ZYM/BH-Bookstore-2023
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upd: optimize key2index

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ZhuangYumin
2023-12-07 14:43:52 +00:00
parent 8b4d8b301f
commit 9c5ab581d0
1 changed files with 28 additions and 18 deletions
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46
backend/include/key2index.hpp
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@ -10,15 +10,26 @@ class String2Index {
private: private:
static const int kBucketSize = 262142; static const int kBucketSize = 262142;
static const int kPageSize = 4096; static const int kPageSize = 4096;
constexpr static char salt1[10] = "mL;]-=eT";
constexpr static char salt2[10] = "9B<mF_me";
constexpr static char sub_salt1[10] = "23333";
constexpr static char sub_salt2[10] = "...";
static inline size_t Hash(std::string str) noexcept {
str = salt1 + str + salt2;
size_t ret = 0;
for (int i = 0; i < str.length(); ++i) ret = ret * 131 + str[i];
return ret;
}
struct Node { struct Node {
char str[66]; size_t main_hash, sub_hash;
int val; int val;
Node() = default; Node() = default;
Node(const std::string &_str, int _val) : val(_val) { Node(std::string str, int _val)
assert(_str.length() <= 64); : main_hash(Hash(str)),
strcpy(str, _str.c_str()); sub_hash(Hash(sub_salt1 + str + sub_salt2)),
} val(_val) {}
}; };
static const int kNodesPerBlock = static const int kNodesPerBlock =
(kPageSize - 3 * sizeof(int)) / sizeof(Node); (kPageSize - 3 * sizeof(int)) / sizeof(Node);
@ -26,26 +37,18 @@ class String2Index {
struct Block { struct Block {
int tot, nxt_idx; int tot, nxt_idx;
Node data[kNodesPerBlock]; Node data[kNodesPerBlock];
char padding[kPageSize - 3 * sizeof(int) - sizeof(Node) * (kNodesPerBlock)]; // char padding[kPageSize - 3 * sizeof(int) - sizeof(Node) *
// (kNodesPerBlock)];
Block() : tot(0), nxt_idx(0) {} Block() : tot(0), nxt_idx(0) {}
Block(int _tot, int _nxt_idx) : tot(_tot), nxt_idx(_nxt_idx) {} Block(int _tot, int _nxt_idx) : tot(_tot), nxt_idx(_nxt_idx) {}
}; };
static_assert(kNodesPerBlock >= 1, "kNodesPerBlock error"); static_assert(kNodesPerBlock >= 1, "kNodesPerBlock error");
static_assert(sizeof(Block) == kPageSize - 4, "Block Size error"); static_assert(sizeof(Block) <= kPageSize - 4, "Block Size error");
DriveArray<Block, kBucketSize, 100> mem; DriveArray<Block, kBucketSize, 100> mem;
int *hash_table = nullptr; int *hash_table = nullptr;
std::string file_name; std::string file_name;
inline size_t Hash(std::string str) noexcept {
const static std::string salt1 = "mL;]-=eT";
const static std::string salt2 = "9B<mF_me";
str = salt1 + str + salt2;
size_t ret = 0;
for (int i = 0; i < str.length(); ++i) ret = ret * 131 + str[i];
return ret;
}
public: public:
String2Index() = default; String2Index() = default;
void OpenFile(const std::string __file_name) noexcept { void OpenFile(const std::string __file_name) noexcept {
@ -104,10 +107,14 @@ class String2Index {
size_t hash_val = Hash(str); size_t hash_val = Hash(str);
int idx = hash_table[hash_val % kBucketSize]; int idx = hash_table[hash_val % kBucketSize];
Block *blk_ptr = new Block; Block *blk_ptr = new Block;
size_t str_main_hash = Hash(str),
str_sub_hash = Hash(sub_salt1 + str + sub_salt2);
while (idx != 0) { while (idx != 0) {
mem.read(*blk_ptr, idx); mem.read(*blk_ptr, idx);
for (int i = 0; i < blk_ptr->tot; ++i) { for (int i = 0; i < blk_ptr->tot; ++i) {
if (blk_ptr->data[i].str == str && blk_ptr->data[i].val == val) { if (blk_ptr->data[i].main_hash == str_main_hash &&
blk_ptr->data[i].sub_hash == str_sub_hash &&
blk_ptr->data[i].val == val) {
int headidx = hash_table[hash_val % kBucketSize]; int headidx = hash_table[hash_val % kBucketSize];
if (headidx == idx) { if (headidx == idx) {
blk_ptr->data[i] = blk_ptr->data[--blk_ptr->tot]; blk_ptr->data[i] = blk_ptr->data[--blk_ptr->tot];
@ -137,10 +144,13 @@ class String2Index {
size_t hash_val = Hash(str); size_t hash_val = Hash(str);
int idx = hash_table[hash_val % kBucketSize]; int idx = hash_table[hash_val % kBucketSize];
Block *blk_ptr = new Block; Block *blk_ptr = new Block;
size_t str_main_hash = Hash(str),
str_sub_hash = Hash(sub_salt1 + str + sub_salt2);
while (idx != 0) { while (idx != 0) {
mem.read(*blk_ptr, idx); mem.read(*blk_ptr, idx);
for (int i = 0; i < blk_ptr->tot; ++i) { for (int i = 0; i < blk_ptr->tot; ++i) {
if (blk_ptr->data[i].str == str) { if (blk_ptr->data[i].main_hash == str_main_hash &&
blk_ptr->data[i].sub_hash == str_sub_hash) {
ret.push_back(blk_ptr->data[i].val); ret.push_back(blk_ptr->data[i].val);
} }
} }