pltbkd commented on code in PR #938: URL: https://github.com/apache/flink-agents/pull/938#discussion_r3702344696
########## api/src/main/java/org/apache/flink/agents/api/subagent/Result.java: ########## @@ -0,0 +1,98 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.flink.agents.api.subagent; + +import com.fasterxml.jackson.annotation.JsonCreator; +import com.fasterxml.jackson.annotation.JsonIgnore; +import com.fasterxml.jackson.annotation.JsonProperty; + +import java.io.PrintWriter; +import java.io.Serializable; +import java.io.StringWriter; + +/** + * Outcome of a {@link Subagent} call. + * + * <p>Sub-agent implementations should capture internal failures into a {@code Result} (via {@link + * #error}) instead of throwing, so callers can inspect {@link #isSuccess()} without try/catch. + * + * <p>The failure cause is carried as a serializable {@code errorMessage} — the full stack trace of + * the failure — rather than a live exception, so that a {@code Result} can be persisted through + * durable execution. + */ +public class Result implements Serializable { + + private static final long serialVersionUID = 1L; + + private final boolean success; + private final Object result; + private final String errorMessage; + + @JsonCreator + public Result( + @JsonProperty("success") boolean success, + @JsonProperty("result") Object result, + @JsonProperty("errorMessage") String errorMessage) { + this.success = success; + this.result = result; + this.errorMessage = errorMessage; + } + + /** Creates a successful result carrying the given value. */ + public static Result ok(Object result) { + return new Result(true, result, null); + } + + /** Creates a failed result carrying the full stack trace of the given exception. */ + public static Result error(Exception exception) { + return new Result(false, null, exception == null ? null : stackTraceOf(exception)); Review Comment: This is by design. As discussed in #909, "sub-agent implementations should intercept internal exceptions and populate Result, without directly exposing them to the caller." The intent is to prevent sub-agent exceptions from directly affecting the caller while avoiding the need for every caller to write its own try-catch. When an exception occurs, the persisted Result carries the failure info; the caller always receives a failed Result rather than the exception itself, so Action behavior stays consistent between first run and replay. **On durable-layer status (SUCCEEDED for failed sub-agent calls):** This is deliberate. SUCCEEDED at the durable layer means "the durable call completed and returned a Result" — the sub-agent's success or failure is carried inside the Result payload (`result.isFailure()`), which is a separate concern from durable execution status. On replay, the caller reads the same failed Result from the persisted `resultPayload`, so processing behavior matches the first run. **On uncapped stack trace:** The current text-based exception (full stack trace as `errorMessage`) was chosen to ensure cross-language transmission. I also felt the full stack trace is more helpful for problem analysis, and since exceptions are typically low-frequency events, storage savings wasn't a primary concern. While I also agree that for the caller the stack trace isn't critical — it's sufficient to find it in logs. I can align with the current convention: persist only exception type + message, and log the full stack trace. If we were to switch to using `DurableExecutionException` directly, besides the cross-language issue, there's also a pre-existing problem where the recovered exception (`RuntimeException` from `toException()`) differs from the original exception type on first execution — `catch` blocks targeting specific exception types would no longer match after recovery. This is unrelated to sub-agent; we can discuss it separately. Does the by-design approach (capturing into Result rather than throwing) seem reasonable, or do you prefer requiring callers to try-catch? -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
