[FLINK-xxx2][Runtime] Declaring processing by chain

flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/operators/asyncprocessing/declare/DeclarationChain.java

@@ -0,0 +1,185 @@
+package org.apache.flink.streaming.runtime.operators.asyncprocessing.declare;
+
+import org.apache.flink.api.common.state.v2.StateFuture;
+import org.apache.flink.util.function.FunctionWithException;
+import org.apache.flink.util.function.ThrowingConsumer;
+
+import java.util.Deque;
+import java.util.LinkedList;
+
+public class DeclarationChain<IN, FIRST> implements ThrowingConsumer<IN, Exception> {
+
+    private final DeclarationContext context;
+
+    private final FunctionWithException<IN, StateFuture<FIRST>, Exception> first;
+
+    private final Deque<Transformation<?, ?>> transformations;
+
+    private DeclarationStage<?> currentStage;
+
+    DeclarationChain(
+            DeclarationContext context,
+            FunctionWithException<IN, StateFuture<FIRST>, Exception> first) {
+        this.context = context;
+        this.first = first;
+        this.transformations = new LinkedList<>();
+    }
+
+    @Override
+    @SuppressWarnings({"unchecked", "rawtypes"})
+    public void accept(IN in) throws Exception {
+        StateFuture future = first.apply(in);
+        for (Transformation trans : transformations) {
+            future = trans.apply(future);
+        }
+    }
+
+    public DeclarationStage<FIRST> firstStage() throws DeclarationException {
+        if (currentStage != null) {
+            throw new DeclarationException(
+                    "Diverged declaration. Please make sure you call firstStage() once.");
+        }
+        DeclarationStage<FIRST> declarationStage = new DeclarationStage<>();
+        currentStage = declarationStage;
+        return declarationStage;
+    }
+
+    Transformation<?, ?> getLastTransformation() {
+        return transformations.getLast();
+    }
+
+    public class DeclarationStage<T> {
+
+        private boolean afterThen = false;
+
+        private void preCheck() throws DeclarationException {
+            if (afterThen) {
+                throw new DeclarationException(
+                        "Double thenCompose called for single declaration block.");
+            }
+            if (currentStage != this) {
+                throw new DeclarationException(
+                        "Diverged declaration. Please make sure you are declaring on the last point.");
+            }
+            afterThen = true;
+        }
+
+        public <U> DeclarationStage<U> thenCompose(
+                FunctionWithException<T, StateFuture<U>, Exception> action)
+                throws DeclarationException {
+            preCheck();
+            DeclarationStage<U> next = new DeclarationStage<>();
+            ComposeTransformation<T, U> trans = new ComposeTransformation<>(action, next);
+            transformations.add(trans);
+            currentStage = next;
+            getLastTransformation().declare();
+            return next;
+        }
+
+        public DeclarationStage<Void> thenAccept(ThrowingConsumer<T, Exception> action)
+                throws DeclarationException {
+            preCheck();
+            DeclarationStage<Void> next = new DeclarationStage<>();
+            AcceptTransformation<T> trans = new AcceptTransformation<>(action, next);
+            transformations.add(trans);
+            currentStage = next;
+            getLastTransformation().declare();
+            return next;
+        }
+
+        public DeclarationStage<T> withName(String name) throws DeclarationException {
+            getLastTransformation().withName(name);
+            return this;
+        }
+
+        public DeclarationChain<IN, FIRST> finish() throws DeclarationException {
+            preCheck();
+            getLastTransformation().declare();
+            return DeclarationChain.this;
+        }
+    }
+
+    interface Transformation<FROM, TO> {
+        StateFuture<TO> apply(StateFuture<FROM> upstream) throws Exception;
+
+        void withName(String name) throws DeclarationException;
+
+        void declare() throws DeclarationException;
+    }
+
+    abstract static class AbstractTransformation<FROM, TO> implements Transformation<FROM, TO> {
+
+        String name = null;
+
+        @Override
+        public void withName(String newName) throws DeclarationException {
+            if (name != null) {
+                throw new DeclarationException("Double naming");
+            }
+            name = newName;
+            declare();
+        }
+    }
+
+    class ComposeTransformation<FROM, TO> extends AbstractTransformation<FROM, TO> {
+
+        DeclarationStage<TO> to;
+
+        FunctionWithException<FROM, StateFuture<TO>, ? extends Exception> action;
+
+        NamedFunction<FROM, StateFuture<TO>> namedFunction;
+
+        ComposeTransformation(
+                FunctionWithException<FROM, StateFuture<TO>, Exception> action,
+                DeclarationStage<TO> to) {
+            this.action = action;
+            this.to = to;
+        }
+
+        @Override
+        public StateFuture<TO> apply(StateFuture<FROM> upstream) throws Exception {
+            return upstream.thenCompose(namedFunction);
+        }
+
+        @Override
+        public void declare() throws DeclarationException {
+            if (namedFunction == null) {
+                if (name == null) {
+                    namedFunction = context.declare(action);
+                } else {
+                    namedFunction = context.declare(name, action);
+                }
+            }
+        }
+    }
+
+    class AcceptTransformation<FROM> extends AbstractTransformation<FROM, Void> {
+
+        DeclarationStage<Void> to;
+
+        ThrowingConsumer<FROM, Exception> action;
+
+        NamedConsumer<FROM> namedFunction;
+
+        AcceptTransformation(ThrowingConsumer<FROM, Exception> action, DeclarationStage<Void> to) {
+            this.action = action;
+            this.to = to;
+        }
+
+        @Override
+        public StateFuture<Void> apply(StateFuture<FROM> upstream) throws Exception {
+            return upstream.thenAccept(namedFunction);
+        }
+
+        @Override
+        public void declare() throws DeclarationException {
+            if (namedFunction == null) {
+                if (name == null) {
+                    namedFunction = context.declare(action);
+                } else {
+                    namedFunction = context.declare(name, action);
+                }
+            }
+        }
+    }
+}

flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/operators/asyncprocessing/declare/DeclarationContext.java

