purushah commented on code in PR #1042:
URL: https://github.com/apache/flink-agents/pull/1042#discussion_r3917117767
##########
api/src/main/java/org/apache/flink/agents/api/chat/model/routing/ModelRouter.java:
##########
@@ -84,30 +96,113 @@ public ModelRouter(ResourceDescriptor descriptor,
ResourceContext resourceContex
}
this.fallbackEnabled =
Boolean.TRUE.equals(descriptor.getArgument("fallback",
Boolean.FALSE));
- String strategyClazz = descriptor.getArgument("strategy_clazz");
+ String typeTag = descriptor.getArgument(STRATEGY_TYPE_KEY);
+ if (typeTag == null || typeTag.isEmpty()) {
+ throw new IllegalArgumentException("ModelRouter requires a routing
strategy.");
+ }
Map<String, Object> strategyArgs =
- descriptor.getArgument("strategy_args",
Collections.emptyMap());
- this.strategy = instantiateStrategy(strategyClazz, strategyArgs);
+ descriptor.getArgument(STRATEGY_ARGS_KEY,
Collections.emptyMap());
+ String executorClass =
descriptor.getArgument(STRATEGY_EXECUTOR_CLASS_KEY);
+ // The declaration constructor owns the per-type argument rules, so a
structurally invalid
+ // configuration fails here (resource construction) with the same
message as at build().
+ this.strategy =
+ new RoutingStrategy(
+ RoutingStrategyType.fromTag(typeTag), strategyArgs,
executorClass);
+ this.compiledRules = compileRules(this.strategy);
+ this.customExecutor = instantiateCustomExecutor(this.strategy);
}
- @SuppressWarnings("unchecked")
- private static RoutingStrategy instantiateStrategy(String clazz,
Map<String, Object> args)
+ /**
+ * Instantiates the user's {@link CustomRoutingExecutor} once per router
instance (routers are
+ * cached per TaskManager), preserving executor instance state across
requests. The construction
Review Comment:
Good catch — "per subtask" is the accurate phrase. Will fix both spots;
since that sentence is what tells executor authors how instance state behaves,
it should be precise.
##########
plan/src/main/java/org/apache/flink/agents/plan/actions/ModelRoutingResolver.java:
##########
@@ -111,12 +188,310 @@ public RoutingDecision call() throws Exception {
if (!router.isCandidate(selectedModel)) {
throw new IllegalStateException(
String.format(
- "Routing strategy for router '%s' returned
non-candidate model '%s'; candidates are %s.",
+ "Routing decision for router '%s' selected
non-candidate model '%s'; candidates are %s.",
model, selectedModel,
router.getCandidateNames()));
}
- decisionSource = ModelRoutingEvent.SOURCE_STRATEGY;
+ decisionSource = concreteSource;
}
+ return finish(requestId, model, router, decision, selectedModel,
decisionSource, ctx);
+ }
+
+ /** Records the decision latency histogram sample (also for decisions the
guards reject). */
+ private static void recordDecisionLatency(RunnerContext ctx,
RoutingDecision decision) {
+ Double decisionMs = decision.getDecisionMs();
+ FlinkAgentsMetricGroup actionMetrics = ctx.getActionMetricGroup();
+ if (actionMetrics != null && decisionMs != null) {
+
actionMetrics.getHistogram("routingDecisionLatencyMs").update(Math.round(decisionMs));
+ }
+ }
+ /**
+ * LLM-as-judge path (framework-managed, per discussion #897): the engine
runs the judge chat
+ * itself through the normal durable/metered/observable invoker path —
durable id {@code
+ * "judge:<router>"} so a recovered run replays the original verdict
instead of re-calling the
+ * judge (with a durable action-state store configured; without one the
judge re-runs on replay,
+ * like any non-deterministic strategy) — then derives the decision from
the verdict as a pure
+ * function ({@link LlmJudgeRoutingExecutor}). The decision (including its
wall time, which
+ * covers the judge call) is persisted under the standard {@code
"route:<router>"} durable call,
+ * preserving the replay-fingerprint property. Verdict abstains are
persisted <i>as
+ * abstains</i>, so a replay after a candidate-set change re-resolves to
the current default
+ * exactly like the strategy path.
