int hh_mem_inner()

in source/hack_parallel/hack_parallel/heap/hh_shared.c [1829:1862]

• 27 lines of code
• 9 McCabe index (conditional complexity)

int hh_mem_inner(value key) {
  check_should_exit();
  unsigned int slot = find_slot(key);
  _Bool good_hash = hashtbl[slot].hash == get_hash(key);
  _Bool non_null_addr = hashtbl[slot].addr != NULL;
  if (good_hash && non_null_addr) {
    // The data is currently in the process of being written, wait until it
    // actually is ready to be used before returning.
    time_t start = 0;
    while (hashtbl[slot].addr == HASHTBL_WRITE_IN_PROGRESS) {
#if defined(__aarch64__) || defined(__powerpc64__)
      asm volatile("yield" : : : "memory");
#else
      asm volatile("pause" : : : "memory");
#endif
      // if the worker writing the data dies, we can get stuck. Timeout check
      // to prevent it.
      time_t now = time(0);
      if (start == 0 || start > now) {
        start = now;
      } else if (now - start > 60) {
        caml_failwith("hh_mem busy-wait loop stuck for 60s");
      }
    }
    return 1;
  } else if (good_hash) {
    // if the hash matches and the key is zero
    // then we've removed the key.
    return -2;
  } else {
    // otherwise the key is simply absent
    return -1;
  }
}