[svn-r10234] Purpose:

Added Packet Table to high-level APIs

Description:
The Packet Table is an API that allows the user to append records
("packets") to a table, and read the back again.  It supports
fixed-length records with a defined datatype and variable-length
records.  It also supports a "current record" index to track the
user's position in the table.

Solution:
The Packet Table code lives in hl/src, and its tests in hl/test.
Some code is shared between the H5TB table and the H5PT Packet Table
in the form of functions in H5HL_private.c.
Some documentation exists for a previous version of the API.  Updated
documentation and C++ wrapper API coming soon.

Platforms tested:
sleipnir, eirene, copper, modi4

1 files changed, 862 insertions, 0 deletions

diff --git a/hl/src/H5PT.c b/hl/src/H5PT.c
new file mode 100644
index 0000000..2c9b359
--- /dev/null
+++ b/hl/src/H5PT.c
@@ -0,0 +1,862 @@
+/****************************************************************************
+ * NCSA HDF                                                                 *
+ * Scientific Data Technologies                                             *
+ * National Center for Supercomputing Applications                          *
+ * University of Illinois at Urbana-Champaign                               *
+ * 605 E. Springfield, Champaign IL 61820                                   *
+ *                                                                          *
+ * For conditions of distribution and use, see the accompanying             *
+ * hdf/COPYING file.                                                        *
+ *                                                                          *
+ ****************************************************************************/
+
+#include "H5PT.h"
+#include "H5HL_private.h"
+#include <stdlib.h>
+
+/*  Packet Table private data */
+
+typedef struct
+{
+  hid_t dset_id;  /* The ID of the dataset containing this table */
+  hid_t dspace_id;  /* Single packet dataspace used for reading and writing one packet at a time */
+  hid_t mem_type_id;  /* The type ID of the memory datatype */
+  hid_t mem_space_id;  /* The space ID of the memory space data will be read into and written from */
+  hsize_t current_index;  /* The index of the packet that get_next_packet will read next */
+  hsize_t set_size;  /* The number of packets currently contained in this table */
+} htbl_t;
+
+static hsize_t H5PT_ptable_count = 0;
+static H5I_type_t H5PT_ptable_id_type = H5I_UNINIT;
+
+#define H5PT_HASH_TABLE_SIZE 64
+
+/* Packet Table private functions */
+herr_t H5PT_close( htbl_t* table );
+herr_t H5PT_create_index(htbl_t *table_id);
+herr_t H5PT_set_index(htbl_t *table_id, hsize_t pt_index);
+
+/*-------------------------------------------------------------------------
+ *
+ * Create/Open/Close functions
+ *
+ *-------------------------------------------------------------------------
+ */
+
+/*-------------------------------------------------------------------------
+ * Function: H5PTcreate_fl
+ *
+ * Purpose: Creates a dataset containing a table and returns the Identifier
+ *          of the table.
+ *
+ * Return: Success: table ID, Failure: Negative
+ *
+ * Programmer: Nat Furrer, nfurrer@ncsa.uiuc.edu
+ *             James Laird, jlaird@ncsa.uiuc.edu
+ *
+ * Date: March 12, 2004
+ *
+ * Comments: This function does not handle compression or fill data 
+ *           currently.  Fill data is not necessary because the 
+ *           table is initially of size 0.
