From c4bd6cb9d38f445da8db6734411fd7b067c3f499 Mon Sep 17 00:00:00 2001 From: Clifford Wolf Date: Wed, 31 Dec 2014 03:58:29 +0100 Subject: [PATCH] major rewrite of hashlib::dict<> --- kernel/hashlib.h | 319 ++++++++++++++++++----------------------------- 1 file changed, 123 insertions(+), 196 deletions(-) diff --git a/kernel/hashlib.h b/kernel/hashlib.h index 3164282f2..a34d194f1 100644 --- a/kernel/hashlib.h +++ b/kernel/hashlib.h @@ -140,8 +140,8 @@ struct hash_obj_ops { inline int hashtable_size(int min_size) { - static std::vector primes = { - 23, 29, 37, 47, 59, 79, 101, 127, 163, 211, 269, 337, 431, 541, 677, + static std::vector zero_and_some_primes = { + 0, 23, 29, 37, 47, 59, 79, 101, 127, 163, 211, 269, 337, 431, 541, 677, 853, 1069, 1361, 1709, 2137, 2677, 3347, 4201, 5261, 6577, 8231, 10289, 12889, 16127, 20161, 25219, 31531, 39419, 49277, 61603, 77017, 96281, 120371, 150473, 188107, 235159, 293957, 367453, 459317, 574157, 717697, @@ -151,13 +151,13 @@ inline int hashtable_size(int min_size) 121590311, 151987889, 189984863, 237481091, 296851369, 371064217 }; - for (auto p : primes) - if (p > min_size) return p; + for (auto p : zero_and_some_primes) + if (p >= min_size) return p; if (sizeof(int) == 4) throw std::length_error("hash table exceeded maximum size. use a ILP64 abi for larger tables."); - for (auto p : primes) + for (auto p : zero_and_some_primes) if (100129 * p > min_size) return 100129 * p; throw std::length_error("hash table exceeded maximum size."); @@ -168,49 +168,26 @@ class dict { struct entry_t { - int link; std::pair udata; + int next; - entry_t() : link(-1) { } - entry_t(const std::pair &udata) : link(1), udata(udata) { } - - bool is_free() const { return link < 0; } - int get_next() const { return (link > 0 ? link : -link) - 2; } - bool get_last() const { return get_next() == -1; } - void set_next_used(int next) { link = next + 2; } - void set_next_free(int next) { link = -(next + 2); } + entry_t() { } + entry_t(const std::pair &udata, int next) : udata(udata), next(next) { } }; std::vector hashtable; std::vector entries; - int free_list, counter, begin_n; - int begin_seek_count; OPS ops; - void init() - { - free_list = -1; - counter = 0; - begin_n = -1; - begin_seek_count = 0; - } - - void init_from(const dict &other) - { - hashtable.clear(); - entries.clear(); - - counter = other.size(); - begin_n = counter - 1; - entries.reserve(counter); - - for (auto &it : other) - entries.push_back(entry_t(it)); - - rehash(); +#if 0 + static inline void do_assert(bool cond) { + if (!cond) throw std::runtime_error("dict<> assert failed."); } +#else + static inline void do_assert(bool) { } +#endif - int mkhash(const K &key) const + int do_hash(const K &key) const { unsigned int hash = 0; if (!hashtable.empty()) @@ -218,145 +195,108 @@ class dict return hash; } - void upd_begin_n(bool do_refree = true) + void do_rehash() { - if (begin_n < -1) { - begin_n = -(begin_n+2); - while (begin_n >= 0 && entries[begin_n].is_free()) { begin_seek_count++; begin_n--; } - if (do_refree && begin_seek_count > int(entries.size() / 2)) refree(); + hashtable.clear(); + hashtable.resize(hashtable_size(entries.size() * hashtable_size_factor), -1); + + for (int i = 0; i < int(entries.size()); i++) { + do_assert(-1 <= entries[i].next && entries[i].next < int(entries.size())); + int hash = do_hash(entries[i].udata.first); + entries[i].next = hashtable[hash]; + hashtable[hash] = i; } } - void refree() + int do_erase(int index, int hash) { - free_list = -1; - begin_n = -1; + do_assert(index < int(entries.size())); + if (hashtable.empty() || index < 0) + return 0; - int last_free = -1; - for (int i = 0; i < int(entries.size()); i++) - if (entries[i].is_free()) { - if (last_free != -1) - entries[last_free].set_next_free(i); - else - free_list = i; - last_free = i; - } else - begin_n = i; - - if (last_free != -1) - entries[last_free].set_next_free(-1); - - begin_seek_count = 0; - } - - void rehash() - { - upd_begin_n(false); - entries.resize(begin_n + 1); + int k = hashtable[hash]; + if (k == index) { + hashtable[hash] = entries[index].next; + } else { + while (entries[k].next != index) { + k = entries[k].next; + do_assert(0 <= k && k < int(entries.size())); + } + entries[k].next = entries[index].next; + } - free_list = -1; - begin_n = -1; + int back_idx = entries.size()-1; - hashtable.clear(); - hashtable.resize(hashtable_size(entries.size() * hashtable_size_factor), -1); + if (index != back_idx) + { + int back_hash = do_hash(entries[back_idx].udata.first); - int last_free = -1; - for (int i = 0; i < int(entries.size()); i++) - if (entries[i].is_free()) { - if (last_free != -1) - entries[last_free].set_next_free(i); - else - free_list = i; - last_free = i; + k = hashtable[back_hash]; + if (k == back_idx) { + hashtable[back_hash] = index; } else { - int hash = mkhash(entries[i].udata.first); - entries[i].set_next_used(hashtable[hash]); - hashtable[hash] = i; - begin_n = i; + while (entries[k].next != back_idx) { + k = entries[k].next; + do_assert(0 <= k && k < int(entries.size())); + } + entries[k].next = index; } - if (last_free != -1) - entries[last_free].set_next_free(-1); + entries[index] = std::move(entries[back_idx]); + } - begin_seek_count = 0; + entries.pop_back(); + + if (entries.empty()) + hashtable.clear(); + + return 1; } - int do_erase(const K &key, int hash) + int do_lookup(const K &key, int &hash) const { - int last_index = -1; - int index = hashtable.empty() ? -1 : hashtable[hash]; - while (1) { - if (index < 0) - return 0; - if (ops.cmp(entries[index].udata.first, key)) { - if (last_index < 0) - hashtable[hash] = entries[index].get_next(); - else - entries[last_index].set_next_used(entries[index].get_next()); - entries[index].udata = std::pair(); - entries[index].set_next_free(free_list); - free_list = index; - if (--counter == 0) - clear(); - else if (index == begin_n) - begin_n = -(begin_n+2); - return 1; - } - last_index = index; - index = entries[index].get_next(); + if (hashtable.empty()) + return -1; + + if (entries.size() * hashtable_size_trigger > hashtable.size()) { + ((dict*)this)->do_rehash(); + hash = do_hash(key); } - } - int lookup_index(const K &key, int hash) const - { - int index = hashtable.empty() ? -1 : hashtable[hash]; - while (1) { - if (index < 0) - return -1; - if (ops.cmp(entries[index].udata.first, key)) - return index; - index = entries[index].get_next(); + int index = hashtable[hash]; + + while (index >= 0 && !ops.cmp(entries[index].udata.first, key)) { + index = entries[index].next; + do_assert(-1 <= index && index < int(entries.size())); } + + return index; } - int insert_at(const std::pair &value, int hash) + int do_insert(const std::pair &value, int &hash) { - if (free_list < 0) - { - free_list = entries.size(); - entries.push_back(entry_t()); - - if (entries.size() * hashtable_size_trigger > hashtable.size()) { - int i = free_list; - entries[i].udata = value; - entries[i].set_next_used(0); - begin_n = i; - counter++; - rehash(); - return i; - } + if (hashtable.empty()) { + entries.push_back(entry_t(value, -1)); + do_rehash(); + hash = do_hash(value.first); + } else { + entries.push_back(entry_t(value, hashtable[hash])); + hashtable[hash] = entries.size() - 1; } - - int i = free_list; - free_list = entries[i].get_next(); - entries[i].udata = value; - entries[i].set_next_used(hashtable[hash]); - hashtable[hash] = i; - if ((begin_n < -1 && -(begin_n+2) <= i) || (begin_n >= -1 && begin_n <= i)) - begin_n = i; - counter++; - return i; + return entries.size() - 1; } public: class iterator { + friend dict; + protected: dict *ptr; int index; public: iterator() { } iterator(dict *ptr, int index) : ptr(ptr), index(index) { } - iterator operator++() { do index--; while (index >= 0 && ptr->entries[index].is_free()); return *this; } + iterator operator++() { index--; return *this; } bool operator==(const iterator &other) const { return index == other.index; } bool operator!=(const iterator &other) const { return index != other.index; } std::pair &operator*() { return ptr->entries[index].udata; } @@ -367,12 +307,14 @@ public: class const_iterator { + friend dict; + protected: const dict *ptr; int index; public: const_iterator() { } const_iterator(const dict *ptr, int index) : ptr(ptr), index(index) { } - const_iterator operator++() { do index--; while (index >= 0 && ptr->entries[index].is_free()); return *this; } + const_iterator operator++() { index--; return *this; } bool operator==(const const_iterator &other) const { return index == other.index; } bool operator!