[svn-r8496] Purpose:

    Code optimization

Description:
    Further reduce the number of copies we make of a hyperslab selection for
chunked I/O, especially when we are only going to throw the old selection away
for a new one.

Platforms tested:
    Solaris 2.7 (arabica)
    FreeBSD 4.9 (sleipnir) w/parallel

8 files changed, 44 insertions, 24 deletions

diff --git a/src/H5A.c b/src/H5A.c
index 00269db..bc065cf 100644
--- a/src/H5A.c
+++ b/src/H5A.c
@@ -241,7 +241,7 @@ H5A_create(const H5G_entry_t *ent, const char *name, const H5T_t *type,
         HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "invalid datatype location")
 
     /* Copy the dataspace for the attribute */
-    attr->ds=H5S_copy(space);
+    attr->ds=H5S_copy(space, FALSE);
 
     /* Mark it initially set to initialized */
     attr->initialized = TRUE; /*for now, set to false later*/
@@ -872,7 +872,7 @@ H5Aget_space(hid_t attr_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not an attribute")
 
     /* Copy the attribute's dataspace */
-    if (NULL==(dst=H5S_copy (attr->ds)))
+    if (NULL==(dst=H5S_copy (attr->ds, FALSE)))
 	HGOTO_ERROR (H5E_ATTR, H5E_CANTINIT, FAIL, "unable to copy dataspace")
 
     /* Atomize */
@@ -1513,7 +1513,7 @@ H5A_copy(const H5A_t *old_attr)
     /* Copy the guts of the attribute */
     new_attr->name=HDstrdup(old_attr->name);
     new_attr->dt=H5T_copy(old_attr->dt, H5T_COPY_ALL);
-    new_attr->ds=H5S_copy(old_attr->ds);
+    new_attr->ds=H5S_copy(old_attr->ds, FALSE);
     if(old_attr->data) {
         if (NULL==(new_attr->data=H5MM_malloc(old_attr->data_size)))
 	    HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
diff --git a/src/H5D.c b/src/H5D.c
index c17dd11..4057cb4 100644
--- a/src/H5D.c
+++ b/src/H5D.c
@@ -1351,7 +1351,7 @@ H5Dget_space(hid_t dset_id)
 	HGOTO_ERROR (H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset")
 
     /* Read the data space message and return a data space object */
-    if (NULL==(space=H5S_copy (dset->space)))
+    if (NULL==(space=H5S_copy (dset->space, FALSE)))
 	HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL, "unable to get data space")
 
     /* Create an atom */
@@ -2086,7 +2086,7 @@ H5D_create(H5G_entry_t *loc, const char *name, hid_t type_id, const H5S_t *space
         HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, NULL, "invalid datatype location")
 
     /* Copy dataspace for dataset */
-    if((new_dset->space = H5S_copy(space))==NULL)
+    if((new_dset->space = H5S_copy(space, FALSE))==NULL)
         HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, NULL, "can't copy dataspace")
 
     /* Set the dataset's dataspace to 'all' selection */
diff --git a/src/H5Dio.c b/src/H5Dio.c
index 4bcc9aa..068782c 100644
--- a/src/H5Dio.c
+++ b/src/H5Dio.c
@@ -2455,7 +2455,7 @@ H5D_create_chunk_map(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *file_sp
         size_t elmt_size;           /* Memory datatype size */
 
         /* Make a copy of equivalent memory space */
-        if((tmp_mspace = H5S_copy(equiv_mspace))==NULL)
+        if((tmp_mspace = H5S_copy(equiv_mspace,TRUE))==NULL)
             HGOTO_ERROR (H5E_DATASPACE, H5E_CANTCOPY, FAIL, "unable to copy memory space")
      
         /* De-select the mem space copy */
@@ -2695,7 +2695,7 @@ H5D_create_chunk_file_map_hyper(const fm_map *fm)
             hssize_t    schunk_points;          /* Number of elements in chunk selection */
 
             /* Create "temporary" chunk for selection operations (copy file space) */
-            if((tmp_fchunk = H5S_copy(fm->file_space))==NULL)
+            if((tmp_fchunk = H5S_copy(fm->file_space,TRUE))==NULL)
                 HGOTO_ERROR (H5E_DATASPACE, H5E_CANTCOPY, FAIL, "unable to copy memory space")
 
             /* Make certain selections are stored in span tree form (not "optimized hyperslab" or "all") */
@@ -2866,7 +2866,7 @@ H5D_create_chunk_mem_map_hyper(const fm_map *fm)
         /* Check if it's OK to share dataspace */
         if(fm->mem_space_copy) {
             /* Copy the memory dataspace & selection to be the chunk's dataspace & selection */
-            if((chunk_info->mspace = H5S_copy(fm->mem_space))==NULL)
+            if((chunk_info->mspace = H5S_copy(fm->mem_space,FALSE))==NULL)
                 HGOTO_ERROR (H5E_DATASPACE, H5E_CANTCOPY, FAIL, "unable to copy memory space")
         } /* end if */
         else {
@@ -2919,7 +2919,7 @@ H5D_create_chunk_mem_map_hyper(const fm_map *fm)
             /* Copy the information */
 
