protobuf/test_table.cc

#include "upb_table.h"
#include "test_util.h"
#include <assert.h>
#include <map>
#include <ext/hash_map>
#include <sys/resource.h>

struct table_entry {
  struct upb_inttable_entry e;
  int32_t value;  /* key+2 */
};

double get_usertime()
{
  struct rusage usage;
  getrusage(RUSAGE_SELF, &usage);
  return usage.ru_utime.tv_sec + (usage.ru_utime.tv_usec/1000000.0);
}

static uint32_t max(uint32_t a, uint32_t b) { return a > b ? a : b; }

/* num_entries must be a power of 2. */
void test(int32_t *keys, size_t num_entries)
{
  /* Initialize structures. */
  struct table_entry *entries = new table_entry[num_entries];
  struct upb_inttable table;
  int32_t largest_key = 0;
  std::map<int32_t, int32_t> m;
  __gnu_cxx::hash_map<int32_t, int32_t> hm;
  for(size_t i = 0; i < num_entries; i++) {
    int32_t key = keys[i];
    largest_key = max(largest_key, key);
    entries[i].e.key = key;
    entries[i].value = key*2;
    m[key] = key*2;
    hm[key] = key*2;
  }
  upb_inttable_init(&table, entries, num_entries, sizeof(struct table_entry));
  printf("size: %lu\n", sizeof(struct table_entry));
  delete[] entries;

  /* Test correctness. */
  for(int32_t i = 0; i < largest_key; i++) {
    struct table_entry *e = (struct table_entry*)upb_inttable_lookup(
        &table, i, sizeof(struct table_entry));
    if(m.find(i) != m.end()) { /* Assume map implementation is correct. */
      assert(e);
      assert(e->e.key == i);
      assert(e->value == i*2);
      assert(m[i] == i*2);
      assert(hm[i] == i*2);
    } else {
      assert(e == NULL);
    }
  }

  /* Test performance. We only test lookups for keys that are known to exist. */
  uintptr_t x = 0;
  const unsigned int iterations = 0xFFFFFF;
  const int32_t mask = num_entries - 1;
  printf("Measuring sequential loop overhead...");
  fflush(stdout);
  double before = get_usertime();
  for(unsigned int i = 0; i < iterations; i++) {
    int32_t key = keys[i & mask];
    x += key;
  }
  double seq_overhead = get_usertime() - before;
  printf("%0.3f seconds for %d iterations\n", seq_overhead, iterations);

  printf("Measuring random loop overhead...");
  rand();
  fflush(stdout);
  before = get_usertime();
  for(unsigned int i = 0; i < iterations; i++) {
    int32_t key = keys[rand() & mask];
    x += key;
  }
  double rand_overhead = get_usertime() - before;
  printf("%0.3f seconds for %d iterations\n", rand_overhead, iterations);

  printf("upb_table(seq): ");
  fflush(stdout);
  before = get_usertime();
  for(unsigned int i = 0; i < iterations; i++) {
    int32_t key = keys[i & mask];
    struct table_entry *e = (struct table_entry*)upb_inttable_lookup(
        &table, key, sizeof(struct table_entry));
    x += (uintptr_t)e;
  }
  double total = get_usertime() - before;
  double without_overhead = total - seq_overhead;
  printf("%0.3f seconds (%0.3f - %0.3f overhead) for %d iterations.  %s/s\n", without_overhead, total, seq_overhead, iterations, eng(iterations/without_overhead, 3, false));

  printf("upb_table(rand): ");
  fflush(stdout);
  before = get_usertime();
  for(unsigned int i = 0; i < iterations; i++) {
    int32_t key = keys[rand() & mask];
    struct table_entry *e = (struct table_entry*)upb_inttable_lookup(
        &table, key, sizeof(struct table_entry));
    x += (uintptr_t)e;
  }
  total = get_usertime() - before;
  without_overhead = total - rand_overhead;
  printf("%0.3f seconds (%0.3f - %0.3f overhead) for %d iterations.  %s/s\n", without_overhead, total, rand_overhead, iterations, eng(iterations/without_overhead, 3, false));

  printf("map(seq): ");
  fflush(stdout);
  before = get_usertime();
  for(unsigned int i = 0; i < iterations; i++) {
    int32_t key = keys[i & mask];
    x += m[key];
  }
  total = get_usertime() - before;
  without_overhead = total - seq_overhead;
  printf("%0.3f seconds (%0.3f - %0.3f overhead) for %d iterations.  %s/s\n", without_overhead, total, seq_overhead, iterations, eng(iterations/without_overhead, 3, false));

  printf("map(rand): ");
  fflush(stdout);
  before = get_usertime();
  for(unsigned int i = 0; i < iterations; i++) {
    int32_t key = keys[rand() & mask];
    x += m[key];
  }
  total = get_usertime() - before;
  without_overhead = total - rand_overhead;
  printf("%0.3f seconds (%0.3f - %0.3f overhead) for %d iterations.  %s/s\n", without_overhead, total, rand_overhead, iterations, eng(iterations/without_overhead, 3, false));

  printf("hash_map(seq): ");
  fflush(stdout);
  before = get_usertime();
  for(unsigned int i = 0; i < iterations; i++) {
    int32_t key = keys[i & mask];
    x += hm[key];
  }
  total = get_usertime() - before;
  without_overhead = total - seq_overhead;
  printf("%0.3f seconds (%0.3f - %0.3f overhead) for %d iterations.  %s/s\n", without_overhead, total, seq_overhead, iterations, eng(iterations/without_overhead, 3, false));

  printf("hash_map(rand): ");
  fflush(stdout);
  before = get_usertime();
  for(unsigned int i = 0; i < iterations; i++) {
    int32_t key = keys[rand() & mask];
    x += hm[key];
  }
  total = get_usertime() - before;
  without_overhead = total - rand_overhead;
  printf("%0.3f seconds (%0.3f - %0.3f overhead) for %d iterations.  %s/s\n\n", without_overhead, total, rand_overhead, iterations, eng(iterations/without_overhead, 3, false));
  upb_inttable_free(&table);
}

int32_t *get_contiguous_keys(int32_t num)
{
  int32_t *buf = new int32_t[num];
  for(int32_t i = 0; i < num; i++)
    buf[i] = i;
  return buf;
}

int main()
{
  int32_t *keys1 = get_contiguous_keys(8);
  printf("Contiguous 1-8 ====\n");
  test(keys1, 8);
  delete[] keys1;

  int32_t *keys2 = get_contiguous_keys(64);
  printf("Contiguous 1-64 ====\n");
  test(keys2, 64);
  delete[] keys2;

  int32_t *keys3 = get_contiguous_keys(512);
  printf("Contiguous 1-512 ====\n");
  test(keys3, 512);
  delete[] keys3;

  int32_t *keys4 = new int32_t[64];
  for(int32_t i = 0; i < 64; i++) {
    if(i < 32)
      keys4[i] = i;
    else
      keys4[i] = 10100+i;
  }
  printf("1-32 and 10033-10064 ====\n");
  test(keys4, 64);
  delete[] keys4;
}