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Cleanup hash_map code

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This commit is contained in:
Maxime Coste 2017-03-07 15:48:04 +00:00
parent ba02498576
commit a1a566e921
1 changed files with 21 additions and 14 deletions
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35
src/hash_map.hh
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@ -17,11 +17,11 @@ struct HashIndex
int index; int index;
}; };
void grow() void resize(size_t new_size)
{ {
kak_assert(new_size > m_entries.size());
Vector<Entry, domain> old_entries = std::move(m_entries); Vector<Entry, domain> old_entries = std::move(m_entries);
constexpr size_t init_size = 4; m_entries.resize(new_size, {0,-1});
m_entries.resize(old_entries.empty() ? init_size : old_entries.size() * 2, {0,-1});
for (auto& entry : old_entries) for (auto& entry : old_entries)
{ {
if (entry.index >= 0) if (entry.index >= 0)
@ -29,12 +29,19 @@ struct HashIndex
} }
} }
void reserve(size_t count)
{
constexpr float max_fill_rate = 0.5f;
const size_t min_size = (size_t)(count / max_fill_rate) + 1;
size_t new_size = m_entries.empty() ? 4 : m_entries.size();
while (new_size < min_size)
new_size *= 2;
if (new_size > m_entries.size())
resize(new_size);
}
void add(size_t hash, int index) void add(size_t hash, int index)
{ {
++m_count;
if ((float)m_count / m_entries.size() > m_max_fill_rate)
grow();
Entry entry{hash, index}; Entry entry{hash, index};
while (true) while (true)
{ {
@ -55,14 +62,13 @@ struct HashIndex
target_slot = candidate_slot; target_slot = candidate_slot;
} }
} }
// no free entries found, grow, try again // no free entries found, resize, try again
grow(); resize(m_entries.size() * 2);
} }
} }
void remove(size_t hash, int index) void remove(size_t hash, int index)
{ {
--m_count;
for (auto slot = compute_slot(hash); slot < m_entries.size(); ++slot) for (auto slot = compute_slot(hash); slot < m_entries.size(); ++slot)
{ {
kak_assert(m_entries[slot].index >= 0); kak_assert(m_entries[slot].index >= 0);
@ -110,14 +116,12 @@ struct HashIndex
size_t compute_slot(size_t hash) const size_t compute_slot(size_t hash) const
{ {
// We assume entries.size() is power of 2 // We assume entries.size() is power of 2
return m_entries.empty() ? 0 : hash & (m_entries.size()-1); return hash & (m_entries.size()-1);
} }
void clear() { m_entries.clear(); } void clear() { m_entries.clear(); }
private: private:
size_t m_count = 0;
static constexpr float m_max_fill_rate = 0.9f;
Vector<Entry, domain> m_entries; Vector<Entry, domain> m_entries;
}; };
@ -137,12 +141,14 @@ struct HashMap
HashMap(std::initializer_list<Item> val) : m_items{val} HashMap(std::initializer_list<Item> val) : m_items{val}
{ {
m_index.reserve(val.size());
for (int i = 0; i < m_items.size(); ++i) for (int i = 0; i < m_items.size(); ++i)
m_index.add(hash_value(m_items[i].key), i); m_index.add(hash_value(m_items[i].key), i);
} }
Value& insert(Item item) Value& insert(Item item)
{ {
m_index.reserve(m_items.size()+1);
m_index.add(hash_value(item.key), (int)m_items.size()); m_index.add(hash_value(item.key), (int)m_items.size());
m_items.push_back(std::move(item)); m_items.push_back(std::move(item));
return m_items.back().value; return m_items.back().value;
@ -181,6 +187,7 @@ struct HashMap
if (index >= 0) if (index >= 0)
return m_items[index].value; return m_items[index].value;
m_index.reserve(m_items.size()+1);
m_index.add(hash, (int)m_items.size()); m_index.add(hash, (int)m_items.size());
m_items.push_back({Key{std::forward<KeyType>(key)}, {}}); m_items.push_back({Key{std::forward<KeyType>(key)}, {}});
return m_items.back().value; return m_items.back().value;
@ -257,7 +264,7 @@ struct HashMap
void reserve(size_t size) void reserve(size_t size)
{ {
m_items.reserve(size); m_items.reserve(size);
// TODO: Reserve in the index as well m_index.reserve(size);
} }
// Equality is taking the order of insertion into account // Equality is taking the order of insertion into account