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moby--moby/daemon/graphdriver/counter.go

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package graphdriver
import "sync"
type minfo struct {
check bool
count int
}
// RefCounter is a generic counter for use by graphdriver Get/Put calls
type RefCounter struct {
counts map[string]*minfo
mu sync.Mutex
checker Checker
}
// NewRefCounter returns a new RefCounter
func NewRefCounter(c Checker) *RefCounter {
return &RefCounter{
checker: c,
counts: make(map[string]*minfo),
}
}
// Increment increaes the ref count for the given id and returns the current count
func (c *RefCounter) Increment(path string) int {
c.mu.Lock()
m := c.counts[path]
if m == nil {
m = &minfo{}
c.counts[path] = m
}
// if we are checking this path for the first time check to make sure
// if it was already mounted on the system and make sure we have a correct ref
// count if it is mounted as it is in use.
if !m.check {
m.check = true
if c.checker.IsMounted(path) {
m.count++
}
}
m.count++
c.mu.Unlock()
return m.count
}
// Decrement decreases the ref count for the given id and returns the current count
func (c *RefCounter) Decrement(path string) int {
c.mu.Lock()
m := c.counts[path]
if m == nil {
m = &minfo{}
c.counts[path] = m
}
// if we are checking this path for the first time check to make sure
// if it was already mounted on the system and make sure we have a correct ref
// count if it is mounted as it is in use.
if !m.check {
m.check = true
if c.checker.IsMounted(path) {
m.count++
}
}
m.count--
c.mu.Unlock()
return m.count
}