Merge pull request #1724 from DLR-AMR/improve_shmem_docu

Documentation: shmem_array_start_writing documentation

Author: spenke91

src/t8_data/t8_shmem.h

@@ -100,6 +100,8 @@ t8_shmem_array_init (t8_shmem_array_t *parray, size_t elem_size, size_t elem_cou
 
 /** Enable writing mode for a shmem array. Only some processes may be allowed
  *  to write into the array, which is indicated by the return value being non-zero.
+ *  The shared memory is managed via inter- and intranode communicators.
+ *  Only rank 0 of the intranode communicator will be allowed to write into the array.
  * \param [in,out]      array Initialized array. Writing will be enabled on certain processes.
  * \return                    True if the calling process can write into the array.
  * \note This function is MPI collective.
@@ -152,31 +154,31 @@ t8_shmem_array_allgather (const void *sendbuf, int sendcount, sc_MPI_Datatype se
  * Computes the recvcount-array and displacement-array for each rank of a node using the
  * sendcount.
  * The total number of items of each node is then used to compute the
- * recvcount-array and displacement-array between nodes. 
- * Use t8_shmem_array_allgather if the sendcount is equal on all procs for better scaling. 
- * 
+ * recvcount-array and displacement-array between nodes.
+ * Use t8_shmem_array_allgather if the sendcount is equal on all procs for better scaling.
+ *
  * \param[in] sendbuf         the source from this process
  * \param[in] sendcount       the number of items to gather on this proc
  * \param[in] sendtype        the type of items to gather
  * \param[in, out] recvarray  array of type recvtype where the data gets written to
  * \param[in] recvtype        the type of items to receive
  * \param[in] comm            the mpi communicator
- * 
+ *
  */
 void
 t8_shmem_array_allgatherv (void *sendbuf, const int sendcount, sc_MPI_Datatype sendtype, t8_shmem_array_t recvarray,
                            sc_MPI_Datatype recvtype, sc_MPI_Comm comm);
 
 /**
- * Fill a t8_shmem array with an Allgather of the prefix operation over all 
- * processes. 
- * 
+ * Fill a t8_shmem array with an Allgather of the prefix operation over all
+ * processes.
+ *
  * The receive array will be
  * (0, send0, send0 op send1, send0 op send1 op send2, ...)
- * 
- * \note the first entry of \a recvarray will be set to 0 using memset. 
- * The entry can be changed after calling t8_shmem_array_prefix 
- * 
+ *
+ * \note the first entry of \a recvarray will be set to 0 using memset.
+ * The entry can be changed after calling t8_shmem_array_prefix
+ *
  * \param[in] sendbuf           The source from this process
  * \param[in, out] recvarray    The destination shmem array
  * \param[in] count             The number of items to gather