+ *
+ * <p>Failure policy: an unparseable or non-candidate verdict always
abstains to the router's
+ * default model. A judge call that exhausts its retries honors the
request's error-handling
+ * strategy, exactly like a throwing rule/custom strategy: {@code FAIL}
surfaces the outage
+ * loudly, {@code IGNORE} degrades to the default with the cause recorded.
Cancellation
+ * propagates and is never persisted as a routing outcome.
+ */
+ private static ResolvedModelRoute resolveViaJudge(
+ UUID requestId,
+ String model,
+ ModelRouter router,
+ RoutingStrategy strategy,
+ RoutingContext routingContext,
+ RunnerContext ctx)
+ throws Exception {
+ long start = System.nanoTime();
+ Agent.ErrorHandlingStrategy errorStrategy =
+
ctx.getConfig().get(AgentExecutionOptions.ERROR_HANDLING_STRATEGY);
+ int numRetries = ChatModelInvoker.configuredRetries(ctx,
errorStrategy);
+ int retryWaitIntervalSec =
ChatModelInvoker.configuredRetryWaitSec(ctx, errorStrategy);
+ String judgeModel = LlmJudgeRoutingExecutor.judgeModel(strategy);
+
+ Map<String, Object> judgeMetadata = new LinkedHashMap<>();
+ judgeMetadata.put("judge_model", judgeModel);
+ String verdictModel = null;
+ String abstainReason = null;
+ // Runtime backstop to the plan-time check: plan validation only sees
descriptor-carried
+ // bindings, so a setup that binds a prompt/tools/skills at the
instance level (or via a
+ // non-Java provider) is caught here. Same policy as a failed judge
call: FAIL is loud
+ // (a config error should not hide), IGNORE abstains so the default
model keeps answering.
+ String misconfigured = judgeSetupMisconfiguration(judgeModel, ctx);
+ if (misconfigured != null && errorStrategy !=
Agent.ErrorHandlingStrategy.IGNORE) {
+ throw new IllegalStateException(misconfigured);
+ }
+ if (misconfigured != null) {
+ abstainReason = misconfigured;
+ } else
+ try {
+ boolean[] truncated = new boolean[1];
+ List<ChatMessage> effective = effectiveJudgeMessages(router,
routingContext, ctx);
+ List<ChatMessage> judgeInput =
+ LlmJudgeRoutingExecutor.buildJudgeMessages(
+ strategy,
+ routingContext,
+ effective,
+
pinnedRenderedIndices(routingContext.getMessages(), effective),
+ truncated);
+ if (truncated[0]) {
+
judgeMetadata.put(LlmJudgeRoutingExecutor.CONTEXT_TRUNCATED_KEY, true);
+ }
+ ChatModelInvoker.ChatAttemptResult judgeResult =
+ ChatModelInvoker.chatWithRetries(
+ requestId,
+ judgeModel,
+ "judge:" + model,
+ judgeInput,
+ Map.of(),
+ null,
+ ctx,
+ errorStrategy,
+ numRetries,
+ retryWaitIntervalSec);
+ ChatModelAction.recordAttemptRetryStats(
+ ctx,
+ requestId,
+ judgeResult.chatModel,
+ judgeResult.retryCount,
+ judgeResult.totalRetryWaitSec);
+ ChatMessage reply = judgeResult.response;
+ Object promptTokens = reply.getExtraArgs().get("promptTokens");
+ Object completionTokens =
reply.getExtraArgs().get("completionTokens");
+ if (promptTokens != null) {
+ judgeMetadata.put("judge_prompt_tokens", promptTokens);
+ }
+ if (completionTokens != null) {
+ judgeMetadata.put("judge_completion_tokens",
completionTokens);
+ }
+ verdictModel =
+ LlmJudgeRoutingExecutor.parseVerdict(
+ reply.getContent(),
router.getCandidateNames())
+ .orElse(null);
+ abstainReason =
+ verdictModel == null ? "judge verdict was not a
candidate name" : null;
+ } catch (InterruptedException cancellation) {
+ // Cancellation surfacing from the between-retries backoff
sleep.