@@ -18,6 +18,7 @@
 
 package org.apache.flink.streaming.runtime.operators.asyncprocessing.declare;
 
+import org.apache.flink.api.common.state.v2.StateFuture;
 import org.apache.flink.util.function.BiFunctionWithException;
 import org.apache.flink.util.function.FunctionWithException;
 import org.apache.flink.util.function.ThrowingConsumer;
@@ -73,6 +74,19 @@ public <T, U, V> NamedBiFunction<T, U, V> declare(
         return declare(manager.nextAssignedName(), callback);
     }
 
+    /**
+     * Declaring a processing chain.
+     * @param first the first code block
+     * @return the chain itself.
+     * @param <IN> the in type of the first block
+     * @param <T> the out type of the state future given by the first block
+     */
+    public <IN, T> DeclarationChain<IN, T>.DeclarationStage<T> declareChain(
+            FunctionWithException<IN, StateFuture<T>, Exception> first)
+            throws DeclarationException {
+        return new DeclarationChain<>(this, first).firstStage();
+    }
+
     DeclarationManager getManager() {
         return manager;
     }

flink-streaming-java/src/test/java/org/apache/flink/streaming/runtime/operators/asyncprocessing/declare/AbstractAsyncStateStreamOperatorDeclarationTest.java

@@ -57,6 +57,20 @@ public class AbstractAsyncStateStreamOperatorDeclarationTest {
                 subtaskIndex);
     }
 
+    protected KeyedOneInputStreamOperatorTestHarness<Integer, Tuple2<Integer, String>, String>
+            createTestHarnessWithChain(
+                    int maxParalelism, int numSubtasks, int subtaskIndex, ElementOrder elementOrder)
+                    throws Exception {
+        TestDeclarationChainOperator testOperator = new TestDeclarationChainOperator(elementOrder);
+        return new KeyedOneInputStreamOperatorTestHarness<>(
+                testOperator,
+                new TestKeySelector(),
+                BasicTypeInfo.INT_TYPE_INFO,
+                maxParalelism,
+                numSubtasks,
+                subtaskIndex);
+    }
+
     @Test
     public void testRecordProcessor() throws Exception {
         try (KeyedOneInputStreamOperatorTestHarness<Integer, Tuple2<Integer, String>, String>
@@ -71,6 +85,20 @@ public void testRecordProcessor() throws Exception {
         }
     }
 
+    @Test
+    public void testRecordProcessorWithChain() throws Exception {
+        try (KeyedOneInputStreamOperatorTestHarness<Integer, Tuple2<Integer, String>, String>
+                testHarness = createTestHarnessWithChain(128, 1, 0, ElementOrder.RECORD_ORDER)) {
+            testHarness.open();
+            TestDeclarationChainOperator testOperator =
+                    (TestDeclarationChainOperator) testHarness.getOperator();
+            ThrowingConsumer<StreamRecord<Tuple2<Integer, String>>, Exception> processor =
+                    RecordProcessorUtils.getRecordProcessor(testOperator);
+            processor.accept(new StreamRecord<>(Tuple2.of(5, "5")));
+            assertThat(testOperator.getValue()).isEqualTo(12);
+        }
+    }
+
     /** A simple testing operator. */
     private static class TestDeclarationOperator extends AbstractAsyncStateStreamOperator<String>
             implements OneInputStreamOperator<Tuple2<Integer, String>, String>,
@@ -138,6 +166,29 @@ public int getValue() {
         }
     }
 
+    private static class TestDeclarationChainOperator extends TestDeclarationOperator {
+
+        TestDeclarationChainOperator(ElementOrder elementOrder) {
+            super(elementOrder);
+        }
+
+        @Override
+        public ThrowingConsumer<StreamRecord<Tuple2<Integer, String>>, Exception> declareProcess(
+                DeclarationContext context) throws DeclarationException {
+
+            return context.<StreamRecord<Tuple2<Integer, String>>, Void>declareChain(
+                            e -> {
+                                value.addAndGet(e.getValue().f0);
+                                return StateFutureUtils.completedVoidFuture();
+                            })
+                    .thenCompose(v -> StateFutureUtils.completedFuture(value.incrementAndGet()))
+                    .withName("adder")
+                    .thenAccept(value::addAndGet)
+                    .withName("doubler")
+                    .finish();
+        }
+    }
+
     /** {@link KeySelector} for tests. */
     static class TestKeySelector implements KeySelector<Tuple2<Integer, String>, Integer> {
         private static final long serialVersionUID = 1L;