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From GitBox <...@apache.org>
Subject [GitHub] [hadoop] JohnZZGithub commented on a change in pull request #2185: HADOOP-15891. provide Regex Based Mount Point In Inode Tree
Date Tue, 01 Sep 2020 18:35:32 GMT

JohnZZGithub commented on a change in pull request #2185:
URL: https://github.com/apache/hadoop/pull/2185#discussion_r481350228



##########
File path: hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/viewfs/RegexMountPoint.java
##########
@@ -0,0 +1,306 @@
+/**
+ * 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
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.hadoop.fs.viewfs;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import java.util.regex.PatternSyntaxException;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.util.StringUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import static org.apache.hadoop.fs.viewfs.InodeTree.SlashPath;
+
+/**
+ * Regex mount point is build to implement regex based mount point.
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Unstable
+class RegexMountPoint<T> {
+  private static final Logger LOGGER =
+      LoggerFactory.getLogger(RegexMountPoint.class.getName());
+
+  private InodeTree inodeTree;
+  private String srcPathRegex;
+  private Pattern srcPattern;
+  private String dstPath;
+  private String interceptorSettingsString;
+  private List<RegexMountPointInterceptor> interceptorList;
+
+  public static final String SETTING_SRCREGEX_SEP = "#.";
+  public static final char INTERCEPTOR_SEP = ';';
+  public static final char INTERCEPTOR_INTERNAL_SEP = ':';
+  // ${var},$var
+  public static final Pattern VAR_PATTERN_IN_DEST =
+      Pattern.compile("\\$((\\{\\w+\\})|(\\w+))");
+
+  // Same var might have different representations.
+  // e.g.
+  // key => $key or key = > ${key}
+  private Map<String, Set<String>> varInDestPathMap;
+
+  public Map<String, Set<String>> getVarInDestPathMap() {
+    return varInDestPathMap;
+  }
+
+  RegexMountPoint(InodeTree inodeTree, String sourcePathRegex,
+      String destPath, String settingsStr) {
+    this.inodeTree = inodeTree;
+    this.srcPathRegex = sourcePathRegex;
+    this.dstPath = destPath;
+    this.interceptorSettingsString = settingsStr;
+    this.interceptorList = new ArrayList<>();
+  }
+
+  /**
+   * Initialize regex mount point.
+   *
+   * @throws IOException
+   */
+  public void initialize() throws IOException {
+    try {
+      srcPattern = Pattern.compile(srcPathRegex);
+    } catch (PatternSyntaxException ex) {
+      throw new IOException(
+          "Failed to initialized mount point due to bad src path regex:"
+              + srcPathRegex + ", dstPath:" + dstPath, ex);
+    }
+    varInDestPathMap = getVarListInString(dstPath);
+    initializeInterceptors();
+  }
+
+  private void initializeInterceptors() throws IOException {
+    if (interceptorSettingsString == null
+        || interceptorSettingsString.isEmpty()) {
+      return;
+    }
+    String[] interceptorStrArray =
+        StringUtils.split(interceptorSettingsString, INTERCEPTOR_SEP);
+    for (String interceptorStr : interceptorStrArray) {
+      RegexMountPointInterceptor interceptor =
+          RegexMountPointInterceptorFactory.create(interceptorStr);
+      if (interceptor == null) {
+        throw new IOException(
+            "Illegal settings String " + interceptorSettingsString);
+      }
+      interceptor.initialize();
+      interceptorList.add(interceptor);
+    }
+  }
+
+  /**
+   * Get $var1 and $var2 style variables in string.
+   *
+   * @param input - the string to be process.
+   * @return
+   */
+  public static Map<String, Set<String>> getVarListInString(String input) {
+    Map<String, Set<String>> varMap = new HashMap<>();
+    Matcher matcher = VAR_PATTERN_IN_DEST.matcher(input);
+    while (matcher.find()) {
+      // $var or ${var}
+      String varName = matcher.group(0);
+      // var or {var}
+      String strippedVarName = matcher.group(1);
+      if (strippedVarName.startsWith("{")) {
+        // {varName} = > varName
+        strippedVarName =
+            strippedVarName.substring(1, strippedVarName.length() - 1);
+      }
+      varMap.putIfAbsent(strippedVarName, new HashSet<>());
+      varMap.get(strippedVarName).add(varName);
+    }
+    return varMap;
+  }
+
+  public String getSrcPathRegex() {
+    return srcPathRegex;
+  }
+
+  public Pattern getSrcPattern() {
+    return srcPattern;
+  }
+
+  public String getDstPath() {
+    return dstPath;
+  }
+
+  public static Pattern getVarPatternInDest() {
+    return VAR_PATTERN_IN_DEST;
+  }
+
+  /**
+   * Get resolved path from regex mount points.
+   *  E.g. link: ^/user/(?<username>\\w+) => s3://$user.apache.com/_${user}
+   *  srcPath: is /user/hadoop/dir1
+   *  resolveLastComponent: true
+   *  then return value is s3://hadoop.apache.com/_hadoop
+   * @param srcPath - the src path to resolve
+   * @param resolveLastComponent - whether resolve the path after last `/`