+ Thread.currentThread().interrupt();
+ throw cancellation;
+ } catch (ChatModelInvoker.ChatAttemptFailed failure) {
+ ChatModelAction.recordAttemptRetryStats(
+ ctx,
+ requestId,
+ failure.chatModel,
+ failure.retryCount,
+ failure.totalRetryWaitSec);
+ // Cancellation surfacing from inside the judge attempt (the
invoker wraps every
+ // attempt exception): it must propagate, never persist as a
routing outcome.
+ if (isCancellation(failure)) {
+ Thread.currentThread().interrupt();
+ throw failure;
+ }
+ // A judge that exhausted its retries honors the request's
error-handling strategy,
+ // exactly like a throwing rule/custom strategy (see class
javadoc).
+ if (errorStrategy != Agent.ErrorHandlingStrategy.IGNORE) {
+ throw failure;
+ }
+ abstainReason = "judge call failed: " + failure.error;
+ }
+
+ RoutingDecision computed;
+ if (verdictModel != null) {
+ RoutingDecision.Builder builder =
+ RoutingDecision.builder(verdictModel).reason("llm judge
verdict");
+ for (Map.Entry<String, Object> entry : judgeMetadata.entrySet()) {
+ builder.metadata(entry.getKey(), entry.getValue());
+ }
+ computed = builder.build();
+ } else {
+ // Persisted as a real abstain: replay resolves to the router's
*current* default, so
+ // a candidate-set change across a restart degrades gracefully
(like the strategy
+ // path) instead of failing the non-candidate guard.
+ computed =
+ new RoutingDecision(
+ null, true, abstainReason, null, new
HashMap<>(judgeMetadata), null);
+ }
+ final RoutingDecision toStore =
+ computed.withDecisionMs((System.nanoTime() - start) /
1_000_000.0);
+
+ // Persist under the standard route id: on recovery the stored
decision (with its original
+ // judge-inclusive wall time) replays; the judge chat above replays
from its own durable
+ // record, so the recomputation feeding this call is deterministic.
+ RoutingDecision decision =
+ ctx.durableExecute(
Review Comment:
Fair question — it deserves its own test. The judge path has enough of its
own orchestration before the shared store that "covered by shared code" is
exactly the kind of claim I shouldn't leave untested. Will add a replay test
that seeds route:<router> for a judge router and asserts the judge is never
invoked.
##########
plan/src/main/java/org/apache/flink/agents/plan/actions/ModelRoutingResolver.java:
##########
@@ -111,12 +188,310 @@ public RoutingDecision call() throws Exception {
if (!router.isCandidate(selectedModel)) {
throw new IllegalStateException(
String.format(
- "Routing strategy for router '%s' returned
non-candidate model '%s'; candidates are %s.",
+ "Routing decision for router '%s' selected
non-candidate model '%s'; candidates are %s.",
model, selectedModel,
router.getCandidateNames()));
}
- decisionSource = ModelRoutingEvent.SOURCE_STRATEGY;
+ decisionSource = concreteSource;
}
+ return finish(requestId, model, router, decision, selectedModel,
decisionSource, ctx);
+ }
+
+ /** Records the decision latency histogram sample (also for decisions the
guards reject). */
+ private static void recordDecisionLatency(RunnerContext ctx,
RoutingDecision decision) {
+ Double decisionMs = decision.getDecisionMs();
+ FlinkAgentsMetricGroup actionMetrics = ctx.getActionMetricGroup();
+ if (actionMetrics != null && decisionMs != null) {
+
actionMetrics.getHistogram("routingDecisionLatencyMs").update(Math.round(decisionMs));
+ }
+ }
+ /**
+ * LLM-as-judge path (framework-managed, per discussion #897): the engine
runs the judge chat
+ * itself through the normal durable/metered/observable invoker path —
durable id {@code
+ * "judge:<router>"} so a recovered run replays the original verdict
instead of re-calling the
+ * judge (with a durable action-state store configured; without one the
judge re-runs on replay,
+ * like any non-deterministic strategy) — then derives the decision from
the verdict as a pure
+ * function ({@link LlmJudgeRoutingExecutor}). The decision (including its
wall time, which
+ * covers the judge call) is persisted under the standard {@code
"route:<router>"} durable call,
+ * preserving the replay-fingerprint property. Verdict abstains are
persisted <i>as
+ * abstains</i>, so a replay after a candidate-set change re-resolves to
the current default
+ * exactly like the strategy path.
