Method build_stripe_hash_table

src/traffic_cache_tool/CacheTool.cc:943–1022

}

void
Cache::build_stripe_hash_table()
{
  int              num_stripes = globalVec_stripe.size();
  CacheStoreBlocks total;
  unsigned int    *forvol         = static_cast<unsigned int *>(ats_malloc(sizeof(unsigned int) * num_stripes));
  unsigned int    *gotvol         = static_cast<unsigned int *>(ats_malloc(sizeof(unsigned int) * num_stripes));
  unsigned int    *rnd            = static_cast<unsigned int *>(ats_malloc(sizeof(unsigned int) * num_stripes));
  unsigned short  *ttable         = static_cast<unsigned short *>(ats_malloc(sizeof(unsigned short) * STRIPE_HASH_TABLE_SIZE));
  unsigned int    *rtable_entries = static_cast<unsigned int *>(ats_malloc(sizeof(unsigned int) * num_stripes));
  unsigned int     rtable_size    = 0;
  int              i              = 0;
  uint64_t         used           = 0;

  // estimate allocation
  for (auto &elt : globalVec_stripe) {
    // printf("stripe length %" PRId64 "\n", elt->_len.count());
    rtable_entries[i]  = static_cast<int64_t>(elt->_len) / Vol_hash_alloc_size;
    rtable_size       += rtable_entries[i];
    uint64_t x         = elt->hash_id.fold();
    // seed random number generator
    rnd[i]  = static_cast<unsigned int>(x);
    total  += elt->_len;
    i++;
  }
  i = 0;
  for (auto &elt : globalVec_stripe) {
    forvol[i]  = total ? static_cast<int64_t>(STRIPE_HASH_TABLE_SIZE * elt->_len) / total : 0;
    used      += forvol[i];
    gotvol[i]  = 0;
    i++;
  }

  // spread around the excess
  int extra = STRIPE_HASH_TABLE_SIZE - used;
  for (int i = 0; i < extra; i++) {
    forvol[i % num_stripes]++;
  }

  // initialize table to "empty"
  for (int i = 0; i < STRIPE_HASH_TABLE_SIZE; i++) {
    ttable[i] = STRIPE_HASH_EMPTY;
  }

  // generate random numbers proportional to allocation
  rtable_pair *rtable = static_cast<rtable_pair *>(ats_malloc(sizeof(rtable_pair) * rtable_size));
  int          rindex = 0;
  for (int i = 0; i < num_stripes; i++) {
    for (int j = 0; j < static_cast<int>(rtable_entries[i]); j++) {
      rtable[rindex].rval = next_rand(&rnd[i]);
      rtable[rindex].idx  = i;
      rindex++;
    }
  }
  assert(rindex == (int)rtable_size);
  // sort (rand #, vol $ pairs)
  qsort(rtable, rtable_size, sizeof(rtable_pair), cmprtable);
  unsigned int width = (1LL << 32) / STRIPE_HASH_TABLE_SIZE;