[fix][fn] Allow retainKeyOrdering on Go functions

pulsar-client-tools/src/main/java/org/apache/pulsar/admin/cli/CmdFunctions.java

@@ -297,10 +297,11 @@ abstract class FunctionDetailsCommand extends BaseCommand {
         @Option(names = "--retainOrdering",
                 description = "Function consumes and processes messages in order", hidden = true)
         protected Boolean deprecatedRetainOrdering;
-        @Option(names = "--retain-ordering", description = "Function consumes and processes messages in order #Java")
+        @Option(names = "--retain-ordering",
+                description = "Function consumes and processes messages in order #Java, Python, Go")
         protected Boolean retainOrdering;
         @Option(names = "--retain-key-ordering",
-                description = "Function consumes and processes messages in key order #Java")
+                description = "Function consumes and processes messages in key order #Java, Python, Go")
         protected Boolean retainKeyOrdering;
         @Option(names = "--batch-builder", description = "BatcherBuilder provides two types of "
                 + "batch construction methods, DEFAULT and KEY_BASED. The default value is: DEFAULT")

pulsar-functions/utils/src/main/java/org/apache/pulsar/functions/utils/FunctionConfigUtils.java

@@ -774,10 +774,6 @@ private static void doGolangChecks(FunctionConfig functionConfig) {
         if (functionConfig.getMaxMessageRetries() != null && functionConfig.getMaxMessageRetries() >= 0) {
             throw new IllegalArgumentException("Message retries not yet supported in Go function");
         }
-
-        if (functionConfig.getRetainKeyOrdering() != null && functionConfig.getRetainKeyOrdering()) {
-            throw new IllegalArgumentException("Retain Key Orderering not yet supported in Go function");
-        }
     }
 
     private static void verifyNoTopicClash(Collection<String> inputTopics, String outputTopic)

pulsar-functions/utils/src/test/java/org/apache/pulsar/functions/utils/FunctionConfigUtilsTest.java

@@ -19,6 +19,7 @@
 package org.apache.pulsar.functions.utils;
 
 import static org.apache.pulsar.common.functions.FunctionConfig.ProcessingGuarantees.EFFECTIVELY_ONCE;
+import static org.apache.pulsar.common.functions.FunctionConfig.Runtime.GO;
 import static org.apache.pulsar.common.functions.FunctionConfig.Runtime.PYTHON;
 import static org.testng.Assert.assertEquals;
 import static org.testng.Assert.assertFalse;
@@ -29,6 +30,7 @@
 import java.lang.reflect.Field;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.concurrent.atomic.AtomicReference;
@@ -763,4 +765,69 @@ public void testConvertProducerSpecToProducerConfigAndBackToProducerSpec() {
                     producerSpec.getCryptoSpec().getProducerEncryptionKeyNameAt(i));
         }
     }
+
+    private static FunctionConfig minimalGoFunctionConfig() {
+        FunctionConfig functionConfig = new FunctionConfig();
+        functionConfig.setTenant("test-tenant");
+        functionConfig.setNamespace("test-namespace");
+        functionConfig.setName("test-function");
+        functionConfig.setInputs(Collections.singletonList("persistent://public/default/input"));
+        functionConfig.setRuntime(GO);
+        functionConfig.setGo("/path/to/function");
+        return functionConfig;
+    }
+
+    @Test
+    public void testGoFunctionAcceptsRetainKeyOrdering() {
+        FunctionConfig functionConfig = minimalGoFunctionConfig();
+        functionConfig.setRetainKeyOrdering(true);
+
+        FunctionConfigUtils.validateNonJavaFunction(functionConfig);
+
+        // The KeyShared subscription the Go runtime selects has to survive conversion, otherwise the
+        // instance never sees it.
+        assertEquals(FunctionConfigUtils.convert(functionConfig).getSource().getSubscriptionType(),
+                SubscriptionType.KEY_SHARED);
+    }
+
+    @Test
+    public void testGoFunctionAcceptsRetainOrdering() {
+        FunctionConfig functionConfig = minimalGoFunctionConfig();
+        functionConfig.setRetainOrdering(true);
+
+        FunctionConfigUtils.validateNonJavaFunction(functionConfig);
+
+        assertEquals(FunctionConfigUtils.convert(functionConfig).getSource().getSubscriptionType(),
+                SubscriptionType.FAILOVER);
+    }
+
+    @Test(expectedExceptions = IllegalArgumentException.class,
+            expectedExceptionsMessageRegExp = "Only one of retain ordering or retain key ordering can be set")
+    public void testGoFunctionRejectsBothOrderingModes() {
+        FunctionConfig functionConfig = minimalGoFunctionConfig();
+        functionConfig.setRetainOrdering(true);
+        functionConfig.setRetainKeyOrdering(true);
+
+        FunctionConfigUtils.validateNonJavaFunction(functionConfig);
+    }
+
+    @Test(expectedExceptions = IllegalArgumentException.class,
+            expectedExceptionsMessageRegExp =
+                    "When effectively once processing guarantee is specified, retain Key ordering cannot be set")
+    public void testGoFunctionRejectsRetainKeyOrderingWithEffectivelyOnce() {
+        FunctionConfig functionConfig = minimalGoFunctionConfig();
+        functionConfig.setRetainKeyOrdering(true);
+        functionConfig.setProcessingGuarantees(EFFECTIVELY_ONCE);
+
+        FunctionConfigUtils.validateNonJavaFunction(functionConfig);
+    }
+
+    @Test(expectedExceptions = IllegalArgumentException.class,
+            expectedExceptionsMessageRegExp = "Message retries not yet supported in Go function")
+    public void testGoFunctionStillRejectsMessageRetries() {
+        FunctionConfig functionConfig = minimalGoFunctionConfig();
+        functionConfig.setMaxMessageRetries(3);
+
+        FunctionConfigUtils.validateNonJavaFunction(functionConfig);
+    }
 }