libgocryptfs/internal/fusefrontend/write_lock.go
Jakob Unterwurzacher 9078a77850 Move pathfs_frontend to internal/fusefrontend
"git status" for reference:

renamed:    pathfs_frontend/args.go -> internal/fusefrontend/args.go
renamed:    pathfs_frontend/compat_darwin.go -> internal/fusefrontend/compat_darwin.go
renamed:    pathfs_frontend/compat_linux.go -> internal/fusefrontend/compat_linux.go
renamed:    pathfs_frontend/file.go -> internal/fusefrontend/file.go
renamed:    pathfs_frontend/file_holes.go -> internal/fusefrontend/file_holes.go
renamed:    pathfs_frontend/fs.go -> internal/fusefrontend/fs.go
renamed:    pathfs_frontend/fs_dir.go -> internal/fusefrontend/fs_dir.go
renamed:    pathfs_frontend/names.go -> internal/fusefrontend/names.go
renamed:    pathfs_frontend/write_lock.go -> internal/fusefrontend/write_lock.go
modified:   main.go
2016-02-06 19:27:59 +01:00

67 lines
1.3 KiB
Go

package fusefrontend
import (
"sync"
)
func init() {
wlock.m = make(map[uint64]*refCntMutex)
}
// wlock - serializes write accesses to each file (identified by inode number)
// Writing partial blocks means we have to do read-modify-write cycles. We
// really don't want concurrent writes there.
// Concurrent full-block writes could actually be allowed, but are not to
// keep the locking simple.
var wlock wlockMap
// wlockMap - usage:
// 1) register
// 2) lock ... unlock ...
// 3) unregister
type wlockMap struct {
mapMutex sync.RWMutex
m map[uint64]*refCntMutex
}
func (w *wlockMap) register(ino uint64) {
w.mapMutex.Lock()
r := w.m[ino]
if r == nil {
r = &refCntMutex{}
w.m[ino] = r
}
r.refCnt++ // this must happen inside the mapMutex lock
w.mapMutex.Unlock()
}
func (w *wlockMap) unregister(ino uint64) {
w.mapMutex.Lock()
r := w.m[ino]
r.refCnt--
if r.refCnt == 0 {
delete(w.m, ino)
}
w.mapMutex.Unlock()
}
func (w *wlockMap) lock(ino uint64) {
w.mapMutex.RLock()
r := w.m[ino]
w.mapMutex.RUnlock()
r.Lock() // this can take a long time - execute outside the mapMutex lock
}
func (w *wlockMap) unlock(ino uint64) {
w.mapMutex.RLock()
r := w.m[ino]
w.mapMutex.RUnlock()
r.Unlock()
}
// refCntMutex - mutex with reference count
type refCntMutex struct {
sync.Mutex
refCnt int
}