Apply timeout control around Java operation

Question

I\'m using a third party Java library to interact with a REST API. The REST API can sometimes take a long time to respond, eventually resulting in a java.net.ConnectExcept

Answer 1

Here's a utility class I wrote, which should do the trick unless I've missed something. Unfortunately it can only return generic Objects and throw generic Exceptions. Others may have better ideas on how to achieve this.

public abstract class TimeoutOperation {

long timeOut = -1;
String name = "Timeout Operation"; 

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public long getTimeOut() {
    return timeOut;
}

public void setTimeOut(long timeOut) {
    this.timeOut = timeOut;
}

public TimeoutOperation (String name, long timeout) {
    this.timeOut = timeout;
}

private Throwable throwable;
private Object result;
private long startTime;

public Object run () throws TimeoutException, Exception {
    Thread operationThread = new Thread (getName()) {
        public void run () {
            try {
                result = doOperation();
            } catch (Exception ex) {
                throwable = ex;
            } catch (Throwable uncaught) {
                throwable = uncaught;
            }
            synchronized (TimeoutOperation.this) {
                TimeoutOperation.this.notifyAll();
            }   
        }
        public synchronized void start() {
            super.start();
        }
    };
    operationThread.start();
    startTime = System.currentTimeMillis();
    synchronized (this) {
        while (operationThread.isAlive() && (getTimeOut() == -1 || System.currentTimeMillis() < startTime + getTimeOut())) {
            try {
                wait (1000L);
            } catch (InterruptedException ex) {}
        }   
    }   
    if (throwable != null) {
        if (throwable instanceof Exception) {
            throw (Exception) throwable;
        } else if (throwable instanceof Error) {
            throw (Error) throwable;
        }   
    }   
    if (result != null) {
        return result;
    }   
    if (System.currentTimeMillis() > startTime + getTimeOut()) {
        throw new TimeoutException("Operation '"+getName()+"' timed out after "+getTimeOut()+" ms");
    } else {
        throw new Exception ("No result, no exception, and no timeout!");
    }
}

public abstract Object doOperation () throws Exception;

public static void main (String [] args) throws Throwable {
    Object o = new TimeoutOperation("Test timeout", 4900) {
        public Object doOperation() throws Exception {
            try {
                Thread.sleep (5000L);
            } catch (InterruptedException ex) {}
            return "OK";
        }
    }.run();
    System.out.println(o);
}   

}