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+
+hid_t H5PTcreate_fl ( hid_t loc_id,
+                              const char *dset_name,
+                              hid_t dtype_id,
+                              hsize_t chunk_size )
+{
+  htbl_t * table = NULL;
+  hid_t dset_id = H5I_BADID;
+  hid_t space_id = H5I_BADID;
+  hid_t plist_id = H5I_BADID;
+  hsize_t dims[1];
+  hsize_t dims_chunk[1];
+  hsize_t maxdims[1];
+  hid_t ret_value;
+
+  /* Register the packet table ID type if this is the first table created */
+  if( H5PT_ptable_id_type < 0)
+    if((H5PT_ptable_id_type = H5Iregister_type(H5PT_HASH_TABLE_SIZE, 0, (H5I_free_t)free)) <0)
+      goto out;
+
+  /* Get memory for the table identifier */
+  table = (htbl_t *)malloc(sizeof(htbl_t));
+
+  /* Create a simple data space with unlimited size */
+  dims[0] = 0;
+  dims_chunk[0] = chunk_size;
+  maxdims[0] = H5S_UNLIMITED;
+  if ( (space_id = H5Screate_simple( 1, dims, maxdims )) < 0 )
+    goto out;
+
+  /* Modify dataset creation properties to enable chunking  */
+  plist_id = H5Pcreate (H5P_DATASET_CREATE);
+  if ( H5Pset_chunk ( plist_id, 1, dims_chunk ) < 0 )
+    goto out;
+
+  /* Create the dataset. */
+  if ( (dset_id=H5Dcreate( loc_id, dset_name, dtype_id, space_id, plist_id))<0 )
+    goto out;
+
+  /* Terminate access to the data space. */
+  if ( H5Sclose( space_id ) < 0 )
+    goto out;
+
+  /* End access to the property list */
+  if ( H5Pclose( plist_id ) < 0 )
+    goto out;
+
+  /* Create the table identifier */
+  table->dset_id = dset_id;
+
+  dims[0] = 1;
+  if ((table->dspace_id = H5Screate_simple(1, dims, NULL)) < 0)
+    goto out;
+
+  if((table->mem_type_id = H5Tcopy(dtype_id)) <0)  
+    goto out;
+
+  /* Create a simple memory data space */
+  if ( (table->mem_space_id = H5Screate_simple( 1, dims, NULL )) < 0 )
+    goto out;
+
+  H5PT_create_index(table);
+  table->set_size = 0;
+
+  /* Get an ID for this table */
+  ret_value = H5Iregister(H5PT_ptable_id_type, table);
+
+  if (ret_value != H5I_INVALID_HID)
+    H5PT_ptable_count++;
+  else
+    H5PT_close(table);
+
+  return ret_value;
+
+  out:
+    H5E_BEGIN_TRY
+    H5Sclose(space_id);
+    H5Pclose(plist_id);
+    H5Dclose(dset_id);
+    if(table)
+    {
+      H5Sclose(table->mem_space_id);
+      H5Sclose(table->dspace_id);
+      free(table);
+    }
+    H5E_END_TRY
+    return H5I_INVALID_HID;
+}
+
+/*-------------------------------------------------------------------------
+ * Function: H5PTcreate_vl
+ *
+ * Purpose: Creates a dataset containing a table of variable length records
+ *          and returns the Identifier of the table.
+ *
+ * Return: Success: table ID, Failure: Negative
+ *
+ * Programmer: Nat Furrer, nfurrer@ncsa.uiuc.edu
+ *             James Laird, jlaird@ncsa.uiuc.edu
+ *
+ * Date: April 12, 2004
+ *
+ * Comments: This function does not handle compression or fill data 
+ *           currently.  Fill data is not necessary because the 
+ *           table is initially of size 0.
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+hid_t H5PTcreate_vl ( hid_t loc_id,
+                                 const char*dset_name,
+                                 hsize_t chunk_size)
+{
+  hid_t ret_value=H5I_BADID;
+  hid_t vltype;
+
+  /* Create a variable length type that uses single bytes as its base type */
+  vltype = H5Tvlen_create(H5T_NATIVE_UCHAR);
+  if (vltype < 0)
+    goto out;
+
+  if((ret_value=H5PTcreate_fl(loc_id, dset_name, vltype, chunk_size)) <0)
+    goto out;
+
+  /* close the vltype */
+  if (H5Tclose(vltype) < 0)
+    goto out;
+
+  return ret_value;
+
+out:
+  if(ret_value != H5I_BADID)
+    H5PTclose(ret_value);
+  return H5I_BADID;
+}
+
+/*-------------------------------------------------------------------------
+ * Function: H5PTopen
+ *
+ * Purpose: Opens a dataset containing a table and returns the Identifier
+ *          of the table.