             /* Copy the memory dataspace */
-            if((chunk_info->mspace = H5S_copy(fm->mem_space))==NULL)
+            if((chunk_info->mspace = H5S_copy(fm->mem_space,TRUE))==NULL)
                 HGOTO_ERROR (H5E_DATASPACE, H5E_CANTCOPY, FAIL, "unable to copy memory space")
 
             /* Release the current selection */
@@ -2927,7 +2927,7 @@ H5D_create_chunk_mem_map_hyper(const fm_map *fm)
                 HGOTO_ERROR (H5E_DATASPACE, H5E_CANTRELEASE, FAIL, "unable to release selection")
 
             /* Copy the file chunk's selection */
-            if(H5S_select_copy(chunk_info->mspace,chunk_info->fspace)<0)
+            if(H5S_select_copy(chunk_info->mspace,chunk_info->fspace,FALSE)<0)
                 HGOTO_ERROR (H5E_DATASPACE, H5E_CANTCOPY, FAIL, "unable to copy selection")
 
             /* Compensate for the chunk offset */
@@ -3166,7 +3166,7 @@ H5D_chunk_mem_cb(void UNUSED *elem, hid_t UNUSED type_id, hsize_t ndims, hssize_
         /* Check if the chunk already has a memory space */
         if(chunk_info->mspace==NULL) {
             /* Copy the template memory chunk dataspace */
-            if((chunk_info->mspace = H5S_copy(fm->mchunk_tmpl))==NULL)
+            if((chunk_info->mspace = H5S_copy(fm->mchunk_tmpl,FALSE))==NULL)
                 HGOTO_ERROR (H5E_DATASPACE, H5E_CANTCOPY, FAIL, "unable to copy file space")
         } /* end else */
 
diff --git a/src/H5S.c b/src/H5S.c
index f326860..a7ede59 100644
--- a/src/H5S.c
+++ b/src/H5S.c
@@ -566,7 +566,7 @@ H5Scopy(hid_t space_id)
         HGOTO_ERROR (H5E_ARGS, H5E_BADTYPE, FAIL, "not a data space");
 
     /* Copy */
-    if (NULL==(dst=H5S_copy (src)))
+    if (NULL==(dst=H5S_copy (src, FALSE)))
         HGOTO_ERROR (H5E_DATASPACE, H5E_CANTINIT, FAIL, "unable to copy data space");
 
     /* Atomize */
@@ -691,7 +691,11 @@ done:
  * Function:	H5S_copy
  *
  * Purpose:	Copies a data space, by copying the extent and selection through
- *          H5S_extent_copy and H5S_select_copy
+ *          H5S_extent_copy and H5S_select_copy.  If the SHARE_SELECTION flag
+ *          is set, then the selection can be shared between the source and
+ *          destination dataspaces.  (This should only occur in situations
+ *          where the destination dataspace will immediately change to a new
+ *          selection)
  *
  * Return:	Success:	A pointer to a new copy of SRC
  *
@@ -705,7 +709,7 @@ done:
  *-------------------------------------------------------------------------
  */
 H5S_t *
-H5S_copy(const H5S_t *src)
+H5S_copy(const H5S_t *src, hbool_t share_selection)
 {
     H5S_t		   *dst = NULL;
     H5S_t		   *ret_value;   /* Return value */
@@ -725,7 +729,7 @@ H5S_copy(const H5S_t *src)
         HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, NULL, "can't copy extent");
 
     /* Copy the source dataspace's selection */
-    if (H5S_select_copy(dst,src)<0)
+    if (H5S_select_copy(dst,src,share_selection)<0)
         HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, NULL, "can't copy select");
 
     /* Set the return value */
diff --git a/src/H5Shyper.c b/src/H5Shyper.c
index 22c1541..169d58a 100644
--- a/src/H5Shyper.c
+++ b/src/H5Shyper.c
@@ -1557,13 +1557,18 @@ done:
  DESCRIPTION
     Copies all the hyperslab selection information from the source
     dataspace to the destination dataspace.
+
+    If the SHARE_SELECTION flag is set, then the selection can be shared
+    between the source and destination dataspaces.  (This should only occur in
+    situations where the destination dataspace will immediately change to a new
+    selection)
  GLOBAL VARIABLES
  COMMENTS, BUGS, ASSUMPTIONS
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
 herr_t
-H5S_hyper_copy (H5S_t *dst, const H5S_t *src)
+H5S_hyper_copy (H5S_t *dst, const H5S_t *src, hbool_t share_selection)
 {
     herr_t ret_value=SUCCEED;   /* return value */
 
