[svn-r6252] Purpose:

    Lots of performance improvements & a couple new internal API interfaces.

Description:
    Performance Improvements:
        - Cached file offset & length sizes in shared file struct, to avoid
            constantly looking them up in the FCPL.
        - Generic property improvements:
            - Added "revision" number to generic property classes to speed
                up comparisons.
            - Changed method of storing properties from using a hash-table
                to the TBBT routines in the library.
            - Share the propery names between classes and the lists derived
                from them.
            - Removed redundant 'def_value' buffer from each property.
            - Switching code to use a "copy on write" strategy for
                properties in each list, where the properties in each list
                are shared with the properties in the class, until a
                property's value is changed in a list.
        - Fixed error in layout code which was allocating too many buffers.
        - Redefined public macros of the form (H5open()/H5check, <variable>)
            internally to only be (<variable>), avoiding innumerable useless
            calls to H5open() and H5check_version().
        - Reuse already zeroed buffers in H5F_contig_fill instead of
            constantly re-zeroing them.
        - Don't write fill values if writing entire dataset.
        - Use gettimeofday() system call instead of time() system when
            checking the modification time of a dataset.
        - Added reference counted string API and use it for tracking the
            names of objects opening in a file (for the ID->name code).
        - Removed redundant H5P_get() calls in B-tree routines.
        - Redefine H5T datatype macros internally to the library, to avoid
            calling H5check redundantly.
        - Keep dataspace information for dataset locally instead of reading
            from disk each time.  Added new module to track open objects
            in a file, to allow this (which will be useful eventually for
            some FPH5 metadata caching issues).
        - Remove H5AC_find macro which was inlining metadata cache lookups,
            and call function instead.
        - Remove redundant memset() calls from H5G_namei() routine.
        - Remove redundant checking of object type when locating objects
            in metadata cache and rely on the address only.
        - Create default dataset object to use when default dataset creation
            property list is used to create datasets, bypassing querying
            for all the property list values.
        - Use default I/O vector size when performing raw data with the
            default dataset transfer property list, instead of querying for
            I/O vector size.
        - Remove H5P_DEFAULT internally to the library, replacing it with
            more specific default property list based on the type of
            property list needed.
        - Remove redundant memset() calls in object header message (H5O*)
            routines.
        - Remove redunant memset() calls in data I/O routines.
        - Split free-list allocation routines into malloc() and calloc()-
            like routines, instead of one combined routine.
        - Remove lots of indirection in H5O*() routines.
        - Simplify metadata cache entry comparison routine (used when
            flushing entire cache out).
        - Only enable metadata cache statistics when H5AC_DEBUG is turned
            on, instead of always tracking them.
        - Simplify address comparison macro (H5F_addr_eq).
        - Remove redundant metadata cache entry protections during dataset
            creation by protecting the object header once and making all
            the modifications necessary for the dataset creation before
            unprotecting it.
        - Reduce # of "number of element in extent" computations performed
            by computing and storing the value during dataspace creation.
        - Simplify checking for group location's file information, when file
            has not been involving in file-mounting operations.
        - Use binary encoding for modification time, instead of ASCII.
        - Hoist H5HL_peek calls (to get information in a local heap)
            out of loops in many group routine.
        - Use static variable for iterators of selections, instead of
            dynamically allocation them each time.
        - Lookup & insert new entries in one step, avoiding traversing
            group's B-tree twice.
        - Fixed memory leak in H5Gget_objname_idx() routine (tangential to
            performance improvements, but fixed along the way).
        - Use free-list for reference counted strings.
        - Don't bother copying object names into cached group entries,
            since they are re-created when an object is opened.

        The benchmark I used to measure these results created several thousand
        small (2K) datasets in a file and wrote out the data for them.  This is
        Elena's "regular.c" benchmark.

        These changes resulted in approximately ~4.3x speedup of the
        development branch when compared to the previous code in the
        development branch and ~1.4x speedup compared to the release
        branch.

