// test block allocation
//
#include <stdio.h>
#include <stdlib.h>

void *emalloc( size_t nbytes) { // malloc() with exit on error
  void *p = malloc(nbytes);
  if(!p) { fprintf( stderr, "malloc() failed\n"); exit(1); } return p;
}

typedef struct node {
 double x; int y; /* ... data ... */ struct node *next;
} Node;

#if BLOCK
static Node *head = 0;
static int block = 1000; // number of nodes to allocate at one time
Node *new_node( void) {
  if( !head) { // allocate a block of nodes
    head = emalloc(block*sizeof(Node)); Node *last = head+block-1;
    for( Node *p = head; p < last; ++p) p->next = p+1; // link the nodes
    last->next = 0;
  }
  Node *n = head; head = head->next; return n; // return head of list
}
void free_node( Node *n) {
  n->next = head; head = n; // insert at head of list
}
#else
#define new_node()   emalloc(sizeof(Node))
#define free_node(n) free(n)
#endif

int main( void)
{
  Node *h = 0; // for linked list

  int N = 1000000, loop = 50;

  for( int i = 0; i < loop; ++i)
  {
    for( int j = 0; j < N; ++j)
    {
      Node *x = new_node();
      // x->next = x;
      // free_node(x);
      x->next = h; h = x; // save in linked-list
    }
  }

#if FREE
  for( int i = 0; i < loop; ++i) // free the list
  {
    for( int j = 0; j < N; ++j)
    {
      Node *x = h; h = x->next; free_node(x);
    }
  }
#endif
}

/* sample runs:

$ make
gcc -O2 -Wall block.c
gcc -O2 -Wall -DBLOCK=1 -o block block.c
gcc -O2 -Wall -DFREE=1 -o a.out+free block.c
gcc -O2 -Wall -DFREE=1 -DBLOCK=1 -o block+free block.c

$ time ./a.out

real    0m1.825s
user    0m1.198s
sys     0m0.623s

$ time ./block

real    0m0.745s
user    0m0.291s
sys     0m0.452s

$ time ./a.out+free

real    0m2.409s
user    0m1.783s
sys     0m0.622s

$ time ./block+free

real    0m0.968s
user    0m0.481s
sys     0m0.483s
$

*/