// Master-worker program to read in a list of files and invoke
// dspace filter-media on each separately using OpenMPI
//
// John Thompson
// 8 June 2012

#include "mpi.h"

#include <stdio.h>
#include <stdlib.h>

#include <fstream>
#include <iostream>
#include <sstream>
#include <string>
#include <vector>

using namespace std;

#define BUFFERSIZE 512

int
main ( int argc, char *argv [] )
{
  int numtasks, rank, rc;            // MPI variables
  unsigned long int seconds = 0;

  if (4 != argc )
  {
    fprintf(stderr,"Usage: mpidspacemediafilter gsdlhome dspacehome filelist\n");
    exit(-1);
  }

  char *gsdlhomedir = argv[1];
  char *dspacehomedir = argv[2];      // location of import script
  char *filelist = argv[3];

  // start MPI environment
  rc = MPI_Init(&argc,&argv);
  if (rc != MPI_SUCCESS)
  {
    fprintf(stderr, "Error starting MPI program. Terminating.\n");
    MPI_Abort(MPI_COMM_WORLD, rc);
  }

  // We'll handle errors ourselves
  MPI_Errhandler_set(MPI_COMM_WORLD, MPI_ERRORS_RETURN);

  // get MPI variables: number of processors and processor number
  MPI_Status stat;
  MPI_Comm_size(MPI_COMM_WORLD, &numtasks);
  MPI_Comm_rank(MPI_COMM_WORLD, &rank);

  // Get processor name too - important when it could be anywhere in a cluster
  int name_length;
  char processor_name[MPI_MAX_PROCESSOR_NAME];
  MPI_Get_processor_name(processor_name, &name_length);

  // master node processing
  if (rank == 0)
  {
    seconds = time(NULL);
    fprintf(stderr, "[M:%lu] Starting on %s\n", seconds, processor_name);
    char incoming[BUFFERSIZE];          // buffer for acknowledgments
    char buffer[BUFFERSIZE];         // buffer to send tasks
    MPI_Request request[BUFFERSIZE];    // request monitor for all tasks
    MPI_Status status[BUFFERSIZE];      // status monitor for all tasks
    int actualTasks = 0;         // number of processors running

    // open file listing filenames to process
    ifstream infile;
    infile.open (filelist);
    string line_str;

    // set initial status of all processors to idle
    fprintf(stderr, "[M] Initializing processor state\n");
    for ( int j=0; j<BUFFERSIZE; j++ )
    {
      incoming[j] = ' ';
    }

    // scan through contents of file listing
    fprintf(stderr, "[M] Processing contents of filelist.txt\n");
    while (!infile.eof ())
    {
      // get a filename
      getline (infile, line_str);
      if (line_str.length() > 0)
      {
        // search for idle processor
        int dest=0;
        int found = 0;
        fprintf(stderr, "[M] Searching for idle processor\n");
        while ((dest<(numtasks-1)) && (found == 0))
        {
          if (incoming[dest] == ' ')
          {
            found = 1;
          }
          else
          {
            dest++;
          }
        }

        // if no idle processor, wait for one to become idle
        if (found == 0)
        {
          fprintf(stderr, "[M] Waiting for processor to become idle\n");
          MPI_Waitany (numtasks-1, request, &dest, status);
        }

        // No need for manifests - just send the identifier of the item
        // to filter to the worker
        fprintf(stderr, "[M] Writing dspace identifier as instruction to worker\n");
        // Jiggerypokery to get around weird compiler error: cannot pass
        // objects of non-POD type ‘struct std::string’ through ‘...’; call
        // will abort at runtime
        char *line = new char [line_str.size() + 1];
        strcpy(line, line_str.c_str());
        sprintf(buffer, "%s", line);
        delete [] line;