+ *
+ * <p>Failure policy: an unparseable or non-candidate verdict always
abstains to the router's
+ * default model. A judge call that exhausts its retries honors the
request's error-handling
+ * strategy, exactly like a throwing rule/custom strategy: {@code FAIL}
surfaces the outage
+ * loudly, {@code IGNORE} degrades to the default with the cause recorded.
Cancellation
+ * propagates and is never persisted as a routing outcome.
+ */
+ private static ResolvedModelRoute resolveViaJudge(
+ UUID requestId,
+ String model,
+ ModelRouter router,
+ RoutingStrategy strategy,
+ RoutingContext routingContext,
+ RunnerContext ctx)
+ throws Exception {
+ long start = System.nanoTime();
+ Agent.ErrorHandlingStrategy errorStrategy =
+
ctx.getConfig().get(AgentExecutionOptions.ERROR_HANDLING_STRATEGY);
+ int numRetries = ChatModelInvoker.configuredRetries(ctx,
errorStrategy);
+ int retryWaitIntervalSec =
ChatModelInvoker.configuredRetryWaitSec(ctx, errorStrategy);
+ String judgeModel = LlmJudgeRoutingExecutor.judgeModel(strategy);
+
+ Map<String, Object> judgeMetadata = new LinkedHashMap<>();
+ judgeMetadata.put("judge_model", judgeModel);
+ String verdictModel = null;
+ String abstainReason = null;
+ // Runtime backstop to the plan-time check: plan validation only sees
descriptor-carried
+ // bindings, so a setup that binds a prompt/tools/skills at the
instance level (or via a
+ // non-Java provider) is caught here. Same policy as a failed judge
call: FAIL is loud
+ // (a config error should not hide), IGNORE abstains so the default
model keeps answering.
+ String misconfigured = judgeSetupMisconfiguration(judgeModel, ctx);
+ if (misconfigured != null && errorStrategy !=
Agent.ErrorHandlingStrategy.IGNORE) {
+ throw new IllegalStateException(misconfigured);
+ }
+ if (misconfigured != null) {
+ abstainReason = misconfigured;
+ } else
+ try {
+ boolean[] truncated = new boolean[1];
+ List<ChatMessage> effective = effectiveJudgeMessages(router,
routingContext, ctx);
+ List<ChatMessage> judgeInput =
+ LlmJudgeRoutingExecutor.buildJudgeMessages(
+ strategy,
+ routingContext,
+ effective,
+
pinnedRenderedIndices(routingContext.getMessages(), effective),
+ truncated);
+ if (truncated[0]) {
+
judgeMetadata.put(LlmJudgeRoutingExecutor.CONTEXT_TRUNCATED_KEY, true);
+ }
+ ChatModelInvoker.ChatAttemptResult judgeResult =
+ ChatModelInvoker.chatWithRetries(
+ requestId,
+ judgeModel,
+ "judge:" + model,
+ judgeInput,
+ Map.of(),
+ null,
+ ctx,
+ errorStrategy,
+ numRetries,
+ retryWaitIntervalSec);
+ ChatModelAction.recordAttemptRetryStats(
+ ctx,
+ requestId,
+ judgeResult.chatModel,
+ judgeResult.retryCount,
+ judgeResult.totalRetryWaitSec);
+ ChatMessage reply = judgeResult.response;
+ Object promptTokens = reply.getExtraArgs().get("promptTokens");
+ Object completionTokens =
reply.getExtraArgs().get("completionTokens");
+ if (promptTokens != null) {
Review Comment:
Good catch — will match the instanceof Number guard the reader already uses,
and extend the test with a non-Number value.
##########
python/flink_agents/api/execution_environment.py:
##########
@@ -237,6 +237,14 @@ def add_resource(
AgentsExecutionEnvironment
The environment to register the resource.
"""
+ if resource_type == ResourceType.MODEL_ROUTER:
Review Comment:
Nice find. The shared helper is cheap, so I'll do it in this PR — one helper
plus a parametrized test over both entry points, rather than leaving a known
duplication for the Python routing work to trip over.
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