+        HDONE_ERROR(H5E_SYM, H5E_PROTECT, FAIL, "unable to unprotect symbol table heap")
+
     /* Reset the link information, if we have a copy */
     if(lnk_copied)
         H5O_msg_reset(H5O_LINK_ID, &obj_lnk);
 
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5G_stab_remove() */
+} /* end H5G_stab_remove_by_idx() */
 
 
 /*-------------------------------------------------------------------------
@@ -393,6 +427,7 @@ done:
 herr_t
 H5G_stab_delete(H5F_t *f, hid_t dxpl_id, const H5O_stab_t *stab)
 {
+    H5HL_t      *heap = NULL;           /* Pointer to local heap */
     H5G_bt_rm_t	udata;		/*data to pass through B-tree	*/
     herr_t  ret_value = SUCCEED;
 
@@ -403,19 +438,32 @@ H5G_stab_delete(H5F_t *f, hid_t dxpl_id, const H5O_stab_t *stab)
     HDassert(H5F_addr_defined(stab->btree_addr));
     HDassert(H5F_addr_defined(stab->heap_addr));
 
+    /* Pin the heap down in memory */
+    if(NULL == (heap = H5HL_protect(f, dxpl_id, stab->heap_addr, H5AC_WRITE)))
+        HGOTO_ERROR(H5E_SYM, H5E_PROTECT, FAIL, "unable to protect symbol table heap")
+
     /* Set up user data for B-tree deletion */
     udata.common.name = NULL;
-    udata.common.heap_addr = stab->heap_addr;
+    udata.common.heap = heap;
 
     /* Delete entire B-tree */
     if(H5B_delete(f, dxpl_id, H5B_SNODE, stab->btree_addr, &udata) < 0)
         HGOTO_ERROR(H5E_SYM, H5E_CANTDELETE, FAIL, "unable to delete symbol table B-tree")
 
+    /* Release resources */
+    if(H5HL_unprotect(f, dxpl_id, heap, stab->heap_addr) < 0)
+        HGOTO_ERROR(H5E_SYM, H5E_PROTECT, FAIL, "unable to unprotect symbol table heap")
+    heap = NULL;
+
     /* Delete local heap for names */
     if(H5HL_delete(f, dxpl_id, stab->heap_addr) < 0)
         HGOTO_ERROR(H5E_SYM, H5E_CANTDELETE, FAIL, "unable to delete symbol table heap")
 
 done:
+    /* Release resources */
+    if(heap && H5HL_unprotect(f, dxpl_id, heap, stab->heap_addr) < 0)
+        HDONE_ERROR(H5E_SYM, H5E_PROTECT, FAIL, "unable to unprotect symbol table heap")
+
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5G_stab_delete() */
 
@@ -437,6 +485,7 @@ H5G_stab_iterate(const H5O_loc_t *oloc, hid_t dxpl_id, H5_iter_order_t order,
     hsize_t skip, hsize_t *last_lnk, hid_t gid,
     H5G_link_iterate_t *lnk_op, void *op_data)
 {
+    H5HL_t              *heap = NULL;           /* Local heap for group */
     H5O_stab_t		stab;		        /* Info about symbol table */
     H5G_link_table_t ltable = {0, NULL};        /* Link table */
     herr_t		ret_value;
@@ -451,6 +500,10 @@ H5G_stab_iterate(const H5O_loc_t *oloc, hid_t dxpl_id, H5_iter_order_t order,
     if(NULL == H5O_msg_read(oloc, H5O_STAB_ID, &stab, dxpl_id))
 	HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "unable to determine local heap address")
 
+    /* Pin the heap down in memory */
+    if(NULL == (heap = H5HL_protect(oloc->file, dxpl_id, stab.heap_addr, H5AC_READ)))
+        HGOTO_ERROR(H5E_SYM, H5E_PROTECT, FAIL, "unable to protect symbol table heap")
+
     /* Check on iteration order */
     /* ("native" iteration order is increasing for this link storage mechanism) */
     if(order != H5_ITER_DEC) {
@@ -458,15 +511,14 @@ H5G_stab_iterate(const H5O_loc_t *oloc, hid_t dxpl_id, H5_iter_order_t order,
 
