rclone/sftp/stringlock.go
Nick Craig-Wood 16d91246c4 sftp: Fix remote race on creating directories
Because there is a period of time between checking a directory needs
creating and creating it, the leads to errors where directories are
attempting to be created twice.

Add locking on a per directory basis to fix while doing mkdir.
2017-02-04 10:29:46 +00:00

52 lines
988 B
Go

package sftp
import (
"sync"
"github.com/ncw/rclone/fs"
)
// stringLock locks for string IDs passed in
type stringLock struct {
mu sync.Mutex // mutex to protect below
locks map[string]chan struct{} // map of locks
}
// newStringLock creates a stringLock
func newStringLock() *stringLock {
return &stringLock{
locks: make(map[string]chan struct{}),
}
}
// Lock locks on the id passed in
func (l *stringLock) Lock(ID string) {
l.mu.Lock()
for {
ch, ok := l.locks[ID]
if !ok {
break
}
// Wait for the channel to be closed
l.mu.Unlock()
fs.Log(nil, "Waiting for stringLock on %q", ID)
<-ch
l.mu.Lock()
}
l.locks[ID] = make(chan struct{})
l.mu.Unlock()
}
// Unlock unlocks on the id passed in. Will panic if Lock with the
// given id wasn't called first.
func (l *stringLock) Unlock(ID string) {
l.mu.Lock()
ch, ok := l.locks[ID]
if !ok {
panic("stringLock: Unlock before Lock")
}
close(ch)
delete(l.locks, ID)
l.mu.Unlock()
}