=(const const_iterator &other) const { return index != other.index; } const std::pair &operator*() const { return ptr->entries[index].udata; } @@ -381,23 +323,22 @@ public: dict() { - init(); } dict(const dict &other) { - init_from(other); + entries = other.entries; + do_rehash(); } dict(dict &&other) { - init(); swap(other); } dict &operator=(const dict &other) { - if (this != &other) - init_from(other); + entries = other.entries; + do_rehash(); return *this; } @@ -409,7 +350,6 @@ public: dict(const std::initializer_list> &list) { - init(); for (auto &it : list) insert(it); } @@ -417,7 +357,6 @@ public: template dict(InputIterator first, InputIterator last) { - init(); insert(first, last); } @@ -430,38 +369,39 @@ public: std::pair insert(const std::pair &value) { - int hash = mkhash(value.first); - int i = lookup_index(value.first, hash); + int hash = do_hash(value.first); + int i = do_lookup(value.first, hash); if (i >= 0) return std::pair(iterator(this, i), false); - i = insert_at(value, hash); + i = do_insert(value, hash); return std::pair(iterator(this, i), true); } int erase(const K &key) { - int hash = mkhash(key); - return do_erase(key, hash); + int hash = do_hash(key); + int index = do_lookup(key, hash); + return do_erase(index, hash); } iterator erase(iterator it) { - int hash = mkhash(it->first); - do_erase(it->first, hash); + int hash = do_hash(it->first); + do_erase(it.index, hash); return ++it; } int count(const K &key) const { - int hash = mkhash(key); - int i = lookup_index(key, hash); + int hash = do_hash(key); + int i = do_lookup(key, hash); return i < 0 ? 0 : 1; } iterator find(const K &key) { - int hash = mkhash(key); - int i = lookup_index(key, hash); + int hash = do_hash(key); + int i = do_lookup(key, hash); if (i < 0) return end(); return iterator(this, i); @@ -469,8 +409,8 @@ public: const_iterator find(const K &key) const { - int hash = mkhash(key); - int i = lookup_index(key, hash); + int hash = do_hash(key); + int i = do_lookup(key, hash); if (i < 0) return end(); return const_iterator(this, i); @@ -478,8 +418,8 @@ public: T& at(const K &key) { - int hash = mkhash(key); - int i = lookup_index(key, hash); + int hash = do_hash(key); + int i = do_lookup(key, hash); if (i < 0) throw std::out_of_range("dict::at()"); return entries[i].udata.second; @@ -487,8 +427,8 @@ public: const T& at(const K &key) const { - int hash = mkhash(key); - int i = lookup_index(key, hash); + int hash = do_hash(key); + int i = do_lookup(key, hash); if (i < 0) throw std::out_of_range("dict::at()"); return entries[i].udata.second; @@ -496,10 +436,10 @@ public: T& operator[](const K &key) { - int hash = mkhash(key); - int i = lookup_index(key, hash); + int hash = do_hash(key); + int i = do_lookup(key, hash); if (i < 0) - i = insert_at(std::pair(key, T()), hash); + i = do_insert(std::pair(key, T()), hash); return entries[i].udata.second; } @@ -507,29 +447,16 @@ public: { hashtable.swap(other.hashtable); entries.swap(other.entries); - std::swap(free_list, other.free_list); - std::swap(counter, other.counter); - std::swap(begin_n, other.begin_n); - std::swap(begin_seek_count, other.begin_seek_count); } bool operator==(const dict &other) const { - if (counter != other.counter) + if (size() != other.size()) return false; - if (counter == 0) - return true; - if (entries.size() < other.entries.size()) - for (auto &it : *this) { - auto oit = other.find(it.first); - if (oit == other.end() || oit->second != it.second) - return false; - } - else - for (auto &oit : other) { - auto it = find(oit.first); - if (it == end() || it->second != oit.second) - return false; - } + for (auto &it : entries) { + auto oit = other.find(it.udata.first); + if (oit == other.end() || oit->second != it.udata.second) + return false; + } return true; } @@ -537,14 +464,14 @@ public: return !(*this == other); } - size_t size() const { return counter; } - bool empty() const { return counter == 0; } - void clear() { hashtable.clear(); entries.clear(); init(); } + size_t size() const { return entries.size(); } + bool empty() const { return entries.empty(); } + void clear() { hashtable.clear(); entries.clear(); } - iterator begin() { upd_begin_n(); return iterator(this, begin_n); } + iterator begin() { return iterator(this, int(entries.size())-1); } iterator end() { return iterator(nullptr, -1); } - const_iterator begin() const { ((dict*)this)->upd_begin_n(); return const_iterator(this, begin_n); } + const_iterator begin() const { return const_iterator(this, int(entries.size())-1); } const_iterator end() const { return const_iterator(nullptr, -1); } }; -- 2.30.2