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/// \file
/// Wrappers for MPI functions. This should be the only compilation
/// unit in the code that directly calls MPI functions. To build a pure
/// serial version of the code with no MPI, do not define DO_MPI. If
/// DO_MPI is not defined then all MPI functionality is replaced with
/// equivalent single task behavior.
#include "parallel.h"
#ifdef DO_MPI
#include <mpi.h>
#endif
#include <stdio.h>
#include <time.h>
#include <string.h>
#include <assert.h>
static int myRank = 0;
static int nRanks = 1;
#ifdef DO_MPI
#ifdef SINGLE
#define REAL_MPI_TYPE MPI_FLOAT
#else
#define REAL_MPI_TYPE MPI_DOUBLE
#endif
#endif
int getNRanks()
{
return nRanks;
}
int getMyRank()
{
return myRank;
}
/// \details
/// For now this is just a check for rank 0 but in principle it could be
/// more complex. It is also possible to suppress practically all
/// output by causing this function to return 0 for all ranks.
int printRank()
{
if (myRank == 0) return 1;
return 0;
}
void timestampBarrier(const char* msg)
{
barrierParallel();
if (! printRank())
return;
time_t t= time(NULL);
char* timeString = ctime(&t);
timeString[24] = '\0'; // clobber newline
#ifndef PRINT_TIMING
timeString[0] = '\0';
#endif
fprintf(screenOut, "%s: %s\n", timeString, msg);
fflush(screenOut);
}
void initParallel(int* argc, char*** argv)
{
#ifdef DO_MPI
MPI_Init(argc, argv);
MPI_Comm_rank(MPI_COMM_WORLD, &myRank);
MPI_Comm_size(MPI_COMM_WORLD, &nRanks);
#endif
}
void destroyParallel()
{
#ifdef DO_MPI
MPI_Finalize();
#endif
}
void barrierParallel()
{
#ifdef DO_MPI
MPI_Barrier(MPI_COMM_WORLD);
#endif
}
/// \param [in] sendBuf Data to send.
/// \param [in] sendLen Number of bytes to send.
/// \param [in] dest Rank in MPI_COMM_WORLD where data will be sent.
/// \param [out] recvBuf Received data.
/// \param [in] recvLen Maximum number of bytes to receive.
/// \param [in] source Rank in MPI_COMM_WORLD from which to receive.
/// \return Number of bytes received.
int sendReceiveParallel(void* sendBuf, int sendLen, int dest,
void* recvBuf, int recvLen, int source)
{
#ifdef DO_MPI
int bytesReceived;
MPI_Status status;
MPI_Sendrecv(sendBuf, sendLen, MPI_BYTE, dest, 0,
recvBuf, recvLen, MPI_BYTE, source, 0,
MPI_COMM_WORLD, &status);
MPI_Get_count(&status, MPI_BYTE, &bytesReceived);
return bytesReceived;
#else
assert(source == dest);
memcpy(recvBuf, sendBuf, sendLen);
return sendLen;
#endif
}
void addIntParallel(int* sendBuf, int* recvBuf, int count)
{
#ifdef DO_MPI
MPI_Allreduce(sendBuf, recvBuf, count, MPI_INT, MPI_SUM, MPI_COMM_WORLD);
#else
for (int ii=0; ii<count; ++ii)
recvBuf[ii] = sendBuf[ii];
#endif
}
void addRealParallel(real_t* sendBuf, real_t* recvBuf, int count)
{
#ifdef DO_MPI
MPI_Allreduce(sendBuf, recvBuf, count, REAL_MPI_TYPE, MPI_SUM, MPI_COMM_WORLD);
#else
for (int ii=0; ii<count; ++ii)
recvBuf[ii] = sendBuf[ii];
#endif
}
void addDoubleParallel(double* sendBuf, double* recvBuf, int count)
{
#ifdef DO_MPI
MPI_Allreduce(sendBuf, recvBuf, count, MPI_DOUBLE, MPI_SUM, MPI_COMM_WORLD);
#else
for (int ii=0; ii<count; ++ii)
recvBuf[ii] = sendBuf[ii];
#endif
}
void maxIntParallel(int* sendBuf, int* recvBuf, int count)
{
#ifdef DO_MPI
MPI_Allreduce(sendBuf, recvBuf, count, MPI_INT, MPI_MAX, MPI_COMM_WORLD);
#else
for (int ii=0; ii<count; ++ii)
recvBuf[ii] = sendBuf[ii];
#endif
}
void minRankDoubleParallel(RankReduceData* sendBuf, RankReduceData* recvBuf, int count)
{
#ifdef DO_MPI
MPI_Allreduce(sendBuf, recvBuf, count, MPI_DOUBLE_INT, MPI_MINLOC, MPI_COMM_WORLD);
#else
for (int ii=0; ii<count; ++ii)
{
recvBuf[ii].val = sendBuf[ii].val;
recvBuf[ii].rank = sendBuf[ii].rank;
}
#endif
}
void maxRankDoubleParallel(RankReduceData* sendBuf, RankReduceData* recvBuf, int count)
{
#ifdef DO_MPI
MPI_Allreduce(sendBuf, recvBuf, count, MPI_DOUBLE_INT, MPI_MAXLOC, MPI_COMM_WORLD);
#else
for (int ii=0; ii<count; ++ii)
{
recvBuf[ii].val = sendBuf[ii].val;
recvBuf[ii].rank = sendBuf[ii].rank;
}
#endif
}
/// \param [in] count Length of buf in bytes.
void bcastParallel(void* buf, int count, int root)
{
#ifdef DO_MPI
MPI_Bcast(buf, count, MPI_BYTE, root, MPI_COMM_WORLD);
#endif
}
int builtWithMpi(void)
{
#ifdef DO_MPI
return 1;
#else
return 0;
#endif
}
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