+ *
+ * Return: Success: table ID, Failure: Negative
+ *
+ * Programmer: Nat Furrer, nfurrer@ncsa.uiuc.edu
+ *             James Laird, jlaird@ncsa.uiuc.edu
+ *
+ * Date: March 10, 2004
+ *
+ * Comments: 
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+hid_t H5PTopen( hid_t loc_id,
+                             char *dset_name )
+{
+  hid_t type_id=H5I_BADID;
+  htbl_t * table = NULL;
+  hid_t ret_value;
+  hsize_t dims[1];
+
+  /* Register the packet table ID type if this is the first table created */
+  if( H5PT_ptable_id_type < 0)
+    if((H5PT_ptable_id_type = H5Iregister_type(H5PT_HASH_TABLE_SIZE, 0, (H5I_free_t)free))<0)
+      goto out;
+
+  table = (htbl_t *) malloc(sizeof(htbl_t));
+
+  /* Open the dataset */
+  table->dset_id = H5Dopen(loc_id, dset_name);
+  if (table->dset_id < 0)
+    goto out;
+
+  /* Create the dataspace */
+  dims[0] = 1;
+  if ((table->dspace_id = H5Screate_simple(1, dims, NULL)) < 0)
+    goto out;
+
+  /* Get the dataset's disk datatype */
+  if ((type_id = H5Dget_type(table->dset_id)) < 0)
+    goto out;
+
+  /* Get the native type for memory */
+  if ((table->mem_type_id = H5Tget_native_type(type_id, H5T_DIR_ASCEND)) < 0)
+    goto out;
+
+  /* Create a simple memory data space */
+  if ( (table->mem_space_id = H5Screate_simple( 1, dims, NULL )) < 0 )
+    goto out;
+
+  /* Initialize the current record pointer */
+  if((H5PT_create_index(table)) <0)
+    goto out;
+
+  /* Get the dataset size from disk */
+  if (H5PTget_num_records( table->dset_id, &(table->set_size)) < 0)
+    goto out;
+
+  /* Get an ID for this table */
+  ret_value = H5Iregister(H5PT_ptable_id_type, table);
+
+  if (ret_value != H5I_INVALID_HID)
+    H5PT_ptable_count++;
+  else
+    H5PT_close(table);
+
+  return ret_value;
+
+out:
+  H5E_BEGIN_TRY
+  H5Tclose(type_id);
+  if(table)
+  {
+    H5Sclose(table->dspace_id);
+    H5Dclose(table->dset_id);
+    H5Tclose(table->mem_type_id);
+    H5Sclose(table->mem_space_id);
+    free(table);
+  }
+  H5E_END_TRY
+  return H5I_INVALID_HID;
+}
+
+
+/*-------------------------------------------------------------------------
+ * Function: H5PT_close
+ *
+ * Purpose: Closes a table (i.e. cleans up all open resources used by a 
+ *          table).
+ *
+ * Return: Success: 0, Failure: -1
+ *
+ * Programmer: Nat Furrer, nfurrer@ncsa.uiuc.edu
+ *             James Laird, jlaird@ncsa.uiuc.edu
+ *
+ * Date: March 10, 2004
+ *
+ * Comments: 
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t H5PT_close( htbl_t* table)
+{
+  herr_t return_status = 0;
+
+  if(table == NULL)
+    goto out;
+
+  /* Close the dataspace */
+  if (H5Sclose( table->dspace_id ) < 0)
+    goto out;
+
+  /* Close the dataset */
+  if (H5Dclose(table->dset_id) < 0)
+    goto out;
+
+  /* Close the memory datatype */
+  if (H5Tclose(table->mem_type_id) < 0)
+    goto out;
+
+  /* Close the memory dataspace */
+  if ( H5Sclose( table->mem_space_id ) < 0 )
+    goto out;
+
+  free(table);
+
+  return 0;
+
+out:
+  if(table)
+  {
+    H5E_BEGIN_TRY
+    H5Sclose( table->dspace_id );
+    H5Dclose(table->dset_id);
+    H5Tclose(table->mem_type_id);
+    H5Sclose( table->mem_space_id );
+    H5E_END_TRY
+    free(table);
+  }
+  return -1;
+}
+
+/*-------------------------------------------------------------------------
+ * Function: H5PTclose
+ *
+ * Purpose: Closes a table (i.e. cleans up all open resources used by a 
+ *          table).
