github.com/zuoyebang/bitalosdb@v1.1.1-0.20240516111551-79a8c4d8ce20/internal/cache/lrucache/entry_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  	"runtime"
    22  	"sync"
    23  	"unsafe"
    24  
    25  	"github.com/zuoyebang/bitalosdb/internal/invariants"
    26  	"github.com/zuoyebang/bitalosdb/internal/manual"
    27  )
    28  
    29  const (
    30  	entrySize            = int(unsafe.Sizeof(entry{}))
    31  	entryAllocCacheLimit = 128
    32  	entriesGoAllocated   = invariants.RaceEnabled || !cgoEnabled
    33  )
    34  
    35  var entryAllocPool = sync.Pool{
    36  	New: func() interface{} {
    37  		return newEntryAllocCache()
    38  	},
    39  }
    40  
    41  func entryAllocNew() *entry {
    42  	a := entryAllocPool.Get().(*entryAllocCache)
    43  	e := a.alloc()
    44  	entryAllocPool.Put(a)
    45  	return e
    46  }
    47  
    48  func entryAllocFree(e *entry) {
    49  	a := entryAllocPool.Get().(*entryAllocCache)
    50  	a.free(e)
    51  	entryAllocPool.Put(a)
    52  }
    53  
    54  type entryAllocCache struct {
    55  	entries []*entry
    56  }
    57  
    58  func newEntryAllocCache() *entryAllocCache {
    59  	c := &entryAllocCache{}
    60  	if !entriesGoAllocated {
    61  		runtime.SetFinalizer(c, freeEntryAllocCache)
    62  	}
    63  	return c
    64  }
    65  
    66  func freeEntryAllocCache(obj interface{}) {
    67  	c := obj.(*entryAllocCache)
    68  	for i, e := range c.entries {
    69  		c.dealloc(e)
    70  		c.entries[i] = nil
    71  	}
    72  }
    73  
    74  func (c *entryAllocCache) alloc() *entry {
    75  	n := len(c.entries)
    76  	if n == 0 {
    77  		if entriesGoAllocated {
    78  			return &entry{}
    79  		}
    80  		b := manual.New(entrySize)
    81  		return (*entry)(unsafe.Pointer(&b[0]))
    82  	}
    83  	e := c.entries[n-1]
    84  	c.entries = c.entries[:n-1]
    85  	return e
    86  }
    87  
    88  func (c *entryAllocCache) dealloc(e *entry) {
    89  	if !entriesGoAllocated {
    90  		buf := (*[manual.MaxArrayLen]byte)(unsafe.Pointer(e))[:entrySize:entrySize]
    91  		manual.Free(buf)
    92  	}
    93  }
    94  
    95  func (c *entryAllocCache) free(e *entry) {
    96  	if len(c.entries) == entryAllocCacheLimit {
    97  		c.dealloc(e)
    98  		return
    99  	}
   100  	c.entries = append(c.entries, e)
   101  }