src/main/java/com/googlesource/gerrit/plugins/findowners/OwnersDb.java - plugins/find-owners - Git at Google

 // Copyright (C) 2017 The Android Open Source Project
 //
 // Licensed 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 com.googlesource.gerrit.plugins.findowners;

 import static java.nio.charset.StandardCharsets.UTF_8;

 import com.google.common.collect.Multimap;
 import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.server.account.AccountCache;
 import com.google.gerrit.server.account.Emails;
 import com.google.gerrit.server.git.GitRepositoryManager;
 import com.google.gerrit.server.project.ProjectState;
 import com.google.gerrit.server.query.change.ChangeData;
 import java.net.InetAddress;
 import java.net.UnknownHostException;
 import java.nio.file.FileSystem;
 import java.nio.file.FileSystems;
 import java.nio.file.PathMatcher;
 import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ObjectReader;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.revwalk.RevTree;
 import org.eclipse.jgit.revwalk.RevWalk;
 import org.eclipse.jgit.treewalk.TreeWalk;

 /** Keep all information about owners and owned files. */
 class OwnersDb {
   private static final FluentLogger logger = FluentLogger.forEnclosingClass();

   private AccountCache accountCache;
   private GitRepositoryManager repoManager;
   private Emails emails;
   private int numOwners = -1; // # of owners of all given files.

   String key = ""; // key to find this OwnersDb in a cache.
   String revision = ""; // tip of branch revision, where OWENRS were found.
   Map<String, Set<String>> dir2Globs = new HashMap<>(); // directory to file globs in the directory
   Map<String, Set<String>> owner2Paths = new HashMap<>(); // owner email to owned dirs or file globs
   Map<String, Set<String>> path2Owners = new HashMap<>(); // dir or file glob to owner emails
   Set<String> readDirs = new HashSet<>(); // directories in which we have checked OWNERS
   Set<String> stopLooking = new HashSet<>(); // directories where OWNERS has "set noparent"
   Map<String, String> preferredEmails = new HashMap<>(); // owner email to preferred email
   List<String> errors = new ArrayList<>(); // error messages
   List<String> logs = new ArrayList<>(); // trace/debug messages

   OwnersDb() {}

   OwnersDb(
       ProjectState projectState,
       AccountCache accountCache,
       Emails emails,
       String key,
       GitRepositoryManager repoManager,
       ChangeData changeData,
       String branch,
       Collection<String> files) {
     this.accountCache = accountCache;
     this.repoManager = repoManager;
     this.emails = emails;
     this.key = key;
     try {
       InetAddress inetAddress = InetAddress.getLocalHost();
       logs.add("HostName:" + inetAddress.getHostName());
     } catch (UnknownHostException e) {
       logException(logs, "HostName:", e);
     }
     logs.add("key:" + key);
     preferredEmails.put("*", "*");
     String projectName = projectState.getName();
     logs.add("project:" + projectName);
     String ownersFileName = Config.getOwnersFileName(projectState, changeData);
     logs.add("ownersFileName:" + ownersFileName);
     try (Repository repo = repoManager.openRepository(projectState.getNameKey())) {
       // Some hacked CL could have a target branch that is not created yet.
       ObjectId id = getBranchId(repo, branch, changeData, logs);
       revision = "";
       if (id != null) {
         for (String fileName : files) {
           // Find OWNERS in fileName's directory and parent directories.
           // Stop looking for a parent directory if OWNERS has "set noparent".
           fileName = Util.addDotPrefix(fileName); // e.g.   "./" "./d1/f1" "./d2/d3/"
           String dir = Util.getParentDir(fileName); // e.g. "."  "./d1"    "./d2"
           logs.add("findOwnersFileFor:" + fileName);
           while (!readDirs.contains(dir)) {
             readDirs.add(dir);
             logs.add("findOwnersFileIn:" + dir);
             String filePath = dir + "/" + ownersFileName;
             String content = getFile(repo, id, filePath, logs);
             if (content != null && !content.isEmpty()) {
               addFile(projectName, branch, dir + "/", dir + "/" + ownersFileName,
                       content.split("\\R+"));
             }
             if (stopLooking.contains(dir + "/") || !dir.contains("/")) {
               break; // stop looking through parent directory
             }
             dir = Util.getDirName(dir); // go up one level
           }
         }
         try {
           revision = repo.exactRef(branch).getObjectId().getName();
         } catch (Exception e) {
           logger.atSevere().withCause(e).log(
               "Fail to get branch revision for %s", Config.getChangeId(changeData));
           logException(logs, "OwnersDb get revision", e);
         }
       }
     } catch (Exception e) {
       logger.atSevere().withCause(e).log(
           "Fail to find repository of project %s", projectName);
       logException(logs, "OwnersDb get repository", e);
     }
     countNumOwners(files);
   }

