hello, everyone, I want to implement a timeout ret...

# coroutines

[Liberty Tom]

hello, everyone, I want to implement a timeout retry mechanism, i wrote below code, but it would not
print Timeout after each 1 seconds, it just print Timeout after each 3 seconds. So how to fix it?

fun main() = runBlocking {
    repeat(5) {
        try {
            withTimeout(1000) {
                withContext(Dispatchers.IO) {
                    ensureActive()
                    println("${Date(System.currentTimeMillis())}: Coroutine is running $it")
                    suspendCancellableCoroutine<Boolean> { continuation ->
                        continuation.resume(blockCall())

                        continuation.invokeOnCancellation {
                            println("${Date(System.currentTimeMillis())}: Coroutine is cancelled")
                        }
                    }
                }
            }
        } catch (e: TimeoutCancellationException) {
            println("${Date(System.currentTimeMillis())}: Timeout")
        }
    }
}

/**
 * it is a block call that takes 3 seconds to complete
 */
private fun blockCall() = try {
    Thread.sleep(3000)
    true
} catch (e: Exception) {
    false
}

[ephemient]

cancellation is cooperative, and blockCall() isn't suspend so it can't be cancelled

[ephemient]

there is a bridge to Java thread interruption which you should try instead

fun main() = runBlocking {
    repeat(5) {
        withTimeoutOrNull(1000) {
            println("starting")
            runInterruptible(Dispatchers.IO) {
                blockCall()
            }
        } ?: println("timeout")
    }
}

[Liberty Tom]

I works well for Thread.sleep(3000) . But if Thread.sleep(3000) change to BluetoothSocket.connect() , it will timeout until the blockCall() complete.

lifecycleScope.launch {
    repeat(5) {
        try {
            withTimeout(1000) {
                println("${Date(System.currentTimeMillis())}: starting")
                runInterruptible(Dispatchers.IO) {
                    blockCall()
                }
            }
        } catch (e: TimeoutCancellationException) {
            // call the BluetoothSocket.close() will immediately interrupt BluetoothSocket.connect()
            // BluetoothSocket.close()
            println("${Date(System.currentTimeMillis())}: timeout")
        }
    }
}

private fun blockCall() = try {
    // Thread.sleep(3000)
    // it is a block call that maybe takes 10 seconds to complete
    // BluetoothSocket.connect()
    true
} catch (e: Exception) {
    println("${Date(System.currentTimeMillis())}: exception")
    false
}

[ephemient]

if it doesn't respect thread interruption (probably it calls native code so it can't be interrupted) then you can't interrupt it

[Danilo Herrera]

From the linked doc:

close() can be used to abort this call from another thread.

Would calling close() in invokeOnCancellation work as you expect?