+   * @return mapped path of the mount point.
+   */
+  public InodeTree.ResolveResult<T> resolve(final String srcPath,
+      final boolean resolveLastComponent) {
+    String pathStrToResolve = getPathToResolve(srcPath, resolveLastComponent);
+    for (RegexMountPointInterceptor interceptor : interceptorList) {
+      pathStrToResolve = interceptor.interceptSource(pathStrToResolve);
+    }
+    LOGGER.debug("Path to resolve:" + pathStrToResolve + ", srcPattern:"
+        + getSrcPathRegex());
+    Matcher srcMatcher = getSrcPattern().matcher(pathStrToResolve);
+    String parsedDestPath = getDstPath();
+    int mappedCount = 0;
+    String resolvedPathStr = "";
+    while (srcMatcher.find()) {
+      resolvedPathStr = pathStrToResolve.substring(0, srcMatcher.end());
+      Map<String, Set<String>> varMap = getVarInDestPathMap();
+      for (Map.Entry<String, Set<String>> entry : varMap.entrySet()) {
+        String regexGroupNameOrIndexStr = entry.getKey();
+        Set<String> groupRepresentationStrSetInDest = entry.getValue();
+        parsedDestPath = replaceRegexCaptureGroupInPath(
+            parsedDestPath, srcMatcher,
+            regexGroupNameOrIndexStr, groupRepresentationStrSetInDest);
+      }
+      ++mappedCount;
+    }
+    if (0 == mappedCount) {
+      return null;
+    }
+    Path remainingPath = getRemainingPathStr(srcPath, resolvedPathStr);
+    for (RegexMountPointInterceptor interceptor : interceptorList) {
+      parsedDestPath = interceptor.interceptResolvedDestPathStr(parsedDestPath);
+      remainingPath =
+          interceptor.interceptRemainingPath(remainingPath);
+    }
+    InodeTree.ResolveResult resolveResult = inodeTree
+        .buildResolveResultForRegexMountPoint(InodeTree.ResultKind.EXTERNAL_DIR,
+            resolvedPathStr, parsedDestPath, remainingPath);
+    return resolveResult;
+  }
+
+  private Path getRemainingPathStr(
+      String srcPath,
+      String resolvedPathStr) {
+    String remainingPathStr = srcPath.substring(resolvedPathStr.length());
+    if (!remainingPathStr.startsWith("/")) {
+      remainingPathStr = "/" + remainingPathStr;
+    }
+    return new Path(remainingPathStr);
+  }
+
+  private String getPathToResolve(
+      String srcPath, boolean resolveLastComponent) {
+    if (resolveLastComponent) {
+      return srcPath;
+    }
+    int lastSlashIndex = srcPath.lastIndexOf(SlashPath.toString());
+    if (lastSlashIndex == -1) {
+      return null;
+    }
+    return srcPath.substring(0, lastSlashIndex);
+  }
+
+  /**
+   * Use capture group named regexGroupNameOrIndexStr in mather to replace
+   * parsedDestPath.
+   * E.g. link: ^/user/(?<username>\\w+) => s3://$user.apache.com/_${user}
+   * srcMatcher is from /user/hadoop.
+   * Then the params will be like following.
+   * parsedDestPath: s3://$user.apache.com/_${user},
+   * regexGroupNameOrIndexStr: user
+   * groupRepresentationStrSetInDest: {user:$user; user:${user}}
+   * return value will be s3://hadoop.apache.com/_hadoop
+   * @param parsedDestPath
+   * @param srcMatcher
+   * @param regexGroupNameOrIndexStr
+   * @param groupRepresentationStrSetInDest
+   * @return return parsedDestPath while ${var},$var replaced or
+   * parsedDestPath nothing found.
+   */
+  private String replaceRegexCaptureGroupInPath(
+      String parsedDestPath,
+      Matcher srcMatcher,
+      String regexGroupNameOrIndexStr,
+      Set<String> groupRepresentationStrSetInDest) {
+    String groupValue = getRegexGroupValueFromMather(
+        srcMatcher, regexGroupNameOrIndexStr);
+    if (groupValue == null) {
+      return parsedDestPath;
+    }
+    for (String varName : groupRepresentationStrSetInDest) {
+      parsedDestPath = parsedDestPath.replace(varName, groupValue);
+      LOGGER.debug("parsedDestPath value is:" + parsedDestPath);
+    }
+    return parsedDestPath;
+  }
+
+  /**
+   * Get matched capture group value from regex matched string. E.g.
+   * Regex: ^/user/(?<username>\\w+), regexGroupNameOrIndexStr: userName
+   * then /user/hadoop should return hadoop while call
+   * getRegexGroupValueFromMather(matcher, usersName)
+   * or getRegexGroupValueFromMather(matcher, 1)
+   *
+   * @param srcMatcher - the matcher to be use
+   * @param regexGroupNameOrIndexStr - the regex group name or index
+   * @return - Null if no matched group named regexGroupNameOrIndexStr found.
+   */
+  private String getRegexGroupValueFromMather(
+      Matcher srcMatcher, String regexGroupNameOrIndexStr) {
+    if (regexGroupNameOrIndexStr.matches("\\d+")) {
+      // group index
+      int groupIndex = Integer.parseUnsignedInt(regexGroupNameOrIndexStr);
+      if (groupIndex >= 0 && groupIndex <= srcMatcher.groupCount()) {
+        return srcMatcher.group(groupIndex);
+      }
+    } else {
+      // named group in regex
+      return srcMatcher.group(regexGroupNameOrIndexStr);
+    }
+    return null;
+  }
+
+  /**

Review comment:
       Good catch.




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