   int getNumOwners() {
     return (numOwners >= 0) ? numOwners : owner2Paths.keySet().size();
   }

   private void countNumOwners(Collection<String> files) {
     logs.add("countNumOwners");
     Map<String, Set<String>> file2Owners = findOwners(files, null, logs);
     if (file2Owners != null) {
       Set<String> emails = new HashSet<>();
       file2Owners.values().forEach(emails::addAll);
       numOwners = emails.size();
     } else {
       numOwners = owner2Paths.keySet().size();
     }
   }

   void addOwnerPathPair(String owner, String path) {
     Util.addToMap(owner2Paths, owner, path);
     Util.addToMap(path2Owners, path, owner);
     if (path.length() > 0 && path.charAt(path.length() - 1) != '/') {
       Util.addToMap(dir2Globs, Util.getDirName(path) + "/", path); // A file glob.
     }
   }

   void addPreferredEmails(Set<String> ownerEmails) {
     List<String> owners = new ArrayList<>(ownerEmails);
     owners.removeIf(o -> preferredEmails.get(o) != null);
     if (!owners.isEmpty()) {
       String[] ownerEmailsAsArray = new String[owners.size()];
       owners.toArray(ownerEmailsAsArray);
       Multimap<String, Account.Id> email2ids = null;
       try {
         email2ids = emails.getAccountsFor(ownerEmailsAsArray);
       } catch (Exception e) {
         logger.atSevere().withCause(e).log("accounts.byEmails failed");
         logException(logs, "getAccountsFor:" + ownerEmailsAsArray[0], e);
       }
       for (String owner : ownerEmailsAsArray) {
         String email = owner;
         try {
           if (email2ids == null) {
             errors.add(owner);
           } else {
             Collection<Account.Id> ids = email2ids.get(owner);
             if (ids == null || ids.size() != 1) {
               errors.add(owner);
             } else {
               // Accounts may have no preferred email.
               email =
                   accountCache
                       .get(ids.iterator().next())
                       .map(a -> a.getAccount().getPreferredEmail())
                       .orElse(null);
             }
           }
         } catch (Exception e) {
           logger.atSevere().withCause(e).log("Fail to find preferred email of %s", owner);
           errors.add(owner);
         }
         preferredEmails.put(owner, email);
       }
     }
   }

   void addFile(String project, String branch, String dirPath, String filePath, String[] lines) {
     Parser parser = new Parser(repoManager, project, branch, filePath, logs);
     Parser.Result result = parser.parseFile(dirPath, lines);
     if (result.stopLooking) {
       stopLooking.add(dirPath);
     }
     addPreferredEmails(result.owner2paths.keySet());
     for (String owner : result.owner2paths.keySet()) {
       String email = preferredEmails.get(owner);
       for (String path : result.owner2paths.get(owner)) {
         addOwnerPathPair(email, path);
       }
     }
     if (Config.getReportSyntaxError()) {
       result.warnings.forEach(w -> logger.atWarning().log(w));
       result.errors.forEach(w -> logger.atSevere().log(w));
     }
   }

