Features to add to the library

[soaringxmc]

@b-fg and @m-kurz

As we planned, an independent lib is highly desirable for briding any CFD solver and redis database. This is the initial version of the lib. It can work when coupled with CaLES CFD solver at this moment. It surely needs improvements. In the following, we will solve

1. Now, MPI_COMM_WORLD is used in the lib. The following work will adapt this to any communicator, such as sub-communicator used some solvers, including sod2d.
2. An additional subroutine willl be added to allow communication of any data type.
3. C++ has not been currently supported, and will be suported when the need comes.

Any further suggestions on the lib?

[soaringxmc]

mpi communicator specification has been supported

[b-fg]

There could also be an option for parallel read/write operations instead of collecting data in the master rank? While we only tested the latter, gather operations on large arrays could be a performance (and memory) bottleneck. I am thinking in terms of transferring the whole computational domain, or large parts of it.

[soaringxmc]

@b-fg That is a good idea. I think the example fortran code here is a good reference for parallel writing/reading to redis database. The capability should be added to the library.
https://www.craylabs.org/docs/sr_fortran_walkthrough.html#parallel-mpi-execution

[soaringxmc]

@LIUJUNLE97
Hi, this is the issue about the parallel communiation. You might refer to the issue if you'd like to update smartredis-mpi for parallel communication.