ipfs-cluster/cmd/ipfs-cluster-service/lock.go
Hector Sanjuan e62d10f83a service: multiple fixes around init and identities
* Fix error messages (they must be in the form "doing something")
* Improve/reword some error messages
* Document the identity.json existance in the cli docs
* Fix a bunch of typos
* Fix missing folder path in the --help
* Fix cluster not locking when configuration is not there but folder is
* Fix force flag not overriding the config overwrite prompt
* Fix deletion of Raft state on re-init (not necessary if identity persists)
* Fix overwriting on identity (should not be overwritten if already exists)

Much of this paves the way to be able to run without service.json:

* Either taking default values (and using env vars) - maybe someday
* Either by getting a configuration template it from somewhere (ipfs, http)
  at runtime - sooner.
2019-05-16 15:31:36 +02:00

70 lines
1.5 KiB
Go

package main
import (
"errors"
"fmt"
"io"
"path"
fslock "github.com/ipfs/go-fs-lock"
)
// lock logic heavily inspired by go-ipfs/repo/fsrepo/lock/lock.go
// 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() {
if l.lockCloser != nil {
checkErr("", errors.New("cannot acquire lock twice"))
}
// we should have a config folder whenever we try to lock
makeConfigFolder()
// set the lock file within this function
logger.Debug("checking lock")
lk, err := fslock.Lock(l.path, lockFileName)
if err != nil {
logger.Debug(err)
l.lockCloser = nil
errStr := "%s. If no other "
errStr += "%s process is running, remove %s, or make sure "
errStr += "that the config folder is writable for the user "
errStr += "running %s."
errStr = fmt.Sprintf(
errStr,
err,
programName,
path.Join(l.path, lockFileName),
programName,
)
checkErr("obtaining execution lock", errors.New(errStr))
}
logger.Debugf("%s execution lock acquired", programName)
l.lockCloser = lk
}
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
}