   private void addOwnerWeights(
       ArrayList<String> paths,
       ArrayList<Integer> distances,
       String file,
       Map<String, Set<String>> file2Owners,
       Map<String, OwnerWeights> map,
       List<String> logs) {
     for (int i = 0; i < paths.size(); i++) {
       logs.add("addOwnerWeightsIn:" + paths.get(i));
       Set<String> owners = path2Owners.get(paths.get(i));
       if (owners == null) {
         continue;
       }
       for (String name : owners) {
         Util.addToMap(file2Owners, file, name);
         if (map == null) {
           continue;
         }
         if (map.containsKey(name)) {
           map.get(name).addFile(file, distances.get(i));
         } else {
           map.put(name, new OwnerWeights(file, distances.get(i)));
         }
       }
     }
   }

   /** Quick method to find owner emails of every file. */
   Map<String, Set<String>> findOwners(Collection<String> files) {
     return findOwners(files, null, new ArrayList<>());
   }

   /** Returns owner emails of every file and set up ownerWeights. */
   Map<String, Set<String>> findOwners(
       Collection<String> files, Map<String, OwnerWeights> ownerWeights, List<String> logs) {
     return findOwners(files.toArray(new String[0]), ownerWeights, logs);
   }

   /** Returns owner emails of every file and set up ownerWeights. */
   Map<String, Set<String>> findOwners(
       String[] files, Map<String, OwnerWeights> ownerWeights, List<String> logs) {
     // Returns a map of file to set of owner emails.
     // If ownerWeights is not null, add to it owner to distance-from-dir;
     // a distance of 1 is the lowest/closest possible distance
     // (which makes the subsequent math easier).
     logs.add("findOwners");
     Arrays.sort(files); // Force an ordered search sequence.
     Map<String, Set<String>> file2Owners = new HashMap<>();
     for (String fileName : files) {
       fileName = Util.addDotPrefix(fileName);
       logs.add("checkFile:" + fileName);
       String dirPath = Util.getParentDir(fileName);
       String baseName = fileName.substring(dirPath.length() + 1);
       int distance = 1;
       FileSystem fileSystem = FileSystems.getDefault();
       // Collect all matched (path, distance) in all OWNERS files for
       // fileName. Add them only if there is no special "*" owner.
       ArrayList<String> paths = new ArrayList<>();
       ArrayList<Integer> distances = new ArrayList<>();
       boolean foundStar = false;
       while (true) {
         int savedSizeOfPaths = paths.size();
         logs.add("checkDir:" + dirPath);
         if (dir2Globs.containsKey(dirPath + "/")) {
           Set<String> patterns = dir2Globs.get(dirPath + "/");
           for (String pat : patterns) {
             PathMatcher matcher = fileSystem.getPathMatcher("glob:" + pat);
             if (matcher.matches(Paths.get(dirPath + "/" + baseName))) {
               foundStar |= findStarOwner(pat, distance, paths, distances);
               // Do not break here, a file could match multiple globs
               // with different owners.
               // OwnerWeights.add won't add duplicated files.
             }
           }
           // NOTE: A per-file directive can only specify owner emails,
           // not "set noparent".
         }
         // If baseName does not match per-file glob, paths is not changed.
         // Then we should check the general non-per-file owners.
         if (paths.size() == savedSizeOfPaths) {
           foundStar |= findStarOwner(dirPath + "/", distance, paths, distances);
         }
         if (foundStar // This file can be approved by anyone, no owner.
             || stopLooking.contains(dirPath + "/") // stop looking parent
             || !dirPath.contains("/") /* root */) {
           break;
         }
         if (paths.size() != savedSizeOfPaths) {
           distance++; // increase distance for each found OWNERS
         }
         dirPath = Util.getDirName(dirPath); // go up one level
       }
       if (!foundStar) {
         addOwnerWeights(paths, distances, fileName, file2Owners, ownerWeights, logs);
       } else {
         logs.add("found * in:" + fileName);
       }
     }
     return file2Owners;
   }

