claudevdm commented on code in PR #40749: URL: https://github.com/apache/beam/pull/40749#discussion_r4383222394
########## sdks/java/io/iceberg/src/main/java/org/apache/beam/sdk/io/iceberg/PathPattern.java: ########## @@ -0,0 +1,236 @@ +/* + * 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.beam.sdk.io.iceberg; + +import static org.apache.beam.sdk.util.Preconditions.checkArgumentNotNull; +import static org.apache.beam.sdk.util.Preconditions.checkStateNotNull; +import static org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions.checkArgument; +import static org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions.checkState; + +import java.io.Serializable; +import java.util.ArrayList; +import java.util.Collections; +import java.util.LinkedHashMap; +import java.util.List; +import java.util.Map; +import java.util.regex.Matcher; +import java.util.regex.Pattern; +import org.apache.beam.sdk.io.FileSystemUtils; +import org.checkerframework.checker.nullness.qual.Nullable; + +/** + * Matches a file path against a glob with {@code {name}} placeholders, and reports what each + * placeholder captured. + * + * <p>Pattern {@code gs://lake/export/{table}/**} over path {@code + * gs://lake/export/orders/part-0.parquet} captures {@code table=orders}. The whole path has to + * match, so the pattern decides both which table a file belongs to and whether it belongs at all. + */ +final class PathPattern implements Serializable { + private static final Pattern PLACEHOLDER = Pattern.compile("\\{(.+?)}"); + + /** A name must survive rendering into a dotted table template: no dots, slashes or blanks. */ + private static final Pattern NAME = Pattern.compile("[A-Za-z0-9_-]+"); + + private final Pattern regex; + private final List<String> captureNames; + + private PathPattern(Pattern regex, List<String> captureNames) { + this.regex = regex; + this.captureNames = Collections.unmodifiableList(captureNames); + } + + /** + * Translates the path pattern to a regex, each placeholder becoming a capturing group. {@code + * gs://lake/{db}/{tbl}/**} becomes {@code gs://lake/([^/]+)/([^/]+)/.*}, which a path has to + * match in full. + */ + static PathPattern compile(String pathPattern) { + List<String> names = placeholders(pathPattern); + checkNamesAreBindable(names, pathPattern); + // the -1 keeps a trailing empty part, so "gs://lake/{tbl}" still yields a group + String[] fixedParts = PLACEHOLDER.split(pathPattern, -1); + checkNoDoubleStarAbovePlaceholders(fixedParts, pathPattern); + checkArgument( + !pathPattern.endsWith("/"), + "'%s' ends with '/', so it names a folder and matches no file; end it with a selector for" + + " the files, such as '**'.", + pathPattern); + Pattern regex = Pattern.compile(toRegex(fixedParts)); + checkState( + regex.matcher("").groupCount() == names.size(), + "'%s' translated to a regex with %s groups for %s placeholders.", + pathPattern, + regex.matcher("").groupCount(), + names.size()); + return new PathPattern(regex, names); + } + + private static void checkNamesAreBindable(List<String> names, String pathPattern) { + for (int i = 0; i < names.size(); i++) { + String name = names.get(i); + checkArgument( + NAME.matcher(name).matches(), + "Placeholder '%s' in '%s' is not a name; use letters, digits, '_' or '-'.", + name, + pathPattern); + checkArgument( + names.indexOf(name) == i, + "Placeholder '%s' appears twice in '%s'; a name can only be captured once.", + name, + pathPattern); + } + } + + // A '**' crosses directory levels, so one above a placeholder leaves the folder that placeholder + // names undetermined: gs://lake/**/{tbl}/** over gs://lake/a/b/c/f.parquet binds tbl to c, but + // only because the regex is greedy. Only the text after the last placeholder may hold one. + private static void checkNoDoubleStarAbovePlaceholders(String[] fixedParts, String pathPattern) { + for (int i = 0; i < fixedParts.length - 1; i++) { + checkArgument( + !fixedParts[i].contains("**"), + "'%s' has a '**' above a placeholder, so the folder that placeholder names is not" + + " determined; a '**' can only come after the last placeholder.", + pathPattern); + } + } Review Comment: These rules are to identify the table membership/name from the {placeholder} parameter. I think we can assume that incoming files represent the datafiles that need to be processed . If we are not able to parse the placeholder from a file then it should be an error. User can just do gs://bucket/{table}/** to achieve the same. MatchAllFiles pattern can be used to filter initial set of files. I can try find a way to validate pattern with 2+ double star if you feel strongly though. -- This is an automated message from the Apache Git Service. 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