github.com/zuoyebang/bitalosdb@v1.1.1-0.20240516111551-79a8c4d8ce20/internal/cache/lrucache/value_normal.go (about)

     1  // Copyright 2021 The Bitalosdb author(hustxrb@163.com) and other contributors.
     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  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  //go:build (!invariants && !tracing) || race
    16  // +build !invariants,!tracing race
    17  
    18  package lrucache
    19  
    20  import (
    21  	"unsafe"
    22  
    23  	"github.com/zuoyebang/bitalosdb/internal/manual"
    24  )
    25  
    26  const valueSize = int(unsafe.Sizeof(Value{}))
    27  
    28  func newValue(n int) *Value {
    29  	if n == 0 {
    30  		return nil
    31  	}
    32  
    33  	if !cgoEnabled {
    34  		v := &Value{buf: make([]byte, n)}
    35  		v.ref.init(1)
    36  		return v
    37  	}
    38  
    39  	b := manual.New(valueSize + n)
    40  	v := (*Value)(unsafe.Pointer(&b[0]))
    41  	v.buf = b[valueSize:]
    42  	v.ref.init(1)
    43  	return v
    44  }
    45  
    46  func (v *Value) free() {
    47  	if !cgoEnabled {
    48  		return
    49  	}
    50  
    51  	n := valueSize + cap(v.buf)
    52  	buf := (*[manual.MaxArrayLen]byte)(unsafe.Pointer(v))[:n:n]
    53  	v.buf = nil
    54  	manual.Free(buf)
    55  }