   /** Returns true if path has '*' owner. */
   private boolean findStarOwner(
       String path, int distance, ArrayList<String> paths, ArrayList<Integer> distances) {
     Set<String> owners = path2Owners.get(path);
     if (owners != null) {
       paths.add(path);
       distances.add(distance);
       if (owners.contains("*")) {
         return true;
       }
     }
     return false;
   }

   /** Returns ObjectId of the given branch, or null. */
   private static ObjectId getBranchId(
       Repository repo, String branch, ChangeData changeData, List<String> logs) {
     String header = "getBranchId:" + branch;
     try {
       ObjectId id = repo.resolve(branch);
       if (id == null && changeData != null && !Checker.isExemptFromOwnerApproval(changeData)) {
         logger.atSevere().log(
             "cannot find branch %s for %s", branch, Config.getChangeId(changeData));
         logs.add(header + " (NOT FOUND)");
       } else {
         logs.add(header + " (FOUND)");
       }
       return id;
     } catch (Exception e) {
       logger.atSevere().withCause(e).log(
           "cannot find branch %s for %s", branch, Config.getChangeId(changeData));
       logException(logs, header, e);
     }
     return null;
   }

   /** Returns file content or empty string; uses project+branch+file names. */
   public static String getRepoFile(GitRepositoryManager repoManager,
       String project, String branch, String file, List<String> logs) {
     // 'file' must be an absolute path from the root of 'project'.
     logs.add("getRepoFile:" + project + ":" + branch + ":" + file);
     try (Repository repo = repoManager.openRepository(new Project.NameKey(project))) {
       ObjectId id = repo.resolve(branch);
       if (id != null) {
         return getFile(repo, id, file, logs);
       }
       logs.add("getRepoFile not found branch " + branch);
     } catch (Exception e) {
       logger.atSevere().withCause(e).log(
           "Fail to find repository of project %s", project);
       logException(logs, "getRepoFile", e);
     }
     return "";
   }

   /** Returns file content or empty string; uses Repository. */
   private static String getFile(
       Repository repo, ObjectId id, String file, List<String> logs) {
     file = Util.gitRepoFilePath(file);
     String header = "getFile:" + file;
     try (RevWalk revWalk = new RevWalk(repo)) {
       RevTree tree = revWalk.parseCommit(id).getTree();
       ObjectReader reader = revWalk.getObjectReader();
       TreeWalk treeWalk = TreeWalk.forPath(reader, file, tree);
       if (treeWalk != null) {
         String content = new String(reader.open(treeWalk.getObjectId(0)).getBytes(), UTF_8);
         logs.add(header + ":" + content);
         return content;
       }
       logs.add(header + " (NOT FOUND)");
     } catch (Exception e) {
       logger.atSevere().withCause(e).log("get file %s", file);
       logException(logs, "getFile", e);
     }
     return "";
   }

   /** Adds a header + exception message to the logs. */
   private static void logException(List<String> logs, String header, Exception e) {
     logs.add(header + " Exception:" + e.getMessage());
   }
 }
	// Copyright (C) 2017 The Android Open Source Project
	//
	// Licensed 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 com.googlesource.gerrit.plugins.findowners;

	import static java.nio.charset.StandardCharsets.UTF_8;

	import com.google.common.collect.Multimap;
	import com.google.common.flogger.FluentLogger;
	import com.google.gerrit.reviewdb.client.Account;
	import com.google.gerrit.reviewdb.client.Project;
	import com.google.gerrit.server.account.AccountCache;
	import com.google.gerrit.server.account.Emails;
	import com.google.gerrit.server.git.GitRepositoryManager;
	import com.google.gerrit.server.project.ProjectState;
	import com.google.gerrit.server.query.change.ChangeData;
	import java.net.InetAddress;
	import java.net.UnknownHostException;
	import java.nio.file.FileSystem;
	import java.nio.file.FileSystems;
	import java.nio.file.PathMatcher;
	import java.nio.file.Paths;
	import java.util.ArrayList;
	import java.util.Arrays;
	import java.util.Collection;
	import java.util.HashMap;
	import java.util.HashSet;
	import java.util.List;
	import java.util.Map;
	import java.util.Set;
	import org.eclipse.jgit.lib.ObjectId;
	import org.eclipse.jgit.lib.ObjectReader;
	import org.eclipse.jgit.lib.Repository;
	import org.eclipse.jgit.revwalk.RevTree;
	import org.eclipse.jgit.revwalk.RevWalk;
	import org.eclipse.jgit.treewalk.TreeWalk;

