[GitHub] [ignite-3] ygerzhedovich commented on a diff in pull request #1469: IGNITE-18227: refactoring scan nodes and add support RO index scans.

[GitBox <gi...@apache.org>]

ygerzhedovich commented on code in PR #1469:
URL: https://github.com/apache/ignite-3/pull/1469#discussion_r1058317496


##########
modules/sql-engine/src/main/java/org/apache/ignite/internal/sql/engine/exec/rel/StorageScanNode.java:
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@@ -0,0 +1,303 @@
+/*
+ * 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.ignite.internal.sql.engine.exec.rel;
+
+import java.util.BitSet;
+import java.util.List;
+import java.util.Queue;
+import java.util.concurrent.Flow;
+import java.util.concurrent.Flow.Publisher;
+import java.util.concurrent.Flow.Subscriber;
+import java.util.concurrent.Flow.Subscription;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.function.Function;
+import java.util.function.Predicate;
+import org.apache.ignite.internal.schema.BinaryRow;
+import org.apache.ignite.internal.sql.engine.exec.ExecutionContext;
+import org.apache.ignite.internal.sql.engine.exec.RowHandler;
+import org.apache.ignite.internal.sql.engine.schema.InternalIgniteTable;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * Based abstract scan node.
+ */
+public abstract class StorageScanNode<RowT> extends AbstractNode<RowT> {
+    /** Special value to highlights that all row were received and we are not waiting any more. */
+    private static final int NOT_WAITING = -1;
+
+    private final Queue<RowT> inBuff = new LinkedBlockingQueue<>(inBufSize);
+
+    private final @Nullable Predicate<RowT> filters;
+
+    private final @Nullable Function<RowT, RowT> rowTransformer;
+
+    private final Function<BinaryRow, RowT> tableRowConverter;
+
+    private int requested;
+
+    private int waiting;
+
+    private boolean inLoop;
+
+    private Subscription activeSubscription;
+
+    /**
+     * Constructor.
+     *
+     * @param ctx Execution context.
+     * @param rowFactory Row factory.
+     * @param schemaTable The table this node should scan.
+     * @param filters Optional filter to filter out rows.
+     * @param rowTransformer Optional projection function.
+     */
+    public StorageScanNode(
+            ExecutionContext<RowT> ctx,
+            RowHandler.RowFactory<RowT> rowFactory,
+            InternalIgniteTable schemaTable,
+            @Nullable Predicate<RowT> filters,
+            @Nullable Function<RowT, RowT> rowTransformer,
+            @Nullable BitSet requiredColumns
+    ) {
+        super(ctx);
+
+        assert context().transaction() != null || context().transactionTime() != null : "Transaction not initialized.";
+
+        tableRowConverter = row -> schemaTable.toRow(context(), row, rowFactory, requiredColumns);
+
+        this.filters = filters;
+        this.rowTransformer = rowTransformer;
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public void request(int rowsCnt) throws Exception {
+        assert rowsCnt > 0 && requested == 0 : "rowsCnt=" + rowsCnt + ", requested=" + requested;
+
+        checkState();
+
+        requested = rowsCnt;
+
+        if (!inLoop) {
+            context().execute(this::push, this::onError);
+        }
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    public void closeInternal() {
+        super.closeInternal();
+
+        if (activeSubscription != null) {
+            activeSubscription.cancel();
+
+            activeSubscription = null;
+        }
+    }
+
+    /** {@inheritDoc} */
+    @Override
+    protected void rewindInternal() {
+        requested = 0;
+        waiting = 0;
+
+        if (activeSubscription != null) {
+            activeSubscription.cancel();
+
+            activeSubscription = null;
+        }
+    }
+
+    /**
+     *  Publisher of scan node.
+     *
+     *  @return Publisher of scan node or {@code null} in case nothing to scan.
+     */
+    protected abstract Publisher<RowT> scan();

Review Comment:
   It is temporal solution due to IGNITE-18466. After fix need to change return type to CompositePublisher and the method will be invoked just once. However you are right the require shed lights for the current situation.



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