kristoffSC commented on code in PR #21393: URL: https://github.com/apache/flink/pull/21393#discussion_r1071233842
########## flink-table/flink-table-code-splitter/src/main/java/org/apache/flink/table/codesplit/BlockStatementSplitter.java: ########## @@ -0,0 +1,331 @@ +/* + * 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.flink.table.codesplit; + +import org.apache.flink.annotation.Internal; +import org.apache.flink.table.codesplit.JavaParser.BlockStatementContext; +import org.apache.flink.table.codesplit.JavaParser.StatementContext; + +import org.antlr.v4.runtime.CharStreams; +import org.antlr.v4.runtime.CommonTokenStream; +import org.antlr.v4.runtime.ParserRuleContext; +import org.antlr.v4.runtime.TokenStreamRewriter; +import org.antlr.v4.runtime.atn.PredictionMode; + +import java.util.ArrayList; +import java.util.Collections; +import java.util.HashMap; +import java.util.List; +import java.util.Map; +import java.util.Map.Entry; + +/** + * Extract statements from IFs, ELSEs and WILEs blocks making them smaller. + * + * <p>BlockStatementSplitter does not recognize if statement operates on local of class member + * variable. Because of that, code must be preprocessed by {@link DeclarationRewriter} which + * converts all local variables extracted as to member variables. + * + * <p><i>Before</i> + * + * <pre><code> + * while (counter > 0) { + * int localA = a + 1000; + * System.out.println(localA); + * if (a > 0) { + * b = a * 2; + * c = b * 2; + * System.out.println(b); + * } else { + * b = a * 3; + * System.out.println(b); + * } + * counter--; + * } + * + * </code></pre> + * + * <p><i>After</i> + * + * <pre><code> + * while (counter > 0) { + * myFun_whileBody0_0(int a); + * if (a > 0) { + * myFun_whileBody0_0_ifBody0(int a); + * } else { + * myFun_whileBody0_0_ifBody1(int a); + * } + * counter--; + * } + * </code></pre> + * + * <p>Where bodies of extracted "methods" are: + * + * <pre><code> + * myFun_whileBody0_0(int a) -> + * int localA = a + 1000; + * System.out.println(localA); + * </code></pre> + * + * <pre><code> + * myFun_whileBody0_0_ifBody0(int a) -> + * b = a * 2; + * c = b * 2; + * System.out.println(b); + * </code></pre> + * + * <pre><code> + * myFun_whileBody0_0_ifBody1(int a) -> + * b = a * 3; + * System.out.println(b); + * </code></pre> + */ +@Internal +public class BlockStatementSplitter { + + private final String code; + + private final String parameters; + + private BlockStatementVisitor visitor; + + /** + * Initialize new BlockStatementSplitter. + * + * @param code a code block that should be rewritten. + * @param parameters parameters definition that should be used for extracted methods. + */ + public BlockStatementSplitter(String code, String parameters) { + this.code = code; + this.parameters = parameters; + } + + /** + * This method extracts statements from IFs, ELSE's and WHILE blocks from block code used during + * initialization of this object. Every entry of returned map can be seen as new method nam (map + * key) and method's body. The block names will be prefixed with provided context. + * + * @param context prefix for extracted blocks. + * @return a map of block name to block statements mappings. The key can be interpreted as name + * of extracted block/method and corresponding List represents individual statements (block' + * lines) for this block. + */ + public Map<String, List<String>> extractBlocks(String context) { + + this.visitor = new BlockStatementVisitor(code, context, parameters); + JavaParser javaParser = new JavaParser(visitor.tokenStream); + javaParser.getInterpreter().setPredictionMode(PredictionMode.SLL); + visitor.visitStatement(javaParser.statement()); + return visitor.getAllBlocks(); + } + + /** + * Rewrite code block that was used for this object initialization. + * + * @return a map which key represent rewritten block name and value represents rewritten code + * block, including calls to extracted methods + */ + public Map<String, String> rewriteBlock() { + visitor.rewrite(); + Map<String, String> rewriteBlocks = new HashMap<>(); + rewriteBlocks.put(visitor.context, visitor.rewriter.getText()); + return rewriteBlocks; + } + + private static void mergeBlocks( + Map<String, List<String>> mergeA, Map<String, List<String>> mergeB) { + + for (Entry<String, List<String>> entry : mergeA.entrySet()) { + mergeB.merge( + entry.getKey(), + entry.getValue(), + (aBlocks, bBlocks) -> { + List<String> merge = new ArrayList<>(aBlocks.size() + bBlocks.size()); + merge.addAll(aBlocks); + merge.addAll(bBlocks); + return merge; + }); + } + } + + private static class BlockStatementVisitor extends JavaParserBaseVisitor<Void> { + + private final List<BlockStatementVisitor> children = new ArrayList<>(); + + private final List<ParserRuleContext> extractedSingleBlocks = new ArrayList<>(); + + private final String context; + + private final CommonTokenStream tokenStream; + + private final TokenStreamRewriter rewriter; + + private final String parameters; + + private int counter = 0; + + private int bscCounter = 0; + + private BlockStatementVisitor(String code, String context, String parameters) { + this.tokenStream = new CommonTokenStream(new JavaLexer(CharStreams.fromString(code))); + this.rewriter = new TokenStreamRewriter(tokenStream); + this.context = context; + this.parameters = parameters; + } + + private BlockStatementVisitor( + TokenStreamRewriter rewriter, String context, String parameters) { + this.tokenStream = null; + this.rewriter = rewriter; + this.context = context; + this.parameters = parameters; + } + + @Override + public Void visitStatement(StatementContext ctx) { + + if (ctx.getChildCount() == 0) { + return null; + } + + if (ctx.WHILE() != null) { + for (StatementContext statement : ctx.statement()) { + BlockStatementVisitor visitor = + new BlockStatementVisitor( + rewriter, context + "_whileBody" + counter++, parameters); + children.add(visitor); + visitor.visitStatement(statement); + } + } else if (ctx.IF() != null) { + for (StatementContext sc : ctx.statement()) { + BlockStatementVisitor visitor = + new BlockStatementVisitor( + rewriter, context + "_ifBody" + counter++, parameters); + children.add(visitor); + visitor.visitStatement(sc); + } + + } else if (ctx.ELSE() != null) { + System.out.println(CodeSplitUtil.getContextString(ctx)); + } else { + if (ctx.block() != null) { + for (BlockStatementContext bsc : ctx.block().blockStatement()) { + if (bsc.statement() != null + && (bsc.statement().IF() != null + || bsc.statement().ELSE() != null + || bsc.statement().WHILE() != null)) { + + String localContext = + String.format("%s_%d", this.context, bscCounter++); + BlockStatementVisitor visitor = + new BlockStatementVisitor(rewriter, localContext, parameters); + visitor.addBlocks(extractedSingleBlocks); + + extractedSingleBlocks.clear(); + children.add(visitor); + visitor.visitStatement(bsc.statement()); + } else { + if (shouldExtract(ctx)) { Review Comment: HI @tsreaper, so what maybe was not fully clear is that `extractedSingleBlocks` is a continuous block of single line statements up to next `block` expression so up to next IF/ELSE/WHILE block. Lets break down below example: Having: ``` public void myFun1(int[] a, int[] b) throws RuntimeException { if (a[0] == 0) { a[11] = b[0]; a[12] = b[0]; if (a[2] == 0) { a[2] = 1; } else { a[2] = b[2]; } a[13] = b[0]; a[14] = b[0]; } else { a[0] = b[0]; a[1] = b[1]; a[2] = b[2]; } } ``` With current implementation will be rewrite to: ``` public void myFun1(int[] a, int[] b) throws RuntimeException { if (a[0] == 0) { myFun1_rewriteGroup1(a, b); myFun1_ifBody0(a, b); } else { myFun1_ifBody1(a, b); } } void myFun1_rewriteGroup1(int[] a, int[] b) throws RuntimeException { myFun1_ifBody0_0(a, b); if (a[2] == 0) { a[2] = 1; } else { a[2] = b[2]; } } void myFun1_ifBody0_0(int[] a, int[] b) throws RuntimeException { a[11] = b[0]; a[12] = b[0]; } void myFun1_ifBody1(int[] a, int[] b) throws RuntimeException { a[0] = b[0]; a[1] = b[1]; a[2] = b[2]; } void myFun1_ifBody0(int[] a, int[] b) throws RuntimeException { a[13] = b[0]; a[14] = b[0]; } ``` The provided example has "non continuous block" of single line statements in `TRUE` branch of first level IF/ELSE block. The block is spitted by nested, 2nd level IF/ELSE block. The first half of the single line statement block (a[11], a[12]) were grouped and extracted to new method together with 2nd level if/esle block - `myFun1_rewriteGroup1()`.In there we can see that those single line statements were extracted further to new method -> `myFun1_ifBody0_0` The second half, expression a[13] and a[14] were extracted to their own method -> `myFun1_ifBody0` While processing a statements, for example `TRUE` branch, whenever we will spot a new IF or ELSE we will "copy all single line statements" to newly created Visitor. The `extractedSingleBlocks` array for the "original visitor" will be cleared and ready to accept new single line statements. This is exactly what happen with a[11], a[12] from example above. They were added to the new Visitor created for 2nd level IF/ELSE. The a[13] and a[14] expressions were were added to cleared `extractedSingleBlocks` array in original Visitor starting a new continuous block. Also maybe refer to this comment -> where I explained the high level logic https://github.com/apache/flink/pull/21393#discussion_r1068750626 -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
