[svn-r14096] There're 3 changes in this checkin as below:

  1. In H5Dwrite and H5Dread, let the data buffer point to a fake address if the application passes
     in an empty buffer.  This is mainly for MPIO programs that some processes may not have any 
     data to write or read but still participate the I/O.  This solution solves some MPI's problem
     like the ChaMPIon on tungsten which doesn't support empty buffer.
  2. The ChaMPIon on tungsten doesn't support complex derived MPI data type correctly and collective
     I/O when some processes don't have any data to write or read correctly.  Detect the compiler
     "cmpicc" in the system-specific config file and set the variables for these two cases to false.
     The PHDF5 library already has set up a way to switch collective chunked I/O to independent 
     under these two cases.
  3. A bug fix - During the work of the optimization for compound data I/O, the case for switching
     collective chunked I/O to independent I/O was leftout.  Fixed it by adding I/O caching to it in
     H5D_multi_chunk_collective_io in H5Dmpio.c.

Tested on tungsten, cobalt, and kagiso for parallel; on linew and smirom for serial.
  

1 files changed, 24 insertions, 0 deletions

diff --git a/src/H5Dio.c b/src/H5Dio.c
index 6e75a93..259eb06 100644
--- a/src/H5Dio.c
+++ b/src/H5Dio.c
@@ -289,6 +289,7 @@ H5Dread(hid_t dset_id, hid_t mem_type_id, hid_t mem_space_id,
     H5D_t		   *dset = NULL;
     const H5S_t		   *mem_space = NULL;
     const H5S_t		   *file_space = NULL;
+    char                    fake_char;
     herr_t                  ret_value=SUCCEED;  /* Return value */
 
     FUNC_ENTER_API(H5Dread, FAIL)
@@ -326,6 +327,13 @@ H5Dread(hid_t dset_id, hid_t mem_type_id, hid_t mem_space_id,
     if (!buf && H5S_GET_SELECT_NPOINTS(file_space)!=0)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no output buffer")
 
+    /* If the buffer is nil, and 0 element is selected, make a fake buffer.
+     * This is for some MPI package like ChaMPIon on NCSA's tungsten which 
+     * doesn't support this feature. 
+     */ 
+    if (!buf)
+        buf = &fake_char;
+
     /* read raw data */
     if (H5D_read(dset, mem_type_id, mem_space, file_space, plist_id, buf/*out*/) < 0)
 	HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "can't read data")
@@ -373,6 +381,7 @@ H5Dwrite(hid_t dset_id, hid_t mem_type_id, hid_t mem_space_id,
     H5D_t		   *dset = NULL;
     const H5S_t		   *mem_space = NULL;
     const H5S_t		   *file_space = NULL;
+    char                    fake_char;
     herr_t                  ret_value=SUCCEED;  /* Return value */
 
     FUNC_ENTER_API(H5Dwrite, FAIL)
@@ -409,6 +418,13 @@ H5Dwrite(hid_t dset_id, hid_t mem_type_id, hid_t mem_space_id,
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms")
     if(!buf && H5S_GET_SELECT_NPOINTS(file_space)!=0)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no output buffer")
+    
+    /* If the buffer is nil, and 0 element is selected, make a fake buffer.
+     * This is for some MPI package like ChaMPIon on NCSA's tungsten which 
+     * doesn't support this feature. 
+     */ 
+    if (!buf)
+        buf = &fake_char;
 
     /* write raw data */
     if(H5D_write(dset, mem_type_id, mem_space, file_space, plist_id, buf) < 0)
@@ -788,6 +804,8 @@ H5D_contig_read(H5D_io_info_t *io_info, hsize_t nelmts,
 
     FUNC_ENTER_NOAPI_NOINIT(H5D_contig_read)
 
+    assert (buf);
+
     /* Initialize storage info for this dataset */
     if (dataset->shared->dcpl_cache.efl.nused > 0)
         HDmemcpy(&store.efl, &(dataset->shared->dcpl_cache.efl), sizeof(H5O_efl_t));
@@ -1066,6 +1084,8 @@ H5D_contig_write(H5D_io_info_t *io_info, hsize_t nelmts,
 
     FUNC_ENTER_NOAPI_NOINIT(H5D_contig_write)
 
+    assert (buf);
+
     /* Initialize storage info for this dataset */
     if(dataset->shared->dcpl_cache.efl.nused > 0)
         HDmemcpy(&store.efl, &(dataset->shared->dcpl_cache.efl), sizeof(H5O_efl_t));
@@ -1344,6 +1364,8 @@ H5D_chunk_read(H5D_io_info_t *io_info, hsize_t nelmts,
 
     FUNC_ENTER_NOAPI_NOINIT(H5D_chunk_read)
 
+    assert (buf);
+
     /* Map elements between file and memory for each chunk*/
     if(H5D_create_chunk_map(dataset, mem_type, file_space, mem_space, &fm) < 0)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "can't build chunk mapping")
@@ -1734,6 +1756,8 @@ H5D_chunk_write(H5D_io_info_t *io_info, hsize_t nelmts,
 
     FUNC_ENTER_NOAPI_NOINIT(H5D_chunk_write)
 
+    assert (buf);
+
     /* Map elements between file and memory for each chunk*/
     if(H5D_create_chunk_map(dataset, mem_type, file_space, mem_space, &fm) < 0)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "can't build chunk mapping")