featzhang commented on code in PR #28114:
URL: https://github.com/apache/flink/pull/28114#discussion_r3235733630
##########
flink-table/flink-table-api-java/src/main/java/org/apache/flink/table/operations/DescribeFunctionOperation.java:
##########
@@ -114,19 +121,78 @@ public TableResultInternal execute(Context ctx) {
Arrays.asList(
"supports constant folding",
String.valueOf(definition.supportsConstantFolding())));
+ final TypeInference typeInference =
+
definition.getTypeInference(ctx.getCatalogManager().getDataTypeFactory());
rows.add(
Arrays.asList(
"signature",
- generateSignature(
- definition.getTypeInference(
-
ctx.getCatalogManager().getDataTypeFactory()),
- function.toString(),
- definition)));
+ generateSignature(typeInference,
function.toString(), definition)));
+ rows.addAll(buildPtfMetadataRows(definition, typeInference));
}
return buildTableResult(
new String[] {"info name", "info value"},
new DataType[] {DataTypes.STRING(), DataTypes.STRING()},
rows.stream().map(List::toArray).toArray(Object[][]::new));
}
+
+ /**
+ * Builds supplemental info rows from the given {@link FunctionDefinition}
and {@link
+ * TypeInference}: a {@code state: <name>} row per state entry (with type
and TTL) and, for
+ * PROCESS_TABLE functions, three capability rows: {@code accepts system
arguments} (whether the
+ * framework auto-injects {@code uid} / {@code on_time}), {@code is
changelog function} (whether
+ * the function implements {@link ChangelogFunction}), and {@code uses
timers} (whether the
+ * function declares an {@code onTimer} method). Returns an empty list
when none apply.
+ */
+ private static List<List<Object>> buildPtfMetadataRows(
+ FunctionDefinition definition, TypeInference typeInference) {
+ final List<List<Object>> rows = new ArrayList<>();
+ typeInference
+ .getStateTypeStrategies()
+ .forEach(
+ (name, strategy) ->
+ rows.add(
+ Arrays.asList(
+ "state: " + name,
formatStateEntry(strategy))));
+ if (definition.getKind() == FunctionKind.PROCESS_TABLE) {
+ rows.add(
+ Arrays.asList(
+ "accepts system arguments",
+
String.valueOf(!typeInference.disableSystemArguments())));
+ rows.add(
+ Arrays.asList(
+ "is changelog function",
+ String.valueOf(definition instanceof
ChangelogFunction)));
+ rows.add(
+ Arrays.asList(
+ "uses timers",
+ String.valueOf(
+ !ExtractionUtils.collectMethods(
+ definition.getClass(),
+ UserDefinedFunctionHelper
+
.PROCESS_TABLE_ON_TIMER)
+ .isEmpty())));
+ }
+ return rows;
+ }
+
+ private static String formatStateEntry(StateTypeStrategy strategy) {
+ // We have no CallContext at DESCRIBE time. Many strategies (including
TTL lookups in
+ // DefaultStateTypeStrategy) ignore the context, but inferType
forwards it to the wrapped
+ // TypeStrategy which may dereference it. Catch and degrade to
<unknown> rather than
+ // failing the entire DESCRIBE for one strategy that needs a real
CallContext.
+ String typeStr;
+ try {
+ typeStr =
strategy.inferType(null).map(Object::toString).orElse("<unknown>");
+ } catch (Exception e) {
+ typeStr = "<unknown>";
+ }
+ final Optional<Duration> ttl;
+ try {
+ ttl = strategy.getTimeToLive(null);
+ } catch (Exception e) {
Review Comment:
`StateTypeStrategy#getTimeToLive(CallContext)` is `@PublicEvolving` and the
parameter is not annotated `@Nullable`, so user-defined strategies are free to
dereference it (e.g. to derive TTL from argument types). Calling it with `null`
here means any such custom strategy degrades to `ttl=<unknown>` in `DESCRIBE`,
with no hint about the cause.
Two options worth considering: (a) document on `StateTypeStrategy` (and
`TypeStrategy`) that DESCRIBE may pass `null` and implementations should be
defensive; or (b) narrow the `catch` to `NullPointerException` and log at
debug, so the cause is at least diagnosable. Same applies to `inferType(null)`
a few lines above.
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