+ *
+ * Return: Success: 0, Failure: -1
+ *
+ * Programmer: Nat Furrer, nfurrer@ncsa.uiuc.edu
+ *             James Laird, jlaird@ncsa.uiuc.edu
+ *
+ * Date: April 21, 2004
+ *
+ * Comments: 
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t H5PTclose( hid_t table_id )
+{
+  htbl_t * table;
+
+  /* Remove the ID from the library */
+  if((table = H5Iremove_verify(table_id, H5PT_ptable_id_type)) ==NULL)
+    goto out;
+
+  /* If the library found the table, remove it */
+  if( H5PT_close(table) < 0)
+    goto out;
+
+  /* One less packet table open */
+  H5PT_ptable_count--;
+
+  /* Remove the packet table type ID if no more packet */
+  /* tables are open                                   */
+  if (H5PT_ptable_count == 0)
+  {
+    H5Idestroy_type(H5PT_ptable_id_type);
+    H5PT_ptable_id_type = H5I_UNINIT;
+  }
+
+  return 0;
+
+out:
+  return -1;
+}
+
+
+/*-------------------------------------------------------------------------
+ *
+ * Write functions
+ *
+ *-------------------------------------------------------------------------
+ */
+
+/*-------------------------------------------------------------------------
+ * Function: H5PTappend
+ *
+ * Purpose: Appends packets to the end of a packet table
+ *
+ * Return: Success: 0, Failure: -1
+ *
+ * Programmer: Nat Furrer, nfurrer@ncsa.uiuc.edu
+ *             James Laird, jlaird@ncsa.uiuc.edu
+ *
+ * Date: March 12, 2004
+ *
+ * Comments: 
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t H5PTappend( hid_t table_id,
+                           hsize_t nrecords,
+                           const void * data )
+{
+  htbl_t * table;
+
+  /* Find the table struct from its ID */
+  if((table = H5Iobject_verify(table_id, H5PT_ptable_id_type)) == NULL)
+    goto out;
+
+  /* If we are asked to write 0 records, just do nothing */
+  if (nrecords == 0)
+    return 0;
+
+  if((H5TBcommon_append_records(table->dset_id, table->mem_type_id, 
+  			nrecords, table->set_size, data)) <0)
+    goto out;
+
+  /* Update table size */
+  table->set_size += nrecords;
+  return 0;
+
+out:
+  return -1;
+}
+
+/*-------------------------------------------------------------------------
+ *
+ * Read functions
+ *
+ *-------------------------------------------------------------------------
+ */
+
+
+/*-------------------------------------------------------------------------
+ * Function: H5PTget_next 
+ *
+ * Purpose: Reads packets starting at the current index and updates 
+ *          that index
+ *
+ * Return: Success: 0, Failure: -1
+ *
+ * Programmer: Nat Furrer, nfurrer@ncsa.uiuc.edu
+ *             James Laird, jlaird@ncsa.uiuc.edu
+ *
+ * Date: March 10, 2004
+ *
+ * Comments:
+ *
+ * Modifications: 
+ *
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t H5PTget_next( hid_t table_id,
+                             hsize_t nrecords,
+                             void * data)
+{
+  htbl_t * table;
+
+  /* Find the table struct from its ID */
+  if((table = H5Iobject_verify(table_id, H5PT_ptable_id_type)) == NULL)
+    goto out;
+
+  /* If nrecords == 0, do nothing */
+  if (nrecords == 0)
+    return 0;
+
+  if((H5TBcommon_read_records(table->dset_id, table->mem_type_id, 
+                              table->current_index, nrecords, table->set_size, data)) < 0)
+    goto out;
+
+  /* Update the current index */
+  table->current_index += nrecords;
+  return 0;
+
+out:
+  return -1;
+}
+
+/*-------------------------------------------------------------------------
+ * Function: H5PTread_packets 
+ *
+ * Purpose: Reads packets from anywhere in a packet table
+ *
+ * Return: Success: 0, Failure: -1
+ *
+ * Programmer: Nat Furrer, nfurrer@ncsa.uiuc.edu
+ *             James Laird, jlaird@ncsa.uiuc.edu
+ *
+ * Date: March 12, 2004
+ *
+ * Comments: 
+ *
+ * Modifications: 
+ *
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t H5PTread_packets( hid_t table_id,
+                         hsize_t start,
