116 lines
2.8 KiB
Go
116 lines
2.8 KiB
Go
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/*
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* Copyright 2021 ByteDance Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package caching
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import (
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`strings`
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`unsafe`
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`github.com/bytedance/sonic/internal/rt`
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)
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type FieldMap struct {
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N uint64
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b unsafe.Pointer
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m map[string]int
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}
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type FieldEntry struct {
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ID int
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Name string
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Hash uint64
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}
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const (
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FieldMap_N = int64(unsafe.Offsetof(FieldMap{}.N))
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FieldMap_b = int64(unsafe.Offsetof(FieldMap{}.b))
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FieldEntrySize = int64(unsafe.Sizeof(FieldEntry{}))
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)
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func newBucket(n int) unsafe.Pointer {
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v := make([]FieldEntry, n)
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return (*rt.GoSlice)(unsafe.Pointer(&v)).Ptr
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}
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func CreateFieldMap(n int) *FieldMap {
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return &FieldMap {
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N: uint64(n * 2),
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b: newBucket(n * 2), // LoadFactor = 0.5
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m: make(map[string]int, n * 2),
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}
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}
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func (self *FieldMap) At(p uint64) *FieldEntry {
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off := uintptr(p) * uintptr(FieldEntrySize)
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return (*FieldEntry)(unsafe.Pointer(uintptr(self.b) + off))
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}
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// Get searches FieldMap by name. JIT generated assembly does NOT call this
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// function, rather it implements its own version directly in assembly. So
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// we must ensure this function stays in sync with the JIT generated one.
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func (self *FieldMap) Get(name string) int {
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h := StrHash(name)
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p := h % self.N
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s := self.At(p)
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/* find the element;
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* the hash map is never full, so the loop will always terminate */
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for s.Hash != 0 {
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if s.Hash == h && s.Name == name {
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return s.ID
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} else {
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p = (p + 1) % self.N
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s = self.At(p)
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}
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}
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/* not found */
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return -1
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}
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func (self *FieldMap) Set(name string, i int) {
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h := StrHash(name)
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p := h % self.N
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s := self.At(p)
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/* searching for an empty slot;
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* the hash map is never full, so the loop will always terminate */
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for s.Hash != 0 {
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p = (p + 1) % self.N
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s = self.At(p)
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}
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/* set the value */
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s.ID = i
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s.Hash = h
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s.Name = name
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/* add the case-insensitive version, prefer the one with smaller field ID */
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key := strings.ToLower(name)
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if v, ok := self.m[key]; !ok || i < v {
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self.m[key] = i
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}
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}
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func (self *FieldMap) GetCaseInsensitive(name string) int {
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if i, ok := self.m[strings.ToLower(name)]; ok {
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return i
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} else {
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return -1
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}
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}
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