orpiske commented on code in PR #7474:
URL: https://github.com/apache/camel/pull/7474#discussion_r854146162
##########
core/camel-core-engine/src/main/docs/modules/eips/pages/resume-strategies.adoc:
##########
@@ -219,3 +219,47 @@ from(from)
.process(exchange -> LOG.info("Received an exchange: {}",
exchange.getMessage().getBody()))
.to(destination);
----
+
+You can also integrate the pausable API and the consumer listener with the
circuit breaker EIP. For instance, it's
+possible to configure the circuit breaker so that it can manipulate the state
of the listener based on success or on
+error conditions on the circuit.
+
+One example, would be to create a event watcher that checks for a downstream
system availability. It watches for error events and, when they happen, it
triggers a scheduled check. On success, it shuts down the scheduled check.
+
+An example implementation of this approach would be similar to this:
+
+[source,java]
+----
+CircuitBreaker circuitBreaker = CircuitBreaker.ofDefaults("pausable");
+
+circuitBreaker.getEventPublisher()
+ .onSuccess(event -> {
+ LOG.info("Downstream call succeeded");
+ if (executorService != null) {
+ executorService.shutdownNow();
+ executorService = null;
+ }
+ })
+ .onError(event -> {
+ LOG.info(
+ "Downstream call error. Starting a thread to simulate checking
for the downstream availability");
+
+ if (executorService == null) {
+ executorService = Executors.newSingleThreadScheduledExecutor();
+ // In a real world scenario, instead of incrementing, it could be
pinging a remote system or
+ // running a similar check to determine whether it's available.
That
+ executorService.scheduleAtFixedRate(() -> someCheckMethod(), 1, 1,
TimeUnit.SECONDS);
+ }
+ });
+
+// Binds the configuration to the registry
+ getCamelContext().getRegistry().bind("pausableCircuit", circuitBreaker);
+
+from(from)
+ .pausable(new KafkaConsumerListener(), o -> canContinue())
+ .routeId("pausable-it")
+ .process(exchange -> LOG.info("Got record from Kafka: {}",
exchange.getMessage().getBody()))
+ .circuitBreaker()
+ .resilience4jConfiguration().circuitBreaker("pausableCircuit").end()
+ .to(to);
Review Comment:
Thanks @davsclaus. With regards to `end()` the CB, do you mean something
like this?
```
.circuitBreaker()
.resilience4jConfiguration().circuitBreaker("pausableCircuit").end()
.to(to);
```
I tried a different interpretation of your suggestion (below), but the DSL
doesn't seem very happy with it because the
`Resilience4jConfigurationDefinition` doesn't resolve the `to`.
```
.circuitBreaker()
.resilience4jConfiguration().circuitBreaker("pausableCircuit")
.to(to)
.end();
```
Any suggestions?
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