Camel and Spring: stop context when route is completed - apache-camel

Question

I would like to run a route once and stop the context when the route is completed. Currently I do the usual Thread.sleep(3000) in the main Java class to leave some time for the route to finish but it's obviously not accurate, my route may take 1 second or 20 seconds I can not know in advance.
The Java class:
public static void main(String[] args) throws Exception {
try (ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("camel-context.xml")) {
CamelContext camelContext = SpringCamelContext.springCamelContext(context);
// context.start(); // apparently not necessary
camelContext.startRoute("route1");
try { Thread.sleep(3000); } catch (InterruptedException e) { e.printStackTrace(); }
// context.stop(); // apparently not necessary
}
}
The Spring xml:
<route id="route1" autoStartup="false">
<from uri="timer://runOnce?repeatCount=1&delay=3000" />
...
</route>
After reading http://camel.465427.n5.nabble.com/Need-control-back-in-the-Main-routine-so-that-we-can-terminate-JVM-td4483312.html#a4484845 especially the 4th post, from Claus Ibsen, I was thinking of using camelContext.getRouteStatus() in a loop with a Thread.sleep() but wherever I try to get the route status in the code (even after the Thread.sleep(3000)), the status is always "started". I don't know any other way to detect when the route is done.
What is the recommended way to stop the Camel context when a/all route(s) is/are completed, using Spring?

Answer 1

The route will never stop because routes do not have complete state. They can just be started, stopped or paused. A route will always be running if it's in the started state unless you do something to change that.
To accomplish what you are looking for, you can do a couple of things:
You can use the controlbus component and stop the route in the last step of your route. That way you can check (for example the way you mentioned checking for camelContext.getRouteStatus()) when you should stop the context as well.
You can write a small Processor that whenever it receives an Exchange it will stop the camelContext. Once ready, you will add it to the last step of your route.
Camel supports onCompletion callbacks, which can be equivalent to the option above. See the camel page.
Probably, the first option is the easiest for your use case, however I would go for the second option. It seems cleaner to me.

Answer 2

A more elegant way would be to use a synchronisation mechanism provided by Java like CountDownLatch. Main thread will wait for the latch to be opened by the Route thread. Something like :
CountDownLatch latch = new CountDownLatch(1);
camelContext.addRoutes(createRoute(latch));
and somewhere in the createRoute Method add a processor at the end of the route to open the latch. This worked perfectly for me.
.process(new Processor() {
#Override
public void process(Exchange exchange) throws Exception {
latch.countDown();
}
});