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// Copyright 2018 The gVisor Authors.
//
// 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 fs
import (
"fmt"
"sync"
)
// DirentCacheLimiter acts as a global limit for all dirent caches in the
// process.
//
// +stateify savable
type DirentCacheLimiter struct {
mu sync.Mutex `state:"nosave"`
max uint64
count uint64 `state:"zerovalue"`
}
// NewDirentCacheLimiter creates a new DirentCacheLimiter.
func NewDirentCacheLimiter(max uint64) *DirentCacheLimiter {
return &DirentCacheLimiter{max: max}
}
func (d *DirentCacheLimiter) tryInc() bool {
d.mu.Lock()
if d.count >= d.max {
d.mu.Unlock()
return false
}
d.count++
d.mu.Unlock()
return true
}
func (d *DirentCacheLimiter) dec() {
d.mu.Lock()
if d.count == 0 {
panic(fmt.Sprintf("underflowing DirentCacheLimiter count: %+v", d))
}
d.count--
d.mu.Unlock()
}
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