database/doris
2
0
Fork 0
Code Issues Pull Requests Actions 3 Packages Projects Releases Wiki Activity

[Enhancement] use std::search to replace custom search (#7999)

Browse Source
This commit is contained in:
Pxl
2022-02-11 10:47:58 +08:00
committed by GitHub
parent 5bd9fdb8c1
commit a4e7c76336
1 changed files with 9 additions and 86 deletions
Download Patch File Download Diff File Expand all files Collapse all files

95
be/src/runtime/string_search.hpp
View File

@ -51,10 +51,10 @@
// agrees to be bound by the terms and conditions of this License
// Agreement.
#ifndef DORIS_BE_SRC_QUERY_BE_RUNTIME_STRING_SEARCH_H
#define DORIS_BE_SRC_QUERY_BE_RUNTIME_STRING_SEARCH_H
#pragma once
#include <cstring>
#include <functional>
#include <vector>
#include "common/logging.h"
@ -62,109 +62,32 @@
namespace doris {
// TODO: This can be sped up with SIDD_CMP_EQUAL_ORDERED or at the very least rewritten
// from published algorithms.
class StringSearch {
public:
virtual ~StringSearch() {}
StringSearch() : _pattern(NULL), _mask(0) {}
StringSearch() : _pattern(nullptr) {}
// Initialize/Precompute a StringSearch object from the pattern
StringSearch(const StringValue* pattern) : _pattern(pattern), _mask(0), _skip(0) {
// Special cases
if (_pattern->len <= 1) {
return;
}
// Build compressed lookup table
int mlast = _pattern->len - 1;
_skip = mlast - 1;
for (int i = 0; i < mlast; ++i) {
bloom_add(_pattern->ptr[i]);
if (_pattern->ptr[i] == _pattern->ptr[mlast]) {
_skip = mlast - i - 1;
}
}
bloom_add(_pattern->ptr[mlast]);
}
StringSearch(const StringValue* pattern) : _pattern(pattern) {}
// search for this pattern in str.
// Returns the offset into str if the pattern exists
// Returns -1 if the pattern is not found
int search(const StringValue* str) const {
// Special cases
if (!str || !_pattern || _pattern->len == 0) {
return -1;
}
int mlast = _pattern->len - 1;
int w = str->len - _pattern->len;
int n = str->len;
int m = _pattern->len;
const char* s = str->ptr;
const char* p = _pattern->ptr;
// Special case if pattern->len == 1
if (m == 1) {
const char* result = reinterpret_cast<const char*>(memchr(s, p[0], n));
if (result != NULL) {
return result - s;
}
auto it = std::search(str->ptr, str->ptr + str->len,
std::default_searcher(_pattern->ptr, _pattern->ptr + _pattern->len));
if (it == str->ptr + str->len) {
return -1;
} else {
return it - str->ptr;
}
// General case.
int j;
// TODO: the original code seems to have an off by one error. It is possible
// to index at w + m which is the length of the input string. Checks have
// been added to make sure that w + m < str->len.
for (int i = 0; i <= w; i++) {
// note: using mlast in the skip path slows things down on x86
if (s[i + m - 1] == p[m - 1]) {
// candidate match
for (j = 0; j < mlast; j++)
if (s[i + j] != p[j]) {
break;
}
if (j == mlast) {
return i;
}
// miss: check if next character is part of pattern
if (i + m < n && !bloom_query(s[i + m])) {
i = i + m;
} else {
i = i + _skip;
}
} else {
// skip: check if next character is part of pattern
if (i + m < n && !bloom_query(s[i + m])) {
i = i + m;
}
}
}
return -1;
}
private:
static const int BLOOM_WIDTH = 64;
void bloom_add(char c) { _mask |= (1UL << (c & (BLOOM_WIDTH - 1))); }
bool bloom_query(char c) const { return _mask & (1UL << (c & (BLOOM_WIDTH - 1))); }
const StringValue* _pattern;
int64_t _mask;
int64_t _skip;
};
} // namespace doris
#endif