int MMKVImpl::SRandMember(DBID db, const Data& key, const StringArrayResult& members, int count)
{
int err = 0;
RWLockGuard<MemorySegmentManager, READ_LOCK> keylock_guard(m_segment);
StringSet* set = GetObject<StringSet>(db, key, V_TYPE_SET, false, err)();
if (IS_NOT_EXISTS(err))
{
return 0;
}
if (0 != err)
{
return err;
}
if (set->empty())
{
return 0;
}
//return whole set
if (count > 0 && count > set->size())
{
StringSet::iterator it = set->begin();
while (it != set->end())
{
it->ToString(members.Get());
it++;
}
return 0;
}
int rand = 0;
for (int i = 0; i < std::abs(count); i++)
{
if (count > 0)
{
if (i == 0)
{
rand = random_between_int32(0, set->size() - 1);
}
else
{
rand += i;
if (rand >= set->size())
{
rand -= set->size();
}
}
}
else
{
rand = random_between_int32(0, set->size() - 1);
}
StringSet::iterator it = set->begin();
it.increment_by(rand);
it->ToString(members.Get());
}
return 0;
}
std::string random_between_string(const std::string& min, const std::string& max)
{
if (min == max)
{
return min;
}
std::string random_key;
for (uint32 i = 0; i < min.size() && i < max.size(); i++)
{
if (min[i] < max[i])
{
if (min[i] == max[i] - 1)
{
random_key.push_back(min[i]);
for (uint32 j = i + 1; j < min.size(); j++)
{
if (min[j] == 127)
{
random_key.push_back(min[j]);
}
else
{
char c = (char) random_between_int32(min[j], 127);
random_key.push_back(c);
if (c > min[j])
{
break;
}
}
}
}
else
{
char c = (char) random_between_int32(min[i], max[i]);
while (c == min[i] || c == max[i])
{
c = (char) random_between_int32(min[i], max[i]);
}
random_key.push_back(c);
}
break;
}
else
{
random_key.push_back(min[i]);
}
}
random_key.append(random_string(5));
return random_key;
}