        Additionally, these changes reduce the total memory used (code and
        data) by the development branch by ~800KB, bringing the development
        branch back into the same ballpark as the release branch.

        I'll send out a more detailed description of the benchmark results
        as a followup note.

    New internal API routines:
        Added "reference counted strings" API for tracking strings that get
            used by multiple owners without duplicating the strings.
        Added "ternary search tree" API for text->object mappings.

Platforms tested:
    Tested h5committest {arabica (fortran), eirene (fortran, C++)
	modi4 (parallel, fortran)}
    Other platforms/configurations tested?
        FreeBSD 4.7 (sleipnir) serial & parallel
        Solaris 2.6 (baldric) serial

1 files changed, 4 insertions, 19 deletions

diff --git a/src/H5R.c b/src/H5R.c
index 795bc56..1ffa827 100644
--- a/src/H5R.c
+++ b/src/H5R.c
@@ -331,7 +331,6 @@ done:
 static hid_t
 H5R_dereference(H5F_t *file, H5R_type_t ref_type, void *_ref)
 {
-    H5D_t *dataset;             /* Pointer to dataset to open */
     H5G_t *group;               /* Pointer to group to open */
     H5T_t *datatype;            /* Pointer to datatype to open */
     H5G_entry_t ent;            /* Symbol table entry */
@@ -428,14 +427,9 @@ H5R_dereference(H5F_t *file, H5R_type_t ref_type, void *_ref)
             break;
 
         case H5G_DATASET:
-            if ((dataset=H5D_open_oid(&ent)) == NULL)
+            /* Open the dataset */
+            if ((ret_value=H5D_open(&ent)) < 0)
                 HGOTO_ERROR(H5E_DATASET, H5E_NOTFOUND, FAIL, "not found");
-
-            /* Create an atom for the dataset */
-            if ((ret_value = H5I_register(H5I_DATASET, dataset)) < 0) {
-                H5D_close(dataset);
-                HGOTO_ERROR(H5E_DATASET, H5E_CANTREGISTER, FAIL, "can't register dataset");
-            }
             break;
 
         default:
@@ -524,7 +518,6 @@ done:
 static H5S_t *
 H5R_get_region(H5F_t *file, H5R_type_t UNUSED ref_type, void *_ref)
 {
-    H5D_t *dataset;             /* Pointer to dataset to open */
     H5G_entry_t ent;            /* Symbol table entry */
     uint8_t *p;                 /* Pointer to OID to store */
     hdset_reg_ref_t *ref=(hdset_reg_ref_t *)_ref; /* Get pointer to correct type of reference struct */
@@ -556,12 +549,8 @@ H5R_get_region(H5F_t *file, H5R_type_t UNUSED ref_type, void *_ref)
     p=(uint8_t *)buf;
     H5F_addr_decode(ent.file,(const uint8_t **)&p,&(ent.header));
 
-    /* Open the dataset object */
-    if ((dataset=H5D_open_oid(&ent)) == NULL)
-        HGOTO_ERROR(H5E_DATASET, H5E_NOTFOUND, NULL, "not found");
-
-    /* Copy the dataspace object */
-    if ((ret_value=H5D_get_space(dataset)) == NULL)
+    /* Open and copy the dataset's dataspace */
+    if ((ret_value=H5S_read(&ent)) == NULL)
         HGOTO_ERROR(H5E_DATASPACE, H5E_NOTFOUND, NULL, "not found");
 
     /* Unserialize the selection */
@@ -571,10 +560,6 @@ H5R_get_region(H5F_t *file, H5R_type_t UNUSED ref_type, void *_ref)
     /* Free the buffer allocated in H5HG_read() */
     H5MM_xfree(buf);
 
-    /* Close the dataset we opened */
-    if (H5D_close(dataset) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CLOSEERROR, NULL, "not found");
-
 done:
     FUNC_LEAVE(ret_value);
 }   /* end H5R_get_region() */