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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include <vespa/vespalib/util/arrayref.h>
#include <vespa/vespalib/stllike/hash_set.h>
#include <vespa/vespalib/stllike/allocator.h>
#include <vespa/vespalib/stllike/hash_set.hpp>
#include <vector>
#include <cassert>
#include <type_traits>
namespace vespalib::eval {
/**
* A map where both keys and values are arrays of some type (K and V
* respectively). All map entries have exactly the same number of keys
* and exactly the same number of values. Keys and values are stored
* in separate vectors external to the map itself in order to reduce
* memory fragmentation both by co-locating the keys and values
* themselves and also by reducing the internal hash node size. Once
* entries are added they cannot be removed. Keys cannot be
* overwritten, but values can.
**/
template <typename K, typename V, typename H = vespalib::hash<K>, typename EQ = std::equal_to<> >
class ArrayArrayMap
{
private:
size_t _keys_per_entry;
size_t _values_per_entry;
std::vector<K, vespalib::allocator_large<K>> _keys;
std::vector<V, vespalib::allocator_large<V>> _values;
public:
size_t keys_per_entry() const { return _keys_per_entry; }
size_t values_per_entry() const { return _values_per_entry; }
struct Tag {
uint32_t id;
static constexpr uint32_t npos() { return uint32_t(-1); }
static Tag make_invalid() { return Tag{npos()}; }
bool valid() const { return (id != npos()); }
};
ConstArrayRef<K> get_keys(Tag tag) const { return {_keys.data() + (tag.id * _keys_per_entry), _keys_per_entry}; }
ArrayRef<V> get_values(Tag tag) { return {&_values[tag.id * _values_per_entry], _values_per_entry}; }
ConstArrayRef<V> get_values(Tag tag) const { return {&_values[tag.id * _values_per_entry], _values_per_entry}; }
struct MyKey {
Tag tag;
uint32_t hash;
};
template <typename T> struct AltKey {
ConstArrayRef<T> key;
uint32_t hash;
};
struct Hash {
H hash_fun;
template <typename T> uint32_t operator()(ConstArrayRef<T> key) const {
uint32_t h = 0;
for (const T &k: key) {
if constexpr (std::is_pointer_v<T>) {
h = h * 31 + hash_fun(*k);
} else {
h = h * 31 + hash_fun(k);
}
}
return h;
}
uint32_t operator()(const MyKey &key) const { return key.hash; }
template <typename T> uint32_t operator()(const AltKey<T> &key) const { return key.hash; }
};
struct Equal {
const ArrayArrayMap &parent;
EQ eq_fun;
Equal(const ArrayArrayMap &parent_in) : parent(parent_in), eq_fun() {}
template <typename T>
bool operator()(const MyKey &a, const AltKey<T> &b) const {
if ((a.hash != b.hash) || (b.key.size() != parent.keys_per_entry())) {
return false;
}
auto a_key = parent.get_keys(a.tag);
for (size_t i = 0; i < a_key.size(); ++i) {
if constexpr (std::is_pointer_v<T>) {
if (!eq_fun(a_key[i], *b.key[i])) {
return false;
}
} else {
if (!eq_fun(a_key[i], b.key[i])) {
return false;
}
}
}
return true;
}
bool operator()(const MyKey &a, const MyKey &b) const {
return operator()(a, AltKey<K>{parent.get_keys(b.tag), b.hash});
}
};
using MapType = vespalib::hash_set<MyKey,Hash,Equal>;
private:
MapType _map;
Hash _hasher;
template <typename T>
Tag add_entry(ConstArrayRef<T> key, uint32_t hash) {
uint32_t tag_id = _map.size();
for (const auto &k: key) {
if constexpr (std::is_pointer_v<T>) {
_keys.push_back(*k);
} else {
_keys.push_back(k);
}
}
_values.resize(_values.size() + _values_per_entry);
auto [pos, was_inserted] = _map.insert(MyKey{{tag_id},hash});
assert(was_inserted);
return Tag{tag_id};
}
public:
ArrayArrayMap(size_t keys_per_entry_in, size_t values_per_entry_in, size_t expected_entries);
ArrayArrayMap(const ArrayArrayMap &) = delete;
ArrayArrayMap & operator = (const ArrayArrayMap &) = delete;
~ArrayArrayMap();
size_t size() const { return _map.size(); }
template <typename T>
Tag lookup(ConstArrayRef<T> key) const {
auto pos = _map.find(AltKey<T>{key, _hasher(key)});
if (pos == _map.end()) {
return Tag::make_invalid();
}
return pos->tag;
}
template <typename T>
Tag add_entry(ConstArrayRef<T> key) {
return add_entry(key, _hasher(key));
}
template <typename T>
std::pair<Tag,bool> lookup_or_add_entry(ConstArrayRef<T> key) {
uint32_t hash = _hasher(key);
auto pos = _map.find(AltKey<T>{key, hash});
if (pos == _map.end()) {
return {add_entry(key, hash), true};
}
return {pos->tag, false};
}
template <typename F>
void each_entry(F &&f) const {
for (uint32_t i = 0; i < size(); ++i) {
f(get_keys(Tag{i}), get_values(Tag{i}));
}
}
};
template <typename K, typename V, typename H, typename EQ>
ArrayArrayMap<K,V,H,EQ>::ArrayArrayMap(size_t keys_per_entry_in, size_t values_per_entry_in, size_t expected_entries)
: _keys_per_entry(keys_per_entry_in), _values_per_entry(values_per_entry_in), _keys(), _values(),
_map(expected_entries * 2, Hash(), Equal(*this)), _hasher()
{
_keys.reserve(_keys_per_entry * expected_entries);
_values.reserve(_values_per_entry * expected_entries);
static_assert(!std::is_pointer_v<K>, "keys cannot be pointers due to auto-deref of alt keys");
}
template <typename K, typename V, typename H, typename EQ>
ArrayArrayMap<K,V,H,EQ>::~ArrayArrayMap() = default;
}
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