*LockedFile
	mutex sync.Mutex
	refs  int // Holds read lock refs.
}

// IsClosed - Check if the rlocked file is already closed.
func (r *RLockedFile) IsClosed() bool {
	r.mutex.Lock()
	defer r.mutex.Unlock()
	return r.refs == 0
}

// IncLockRef - is used by called to indicate lock refs.
func (r *RLockedFile) IncLockRef() {
	r.mutex.Lock()
	r.refs++
	r.mutex.Unlock()
}

}

// TryLockedOpenFile - tries a new write lock, functionality
// it is similar to LockedOpenFile with with syscall.LOCK_EX
// mode but along with syscall.LOCK_NB such that the function
// doesn't wait forever but instead returns if it cannot
// acquire a write lock.
func TryLockedOpenFile(path string, flag int, perm os.FileMode) (*LockedFile, error) {
	return lockedOpenFile(path, flag, perm, syscall.LOCK_NB)
}

// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package cmd

import (
	"errors"
)

var (
	errLockConflict       = errors.New("lock conflict")
	errLockNotInitialized = errors.New("lock not initialized")
	errLockNotFound       = errors.New("lock not found")

```sh
aws s3api put-object --bucket testbucket --key lockme --object-lock-mode GOVERNANCE --object-lock-retain-until-date "2019-11-20"  --body /etc/issue
```

		ilm       lifecycle.Lifecycle
		retention lock.Retention
		obj       ObjectInfo
		want      lifecycle.Action
	}{
		{
			// with object locking
			ilm:       *deleteAllLc,
			retention: lock.Retention{LockEnabled: true},
			obj:       obj,
			want:      lifecycle.NoneAction,
		},
		{
			// without object locking
			ilm:       *deleteAllLc,
			retention: lock.Retention{},
			obj:       obj,

			ok = true
		}
	}
	if ok {
		lock := z.serverPools[0].NewNSLock(minioMetaBucket, rebalMetaName)
		lkCtx, err := lock.GetLock(ctx, globalOperationTimeout)
		if err != nil {
			rebalanceLogIf(ctx, fmt.Errorf("failed to acquire write lock on %s/%s: %w", minioMetaBucket, rebalMetaName, err))
			return err
		}
		defer lock.Unlock(lkCtx)

		ctx = lkCtx.Context()

import (
	"io"
	"os"

	"github.com/minio/minio/internal/lock"
)

// AppendFile - appends the file "src" to the file "dst"
func AppendFile(dst string, src string, osync bool) error {
	appendFile, err := lock.Open(dst, os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0o666)
	if err != nil {
		return err
	}
	defer appendFile.Close()

	srcFile, err := lock.Open(src, os.O_RDONLY, 0o666)
	if err != nil {
		return err
	}

func (sys *BucketTargetSys) markOffline(ep *url.URL) {
	sys.hMutex.Lock()
	defer sys.hMutex.Unlock()
	if h, ok := sys.hc[ep.Host]; ok {
		h.Online = false
		sys.hc[ep.Host] = h
	}
}

func (sys *BucketTargetSys) initHC(ep *url.URL) {
	sys.hMutex.Lock()
	sys.hc[ep.Host] = epHealth{
		Endpoint: ep.Host,
		Scheme:   ep.Scheme,
		Online:   true,
	}

package dsync

// Dsync represents dsync client object which is initialized with
// authenticated clients, used to initiate lock REST calls.
type Dsync struct {
	// List of rest client objects, one per lock server.
	GetLockers func() ([]NetLocker, string)

	// Timeouts to apply.
	Timeouts Timeouts

	r  io.Reader
	mu sync.Mutex
}

func (d *disconnectReader) Read(p []byte) (n int, err error) {
	d.mu.Lock()
	defer d.mu.Unlock()
	if d.r != nil {
		return d.r.Read(p)
	}
	return 0, errors.New("reader closed")
}

func (d *disconnectReader) Close() error {
	d.mu.Lock()
	d.r = nil
	d.mu.Unlock()
	return nil
}