	/** Keep all information about owners and owned files. */
	class OwnersDb {
	private static final FluentLogger logger = FluentLogger.forEnclosingClass();

	private AccountCache accountCache;
	private GitRepositoryManager repoManager;
	private Emails emails;
	private int numOwners = -1; // # of owners of all given files.

	String key = ""; // key to find this OwnersDb in a cache.
	String revision = ""; // tip of branch revision, where OWENRS were found.
	Map<String, Set<String>> dir2Globs = new HashMap<>(); // directory to file globs in the directory
	Map<String, Set<String>> owner2Paths = new HashMap<>(); // owner email to owned dirs or file globs
	Map<String, Set<String>> path2Owners = new HashMap<>(); // dir or file glob to owner emails
	Set<String> readDirs = new HashSet<>(); // directories in which we have checked OWNERS
	Set<String> stopLooking = new HashSet<>(); // directories where OWNERS has "set noparent"
	Map<String, String> preferredEmails = new HashMap<>(); // owner email to preferred email
	List<String> errors = new ArrayList<>(); // error messages
	List<String> logs = new ArrayList<>(); // trace/debug messages

	OwnersDb() {}

	OwnersDb(
	ProjectState projectState,
	AccountCache accountCache,
	Emails emails,
	String key,
	GitRepositoryManager repoManager,
	ChangeData changeData,
	String branch,
	Collection<String> files) {
	this.accountCache = accountCache;
	this.repoManager = repoManager;
	this.emails = emails;
	this.key = key;
	try {
	InetAddress inetAddress = InetAddress.getLocalHost();
	logs.add("HostName:" + inetAddress.getHostName());
	} catch (UnknownHostException e) {
	logException(logs, "HostName:", e);
	}
	logs.add("key:" + key);
	preferredEmails.put("", "");
	String projectName = projectState.getName();
	logs.add("project:" + projectName);
	String ownersFileName = Config.getOwnersFileName(projectState, changeData);
	logs.add("ownersFileName:" + ownersFileName);
	try (Repository repo = repoManager.openRepository(projectState.getNameKey())) {
	// Some hacked CL could have a target branch that is not created yet.
	ObjectId id = getBranchId(repo, branch, changeData, logs);
	revision = "";
	if (id != null) {
	for (String fileName : files) {
	// Find OWNERS in fileName's directory and parent directories.
	// Stop looking for a parent directory if OWNERS has "set noparent".
	fileName = Util.addDotPrefix(fileName); // e.g. "./" "./d1/f1" "./d2/d3/"
	String dir = Util.getParentDir(fileName); // e.g. "." "./d1" "./d2"
	logs.add("findOwnersFileFor:" + fileName);
	while (!readDirs.contains(dir)) {
	readDirs.add(dir);
	logs.add("findOwnersFileIn:" + dir);
	String filePath = dir + "/" + ownersFileName;
	String content = getFile(repo, id, filePath, logs);
	if (content != null && !content.isEmpty()) {
	addFile(projectName, branch, dir + "/", dir + "/" + ownersFileName,
	content.split("\\R+"));
	}
	if (stopLooking.contains(dir + "/") \|\| !dir.contains("/")) {
	break; // stop looking through parent directory
	}
	dir = Util.getDirName(dir); // go up one level
	}
	}
	try {
	revision = repo.exactRef(branch).getObjectId().getName();
	} catch (Exception e) {
	logger.atSevere().withCause(e).log(
	"Fail to get branch revision for %s", Config.getChangeId(changeData));
	logException(logs, "OwnersDb get revision", e);
	}
	}
	} catch (Exception e) {
	logger.atSevere().withCause(e).log(
	"Fail to find repository of project %s", projectName);
	logException(logs, "OwnersDb get repository", e);
	}
	countNumOwners(files);
	}

