ceremonyclient/pebble/internal/cache/refcnt_tracing.go

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2024-01-03 07:31:42 +00:00
// Copyright 2020 The LevelDB-Go and Pebble Authors. All rights reserved. Use
// of this source code is governed by a BSD-style license that can be found in
// the LICENSE file.
//go:build tracing
// +build tracing
package cache
import (
"fmt"
"runtime/debug"
"strings"
"sync"
"sync/atomic"
)
// refcnt provides an atomic reference count, along with a tracing facility for
// debugging logic errors in manipulating the reference count. This version is
// used when the "tracing" build tag is enabled.
type refcnt struct {
val atomic.Int32
sync.Mutex
msgs []string
}
func (v *refcnt) init(val int32) {
v.val.Store(val)
v.trace("init")
}
func (v *refcnt) refs() int32 {
return v.val.Load()
}
func (v *refcnt) acquire() {
switch n := v.val.Add(1); {
case n <= 1:
panic(fmt.Sprintf("pebble: inconsistent reference count: %d", n))
}
v.trace("acquire")
}
func (v *refcnt) release() bool {
n := v.val.Add(-1)
switch {
case n < 0:
panic(fmt.Sprintf("pebble: inconsistent reference count: %d", n))
}
v.trace("release")
return n == 0
}
func (v *refcnt) trace(msg string) {
s := fmt.Sprintf("%s: refs=%d\n%s", msg, v.refs(), debug.Stack())
v.Lock()
v.msgs = append(v.msgs, s)
v.Unlock()
}
func (v *refcnt) traces() string {
v.Lock()
s := strings.Join(v.msgs, "\n")
v.Unlock()
return s
}