Implement a timeout in BluetoothSocket inputstream.read() in Android

Question

Is it possible to implement a timeout in an inputstream.read() function from a BluetoothSocket in Android?

I\'ve tried using Thread.sleep() but this only pauses my a

Answer 1

You could do something like this:

InputStream in = someBluetoothSocket.getInputStream();
int timeout = 0;
int maxTimeout = 8; // leads to a timeout of 2 seconds
int available = 0;

while((available = in.available()) == 0 && timeout < maxTimeout) {
    timeout++;
    // throws interrupted exception
    Thread.sleep(250);
}

byte[] read = new byte[available];
in.read(read);

This way you are able to initially read from a stream with a specific timeout. If u want to implement a timeout at any time of reading you can try something like this:

Thread readThread = new ReadThread(); // being a thread you use to read from an InputStream
try {
   synchronized (readThread) {
      // edit: start readThread here
      readThread.start();
      readThread.wait(timeOutInMilliSeconds);
   }
catch (InterruptedException e) {}

using this you may need some kind of event handler to notify your application if the thread actually read something from the input stream.

I hope that helps!

----edit:

I implemented an example without using any handlers.

Socket s = new Socket("localhost", 8080);
    final InputStream in = s.getInputStream();

    Thread readThread = new Thread(new Runnable() {
        public void run() {
            int read = 0;
            try {
                while((read = in.read()) >= 0) {
                    System.out.println(new String(new byte[]{ (byte) read }));
                }
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    });

    synchronized (readThread) {
        readThread.start();
        try {
            readThread.wait(2000);

            if(readThread.isAlive()) {
                                    // probably really not good practice!
                in.close();
                System.out.println("Timeout exceeded!");
            }
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

Answer 2

A Kotlin extension function for socket read with timeout:

fun InputStream.read(
  buffer: ByteArray,
  offset: Int,
  length: Int,
  timeout: Long
): Int = runBlocking {
    val readAsync = async {
        if (available() > 0) read(buffer, offset, length) else 0
    }
    var byteCount = 0
    var retries = 3
    while (byteCount == 0 && retries > 0) {
        withTimeout(timeout) {
            byteCount = readAsync.await()
        }
        delay(timeout)
        retries--
    }
    byteCount
}