github.com/zuoyebang/bitalosdb@v1.1.1-0.20240516111551-79a8c4d8ce20/internal/cache/lrucache/refcnt_tracing.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 tracing
    16  // +build tracing
    17  
    18  package lrucache
    19  
    20  import (
    21  	"fmt"
    22  	"runtime/debug"
    23  	"strings"
    24  	"sync"
    25  	"sync/atomic"
    26  )
    27  
    28  type refcnt struct {
    29  	val int32
    30  	sync.Mutex
    31  	msgs []string
    32  }
    33  
    34  func (v *refcnt) init(val int32) {
    35  	v.val = val
    36  	v.trace("init")
    37  }
    38  
    39  func (v *refcnt) refs() int32 {
    40  	return atomic.LoadInt32(&v.val)
    41  }
    42  
    43  func (v *refcnt) acquire() {
    44  	switch n := atomic.AddInt32(&v.val, 1); {
    45  	case n <= 1:
    46  		panic(fmt.Sprintf("cache: inconsistent reference count: %d", n))
    47  	}
    48  	v.trace("acquire")
    49  }
    50  
    51  func (v *refcnt) release() bool {
    52  	n := atomic.AddInt32(&v.val, -1)
    53  	switch {
    54  	case n < 0:
    55  		panic(fmt.Sprintf("cache: inconsistent reference count: %d", n))
    56  	}
    57  	v.trace("release")
    58  	return n == 0
    59  }
    60  
    61  func (v *refcnt) trace(msg string) {
    62  	s := fmt.Sprintf("%s: refs=%d\n%s", msg, v.refs(), debug.Stack())
    63  	v.Lock()
    64  	v.msgs = append(v.msgs, s)
    65  	v.Unlock()
    66  }
    67  
    68  func (v *refcnt) traces() string {
    69  	v.Lock()
    70  	s := strings.Join(v.msgs, "\n")
    71  	v.Unlock()
    72  	return s
    73  }