comm_mpi_nxn.h

/*
Multiscale Universal Interface Code Coupling Library

Copyright (C) 2017 Y. H. Tang, S. Kudo, X. Bian, Z. Li, G. E. Karniadakis

This software is jointly licensed under the Apache License, Version 2.0
and the GNU General Public License version 3, you may use it according
to either.

** Apache License, version 2.0 **

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

** GNU General Public License, version 3 **

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

** File Details **

Filename: comm_mpi_nxn.h
Created: Mar 4, 2014
Author: S. Kudo
Description:
*/

#ifndef COMM_MPI_NXN_H
#define COMM_MPI_NXN_H

#include <algorithm>
#include <list>
#include <deque>
#include <vector>
#include <mpi.h>
#include "comm.h"

namespace mui {
class mpicomm_nxn : public communicator {
private:
	int tag;
	MPI_Comm local_comm;
	MPI_Comm intercomm;
	std::list<std::pair<MPI_Request,std::vector<char> > > bufs;
	std::deque<char> recv_buf;
public:
	mpicomm_nxn( int tag_, MPI_Comm local_comm_, MPI_Comm remote_comm )
		: tag(tag_), local_comm(local_comm_)
	{
		MPI_Intercomm_create( local_comm_, 0, remote_comm, 0, tag, &intercomm );
	}
	virtual ~mpicomm_nxn(){}
	virtual int local_size() const {
		int size;
		MPI_Comm_size(local_comm,&size);
		return size;
	}
	virtual int remote_size() const {
		int size;
		MPI_Comm_remote_size(inter_comm,&size);
		return size;
	}

protected:
	std::size_t send_impl_( const char* ptr, std::size_t size, std::vector<bool> is_sending ) {
		_M_test();
		if( local_rank == 0 ){
			std::vector<int> recvsizes(local_size());
			MPI_Gather((void*)&size, 1, MPI_INT,
			           (void*)recvsizes.data(), 1, MPI_INT,
			           0, local_comm);
			std::vector<int> displ(local_size());
			for( std::size_t i=0; i<displ.size(); ++i ) displ[i] = (!i ? 0: displ[i-1]+recvsizes[i-1]);
			int total=0;
			for( int v : recvsizes ) total += v;

			bufs.push_back(std::make_pair(MPI_Request(),std::vector<char>(total)));
			MPI_Gatherv(const_cast<char*>(ptr), size, MPI_BYTE,
			            bufs.back().second.data(), recvsizes.data(), displ.data(), MPI_BYTE, 0, local_comm );
			MPI_Isend(bufs.back().second.data(), total, MPI_BYTE, 0, tag, intercomm, &(bufs.back().first));
		} else {
			MPI_Gather((void*)&size, 1, MPI_INT,
			           NULL, 0, MPI_INT, 0, local_comm);
			MPI_Gatherv(const_cast<char*>(ptr), size, MPI_BYTE,
			            0, 0, 0, MPI_BYTE, 0, local_comm );
		}
		return size;
	}
	std::size_t recv_impl_( char* ptr, std::size_t size ) {
		_M_test();
		int count;
		std::vector<char> temp;
		if( local_rank() ==  0 ){
			MPI_Status status;
			MPI_Probe(0, tag, intercomm, &status);
			MPI_Get_count(&statuc,MPI_BYTE,&count);
			temp.resize(count);
			MPI_Recv(temp.data(),count,MPI_BYTE,0,tag,intercomm,MPI_IGNORE);
		}
		MPI_Bcast(&count,1,MPI_INT,0,local_comm);
		if( local_rank() != 0 ) temp.resize(count);
		MPI_Bcast(temp.data(),count,MPI_BYTE,0,local_comm);
		recv_buf.insert(recv_buf.end(), temp.begin(), temp.end());

		std::size_t ret_size = std::min(size,recv_buf.size());
		std::copy_n(recv_buf.begin(),ret_size,ptr);
		return ret_size;
	}
	int try_recv_impl_( char* ptr, std::size_t size, std::size_t* received_size ){
		// not implemented yet
		throw("mui::mpicomm::try_recv_impl_ is not implemented yet.");
	}
private:
	int local_rank() const {
		int rank;
		MPI_Comm_rank(local_comm,&rank);
		return rank;
	}
	
	void _M_test() {
		if( local_rank() == 0 ){
			int test = true;
			while( test&&!bufs.empty() ) {
				MPI_Test(&(bufs.front().first),&test,MPI_STATUS_IGNORE);
				if( test ) bufs.pop_front();
			}
		}
	}

};
}
#endif