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/* ----------------------------------------------------------------------
MR-MPI = MapReduce-MPI library
http://www.cs.sandia.gov/~sjplimp/mapreduce.html
Steve Plimpton, sjplimp@sandia.gov, Sandia National Laboratories
Copyright (2009) Sandia Corporation. Under the terms of Contract
DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
certain rights in this software. This software is distributed under
the modified Berkeley Software Distribution (BSD) License.
See the README file in the top-level MapReduce directory.
------------------------------------------------------------------------- */
// MapReduce word frequency example in C++
// Syntax: wordfreq file1 dir1 file2 dir2 ...
// (1) read all files and files in dirs
// (2) parse into words separated by whitespace
// (3) count occurrence of each word in all files
// (4) print top 10 words
#include "mpi.h"
#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "sys/stat.h"
#include "mapreduce.h"
#include "keyvalue.h"
using namespace MAPREDUCE_NS;
void fileread(int, char *, KeyValue *, void *);
void sum(char *, int, char *, int, int *, KeyValue *, void *);
int ncompare(char *, int, char *, int);
void output(uint64_t, char *, int, char *, int, KeyValue *, void *);
struct Count {
int n,limit,flag;
};
/* ---------------------------------------------------------------------- */
int main(int narg, char **args)
{
MPI_Init(&narg,&args);
int me,nprocs;
MPI_Comm_rank(MPI_COMM_WORLD,&me);
MPI_Comm_size(MPI_COMM_WORLD,&nprocs);
if (narg <= 1) {
if (me == 0) printf("Syntax: wordfreq file1 file2 ...\n");
MPI_Abort(MPI_COMM_WORLD,1);
}
MapReduce *mr = new MapReduce(MPI_COMM_WORLD);
mr->verbosity = 2;
mr->timer = 1;
//mr->memsize = 1;
//mr->outofcore = 1;
MPI_Barrier(MPI_COMM_WORLD);
double tstart = MPI_Wtime();
int nwords = mr->map(narg-1,&args[1],0,1,0,fileread,NULL);
int nfiles = mr->mapfilecount;
mr->collate(NULL);
int nunique = mr->reduce(sum,NULL);
MPI_Barrier(MPI_COMM_WORLD);
double tstop = MPI_Wtime();
mr->sort_values(&ncompare);
Count count;
count.n = 0;
count.limit = 10;
count.flag = 0;
mr->map(mr,output,&count);
mr->gather(1);
mr->sort_values(ncompare);
count.n = 0;
count.limit = 10;
count.flag = 1;
mr->map(mr,output,&count);
delete mr;
if (me == 0) {
printf("%d total words, %d unique words\n",nwords,nunique);
printf("Time to process %d files on %d procs = %g (secs)\n",
nfiles,nprocs,tstop-tstart);
}
MPI_Finalize();
}
/* ----------------------------------------------------------------------
read a file
for each word in file, emit key = word, value = NULL
------------------------------------------------------------------------- */
void fileread(int itask, char *fname, KeyValue *kv, void *ptr)
{
// filesize = # of bytes in file
struct stat stbuf;
int flag = stat(fname,&stbuf);
if (flag < 0) {
printf("ERROR: Could not query file size\n");
MPI_Abort(MPI_COMM_WORLD,1);
}
int filesize = stbuf.st_size;
FILE *fp = fopen(fname,"r");
char *text = new char[filesize+1];
int nchar = fread(text,1,filesize,fp);
text[nchar] = '\0';
fclose(fp);
char *whitespace = " \t\n\f\r\0";
char *word = strtok(text,whitespace);
while (word) {
kv->add(word,strlen(word)+1,NULL,0);
word = strtok(NULL,whitespace);
}
delete [] text;
}
/* ----------------------------------------------------------------------
count word occurrence
emit key = word, value = # of multi-values
------------------------------------------------------------------------- */
void sum(char *key, int keybytes, char *multivalue,
int nvalues, int *valuebytes, KeyValue *kv, void *ptr)
{
kv->add(key,keybytes,(char *) &nvalues,sizeof(int));
}
/* ----------------------------------------------------------------------
compare two counts
order values by count, largest first
------------------------------------------------------------------------- */
int ncompare(char *p1, int len1, char *p2, int len2)
{
int i1 = *(int *) p1;
int i2 = *(int *) p2;
if (i1 > i2) return -1;
else if (i1 < i2) return 1;
else return 0;
}
/* ----------------------------------------------------------------------
process a word and its count
depending on flag, emit KV or print it, up to limit
------------------------------------------------------------------------- */
void output(uint64_t itask, char *key, int keybytes, char *value,
int valuebytes, KeyValue *kv, void *ptr)
{
Count *count = (Count *) ptr;
count->n++;
if (count->n > count->limit) return;
int n = *(int *) value;
if (count->flag) printf("%d %s\n",n,key);
else kv->add(key,keybytes,(char *) &n,sizeof(int));
}
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