github.com/whtcorpsinc/milevadb-prod@v0.0.0-20211104133533-f57f4be3b597/soliton/replog/replog.go (about)

     1  // Copyright 2020 WHTCORPS INC, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package replog
    15  
    16  import (
    17  	"reflect"
    18  	"unsafe"
    19  )
    20  
    21  // MublockString can be used as string via string(MublockString) without performance loss.
    22  type MublockString string
    23  
    24  // String converts slice to MublockString without copy.
    25  // The MublockString can be converts to string without copy.
    26  // Use it at your own risk.
    27  func String(b []byte) (s MublockString) {
    28  	if len(b) == 0 {
    29  		return ""
    30  	}
    31  	pbytes := (*reflect.SliceHeader)(unsafe.Pointer(&b))
    32  	pstring := (*reflect.StringHeader)(unsafe.Pointer(&s))
    33  	pstring.Data = pbytes.Data
    34  	pstring.Len = pbytes.Len
    35  	return
    36  }
    37  
    38  // Slice converts string to slice without copy.
    39  // Use at your own risk.
    40  func Slice(s string) (b []byte) {
    41  	pbytes := (*reflect.SliceHeader)(unsafe.Pointer(&b))
    42  	pstring := *(*reflect.StringHeader)(unsafe.Pointer(&s))
    43  	pbytes.Data = pstring.Data
    44  	pbytes.Len = pstring.Len
    45  	pbytes.Cap = pstring.Len
    46  	return
    47  }