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#pragma once
#include <Common/HashTable/SmallTable.h>
#include <Common/HashTable/HashSet.h>
#include <Common/HyperLogLogCounter.h>
#include <Core/Defines.h>
namespace DB
{
namespace ErrorCodes
{
extern const int LOGICAL_ERROR;
}
namespace details
{
enum class ContainerType : uint8_t { SMALL = 1, MEDIUM = 2, LARGE = 3 };
static inline ContainerType max(const ContainerType & lhs, const ContainerType & rhs)
{
uint8_t res = std::max(static_cast<uint8_t>(lhs), static_cast<uint8_t>(rhs));
return static_cast<ContainerType>(res);
}
}
/** For a small number of keys - an array of fixed size "on the stack".
* For the average, HashSet is allocated.
* For large, HyperLogLog is allocated.
*/
template
<
typename Key,
typename HashContainer,
UInt8 small_set_size_max,
UInt8 medium_set_power2_max,
UInt8 K,
typename Hash = IntHash32<Key>,
typename HashValueType = UInt32,
typename BiasEstimator = TrivialBiasEstimator,
HyperLogLogMode mode = HyperLogLogMode::FullFeatured,
typename DenominatorType = double
>
class CombinedCardinalityEstimator
{
public:
using Self = CombinedCardinalityEstimator
<
Key,
HashContainer,
small_set_size_max,
medium_set_power2_max,
K,
Hash,
HashValueType,
BiasEstimator,
mode,
DenominatorType
>;
using value_type = Key;
private:
using Small = SmallSet<Key, small_set_size_max>;
using Medium = HashContainer;
using Large = HyperLogLogCounter<K, Key, Hash, HashValueType, DenominatorType, BiasEstimator, mode>;
public:
CombinedCardinalityEstimator()
{
setContainerType(details::ContainerType::SMALL);
}
~CombinedCardinalityEstimator()
{
destroy();
}
void insert(Key value)
{
auto container_type = getContainerType();
if (container_type == details::ContainerType::SMALL)
{
if (small.find(value) == small.end())
{
if (!small.full())
small.insert(value);
else
{
toMedium();
getContainer<Medium>().insert(value);
}
}
}
else if (container_type == details::ContainerType::MEDIUM)
{
auto & container = getContainer<Medium>();
if (container.size() < medium_set_size_max)
container.insert(value);
else
{
toLarge();
getContainer<Large>().insert(value);
}
}
else if (container_type == details::ContainerType::LARGE)
getContainer<Large>().insert(value);
}
UInt64 size() const
{
auto container_type = getContainerType();
if (container_type == details::ContainerType::SMALL)
return small.size();
else if (container_type == details::ContainerType::MEDIUM)
return getContainer<Medium>().size();
else if (container_type == details::ContainerType::LARGE)
return getContainer<Large>().size();
else
throw Poco::Exception("Internal error", ErrorCodes::LOGICAL_ERROR);
}
void merge(const Self & rhs)
{
auto container_type = getContainerType();
auto max_container_type = details::max(container_type, rhs.getContainerType());
if (container_type != max_container_type)
{
if (max_container_type == details::ContainerType::MEDIUM)
toMedium();
else if (max_container_type == details::ContainerType::LARGE)
toLarge();
}
if (rhs.getContainerType() == details::ContainerType::SMALL)
{
for (const auto & x : rhs.small)
insert(x.getValue());
}
else if (rhs.getContainerType() == details::ContainerType::MEDIUM)
{
for (const auto & x : rhs.getContainer<Medium>())
insert(x.getValue());
}
else if (rhs.getContainerType() == details::ContainerType::LARGE)
getContainer<Large>().merge(rhs.getContainer<Large>());
}
/// You can only call for an empty object.
void read(DB::ReadBuffer & in)
{
UInt8 v;
readBinary(v, in);
auto container_type = static_cast<details::ContainerType>(v);
if (container_type == details::ContainerType::SMALL)
small.read(in);
else if (container_type == details::ContainerType::MEDIUM)
{
toMedium();
getContainer<Medium>().read(in);
}
else if (container_type == details::ContainerType::LARGE)
{
toLarge();
getContainer<Large>().read(in);
}
}
void readAndMerge(DB::ReadBuffer & in)
{
auto container_type = getContainerType();
/// If readAndMerge is called with an empty state, just deserialize
/// the state is specified as a parameter.
if ((container_type == details::ContainerType::SMALL) && small.empty())
{
read(in);
return;
}
UInt8 v;
readBinary(v, in);
auto rhs_container_type = static_cast<details::ContainerType>(v);
auto max_container_type = details::max(container_type, rhs_container_type);
if (container_type != max_container_type)
{
if (max_container_type == details::ContainerType::MEDIUM)
toMedium();
else if (max_container_type == details::ContainerType::LARGE)
toLarge();
}
if (rhs_container_type == details::ContainerType::SMALL)
{
typename Small::Reader reader(in);
while (reader.next())
insert(reader.get());
}
else if (rhs_container_type == details::ContainerType::MEDIUM)
{
typename Medium::Reader reader(in);
while (reader.next())
insert(reader.get());
}
else if (rhs_container_type == details::ContainerType::LARGE)
getContainer<Large>().readAndMerge(in);
}
void write(DB::WriteBuffer & out) const
{
auto container_type = getContainerType();
writeBinary(static_cast<UInt8>(container_type), out);
if (container_type == details::ContainerType::SMALL)
small.write(out);
else if (container_type == details::ContainerType::MEDIUM)
getContainer<Medium>().write(out);
else if (container_type == details::ContainerType::LARGE)
getContainer<Large>().write(out);
}
private:
void toMedium()
{
if (getContainerType() != details::ContainerType::SMALL)
throw Poco::Exception("Internal error", ErrorCodes::LOGICAL_ERROR);
auto tmp_medium = std::make_unique<Medium>();
for (const auto & x : small)
tmp_medium->insert(x.getValue());
medium = tmp_medium.release();
setContainerType(details::ContainerType::MEDIUM);
}
void toLarge()
{
auto container_type = getContainerType();
if ((container_type != details::ContainerType::SMALL) && (container_type != details::ContainerType::MEDIUM))
throw Poco::Exception("Internal error", ErrorCodes::LOGICAL_ERROR);
auto tmp_large = std::make_unique<Large>();
if (container_type == details::ContainerType::SMALL)
{
for (const auto & x : small)
tmp_large->insert(x.getValue());
}
else if (container_type == details::ContainerType::MEDIUM)
{
for (const auto & x : getContainer<Medium>())
tmp_large->insert(x.getValue());
destroy();
}
large = tmp_large.release();
setContainerType(details::ContainerType::LARGE);
}
void NO_INLINE destroy()
{
auto container_type = getContainerType();
clearContainerType();
if (container_type == details::ContainerType::MEDIUM)
{
delete medium;
medium = nullptr;
}
else if (container_type == details::ContainerType::LARGE)
{
delete large;
large = nullptr;
}
}
template <typename T>
inline T & getContainer()
{
return *reinterpret_cast<T *>(address & mask);
}
template <typename T>
inline const T & getContainer() const
{
return *reinterpret_cast<T *>(address & mask);
}
void setContainerType(details::ContainerType t)
{
address &= mask;
address |= static_cast<UInt8>(t);
}
inline details::ContainerType getContainerType() const
{
return static_cast<details::ContainerType>(address & ~mask);
}
void clearContainerType()
{
address &= mask;
}
Small small;
union
{
Medium * medium;
Large * large;
UInt64 address = 0;
};
static const UInt64 mask = 0xFFFFFFFFFFFFFFFC;
static const UInt32 medium_set_size_max = 1ULL << medium_set_power2_max;
};
}
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