binary-trees C++ g++ #9 program

/* The Computer Language Benchmarks Game
 * https://salsa.debian.org/benchmarksgame-team/benchmarksgame/
 *
 * contributed by Jon Harrop
 * modified by Alex Mizrahi
 * modified by Andreas Schäfer
 * very minor omp tweak by The Anh Tran
 * modified to use apr_pools by Dave Compton
 *  *reset*
 */

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


const size_t    LINE_SIZE = 64;

class Apr
{
public:
    Apr() 
    {
        apr_initialize();
    }

    ~Apr() 
    {
        apr_terminate();
    }
};

struct Node 
{
    Node *l, *r;
    
    int check() const 
    {
        if (l)
            return l->check() + 1 + r->check();
        else return 1;
    }
};

class NodePool
{
public:
    NodePool() 
    {
        apr_pool_create_unmanaged(&pool);
    }

    ~NodePool() 
    {
        apr_pool_destroy(pool);
    }

    Node* alloc()
    {
        return (Node *)apr_palloc(pool, sizeof(Node));
    }

    void clear()
    {
        apr_pool_clear(pool);
    }

private:
    apr_pool_t* pool;
};

Node *make(int d, NodePool &store)
{
    Node* root = store.alloc();

    if(d>0){
        root->l=make(d-1, store);
        root->r=make(d-1, store);
    }else{
        root->l=root->r=0;
    }

    return root;
}

int main(int argc, char *argv[]) 
{
    Apr apr;
    int min_depth = 4;
    int max_depth = std::max(min_depth+2,
                             (argc == 2 ? atoi(argv[1]) : 10));
    int stretch_depth = max_depth+1;

    // Alloc then dealloc stretchdepth tree
    {
        NodePool store;
        Node *c = make(stretch_depth, store);
        std::cout << "stretch tree of depth " << stretch_depth << "\t "
                  << "check: " << c->check() << std::endl;
    }

    NodePool long_lived_store;
    Node *long_lived_tree = make(max_depth, long_lived_store);

    // buffer to store output of each thread
    char *outputstr = (char*)malloc(LINE_SIZE * (max_depth +1) * sizeof(char));

    #pragma omp parallel for 
    for (int d = min_depth; d <= max_depth; d += 2) 
    {
        int iterations = 1 << (max_depth - d + min_depth);
        int c = 0;

        // Create a memory pool for this thread to use.
        NodePool store;

        for (int i = 1; i <= iterations; ++i) 
        {
            Node *a = make(d, store);
            c += a->check();
            store.clear();
        }

        // each thread write to separate location
        sprintf(outputstr + LINE_SIZE * d, "%d\t trees of depth %d\t check: %d\n",
           iterations, d, c);
    }

    // print all results
    for (int d = min_depth; d <= max_depth; d += 2) 
        printf("%s", outputstr + (d * LINE_SIZE) );
    free(outputstr);

    std::cout << "long lived tree of depth " << max_depth << "\t "
              << "check: " << (long_lived_tree->check()) << "\n";

    return 0;
}
    

NOTES:
64-bit Ubuntu quad core
g++ (Ubuntu 9.3.0-10ubuntu2) 9.3.0


Mon, 04 May 2020 17:10:19 GMT

MAKE:
/usr/bin/g++ -c -pipe -O3 -fomit-frame-pointer -march=core2  -fopenmp -I/usr/include/apr-1.0 binarytrees.gpp-9.c++ -o binarytrees.gpp-9.c++.o &&  \
        /usr/bin/g++ binarytrees.gpp-9.c++.o -o binarytrees.gpp-9.gpp_run -fopenmp -lapr-1 
rm binarytrees.gpp-9.c++

5.49s to complete and log all make actions

COMMAND LINE:
./binarytrees.gpp-9.gpp_run 21

PROGRAM OUTPUT:
stretch tree of depth 22	 check: 8388607
2097152	 trees of depth 4	 check: 65011712
524288	 trees of depth 6	 check: 66584576
131072	 trees of depth 8	 check: 66977792
32768	 trees of depth 10	 check: 67076096
8192	 trees of depth 12	 check: 67100672
2048	 trees of depth 14	 check: 67106816
512	 trees of depth 16	 check: 67108352
128	 trees of depth 18	 check: 67108736
32	 trees of depth 20	 check: 67108832
long lived tree of depth 21	 check: 4194303