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