7e1e98d582
License: MIT Signed-off-by: Adrian Lanzafame <adrianlanzafame92@gmail.com>
59 lines
1.4 KiB
Go
59 lines
1.4 KiB
Go
// lock logic heavily inspired by go-ipfs/repo/fsrepo/lock/lock.go
|
|
package main
|
|
|
|
import (
|
|
"fmt"
|
|
"io"
|
|
"path"
|
|
|
|
filelock "go4.org/lock"
|
|
)
|
|
|
|
// The name of the file used for locking
|
|
const lockFileName = "cluster.lock"
|
|
|
|
var locker *lock
|
|
|
|
// lock helps to coordinate procees via a lock file
|
|
type lock struct {
|
|
lockCloser io.Closer
|
|
path string
|
|
}
|
|
|
|
func (l *lock) lock() error {
|
|
if l.lockCloser != nil {
|
|
return fmt.Errorf("cannot acquire lock twice")
|
|
}
|
|
// set the lock file within this function
|
|
logger.Debug("checking lock")
|
|
lk, err := filelock.Lock(path.Join(l.path, lockFileName))
|
|
if err != nil {
|
|
logger.Debug(err)
|
|
l.lockCloser = nil
|
|
errStr := fmt.Sprintf(`could not obtain execution lock. If no other process
|
|
is running, remove %s, or make sure that the config folder is
|
|
writable for the user running ipfs-cluster. Run with -d for more information
|
|
about the error`, path.Join(l.path, lockFileName))
|
|
logger.Error(errStr)
|
|
return fmt.Errorf("could not obtain execution lock")
|
|
}
|
|
logger.Debug("Success! ipfs-cluster-service lock acquired")
|
|
l.lockCloser = lk
|
|
return nil
|
|
}
|
|
|
|
func (l *lock) tryUnlock() error {
|
|
// Noop in the uninitialized case
|
|
if l.lockCloser == nil {
|
|
logger.Debug("locking not initialized, unlock is noop")
|
|
return nil
|
|
}
|
|
err := l.lockCloser.Close()
|
|
if err != nil {
|
|
return err
|
|
}
|
|
logger.Debug("Successfully released execution lock")
|
|
l.lockCloser = nil
|
|
return nil
|
|
}
|