[IGNITE-15581] Proper business-logic exception propagation from raft listener to client code

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.0.0-alpha4
• Labels: ignite-3
• Assignee: Mirza Aliev
• Reporter: Alexander Lapin
• Reviewer: Vladislav Pyatkov
• Created: 23/Sep/21 18:16
• Updated: 09/Nov/21 15:31
• Resolved: 09/Nov/21 15:31

Description

Problem.
In case of business logic exceptions thrown from within raft listeners it's recommended to use

clo.result(throwable)

Such throwable is propagated to raft client in ActionResponse container and later on competes client future in common but not an exceptional way (which is a problem):

        return fut.thenApply(resp -> (R) resp.result());

    @Override public <R> CompletableFuture<R> run(Command cmd) {
        Peer leader = this.leader;

        if (leader == null)
            return refreshLeader().thenCompose(res -> run(cmd));

        ActionRequest req = factory.actionRequest().command(cmd).groupId(groupId).readOnlySafe(true).build();

        CompletableFuture<ActionResponse> fut = new CompletableFuture<>();

        sendWithRetry(leader, req, currentTimeMillis() + timeout, fut);

        return fut.thenApply(resp -> (R) resp.result());
    }

Client future usually have some specific generic type, for example CompletableFuture<Void>, that doesn't match an exception, so client future is completed exceptionally with ClassCastException with the cause of initial server side throwable.

Issue Links

• links to: GitHub Pull Request #418