Is decorated function returned by Retry threadsafe? - resilience4j

Question

I have a class that sends a message to a remote service as shown below.
I'm using resilience4j-retry to retry the network call. As the retry instance is thread safe according to the documentation, I'm creating it in the class level and reusing it.
public class RemoteMessageService {
Retry retry = Retry.of("RemoteMessageService", RetryConfig.custom()
.maxAttempts(5)
.retryExceptions(ProcessingException.class)
.intervalFunction(IntervalFunction.ofExponentialBackoff())
.build());
public void postMessageWithRetry(final String message){
Function<Integer, Void> postMessageFunction = Retry.decorateFunction(retry, this::postMessage);
try {
postMessageFunction.apply(message)
} catch (final ProcessingException e) {
LOG.warn("Got processing exception: {}", e.getMessage());
} catch (final Exception e) {
LOG.error("Got unknown exception: {}", e.getMessage());
}
}
private Void postMessage(final String message){
// Do a network call to send the message to a rest service
// throw ProcessingException in case of timeout
return null;
}
}
My question is if the decorated function returned by Retry.decorateFunction(retry, this::postMessage); is also thread safe?
In that case I could move this to class level instead of repeating it every time the postMessageWithRetry function is called.

Answer 1

After looking into the resilience4j-retry code, I found that the decorated function is in fact thread safe; as long as the function that we decorate in the first place is thread safe.
So I can rewrite the code as below since the postMessage function is thread safe, and therefor the decorated postMessageFunction function is also thread safe.
public class RemoteMessageService {
private final Retry retry = Retry.of("RemoteMessageService", RetryConfig.custom()
.maxAttempts(5)
.retryExceptions(ProcessingException.class)
.intervalFunction(IntervalFunction.ofExponentialBackoff())
.build());
private final Function<Integer, Void> postMessageFunction = Retry.decorateFunction(retry, this::postMessage);
public void postMessageWithRetry(final String message) {
try {
postMessageFunction.apply(message)
} catch (final ProcessingException e) {
LOG.warn("Got processing exception: {}", e.getMessage());
} catch (final Exception e) {
LOG.error("Got unknown exception: {}", e.getMessage());
}
}
private Void postMessage(final String message) {
// Do a network call to send the message to a rest service
// throw ProcessingException in case of timeout
return null;
}
}