added a test for existing datasets to write calls

src/H5Block.c

@@ -1411,6 +1411,9 @@ _H5Block_write_data (
 	struct H5BlockStruct *b = f->block;
 
 #if H5_VERS_MAJOR == 1 && H5_VERS_MINOR == 8
+	htri_t exists = H5Lexists ( b->field_group_id, name, H5P_DEFAULT );
+	if ( exists > 0 ) return HANDLE_H5D_EXISTS_ERR ( name, f->timestep );
+
 	dataset = H5Dcreate2 (
 		b->field_group_id,
 		name,

src/H5MultiBlock.c

@@ -57,7 +57,7 @@
 
 #ifdef PARALLEL_IO
 
-#define HALO_EXCHANGE_METHOD _halo_exchange_buffers
+#define HALO_EXCHANGE_METHOD _halo_exchange_vectors
 
 /*******************************************************************************
 * Static functions
@@ -176,8 +176,8 @@ _nth_root_int_divisor (const int m, const int n)
 	int i, root;
 	double p;
 
-	p = 1.0 / (double) n;
-	root = (int) ceil ( pow ((double) m, p) );
+	p = 1.0 / (double)n;
+	root = (int) ceil ( pow ( (double)m, p ) );
 	for (i=root; i<=m; i++)
 	{
 		if (m % i == 0) return i;
@@ -541,6 +541,9 @@ _halo_exchange_buffers (
 
 	struct H5MultiBlockStruct *mb = f->multiblock;
 
+	if ( f->myproc == 0 ) _H5Part_print_info (
+			"Using halo exchange method _halo_exchange_buffers");
+
 	bufsize = count * blocklen;
 	ibufsize = (int)bufsize;
 	if ( (h5part_int64_t)ibufsize != bufsize ) return HANDLE_MPI_INT64_ERR;
@@ -599,6 +602,9 @@ _halo_exchange_vectors (
 	h5part_int64_t herr;
 	MPI_Datatype halo_vector;
 
+	if ( f->myproc == 0 ) _H5Part_print_info (
+			"Using halo exchange method _halo_exchange_vectors");
+
 	icount = (int)count;
 	if ( (h5part_int64_t)icount != count ) return HANDLE_MPI_INT64_ERR;
 

src/H5Part.c

@@ -744,6 +744,9 @@ _write_data (
 			      name, (long long)f->timestep );
 
 #if H5_VERS_MAJOR == 1 && H5_VERS_MINOR == 8
+	htri_t exists = H5Lexists ( f->timegroup, name, H5P_DEFAULT );
+	if ( exists > 0 ) return HANDLE_H5D_EXISTS_ERR ( name, f->timestep );
+
 	dataset_id = H5Dcreate2 ( 
 		f->timegroup,
 		name,

src/H5PartErrors.h

@@ -165,6 +165,13 @@
 		"Cannot create dataset for name \"%s\", step \"%lld\".", \
 		s, (long long) n );
 
+#define HANDLE_H5D_EXISTS_ERR( s, n ) \
+	 (*_err_handler) ( \
+		_H5Part_get_funcname(), \
+		H5PART_ERR_HDF5, \
+		"Dataset already exists with name \"%s\", step \"%lld\".", \
+		s, (long long) n );
+
 #define HANDLE_H5D_GET_SPACE_ERR \
 	 (*_err_handler) ( \
 		_H5Part_get_funcname(), \