         /* Build udata to pass through H5B_iterate() to H5G_node_iterate() */
         udata.group_id = gid;
-        udata.heap_addr = stab.heap_addr;
+        udata.heap = heap;
         udata.skip = skip;
         udata.final_ent = last_lnk;
         udata.lnk_op = lnk_op;
         udata.op_data = op_data;
 
         /* Iterate over the group members */
-        if((ret_value = H5B_iterate(oloc->file, dxpl_id, H5B_SNODE,
-                  H5G_node_iterate, stab.btree_addr, &udata)) < 0)
+        if((ret_value = H5B_iterate(oloc->file, dxpl_id, H5B_SNODE, H5G_node_iterate, stab.btree_addr, &udata)) < 0)
             HERROR(H5E_SYM, H5E_CANTNEXT, "iteration operator failed");
 
         /* Check for too high of a starting index (ex post facto :-) */
@@ -477,9 +529,9 @@ H5G_stab_iterate(const H5O_loc_t *oloc, hid_t dxpl_id, H5_iter_order_t order,
     else {
         H5G_bt_it_bt_t udata;                   /* User data to pass to B-tree callback */
 
-        /* Build udata to pass through H5B_iterate() to H5G_node_iterate() */
+        /* Build udata to pass through H5B_iterate() to H5G_node_build_table() */
         udata.alloc_nlinks = 0;
-        udata.heap_addr = stab.heap_addr;
+        udata.heap = heap;
         udata.ltable = &ltable;
 
         /* Iterate over the group members */
@@ -502,8 +554,10 @@ H5G_stab_iterate(const H5O_loc_t *oloc, hid_t dxpl_id, H5_iter_order_t order,
 
 done:
     /* Release resources */
+    if(heap && H5HL_unprotect(oloc->file, dxpl_id, heap, stab.heap_addr) < 0)
+        HDONE_ERROR(H5E_SYM, H5E_PROTECT, FAIL, "unable to unprotect symbol table heap")
     if(ltable.lnks && H5G_link_release_table(&ltable) < 0)
-        HDONE_ERROR(H5E_SYM, H5E_CANTFREE, H5G_UNKNOWN, "unable to release link table")
+        HDONE_ERROR(H5E_SYM, H5E_CANTFREE, FAIL, "unable to release link table")
 
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5G_stab_iterate() */
@@ -567,34 +621,23 @@ static herr_t
 H5G_stab_get_name_by_idx_cb(const H5G_entry_t *ent, void *_udata)
 {
     H5G_bt_it_gnbi_t	*udata = (H5G_bt_it_gnbi_t *)_udata;
-    H5HL_t *heap = NULL;                /* Pointer to local heap for group */
     size_t name_off;                    /* Offset of name in heap */
     const char *name;                   /* Pointer to name string in heap */
-    herr_t ret_value = SUCCEED;         /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT(H5G_stab_get_name_by_idx_cb)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5G_stab_get_name_by_idx_cb)
 
     /* Sanity check */
     HDassert(ent);
-    HDassert(udata);
+    HDassert(udata && udata->heap);
 
     /* Get name offset in heap */
     name_off = ent->name_off;
-
-    /* Pin the heap down in memory */
-    if(NULL == (heap = H5HL_protect(udata->common.f, udata->common.dxpl_id, udata->heap_addr, H5AC_READ)))
-        HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "unable to protect symbol name")
-
-    name = H5HL_offset_into(udata->common.f, heap, name_off);
+    name = H5HL_offset_into(udata->common.f, udata->heap, name_off);
     HDassert(name);
     udata->name = H5MM_strdup(name);
     HDassert(udata->name);
 
-done:
-    if(heap && H5HL_unprotect(udata->common.f, udata->common.dxpl_id, heap, udata->heap_addr, H5AC__NO_FLAGS_SET) < 0)
-        HDONE_ERROR(H5E_SYM, H5E_PROTECT, FAIL, "unable to unprotect symbol name")
-
-    FUNC_LEAVE_NOAPI(ret_value)
+    FUNC_LEAVE_NOAPI(SUCCEED)
 } /* end H5G_stab_get_name_by_idx_cb */
 
 
@@ -615,6 +658,7 @@ ssize_t
 H5G_stab_get_name_by_idx(H5O_loc_t *oloc, H5_iter_order_t order, hsize_t n,
     char* name, size_t size, hid_t dxpl_id)
 {
+    H5HL_t      *heap = NULL;           /* Pointer to local heap */
     H5O_stab_t		stab;	        /* Info about local heap & B-tree */
     H5G_bt_it_gnbi_t	udata;          /* Iteration information */
     ssize_t		ret_value;      /* Return value */
@@ -628,6 +672,10 @@ H5G_stab_get_name_by_idx(H5O_loc_t *oloc, H5_iter_order_t order, hsize_t n,
     if(NULL == H5O_msg_read(oloc, H5O_STAB_ID, &stab, dxpl_id))
 	HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "unable to determine local heap address")
 
+    /* Pin the heap down in memory */
+    if(NULL == (heap = H5HL_protect(oloc->file, dxpl_id, stab.heap_addr, H5AC_READ)))
+        HGOTO_ERROR(H5E_SYM, H5E_PROTECT, FAIL, "unable to protect symbol table heap")
+
     /* Remap index for decreasing iteration order */
     if(order == H5_ITER_DEC) {
         hsize_t nlinks = 0;           /* Number of links in group */
@@ -642,11 +690,10 @@ H5G_stab_get_name_by_idx(H5O_loc_t *oloc, H5_iter_order_t order, hsize_t n,
 
     /* Set iteration information */
     udata.common.f = oloc->file;
-    udata.common.dxpl_id = dxpl_id;
     udata.common.idx = n;
     udata.common.num_objs = 0;
     udata.common.op = H5G_stab_get_name_by_idx_cb;
-    udata.heap_addr = stab.heap_addr;
+    udata.heap = heap;
     udata.name = NULL;
 
     /* Iterate over the group members */
@@ -668,6 +715,10 @@ H5G_stab_get_name_by_idx(H5O_loc_t *oloc, H5_iter_order_t order, hsize_t n,
     } /* end if */
 
 done:
+    /* Release resources */
+    if(heap && H5HL_unprotect(oloc->file, dxpl_id, heap, stab.heap_addr) < 0)
+        HDONE_ERROR(H5E_SYM, H5E_PROTECT, FAIL, "unable to unprotect symbol table heap")
+
     /* Free the duplicated name */
     if(udata.name != NULL)
         H5MM_xfree(udata.name);
@@ -719,7 +770,7 @@ H5G_stab_get_type_by_idx_cb(const H5G_entry_t *ent, void *_udata)
                 tmp_oloc.addr = ent->header;
 
                 /* Get the type of the object */
-                if(H5O_obj_type(&tmp_oloc, &obj_type, udata->common.dxpl_id) < 0)
+                if(H5O_obj_type(&tmp_oloc, &obj_type, udata->dxpl_id) < 0)
                     HGOTO_ERROR(H5E_SYM, H5E_CANTGET, FAIL, "can't get object type")
                 udata->type = H5G_map_obj_type(obj_type);
             }
@@ -764,10 +815,10 @@ H5G_stab_get_type_by_idx(H5O_loc_t *oloc, hsize_t idx, hid_t dxpl_id)
 
     /* Set iteration information */
     udata.common.f = oloc->file;
-    udata.common.dxpl_id = dxpl_id;
     udata.common.idx = idx;
     udata.common.num_objs = 0;
     udata.common.op = H5G_stab_get_type_by_idx_cb;
+    udata.dxpl_id = dxpl_id;
     udata.type = H5G_UNKNOWN;
 
     /* Iterate over the group members */
@@ -803,18 +854,16 @@ done:
 static herr_t
 H5G_stab_lookup_cb(const H5G_entry_t *ent, void *_udata)
 {
-    H5G_stab_fnd_ud2_t *udata = (H5G_stab_fnd_ud2_t *)_udata;   /* 'User data' passed in */
+    H5G_stab_fnd_ud_t *udata = (H5G_stab_fnd_ud_t *)_udata;   /* 'User data' passed in */
     herr_t ret_value = SUCCEED; /* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT(H5G_stab_lookup_cb)
 
-    /* Set link info */
-    if(udata->lnk) {
+    /* Check for setting link info */
+    if(udata->lnk)
         /* Convert the entry to a link */
-        if(H5G_ent_to_link(udata->file, udata->dxpl_id, udata->lnk, udata->heap_addr,
-                NULL, ent, udata->name) < 0)
+        if(H5G_ent_to_link(udata->file, udata->lnk, udata->heap, ent, udata->name) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTCONVERT, FAIL, "unable to convert symbol table entry to link")
-    } /* end if */
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
@@ -838,8 +887,9 @@ herr_t
 H5G_stab_lookup(H5O_loc_t *grp_oloc, const char *name, H5O_link_t *lnk,
     hid_t dxpl_id)
 {
+    H5HL_t      *heap = NULL;   /* Pointer to local heap */
     H5G_bt_lkp_t bt_udata;      /* Data to pass through B-tree	*/
-    H5G_stab_fnd_ud2_t udata;   /* 'User data' to give to callback */
+    H5G_stab_fnd_ud_t udata;    /* 'User data' to give to callback */
     H5O_stab_t stab;		/* Symbol table message		*/
     herr_t     ret_value = SUCCEED;     /* Return value */
 
@@ -850,28 +900,35 @@ H5G_stab_lookup(H5O_loc_t *grp_oloc, const char *name, H5O_link_t *lnk,
     HDassert(name && *name);
     HDassert(lnk);
 
+    /* Retrieve the symbol table message for the group */
+    if(NULL == H5O_msg_read(grp_oloc, H5O_STAB_ID, &stab, dxpl_id))
+        HGOTO_ERROR(H5E_SYM, H5E_BADMESG, FAIL, "can't read message")
+
+    /* Pin the heap down in memory */
+    if(NULL == (heap = H5HL_protect(grp_oloc->file, dxpl_id, stab.heap_addr, H5AC_READ)))
+        HGOTO_ERROR(H5E_SYM, H5E_PROTECT, FAIL, "unable to protect symbol table heap")
+
     /* Set up user data to pass to 'find' operation callback */
     udata.file = grp_oloc->file;
-    udata.dxpl_id = dxpl_id;
     udata.name = name;
     udata.lnk = lnk;
+    udata.heap = heap;
 
     /* Set up the user data for actual B-tree find operation */
-    if(NULL == H5O_msg_read(grp_oloc, H5O_STAB_ID, &stab, dxpl_id))
-        HGOTO_ERROR(H5E_SYM, H5E_BADMESG, FAIL, "can't read message")
     bt_udata.common.name = name;
-    bt_udata.common.heap_addr = stab.heap_addr;
+    bt_udata.common.heap = heap;
     bt_udata.op = H5G_stab_lookup_cb;
     bt_udata.op_data = &udata;
 
-    /* Finish up user data to pass to 'find' operation callback */
-    udata.heap_addr = stab.heap_addr;
-
     /* Search the B-tree */
     if(H5B_find(grp_oloc->file, dxpl_id, H5B_SNODE, stab.btree_addr, &bt_udata) < 0)
         HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "not found")
 
 done:
+    /* Release resources */
+    if(heap && H5HL_unprotect(grp_oloc->file, dxpl_id, heap, stab.heap_addr) < 0)
+        HDONE_ERROR(H5E_SYM, H5E_PROTECT, FAIL, "unable to unprotect symbol table heap")
+
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5G_stab_lookup() */
 
@@ -894,7 +951,6 @@ static herr_t
 H5G_stab_lookup_by_idx_cb(const H5G_entry_t *ent, void *_udata)
 {
     H5G_bt_it_lbi_t *udata = (H5G_bt_it_lbi_t *)_udata;
-    H5HL_t *heap = NULL;                /* Pointer to local heap for group */
     const char *name;                   /* Pointer to name string in heap */
     herr_t ret_value = SUCCEED;         /* Return value */
 
