var ErrAlreadyLocked = errors.New("file already locked")

// RLockedFile represents a read locked file, implements a special
// closer which only closes the associated *os.File when the ref count.
// has reached zero, i.e when all the readers have given up their locks.
type RLockedFile struct {
	*LockedFile
	mutex sync.Mutex
	refs  int // Holds read lock refs.
}

// IsClosed - Check if the rlocked file is already closed.

/// tip

The next sections are **not necessarily "advanced"**.

And it's possible that for your use case, the solution is in one of them.

///

## Read the Tutorial first { #read-the-tutorial-first }

The next sections assume you already read the main [Tutorial - User Guide: Security](../../tutorial/security/index.md).

        NameServicePacket.writeInt2(2, src, 6);
        NameServicePacket.writeInt2(3, src, 8);
        NameServicePacket.writeInt2(4, src, 10);

        int read = packet.readHeaderWireFormat(src, 0);
        assertEquals(NameServicePacket.HEADER_LENGTH, read);

        assertEquals(0x1234, packet.nameTrnId);
        assertTrue(packet.isResponse);
        assertEquals(NameServicePacket.QUERY, packet.opCode);

# WebSockets

When defining WebSockets, you normally declare a parameter of type `WebSocket` and with it you can read data from the client and send data to it.

Read more about it in the [FastAPI docs for WebSockets](https://fastapi.tiangolo.com/advanced/websockets/)

It is provided directly by Starlette, but you can import it from `fastapi`:

```python
from fastapi import WebSocket
```

/// tip

        assertTrue(region.hasAccess(RdmaAccess.LOCAL_READ), "Should have local read access");
        assertTrue(region.hasAccess(RdmaAccess.LOCAL_WRITE), "Should have local write access");
        assertFalse(region.hasAccess(RdmaAccess.REMOTE_READ), "Should not have remote read access");

        // Test cleanup
        region.close();

            // Simulate RDMA read operation
            log.debug("DiSNI RDMA read request: {} bytes from remote address 0x{}", bytesToRead, Long.toHexString(remoteAddress));

            return bytesToRead;

        } catch (Exception e) {
            state = RdmaConnectionState.ERROR;
            throw new IOException("DiSNI RDMA read failed", e);
        }
    }

    @Override

func FuzzReader(f *testing.F) {
	testdata, err := os.ReadDir("testdata")
	if err != nil {
		f.Fatalf("failed to read testdata directory: %s", err)
	}
	for _, de := range testdata {
		if de.IsDir() {
			continue
		}
		b, err := os.ReadFile(filepath.Join("testdata", de.Name()))
		if err != nil {
			f.Fatalf("failed to read testdata: %s", err)
		}
		f.Add(b)
	}

	f.Fuzz(func(t *testing.T, b []byte) {

And it's possible that for your use case, the solution is in one of them.

///

## Read the Tutorial first { #read-the-tutorial-first }

You could still use most of the features in **FastAPI** with the knowledge from the main [Tutorial - User Guide](../tutorial/index.md).

}

// RLock holds a read lock on lm.
//
// If one or more read lock are already in use, it will grant another lock.
// Otherwise the calling go routine blocks until the mutex is available.
func (lm *LRWMutex) RLock() {
	const isWriteLock = false
	lm.lockLoop(context.Background(), lm.id, lm.source, 1<<63-1, isWriteLock)
}

// GetRLock tries to get a read lock on lm before the timeout occurs.

 *  Fix: Honor interceptors' changes to connect and read timeouts.

 *  Fix: Recover gracefully when a cached response is corrupted on disk.

 *  Fix: Don't leak file handles when a cache disk write fails.

 *  Fix: Don't hang when the public suffix database cannot be loaded. We had a bug where a failure
    reading the public suffix database would cause subsequent reads to hang when they should have
    crashed.