+                         hsize_t nrecords,
+                         void *data)
+{
+  htbl_t * table;
+
+  /* find the table struct from its ID */
+  table = H5Iobject_verify(table_id, H5PT_ptable_id_type);
+  if (table == NULL)
+    goto out;
+
+  /* If nrecords == 0, do nothing */
+  if (nrecords == 0)
+    return 0;
+
+  if( H5TBcommon_read_records(table->dset_id, table->mem_type_id, 
+                              start, nrecords, table->set_size, data) < 0)
+    goto out;
+
+  return 0;
+
+out:
+  return -1;
+}
+
+/*-------------------------------------------------------------------------
+ * 
+ * Table attribute functions
+ * 
+ *-------------------------------------------------------------------------
+ */
+
+/*-------------------------------------------------------------------------
+ * Function: H5PT_create_index, H5PT_set_index
+ *
+ * Purpose: Resets and sets the current record index for a packet table
+ *
+ * Return: Success: 0, Failure: -1
+ *
+ * Programmer: Nat Furrer, nfurrer@ncsa.uiuc.edu
+ *  		   James Laird, jlaird@ncsa.uiuc.edu
+ *
+ * Date: March 12, 2004
+ *
+ * Comments: 
+ *
+ * Modifications: 
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t H5PT_create_index(htbl_t *table)
+{
+  if( table != NULL)
+  {
+    table->current_index = 0;
+    return 0;
+  }
+  return -1;
+}
+
+herr_t H5PT_set_index(htbl_t *table, hsize_t index)
+{
+  /* Ensure index is valid */
+  if( table != NULL )
+  {
+    if( index < table->set_size )
+    {
+      table->current_index = index;
+      return 0;
+    }
+  }
+  return -1;
+}
+
+/*-------------------------------------------------------------------------
+ * Function: H5PTcreate_index, H5PTset_index
+ *
+ * Purpose: Resets and sets the current record index for a packet table
+ *
+ * Return: Success: 0, Failure: -1
+ *
+ * Programmer: Nat Furrer, nfurrer@ncsa.uiuc.edu
+ *             James Laird, jlaird@ncsa.uiuc.edu
+ *
+ * Date: April 23, 2004
+ *
+ * Comments: 
+ *
+ * Modifications: 
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t H5PTcreate_index(hid_t table_id)
+{
+  htbl_t * table;
+
+  /* find the table struct from its ID */
+  if((table = H5Iobject_verify(table_id, H5PT_ptable_id_type)) == NULL)
+    return -1;
+
+  return H5PT_create_index(table);
+}
+
+herr_t H5PTset_index(hid_t table_id, hsize_t pt_index)
+{
+  htbl_t * table;
+
+  /* find the table struct from its ID */
+  if((table = H5Iobject_verify(table_id, H5PT_ptable_id_type)) == NULL)
+    return -1;
+
+  return H5PT_set_index(table, pt_index);
+}
+/*-------------------------------------------------------------------------
+ *
+ * Inquiry functions
+ *
+ *-------------------------------------------------------------------------
+ */
+
+
+/*-------------------------------------------------------------------------
+ * Function: H5PTget_num_records 
+ *
+ * Purpose: Returns by reference the number of records in the dataset
+ *
+ * Return: Success: 0, Failure: -1
+ *
+ * Programmer: Nat Furrer, nfurrer@ncsa.uiuc.edu
+ *             James Laird, jlaird@ncsa.uiuc.edu
+ *
+ * Date: March 8, 2004
+ *
+ * Comments:  Called by H5PTget_field_info
+ *
+ * Modifications: 
+ *
+ *
+ *-------------------------------------------------------------------------
+ */
+
+herr_t H5PTget_num_records( hid_t dataset_id, hsize_t *nrecords)
+{   
+  hid_t      space_id = H5I_BADID;
+  hsize_t    dims[1];
+
+  /* Get the dataspace handle */
+  if ( (space_id = H5Dget_space( dataset_id )) < 0 )
+    goto out;
+    
+  /* Get records */
+  if ( H5Sget_simple_extent_dims( space_id, dims, NULL) < 0 )
+    goto out;
+
+  /* Terminate access to the dataspace */
+  if ( H5Sclose( space_id ) < 0 )
+    goto out;
+    
+  *nrecords = dims[0];
+
+  return 0;
+
+out:
+  H5E_BEGIN_TRY
+  H5Sclose(space_id);
+  H5E_END_TRY
+  return -1;
+}
+
+/*-------------------------------------------------------------------------
