Changing the prefix of external file and VDS from empty string to null for performance improvement.

1 files changed, 16 insertions, 19 deletions

diff --git a/src/H5Dint.c b/src/H5Dint.c
index 15a2050..736f17c 100644
--- a/src/H5Dint.c
+++ b/src/H5Dint.c
@@ -1133,7 +1133,7 @@ H5D__build_file_prefix(const H5D_t *dset, H5F_prefix_open_t prefix_type, char **
         /* filename is interpreted as relative to the current directory,
          * does not need to be expanded
          */
-        *file_prefix = "";
+        *file_prefix = NULL;
     } /* end if */
     else {
         if(HDstrncmp(prefix, "${ORIGIN}", HDstrlen("${ORIGIN}")) == 0) {
@@ -1382,10 +1382,8 @@ done:
             } /* end if */
             if(new_dset->shared->dcpl_id != 0 && H5I_dec_ref(new_dset->shared->dcpl_id) < 0)
                 HDONE_ERROR(H5E_DATASET, H5E_CANTDEC, NULL, "unable to decrement ref count on property list")
-            if(new_dset->shared->extfile_prefix && new_dset->shared->extfile_prefix[0] != '\0')
-                new_dset->shared->extfile_prefix = (char *)H5MM_xfree(new_dset->shared->extfile_prefix);
-            if(new_dset->shared->vds_prefix && new_dset->shared->vds_prefix[0] != '\0')
-                new_dset->shared->vds_prefix = (char *)H5MM_xfree(new_dset->shared->vds_prefix);
+            new_dset->shared->extfile_prefix = (char *)H5MM_xfree(new_dset->shared->extfile_prefix);
+            new_dset->shared->vds_prefix = (char *)H5MM_xfree(new_dset->shared->vds_prefix);
             new_dset->shared = H5FL_FREE(H5D_shared_t, new_dset->shared);
         } /* end if */
         new_dset->oloc.file = NULL;
@@ -1540,8 +1538,13 @@ H5D_open(const H5G_loc_t *loc, hid_t dapl_id)
         /* Check whether the external file prefix of the already open dataset
          * matches the new external file prefix
          */
-        if(HDstrcmp(extfile_prefix, dataset->shared->extfile_prefix) != 0)
-            HGOTO_ERROR(H5E_DATASET, H5E_CANTOPENOBJ, NULL, "new external file prefix does not match external file prefix of already open dataset")
+        if(extfile_prefix && dataset->shared->extfile_prefix) {
+            if(HDstrcmp(extfile_prefix, dataset->shared->extfile_prefix) != 0)
+                HGOTO_ERROR(H5E_DATASET, H5E_CANTOPENOBJ, NULL, "new external file prefix does not match external file prefix of already open dataset")
+        } else {
+            if(extfile_prefix || dataset->shared->extfile_prefix)
+                HGOTO_ERROR(H5E_DATASET, H5E_CANTOPENOBJ, NULL, "new external file prefix does not match external file prefix of already open dataset")
+        }
 
         /* Check if the object has been opened through the top file yet */
         if(H5FO_top_count(dataset->oloc.file, dataset->oloc.addr) == 0) {
@@ -1559,19 +1562,15 @@ H5D_open(const H5G_loc_t *loc, hid_t dapl_id)
     ret_value = dataset;
 
 done:
-    if(extfile_prefix && extfile_prefix[0] != '\0')
-        extfile_prefix = (char *)H5MM_xfree(extfile_prefix);
-    if(vds_prefix && vds_prefix[0] != '\0')
-        vds_prefix = (char *)H5MM_xfree(vds_prefix);
+    extfile_prefix = (char *)H5MM_xfree(extfile_prefix);
+    vds_prefix = (char *)H5MM_xfree(vds_prefix);
 
     if(ret_value == NULL) {
         /* Free the location--casting away const*/
         if(dataset) {
             if(shared_fo == NULL && dataset->shared) {   /* Need to free shared fo */
-                if(dataset->shared->extfile_prefix && dataset->shared->extfile_prefix[0] != '\0')
-                    dataset->shared->extfile_prefix = (char *)H5MM_xfree(dataset->shared->extfile_prefix);
-                if(dataset->shared->vds_prefix && dataset->shared->vds_prefix[0] != '\0')
-                    dataset->shared->vds_prefix = (char *)H5MM_xfree(dataset->shared->vds_prefix);
+                dataset->shared->extfile_prefix = (char *)H5MM_xfree(dataset->shared->extfile_prefix);
+                dataset->shared->vds_prefix = (char *)H5MM_xfree(dataset->shared->vds_prefix);
                 dataset->shared = H5FL_FREE(H5D_shared_t, dataset->shared);
             }
 
@@ -1950,12 +1949,10 @@ H5D_close(H5D_t *dataset)
             HDONE_ERROR(H5E_DATASET, H5E_CANTRELEASE, FAIL, "unable to destroy layout info")
 
         /* Free the external file prefix */
-        if(dataset->shared->extfile_prefix && dataset->shared->extfile_prefix[0] != '\0')
-            dataset->shared->extfile_prefix = (char *)H5MM_xfree(dataset->shared->extfile_prefix);
+        dataset->shared->extfile_prefix = (char *)H5MM_xfree(dataset->shared->extfile_prefix);
 
         /* Free the vds file prefix */
-        if(dataset->shared->vds_prefix && dataset->shared->vds_prefix[0] != '\0')
-            dataset->shared->vds_prefix = (char *)H5MM_xfree(dataset->shared->vds_prefix);
+        dataset->shared->vds_prefix = (char *)H5MM_xfree(dataset->shared->vds_prefix);
 
         /* Release layout, fill-value, efl & pipeline messages */
         if(dataset->shared->dcpl_id != H5P_DATASET_CREATE_DEFAULT)