@@ -1575,8 +1580,14 @@ H5S_hyper_copy (H5S_t *dst, const H5S_t *src)
     /* Check if there is hyperslab span information to copy */
     /* (Regular hyperslab information is copied with the selection structure) */
     if(src->select.sel_info.hslab.span_lst!=NULL) {
-        /* Copy the hyperslab span information */
-        dst->select.sel_info.hslab.span_lst=H5S_hyper_copy_span(src->select.sel_info.hslab.span_lst);
+        if(share_selection) {
+            /* Share the source's span tree by incrementing the reference count on it */
+            dst->select.sel_info.hslab.span_lst=src->select.sel_info.hslab.span_lst;
+            dst->select.sel_info.hslab.span_lst->count++;
+        } /* end if */
+        else
+            /* Copy the hyperslab span information */
+            dst->select.sel_info.hslab.span_lst=H5S_hyper_copy_span(src->select.sel_info.hslab.span_lst);
     } /* end if */
 
 done:
diff --git a/src/H5Spkg.h b/src/H5Spkg.h
index dbc7048..d34f834 100644
--- a/src/H5Spkg.h
+++ b/src/H5Spkg.h
@@ -217,7 +217,7 @@ H5_DLL herr_t H5S_hyper_iter_init(H5S_sel_iter_t *iter, const H5S_t *space);
 /* Hyperslab selection functions */
 H5_DLL herr_t H5S_hyper_release(H5S_t *space);
 H5_DLL hsize_t H5S_hyper_npoints(const H5S_t *space);
-H5_DLL herr_t H5S_hyper_copy(H5S_t *dst, const H5S_t *src);
+H5_DLL herr_t H5S_hyper_copy(H5S_t *dst, const H5S_t *src, hbool_t share_selection);
 H5_DLL htri_t H5S_hyper_is_valid(const H5S_t *space);
 H5_DLL hssize_t H5S_hyper_serial_size(const H5S_t *space);
 H5_DLL herr_t H5S_hyper_serialize(const H5S_t *space, uint8_t *buf);
diff --git a/src/H5Sprivate.h b/src/H5Sprivate.h
index 343fa2a..947c34b 100644
--- a/src/H5Sprivate.h
+++ b/src/H5Sprivate.h
@@ -173,7 +173,7 @@ typedef struct H5S_conv_t {
 } H5S_conv_t;
 
 /* Operations on dataspaces */
-H5_DLL H5S_t *H5S_copy(const H5S_t *src);
+H5_DLL H5S_t *H5S_copy(const H5S_t *src, hbool_t share_selection);
 H5_DLL herr_t H5S_close(H5S_t *ds);
 H5_DLL H5S_conv_t *H5S_find(const H5S_t *mem_space, const H5S_t *file_space,
                 unsigned flags, hbool_t *use_par_opt_io);
@@ -228,7 +228,7 @@ H5_DLL htri_t H5S_select_valid(const H5S_t *space);
 H5_DLL hssize_t H5S_get_select_npoints(const H5S_t *space);
 H5_DLL herr_t H5S_get_select_bounds(const H5S_t *space, hssize_t *start, hssize_t *end);
 H5_DLL herr_t H5S_select_offset(H5S_t *space, const hssize_t *offset);
-H5_DLL herr_t H5S_select_copy(H5S_t *dst, const H5S_t *src);
+H5_DLL herr_t H5S_select_copy(H5S_t *dst, const H5S_t *src, hbool_t share_selection);
 H5_DLL htri_t H5S_select_shape_same(const H5S_t *space1, const H5S_t *space2);
 H5_DLL herr_t H5S_select_release(H5S_t *ds);
 
diff --git a/src/H5Sselect.c b/src/H5Sselect.c
index d232cdf..1e79410 100644
--- a/src/H5Sselect.c
+++ b/src/H5Sselect.c
@@ -113,13 +113,18 @@ done:
  DESCRIPTION
     Copies all the selection information (include offset) from the source
     dataspace to the destination dataspace.
+
+    If the SHARE_SELECTION flag is set, then the selection can be shared
+    between the source and destination dataspaces.  (This should only occur in
+    situations where the destination dataspace will immediately change to a new
+    selection)
  GLOBAL VARIABLES
  COMMENTS, BUGS, ASSUMPTIONS
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
 herr_t
-H5S_select_copy (H5S_t *dst, const H5S_t *src)
+H5S_select_copy (H5S_t *dst, const H5S_t *src, hbool_t share_selection)
 {
     herr_t ret_value=SUCCEED;     /* return value */
 
@@ -132,7 +137,7 @@ H5S_select_copy (H5S_t *dst, const H5S_t *src)
     /* Copy regular fields */
     HDmemcpy(&dst->select,&src->select,sizeof(H5S_select_t));
 
-/* Need to copy order information still */
+/* Need to copy permutation order information still */
 
     /* Copy offset information */
     if(src->extent.u.simple.rank>0) {
@@ -166,7 +171,7 @@ H5S_select_copy (H5S_t *dst, const H5S_t *src)
                     break;
 
                 case H5S_SEL_HYPERSLABS:
-                    ret_value=H5S_hyper_copy(dst,src);
+                    ret_value=H5S_hyper_copy(dst,src,share_selection);
                     break;
 
                 default: