ClickHouse/dbms/Common/HashTable/TwoLevelHashTable.h

336 lines
9.8 KiB
C++
Raw Normal View History

#pragma once
#include <Common/HashTable/HashTable.h>
2017-05-07 20:25:26 +00:00
/** Two-level hash table.
* Represents 256 (or 1ULL << BITS_FOR_BUCKET) small hash tables (buckets of the first level).
2017-05-07 20:25:26 +00:00
* To determine which one to use, one of the bytes of the hash function is taken.
*
2017-05-07 20:25:26 +00:00
* Usually works a little slower than a simple hash table.
* However, it has advantages in some cases:
* - if you need to merge two hash tables together, then you can easily parallelize it by buckets;
* - delay during resizes is amortized, since the small hash tables will be resized separately;
* - in theory, resizes are cache-local in a larger range of sizes.
*/
template <size_t initial_size_degree = 8>
struct TwoLevelHashTableGrower : public HashTableGrower<initial_size_degree>
{
2017-05-07 20:25:26 +00:00
/// Increase the size of the hash table.
void increaseSize()
{
this->size_degree += this->size_degree >= 15 ? 1 : 2;
}
};
template
<
typename Key,
typename Cell,
typename Hash,
typename Grower,
typename Allocator, /// TODO WithStackMemory
typename ImplTable = HashTable<Key, Cell, Hash, Grower, Allocator>,
size_t BITS_FOR_BUCKET = 8
>
class TwoLevelHashTable :
private boost::noncopyable,
protected Hash /// empty base optimization
{
protected:
friend class const_iterator;
friend class iterator;
using HashValue = size_t;
using Self = TwoLevelHashTable;
public:
using Impl = ImplTable;
static constexpr size_t NUM_BUCKETS = 1ULL << BITS_FOR_BUCKET;
static constexpr size_t MAX_BUCKET = NUM_BUCKETS - 1;
size_t hash(const Key & x) const { return Hash::operator()(x); }
/// NOTE Bad for hash tables with more than 2^32 cells.
static size_t getBucketFromHash(size_t hash_value) { return (hash_value >> (32 - BITS_FOR_BUCKET)) & MAX_BUCKET; }
protected:
typename Impl::iterator beginOfNextNonEmptyBucket(size_t & bucket)
{
while (bucket != NUM_BUCKETS && impls[bucket].empty())
++bucket;
if (bucket != NUM_BUCKETS)
return impls[bucket].begin();
--bucket;
return impls[MAX_BUCKET].end();
}
typename Impl::const_iterator beginOfNextNonEmptyBucket(size_t & bucket) const
{
while (bucket != NUM_BUCKETS && impls[bucket].empty())
++bucket;
if (bucket != NUM_BUCKETS)
return impls[bucket].begin();
--bucket;
return impls[MAX_BUCKET].end();
}
public:
using key_type = typename Impl::key_type;
2019-10-29 15:16:51 +00:00
using mapped_type = typename Impl::mapped_type;
using value_type = typename Impl::value_type;
2019-10-29 15:16:51 +00:00
using cell_type = typename Impl::cell_type;
using LookupResult = typename Impl::LookupResult;
using ConstLookupResult = typename Impl::ConstLookupResult;
Impl impls[NUM_BUCKETS];
TwoLevelHashTable() {}
2017-05-07 20:25:26 +00:00
/// Copy the data from another (normal) hash table. It should have the same hash function.
template <typename Source>
TwoLevelHashTable(const Source & src)
{
typename Source::const_iterator it = src.begin();
/// It is assumed that the zero key (stored separately) is first in iteration order.
if (it != src.end() && it.getPtr()->isZero(src))
{
A Proper lookup table that uses HashTable's API This is the first step of allowing heterogeneous cells in hash tables. performance test results are ``` 1. HashMap<UInt16, UInt8, TrivialHash, HashTableFixedGrower<16>>; 2. NewLookupMap<UInt16, UInt8> ResolutionWidth 30000 1 .................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................223550276.46 ResolutionWidth 30000 2 .................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................248772721.24 Best: 2 - 24877272124 ResolutionWidth 100000 1 ..........................................................................................................................................................................................................................................................238498413.99 ResolutionWidth 100000 2 ..........................................................................................................................................................................................................................................................261808889.98 Best: 2 - 26180888998 ResolutionWidth 300000 1 ...................................................................................239307348.81 ResolutionWidth 300000 2 ...................................................................................257592761.30 Best: 2 - 25759276130 ResolutionWidth 1000000 1 .........................240144759.26 ResolutionWidth 1000000 2 .........................257093531.91 Best: 2 - 25709353191 ResolutionWidth 5000000 1 .....241573260.35 ResolutionWidth 5000000 2 .....259314162.79 Best: 2 - 25931416279 ResolutionDepth 30000 1 .................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................217108119.84 ResolutionDepth 30000 2 .................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................249459504.41 Best: 2 - 24945950441 ResolutionDepth 100000 1 ..........................................................................................................................................................................................................................................................229065162.17 ResolutionDepth 100000 2 ..........................................................................................................................................................................................................................................................253769105.64 Best: 2 - 25376910564 ResolutionDepth 300000 1 ...................................................................................233079225.18 ResolutionDepth 300000 2 ...................................................................................256316273.78 Best: 2 - 25631627378 ResolutionDepth 1000000 1 .........................234184633.51 ResolutionDepth 1000000 2 .........................261100491.57 Best: 2 - 26110049157 ResolutionDepth 5000000 1 .....233118795.66 ResolutionDepth 5000000 2 .....252436160.41 Best: 2 - 25243616041 ```
2019-02-28 09:35:38 +00:00
insert(it->getValue());
++it;
}
for (; it != src.end(); ++it)
{
const Cell * cell = it.getPtr();
size_t hash_value = cell->getHash(src);
size_t buck = getBucketFromHash(hash_value);
impls[buck].insertUniqueNonZero(cell, hash_value);
}
}
class iterator
{
Self * container;
size_t bucket;
typename Impl::iterator current_it;
friend class TwoLevelHashTable;
iterator(Self * container_, size_t bucket_, typename Impl::iterator current_it_)
: container(container_), bucket(bucket_), current_it(current_it_) {}
public:
iterator() {}
bool operator== (const iterator & rhs) const { return bucket == rhs.bucket && current_it == rhs.current_it; }
bool operator!= (const iterator & rhs) const { return !(*this == rhs); }
iterator & operator++()
{
++current_it;
if (current_it == container->impls[bucket].end())
{
++bucket;
current_it = container->beginOfNextNonEmptyBucket(bucket);
}
return *this;
}
A Proper lookup table that uses HashTable's API This is the first step of allowing heterogeneous cells in hash tables. performance test results are ``` 1. HashMap<UInt16, UInt8, TrivialHash, HashTableFixedGrower<16>>; 2. NewLookupMap<UInt16, UInt8> ResolutionWidth 30000 1 .................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................223550276.46 ResolutionWidth 30000 2 .................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................248772721.24 Best: 2 - 24877272124 ResolutionWidth 100000 1 ..........................................................................................................................................................................................................................................................238498413.99 ResolutionWidth 100000 2 ..........................................................................................................................................................................................................................................................261808889.98 Best: 2 - 26180888998 ResolutionWidth 300000 1 ...................................................................................239307348.81 ResolutionWidth 300000 2 ...................................................................................257592761.30 Best: 2 - 25759276130 ResolutionWidth 1000000 1 .........................240144759.26 ResolutionWidth 1000000 2 .........................257093531.91 Best: 2 - 25709353191 ResolutionWidth 5000000 1 .....241573260.35 ResolutionWidth 5000000 2 .....259314162.79 Best: 2 - 25931416279 ResolutionDepth 30000 1 .................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................217108119.84 ResolutionDepth 30000 2 .................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................249459504.41 Best: 2 - 24945950441 ResolutionDepth 100000 1 ..........................................................................................................................................................................................................................................................229065162.17 ResolutionDepth 100000 2 ..........................................................................................................................................................................................................................................................253769105.64 Best: 2 - 25376910564 ResolutionDepth 300000 1 ...................................................................................233079225.18 ResolutionDepth 300000 2 ...................................................................................256316273.78 Best: 2 - 25631627378 ResolutionDepth 1000000 1 .........................234184633.51 ResolutionDepth 1000000 2 .........................261100491.57 Best: 2 - 26110049157 ResolutionDepth 5000000 1 .....233118795.66 ResolutionDepth 5000000 2 .....252436160.41 Best: 2 - 25243616041 ```
2019-02-28 09:35:38 +00:00
Cell & operator* () const { return *current_it; }
Cell * operator->() const { return current_it.getPtr(); }
Cell * getPtr() const { return current_it.getPtr(); }
size_t getHash() const { return current_it.getHash(); }
};
class const_iterator
{
Self * container;
size_t bucket;
typename Impl::const_iterator current_it;
friend class TwoLevelHashTable;
const_iterator(Self * container_, size_t bucket_, typename Impl::const_iterator current_it_)
: container(container_), bucket(bucket_), current_it(current_it_) {}
public:
const_iterator() {}
const_iterator(const iterator & rhs) : container(rhs.container), bucket(rhs.bucket), current_it(rhs.current_it) {}
bool operator== (const const_iterator & rhs) const { return bucket == rhs.bucket && current_it == rhs.current_it; }
bool operator!= (const const_iterator & rhs) const { return !(*this == rhs); }
const_iterator & operator++()
{
++current_it;
if (current_it == container->impls[bucket].end())
{
++bucket;
current_it = container->beginOfNextNonEmptyBucket(bucket);
}
return *this;
}
A Proper lookup table that uses HashTable's API This is the first step of allowing heterogeneous cells in hash tables. performance test results are ``` 1. HashMap<UInt16, UInt8, TrivialHash, HashTableFixedGrower<16>>; 2. NewLookupMap<UInt16, UInt8> ResolutionWidth 30000 1 .................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................223550276.46 ResolutionWidth 30000 2 .................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................248772721.24 Best: 2 - 24877272124 ResolutionWidth 100000 1 ..........................................................................................................................................................................................................................................................238498413.99 ResolutionWidth 100000 2 ..........................................................................................................................................................................................................................................................261808889.98 Best: 2 - 26180888998 ResolutionWidth 300000 1 ...................................................................................239307348.81 ResolutionWidth 300000 2 ...................................................................................257592761.30 Best: 2 - 25759276130 ResolutionWidth 1000000 1 .........................240144759.26 ResolutionWidth 1000000 2 .........................257093531.91 Best: 2 - 25709353191 ResolutionWidth 5000000 1 .....241573260.35 ResolutionWidth 5000000 2 .....259314162.79 Best: 2 - 25931416279 ResolutionDepth 30000 1 .................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................217108119.84 ResolutionDepth 30000 2 .................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................249459504.41 Best: 2 - 24945950441 ResolutionDepth 100000 1 ..........................................................................................................................................................................................................................................................229065162.17 ResolutionDepth 100000 2 ..........................................................................................................................................................................................................................................................253769105.64 Best: 2 - 25376910564 ResolutionDepth 300000 1 ...................................................................................233079225.18 ResolutionDepth 300000 2 ...................................................................................256316273.78 Best: 2 - 25631627378 ResolutionDepth 1000000 1 .........................234184633.51 ResolutionDepth 1000000 2 .........................261100491.57 Best: 2 - 26110049157 ResolutionDepth 5000000 1 .....233118795.66 ResolutionDepth 5000000 2 .....252436160.41 Best: 2 - 25243616041 ```
2019-02-28 09:35:38 +00:00
const Cell & operator* () const { return *current_it; }
const Cell * operator->() const { return current_it->getPtr(); }
const Cell * getPtr() const { return current_it.getPtr(); }
size_t getHash() const { return current_it.getHash(); }
};
const_iterator begin() const
{
size_t buck = 0;
typename Impl::const_iterator impl_it = beginOfNextNonEmptyBucket(buck);
return { this, buck, impl_it };
}
iterator begin()
{
size_t buck = 0;
typename Impl::iterator impl_it = beginOfNextNonEmptyBucket(buck);
return { this, buck, impl_it };
}
const_iterator end() const { return { this, MAX_BUCKET, impls[MAX_BUCKET].end() }; }
iterator end() { return { this, MAX_BUCKET, impls[MAX_BUCKET].end() }; }
2017-05-07 20:25:26 +00:00
/// Insert a value. In the case of any more complex values, it is better to use the `emplace` function.
