return lockedOpenFile(path, flag, perm, syscall.F_SETLK)
}

// LockedOpenFile - initializes a new lock and protects
// the file from concurrent access across mount points.
// This implementation doesn't support all the open
// flags and shouldn't be considered as replacement
// for os.OpenFile().
func LockedOpenFile(path string, flag int, perm os.FileMode) (*LockedFile, error) {

There are many ways to handle security, authentication and authorization.

And it normally is a complex and "difficult" topic.

In many frameworks and systems just handling security and authentication takes a big amount of effort and code (in many cases it can be 50% or more of all the code written).

		if osErrToFileErr(err) == errFileNotFound {
			return nil
		}
		if !osIsPermission(err) {
			return osErrToFileErr(err)
		}
		// There may be permission error when dirPath
		// is at the root of the disk mount that may
		// not have the permissions to avoid 'noatime'
		fd, err = openFileWithFD(dirPath, os.O_RDONLY, 0o666)
		if err != nil {
			if osErrToFileErr(err) == errFileNotFound {
				return nil
			}

```
rm -rf /tmp/etcd-data.tmp && mkdir -p /tmp/etcd-data.tmp && \
  podman rmi gcr.io/etcd-development/etcd:v3.3.9 || true && \
  podman run \
  -p 2379:2379 \
  -p 2380:2380 \
  --mount type=bind,source=/tmp/etcd-data.tmp,destination=/etcd-data \
  --name etcd-gcr-v3.3.9 \
  gcr.io/etcd-development/etcd:v3.3.9 \
  /usr/local/bin/etcd \
  --name s1 \
  --data-dir /etcd-data \

  static final int DEFAULT_SIZE = 3;

  /**
   * Minimum size of the hash table of a compact hash-based collection. Because small hash tables
   * use a byte[], any smaller size uses the same amount of memory due to object padding.
   */
  private static final int MIN_HASH_TABLE_SIZE = 4;

  private static final int BYTE_MAX_SIZE = 1 << Byte.SIZE; // 2^8 = 256

	return lockedOpenFile(path, flag, perm, syscall.LOCK_NB)
}

// LockedOpenFile - initializes a new lock and protects
// the file from concurrent access across mount points.
// This implementation doesn't support all the open
// flags and shouldn't be considered as replacement
// for os.OpenFile().
func LockedOpenFile(path string, flag int, perm os.FileMode) (*LockedFile, error) {

			}
			if devName != "" {
				info.Name = devName
				qst, err := bfs.SysBlockDeviceQueueStats(devName)
				if err != nil { // Mostly not found error
					// Check if there is a parent device:
					//   e.g. if the mount is based on /dev/nvme0n1p1, let's calculate the
					//        real device name (nvme0n1) to get its sysfs information
					parentDevPath, e := os.Readlink("/sys/class/block/" + devName)
					if e == nil {

    }
  }

  /**
   * This neat test shows that no matter what weights we use in our requests, if we push X amount of
   * permits in a cool state, where X = rate * timeToCoolDown, and we have specified a
   * timeToWarmUp() period, it will cost as the prescribed amount of time. E.g., calling
   * [acquire(5), acquire(1)] takes exactly the same time as [acquire(2), acquire(3), acquire(1)].
   */

    }
  }

  /**
   * This neat test shows that no matter what weights we use in our requests, if we push X amount of
   * permits in a cool state, where X = rate * timeToCoolDown, and we have specified a
   * timeToWarmUp() period, it will cost as the prescribed amount of time. E.g., calling
   * [acquire(5), acquire(1)] takes exactly the same time as [acquire(2), acquire(3), acquire(1)].
   */

Esta sub-aplicación es solo otra aplicación estándar de FastAPI, pero es la que se "montará":

{* ../../docs_src/sub_applications/tutorial001_py39.py hl[11, 14:16] *}

### Montar la sub-aplicación { #mount-the-sub-application }

En tu aplicación de nivel superior, `app`, monta la sub-aplicación, `subapi`.

En este caso, se montará en el path `/subapi`:

{* ../../docs_src/sub_applications/tutorial001_py39.py hl[11, 19] *}