+ * Function: H5PTget_num_packets 
+ *
+ * Purpose: Returns by reference the number of packets in the dataset
+ *
+ * Return: Success: 0, Failure: -1
+ *
+ * Programmer: Nat Furrer, nfurrer@ncsa.uiuc.edu
+ *             James Laird, jlaird@ncsa.uiuc.edu
+ *
+ * Date: March 12, 2004
+ *
+ * Comments:
+ *
+ * Modifications: 
+ *
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t H5PTget_num_packets( hid_t table_id, hsize_t *nrecords)
+{
+  htbl_t * table;
+
+  /* find the table struct from its ID */
+  if((table = H5Iobject_verify(table_id, H5PT_ptable_id_type)) == NULL)
+    goto out;
+
+  *nrecords = table->set_size;
+
+  return 0;
+out:
+  return -1;
+}
+
+
+/*-------------------------------------------------------------------------
+ * Function: H5PTis_valid 
+ *
+ * Purpose: Validates a table identifier
+ *
+ * Return: Success: 0, Failure: -1
+ *
+ * Programmer: Nat Furrer, nfurrer@ncsa.uiuc.edu
+ *             James Laird, jlaird@ncsa.uiuc.edu
+ *
+ * Date: March 12, 2004
+ *
+ * Comments:
+ *
+ * Modifications: 
+ *
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t H5PTis_valid(hid_t table_id)
+{
+  htbl_t * table;
+
+  /* find the table struct from its ID */
+  if((table = H5Iobject_verify(table_id, H5PT_ptable_id_type)) ==NULL)
+    return -1;
+
+  return 0;
+}
+
+/*-------------------------------------------------------------------------
+ * Function: H5PTis_varlen 
+ *
+ * Purpose: Returns 1 if a table_id corresponds to a packet table of variable-
+ *          length records or 0 for fixed-length records.
+ *
+ * Return: True: 1, False: 0, Failure: -1
+ *
+ * Programmer: Nat Furrer, nfurrer@ncsa.uiuc.edu
+ *             James Laird, jlaird@ncsa.uiuc.edu
+ *
+ * Date: April 14, 2004
+ *
+ * Comments:
+ *
+ * Modifications: 
+ *
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t H5PTis_varlen(hid_t table_id)
+{
+  H5T_class_t type;
+  htbl_t * table;
+
+  /* find the table struct from its ID */
+  if((table = H5Iobject_verify(table_id, H5PT_ptable_id_type)) == NULL)
+    goto out;
+
+  if((type = H5Tget_class( table->mem_type_id )) == H5T_NO_CLASS)
+    goto out;
+
+  if( type == H5T_VLEN )
+    return 1;
+  else
+    return 0;
+out:
+  return -1;
+}
+
+/*-------------------------------------------------------------------------
+ * 
+ * Memory Management functions
+ * 
+ *-------------------------------------------------------------------------
+ */
+
+/*-------------------------------------------------------------------------
+ * Function: H5PTfree_vlen_readbuff
+ *
+ * Purpose: Frees memory used when reading from a variable length packet 
+ *          table.
+ *
+ * Return: Success: 0, Failure: -1
+ *          -2 if memory was reclaimed but another error occurred
+ *
+ * Programmer: Nat Furrer, nfurrer@ncsa.uiuc.edu
+ *             James Laird, jlaird@ncsa.uiuc.edu
+ *
+ * Date: April 12, 2004
+ *
+ * Comments:
+ *
+ * Modifications: 
+ *
+ *
+ *-------------------------------------------------------------------------
+ */
+
+herr_t H5PTfree_vlen_readbuff( hid_t table_id,
+                               hsize_t bufflen,
+                               void * buff )
+{
+  hid_t space_id = H5I_BADID;
+  htbl_t * table;
+  herr_t ret_value;
+
+  /* find the table struct from its ID */
+  if((table = H5Iobject_verify(table_id, H5PT_ptable_id_type)) == NULL)
+    goto out;
+
+  if ((space_id = H5Screate_simple(1, &bufflen, NULL)) < 0)
+    goto out;
+
+  /* Free the memory.  If this succeeds, ret_value should be 0. */
+  if((ret_value = H5Dvlen_reclaim(table->mem_type_id, space_id, H5P_DEFAULT, buff)) < 0)
+    goto out;
+
+  /* If the dataspace cannot be closed, return -2 to indicate that memory */
+  /* was freed successfully but an error still occurred. */
+  if(H5Sclose(space_id) < 0)
+    return -2;
+
+  return ret_value;
+
+out:
+  H5E_BEGIN_TRY
+    H5Sclose(space_id);
+  H5E_END_TRY
+  return -1;
+}