hashtabletest.cpp

hashtabletest.cpp

#include "tbb/concurrent_hash_map.h"
#include "tbb/blocked_range.h"
#include "tbb/parallel_for.h"
#include <string>
#include <stdio.h>

using namespace tbb;
using namespace std;

struct MyHashCompare {
    static size_t hash( const string& x ) {
        size_t h = 0;
        for( const char* s = x.c_str(); *s; ++s )
            h = (h*17)^*s;
        return h;
    }

    static bool equal( const string& x, const string& y ) {
        return x==y;
    }
};

typedef concurrent_hash_map<string,int,MyHashCompare> StringTable;

struct Tally {
    StringTable& table;
    Tally( StringTable& table_ ) : table(table_) {}
    void operator()( const blocked_range<string*> range ) const {
        for( string* p=range.begin(); p!=range.end(); ++p ) {
            StringTable::accessor a;
            table.insert( a, *p );
           a->second += 1;
        }
    }
};
const size_t N = 1000000;
string Data[N];
void CountOccurrences() {

    StringTable table;

    parallel_for( blocked_range<string*>( Data, Data+N, 1000 ),
    Tally(table) );

    for( StringTable::iterator i=table.begin(); i!=table.end(); ++i )
        printf("%s %d\n",i->first.c_str(),i->second);
}