lib/mpi: add some doc

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>

diff --git a/lib/mpi.nit b/lib/mpi.nit
index 20ff9af..1d8c406 100644 (file)
--- a/lib/mpi.nit
+++ b/lib/mpi.nit
@@ -123,26 +123,34 @@ class MPI
                return deserialized
        end
 
+       # Send an empty buffer, only for the `tag`
        fun send_empty(dest: Rank, tag: Tag, comm: Comm): SuccessOrError
        `{
                return MPI_Send(NULL, 0, MPI_CHAR, dest, tag, comm);
        `}
 
+       # Receive an empty buffer, only for the `tag`
        fun recv_empty(dest: Rank, tag: Tag, comm: Comm): SuccessOrError
        `{
                return MPI_Recv(NULL, 0, MPI_CHAR, dest, tag, comm, MPI_STATUS_IGNORE);
        `}
 
-       fun native_send(data: NativeCArray, count: Int, data_type: DataType, dest: Rank, tag: Tag, comm: Comm): SuccessOrError
+       # Send a `NativeCArray` `buffer` with a given `count` of `data_type`
+       fun native_send(buffer: NativeCArray, count: Int, data_type: DataType, dest: Rank, tag: Tag, comm: Comm): SuccessOrError
        `{
-               return MPI_Send(data, count, data_type, dest, tag, comm);
+               return MPI_Send(buffer, count, data_type, dest, tag, comm);
        `}
 
-       fun native_recv(data: NativeCArray, count: Int, data_type: DataType, dest: Rank, tag: Tag, comm: Comm, status: Status): SuccessOrError
+       # Receive into a `NativeCArray` `buffer` with a given `count` of `data_type`
+       fun native_recv(buffer: NativeCArray, count: Int, data_type: DataType, dest: Rank, tag: Tag, comm: Comm, status: Status): SuccessOrError
        `{
-               return MPI_Recv(data, count, data_type, dest, tag, comm, status);
+               return MPI_Recv(buffer, count, data_type, dest, tag, comm, status);
        `}
 
+       # Probe for the next data to receive, store the result in `status`
+       #
+       # Note: If you encounter an error where the next receive does not correspond
+       # to the last `probe`, call this method twice to ensure a correct result.
        fun probe(source: Rank, tag: Tag, comm: Comm, status: Status): SuccessOrError
        `{
                return MPI_Probe(source, tag, comm, status);
@@ -157,8 +165,13 @@ end
 
 # An MPI communicator
 extern class Comm `{ MPI_Comm `}
+       # The _null_ communicator, targeting no processors
        new null_ `{ return MPI_COMM_NULL; `}
+
+       # The _world_ communicator, targeting all processors
        new world `{ return MPI_COMM_WORLD; `}
+
+       # The _self_ communicator, targeting this processor only
        new self_ `{ return MPI_COMM_SELF; `}
 
        # Number of processors in this communicator
@@ -278,6 +291,7 @@ end
 
 # An MPI rank within a communcator
 extern class Rank `{ int `}
+       # Special rank accepting any processor
        new any `{ return MPI_ANY_SOURCE; `}
 
        # This Rank as an `Int`
@@ -287,6 +301,7 @@ end
 
 # An MPI tag, can be defined using `Int::tag`
 extern class Tag `{ int `}
+       # Special tag accepting any tag
        new any `{ return MPI_ANY_TAG; `}
 
        # This tag as an `Int`