std::pair<LookupResult, bool> ALWAYS_INLINE insert(const value_type & x)
{
size_t hash_value = hash(Cell::getKey(x));
std::pair<LookupResult, bool> res;
emplace(Cell::getKey(x), res.first, res.second, hash_value);
if (res.second)
2019-10-29 15:16:51 +00:00
insertSetMapped(res.first->getMapped(), x);
return res;
}
2017-05-07 20:25:26 +00:00
/** Insert the key,
* return an iterator to a position that can be used for `placement new` of value,
2017-05-07 20:25:26 +00:00
* as well as the flag - whether a new key was inserted.
*
* You have to make `placement new` values if you inserted a new key,
2017-05-07 20:25:26 +00:00
* since when destroying a hash table, the destructor will be invoked for it!
*
2017-05-07 20:25:26 +00:00
* Example usage:
*
* Map::iterator it;
* bool inserted;
* map.emplace(key, it, inserted);
* if (inserted)
* new(&it->second) Mapped(value);
*/
template <typename KeyHolder>
void ALWAYS_INLINE emplace(KeyHolder && key_holder, LookupResult & it, bool & inserted)
{
size_t hash_value = hash(keyHolderGetKey(key_holder));
emplace(key_holder, it, inserted, hash_value);
}
2017-05-07 20:25:26 +00:00
/// Same, but with a precalculated values of hash function.
template <typename KeyHolder>
void ALWAYS_INLINE emplace(KeyHolder && key_holder, LookupResult & it,
bool & inserted, size_t hash_value)
{
size_t buck = getBucketFromHash(hash_value);
impls[buck].emplace(key_holder, it, inserted, hash_value);
}
LookupResult ALWAYS_INLINE find(Key x, size_t hash_value)
{
size_t buck = getBucketFromHash(hash_value);
return impls[buck].find(x, hash_value);
}
ConstLookupResult ALWAYS_INLINE find(Key x, size_t hash_value) const
{
return const_cast<std::decay_t<decltype(*this)> *>(this)->find(x, hash_value);
}
LookupResult ALWAYS_INLINE find(Key x) { return find(x, hash(x)); }
ConstLookupResult ALWAYS_INLINE find(Key x) const { return find(x, hash(x)); }
void write(DB::WriteBuffer & wb) const
{
for (size_t i = 0; i < NUM_BUCKETS; ++i)
impls[i].write(wb);
}
void writeText(DB::WriteBuffer & wb) const
{
for (size_t i = 0; i < NUM_BUCKETS; ++i)
{
if (i != 0)
DB::writeChar(',', wb);
impls[i].writeText(wb);
}
}
void read(DB::ReadBuffer & rb)
{
for (size_t i = 0; i < NUM_BUCKETS; ++i)
impls[i].read(rb);
}
void readText(DB::ReadBuffer & rb)
{
for (size_t i = 0; i < NUM_BUCKETS; ++i)
{
if (i != 0)
DB::assertChar(',', rb);
impls[i].readText(rb);
}
}
size_t size() const
{
size_t res = 0;
for (size_t i = 0; i < NUM_BUCKETS; ++i)
res += impls[i].size();
return res;
}
bool empty() const
{
for (size_t i = 0; i < NUM_BUCKETS; ++i)
if (!impls[i].empty())
return false;
return true;
}
size_t getBufferSizeInBytes() const
{
size_t res = 0;
for (size_t i = 0; i < NUM_BUCKETS; ++i)
res += impls[i].getBufferSizeInBytes();
return res;
}
};