@@ -902,26 +958,18 @@ H5G_stab_lookup_by_idx_cb(const H5G_entry_t *ent, void *_udata)
 
     /* Sanity check */
     HDassert(ent);
-    HDassert(udata);
+    HDassert(udata && udata->heap);
 
-    /* Pin the heap down in memory */
-    if(NULL == (heap = H5HL_protect(udata->common.f, udata->common.dxpl_id, udata->heap_addr, H5AC_READ)))
-        HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "unable to protect symbol name")
-
-    /* Duplicate the link name */
-    name = H5HL_offset_into(udata->common.f, heap, ent->name_off);
+    /* Get a pointer to the link name */
+    name = H5HL_offset_into(udata->common.f, udata->heap, ent->name_off);
     HDassert(name);
 
     /* Convert the entry to a link */
-    if(H5G_ent_to_link(udata->common.f, udata->common.dxpl_id, udata->lnk, HADDR_UNDEF, heap, ent, name) < 0)
+    if(H5G_ent_to_link(udata->common.f, udata->lnk, udata->heap, ent, name) < 0)
         HGOTO_ERROR(H5E_SYM, H5E_CANTCONVERT, FAIL, "unable to convert symbol table entry to link")
     udata->found = TRUE;
 
 done:
-    /* Unlock the heap */
-    if(heap && H5HL_unprotect(udata->common.f, udata->common.dxpl_id, heap, udata->heap_addr, H5AC__NO_FLAGS_SET) < 0)
-        HDONE_ERROR(H5E_SYM, H5E_PROTECT, FAIL, "unable to unprotect symbol name")
-
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5G_stab_lookup_by_idx_cb */
 
@@ -943,6 +991,7 @@ herr_t
 H5G_stab_lookup_by_idx(H5O_loc_t *grp_oloc, H5_iter_order_t order, hsize_t n,
     H5O_link_t *lnk, hid_t dxpl_id)
 {
+    H5HL_t      *heap = NULL;   /* Pointer to local heap */
     H5G_bt_it_lbi_t udata;             /* Iteration information */
     H5O_stab_t stab;		        /* Symbol table message */
     herr_t     ret_value = SUCCEED;     /* Return value */
@@ -957,6 +1006,10 @@ H5G_stab_lookup_by_idx(H5O_loc_t *grp_oloc, H5_iter_order_t order, hsize_t n,
     if(NULL == H5O_msg_read(grp_oloc, H5O_STAB_ID, &stab, dxpl_id))
 	HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "unable to determine local heap address")
 
+    /* Pin the heap down in memory */
+    if(NULL == (heap = H5HL_protect(grp_oloc->file, dxpl_id, stab.heap_addr, H5AC_READ)))
+        HGOTO_ERROR(H5E_SYM, H5E_PROTECT, FAIL, "unable to protect symbol table heap")
+
     /* Remap index for decreasing iteration order */
     if(order == H5_ITER_DEC) {
         hsize_t nlinks = 0;           /* Number of links in group */
@@ -971,11 +1024,10 @@ H5G_stab_lookup_by_idx(H5O_loc_t *grp_oloc, H5_iter_order_t order, hsize_t n,
 
     /* Set iteration information */
     udata.common.f = grp_oloc->file;
-    udata.common.dxpl_id = dxpl_id;
     udata.common.idx = n;
     udata.common.num_objs = 0;
     udata.common.op = H5G_stab_lookup_by_idx_cb;
-    udata.heap_addr = stab.heap_addr;
+    udata.heap = heap;
     udata.lnk = lnk;
     udata.found = FALSE;
 
@@ -988,6 +1040,10 @@ H5G_stab_lookup_by_idx(H5O_loc_t *grp_oloc, H5_iter_order_t order, hsize_t n,
 	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "index out of bound")
 
 done:
+    /* Release resources */
+    if(heap && H5HL_unprotect(grp_oloc->file, dxpl_id, heap, stab.heap_addr) < 0)
+        HDONE_ERROR(H5E_SYM, H5E_PROTECT, FAIL, "unable to unprotect symbol table heap")
+
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5G_stab_lookup_by_idx() */