forked from GoogleCloudPlatform/gcsfuse
/
lookup_count.go
63 lines (52 loc) · 1.49 KB
/
lookup_count.go
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// Copyright 2015 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package inode
import (
"fmt"
"github.com/jacobsa/fuse/fuseops"
)
// A helper struct for implementing lookup counts. The only value added is some
// paranoid panics. External synchronization is required.
//
// May be embedded within a larger struct. Use Init to initialize.
type lookupCount struct {
id fuseops.InodeID
count uint64
destroyed bool
}
func (lc *lookupCount) Init(id fuseops.InodeID) {
lc.id = id
}
func (lc *lookupCount) Inc() {
if lc.destroyed {
panic(fmt.Sprintf("Inode %v has already been destroyed", lc.id))
}
lc.count++
}
func (lc *lookupCount) Dec(n uint64) (destroy bool) {
if lc.destroyed {
panic(fmt.Sprintf("Inode %v has already been destroyed", lc.id))
}
// Make sure n is in range.
if n > lc.count {
panic(fmt.Sprintf(
"n is greater than lookup count: %v vs. %v",
n,
lc.count))
}
// Decrement.
lc.count -= n
destroy = lc.count == 0
return
}