steffenvan commented on code in PR #1435: URL: https://github.com/apache/jackrabbit-oak/pull/1435#discussion_r1596521013
########## oak-run-commons/src/main/java/org/apache/jackrabbit/oak/index/indexer/document/flatfile/pipelined/MongoDownloaderRegexUtils.java: ########## @@ -0,0 +1,170 @@ +/* + * 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.jackrabbit.oak.index.indexer.document.flatfile.pipelined; + +import com.mongodb.client.model.Filters; +import org.apache.jackrabbit.oak.commons.PathUtils; +import org.apache.jackrabbit.oak.plugins.document.NodeDocument; +import org.apache.jackrabbit.oak.plugins.document.util.Utils; +import org.bson.conversions.Bson; +import org.jetbrains.annotations.NotNull; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.util.ArrayList; +import java.util.List; +import java.util.TreeSet; +import java.util.regex.Pattern; +import java.util.stream.Collectors; + +class MongoDownloaderRegexUtils { + private static final Logger LOG = LoggerFactory.getLogger(PipelinedMongoDownloadTask.class); + + final static Pattern LONG_PATH_ID_PATTERN = Pattern.compile("^[0-9]{1,3}:h"); + + /** + * Creates the filter to be used in the Mongo query + * + * @param mongoFilterPaths The paths to be included/excluded in the filter. These define subtrees to be included or excluded. + * (see {@link MongoRegexPathFilterFactory.MongoFilterPaths} for details) + * @param customExcludeEntriesRegex Documents with paths matching this regex are excluded from download + * @return The filter to be used in the Mongo query, or null if no filter is required + */ + static Bson computeMongoQueryFilter(@NotNull MongoRegexPathFilterFactory.MongoFilterPaths mongoFilterPaths, String customExcludeEntriesRegex) { + var filters = new ArrayList<Bson>(); + + List<Pattern> includedPatterns = compileIncludedDirectoriesRegex(mongoFilterPaths.included); + if (!includedPatterns.isEmpty()) { + // The conditions above on the _id field is not enough to match all JCR nodes in the given paths because nodes + // with paths longer than a certain threshold, are represented by Mongo documents where the _id field is replaced + // by a hash and the full path is stored in an additional field _path. To retrieve these long path documents, + // we could add a condition on the _path field, but this would slow down substantially scanning the DB, because + // the _path field is not part of the index used by this query (it's an index on _modified, _id). Therefore, + // Mongo would have to retrieve every document from the column store to evaluate the filter condition. So instead + // we add below a condition to download all the long path documents. These documents can be identified by the + // format of the _id field (<n>:h<hash>), so it is possible to identify them using only the index. + // This might download documents for nodes that are not in the included paths, but those documents will anyway + // be filtered in the transform stage. And in most repositories, the number of long path documents is very small, + // often there are none, so the extra documents downloaded will not slow down by much the download. However, the + // performance gains of evaluating the filter of the query using only the index are very significant, especially + // when the index requires only a small number of nodes. + var patternsWithLongPathInclude = new ArrayList<>(includedPatterns); + patternsWithLongPathInclude.add(LONG_PATH_ID_PATTERN); + filters.add(Filters.in(NodeDocument.ID, patternsWithLongPathInclude)); + } + + // The Mongo filter returned here will download the top level path of each excluded subtree, which in theory + // should be excluded. That is, if the tree /a/b/c is excluded, the filter will download /a/b/c but none of + // its descendants. + // This is done because excluding also the top level path would add extra complexity to the filter and + // would not have any measurable impact on performance because it only downloads a few extra documents, one + // for each excluded subtree. The transform stage will anyway filter out these paths. + List<Pattern> filterPatterns = compileExcludedDirectoriesRegex(mongoFilterPaths.excluded); + filterPatterns.forEach(p -> filters.add(Filters.regex(NodeDocument.ID, p))); + + Pattern customRegexExcludePattern = compileCustomExcludedPatterns(customExcludeEntriesRegex); + if (customRegexExcludePattern != null) { + filters.add(Filters.regex(NodeDocument.ID, customRegexExcludePattern)); + } + + if (filters.isEmpty()) { + return null; + } else if (filters.size() == 1) { + return filters.get(0); + } else { + return Filters.and(filters); + } + } + + private static List<Pattern> compileIncludedDirectoriesRegex(List<String> includedPaths) { + return compileDirectoryRegex(includedPaths, false); + } + + private static List<Pattern> compileExcludedDirectoriesRegex(List<String> excludedPaths) { + return compileDirectoryRegex(excludedPaths, true); + } + + private static List<Pattern> compileDirectoryRegex(List<String> paths, boolean negate) { + if (paths.isEmpty()) { + return List.of(); + } + if (paths.size() == 1 && paths.get(0).equals("/")) { + return List.of(); + } + ArrayList<Pattern> patterns = new ArrayList<>(); + for (String path : paths) { + if (!path.endsWith("/")) { + path = path + "/"; + } + String regex = "^[0-9]{1,3}:" + Pattern.quote(path); + Pattern pattern; + if (negate) { + pattern = compileExcludedDirectoryRegex(regex); + } else { + pattern = Pattern.compile(regex); + } + patterns.add(pattern); + } + return patterns; + } + + static Pattern compileExcludedDirectoryRegex(String regex) { + // https://stackoverflow.com/questions/1240275/how-to-negate-specific-word-in-regex + return Pattern.compile("^(?!" + regex + ")"); + } + + static Pattern compileCustomExcludedPatterns(String customRegexPattern) { + if (customRegexPattern == null || customRegexPattern.trim().isEmpty()) { + LOG.info("Mongo custom regex is disabled"); + return null; + } else { + LOG.info("Excluding nodes with paths matching regex: {}", customRegexPattern); + var negatedRegex = "^(?!.*(" + customRegexPattern + ")$)"; + return Pattern.compile(negatedRegex); + } + } + + /** + * Returns all the ancestors paths of the given list of paths. That is, if the list is ["/a/b/c", "/a/b/d"], + * this method will return ["/", "/a", "/a/b", "/a/b/c", "/a/b/d"]. Note that the paths on the input list are also + * returned, even though they are not strictly ancestors of themselves. + */ + static List<String> getAncestors(List<String> paths) { + TreeSet<String> ancestors = new TreeSet<>(); + for (String child : paths) { + String parent = child; + while (true) { + ancestors.add(parent); + if (PathUtils.denotesRoot(parent)) { + break; + } + parent = PathUtils.getParentPath(parent); + } + } + return new ArrayList<>(ancestors); + } Review Comment: Since we only use the TreeSet to maintain a sorted order in the end (and not intermittently) I think we could use a hash set and sort in the end, but that's just a minor thing. In theory it's still the same O-complexity, but in practice I think it should be quite faster, as because of the cache locality benefits of sorting an `ArrayList`. ```suggestion static List<String> getAncestors(List<String> paths) { HashSet<String> ancestors = new HashSet<>(); for (String child : paths) { String parent = child; while (!PathUtils.denotesRoot(parent)) { ancestors.add(parent); parent = PathUtils.getParentPath(parent); } ancestors.add(parent); // add the root path as well } List<String> sortedAncestors = new ArrayList<>(ancestors); Collections.sort(sortedAncestors); return sortedAncestors; } ``` But I would like change the `while(true)` to condition on the the root check instead. -- 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. 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