        // mark processors as busy
        incoming[dest] = 'B';
        // send out the job to the processor
        fprintf(stderr, "[M] Asking worker %d to start\n", (dest + 1));
        MPI_Send (&buffer, strlen (buffer)+1, MPI_CHAR, dest+1, 1, MPI_COMM_WORLD);
        // wait for a done acknowledgement
        MPI_Irecv (&incoming[dest], 1, MPI_CHAR, dest+1, 1, MPI_COMM_WORLD, &request[dest]);
        fprintf(stderr, "[M] Worker %d replied that it has started\n", (dest + 1));
        // update counter of actual tasks
        if (dest > actualTasks)
        {
          actualTasks = dest;
          fprintf(stderr, "[M] Increased the number of running workers to: %d\n", actualTasks);
        }
      }
    }

    infile.close();

    // wait until all outstanding tasks are completed
    fprintf(stderr, "[M] Waiting for all outstanding tasks to complete\n");
    int dest;
    for ( int k=0; k<actualTasks; k++ )
    {
      MPI_Waitany (actualTasks, request, &dest, status);
    }

    // send message to end all processing engines
    fprintf(stderr,"[M] Master asking children to exit\n");
    char endstr[5] = "end";
    for ( int i=1; i<numtasks; i++ )
    {
      MPI_Send (endstr, 4, MPI_CHAR, i, 1, MPI_COMM_WORLD);
    }

    seconds = time(NULL);
    fprintf(stderr, "[M:%lu] Master will exit when workers complete\n", seconds);
  }
  // slave node processing
  else
  {
    seconds = time(NULL);
    fprintf(stderr, "[W%d:%lu] Starting on %s\n", rank, seconds, processor_name);

    // Check to see if GSDLHOME exists in the environment (it will on multicore
    // computer, but won't on compute nodes in a cluster). It will be NULL if
    // source setup.bash hasn't been run (on this computer).
    const char * gsdlhometest = getenv("GSDLHOME");

    char incoming[BUFFERSIZE];
    int counter = 0;
    do
    {
      // wait for instruction from master
      fprintf(stderr, "[W%d] Waiting for instructions from master...\n", rank);
      int resval = MPI_Recv (&incoming, BUFFERSIZE, MPI_CHAR, 0, 1, MPI_COMM_WORLD, &stat);
      if (resval != MPI_SUCCESS)
      {
        fprintf(stderr, "[W%d] Error when recieving message from master... terminating (%d).\n", rank, resval);
        MPI_Abort(MPI_COMM_WORLD, rc);
      }
      else
      {
        fprintf(stderr, "[W%d] Recieved instruction: %s\n", rank, incoming);
      }
      counter++;
      if (strcmp (incoming, "end") != 0)
      {
        // process a received job
        seconds = time(NULL);
        fprintf(stderr, "[W%d:%lu] Processing: %s\n", rank, seconds, incoming, counter);

        // create DSpace filter-media command
        // - incoming now contains the identifier of the item to filter
        char command[2048];
        if (gsdlhometest != NULL)
        {
          sprintf (command, "%s/bin/dspace filter-media -f -i \"%s\" > /tmp/dspace_media_filter-P%d-C%d.log 2>&1", dspacehomedir, incoming, rank, counter);
        }
        else
        {
          sprintf (command, "bash -c \"cd %s && source setup.bash > /dev/null && %s/bin/dspace filter-media -f -i %s > /tmp/dspace_media_filter-P%d-C%d.log 2>&1\"", gsdlhomedir, dspacehomedir, incoming, rank, counter);
        }
        fprintf(stderr, "[W%d] system('%s')\n", rank, command);
        // invoke dspace
        system (command);

        // send completed message
        char line = ' ';
        MPI_Send (&line, 1, MPI_CHAR, 0, 1, MPI_COMM_WORLD);
        seconds = time(NULL);
        fprintf(stderr, "[W%d:%lu] Process complete\n", rank, seconds);
      }
    }
    while (strcmp (incoming, "end") != 0);
    // stop when "end" instruction is received
    seconds = time(NULL);
    fprintf(stderr, "[W%d:%lu] Worker exiting\n", rank, seconds);
  }

  // clean up MPI environment
  if (rank == 0)
  {
    fprintf(stderr,"[M] Finalizing...\n");
  }
  else
  {
    fprintf(stderr,"[W%d] Finalizing...\n", rank);
  }
  MPI_Finalize();
}