	int getNumOwners() {
	return (numOwners >= 0) ? numOwners : owner2Paths.keySet().size();
	}

	private void countNumOwners(Collection<String> files) {
	logs.add("countNumOwners");
	Map<String, Set<String>> file2Owners = findOwners(files, null, logs);
	if (file2Owners != null) {
	Set<String> emails = new HashSet<>();
	file2Owners.values().forEach(emails::addAll);
	numOwners = emails.size();
	} else {
	numOwners = owner2Paths.keySet().size();
	}
	}

	void addOwnerPathPair(String owner, String path) {
	Util.addToMap(owner2Paths, owner, path);
	Util.addToMap(path2Owners, path, owner);
	if (path.length() > 0 && path.charAt(path.length() - 1) != '/') {
	Util.addToMap(dir2Globs, Util.getDirName(path) + "/", path); // A file glob.
	}
	}

	void addPreferredEmails(Set<String> ownerEmails) {
	List<String> owners = new ArrayList<>(ownerEmails);
	owners.removeIf(o -> preferredEmails.get(o) != null);
	if (!owners.isEmpty()) {
	String[] ownerEmailsAsArray = new String[owners.size()];
	owners.toArray(ownerEmailsAsArray);
	Multimap<String, Account.Id> email2ids = null;
	try {
	email2ids = emails.getAccountsFor(ownerEmailsAsArray);
	} catch (Exception e) {
	logger.atSevere().withCause(e).log("accounts.byEmails failed");
	logException(logs, "getAccountsFor:" + ownerEmailsAsArray[0], e);
	}
	for (String owner : ownerEmailsAsArray) {
	String email = owner;
	try {
	if (email2ids == null) {
	errors.add(owner);
	} else {
	Collection<Account.Id> ids = email2ids.get(owner);
	if (ids == null \|\| ids.size() != 1) {
	errors.add(owner);
	} else {
	// Accounts may have no preferred email.
	email =
	accountCache
	.get(ids.iterator().next())
	.map(a -> a.getAccount().getPreferredEmail())
	.orElse(null);
	}
	}
	} catch (Exception e) {
	logger.atSevere().withCause(e).log("Fail to find preferred email of %s", owner);
	errors.add(owner);
	}
	preferredEmails.put(owner, email);
	}
	}
	}

	void addFile(String project, String branch, String dirPath, String filePath, String[] lines) {
	Parser parser = new Parser(repoManager, project, branch, filePath, logs);
	Parser.Result result = parser.parseFile(dirPath, lines);
	if (result.stopLooking) {
	stopLooking.add(dirPath);
	}
	addPreferredEmails(result.owner2paths.keySet());
	for (String owner : result.owner2paths.keySet()) {
	String email = preferredEmails.get(owner);
	for (String path : result.owner2paths.get(owner)) {
	addOwnerPathPair(email, path);
	}
	}
	if (Config.getReportSyntaxError()) {
	result.warnings.forEach(w -> logger.atWarning().log(w));
	result.errors.forEach(w -> logger.atSevere().log(w));
	}
	}

	private void addOwnerWeights(
	ArrayList<String> paths,
	ArrayList<Integer> distances,
	String file,
	Map<String, Set<String>> file2Owners,
	Map<String, OwnerWeights> map,
	List<String> logs) {
	for (int i = 0; i < paths.size(); i++) {
	logs.add("addOwnerWeightsIn:" + paths.get(i));
	Set<String> owners = path2Owners.get(paths.get(i));
	if (owners == null) {
	continue;
	}
	for (String name : owners) {
	Util.addToMap(file2Owners, file, name);
	if (map == null) {
	continue;
	}
	if (map.containsKey(name)) {
	map.get(name).addFile(file, distances.get(i));
	} else {
	map.put(name, new OwnerWeights(file, distances.get(i)));
	}
	}
	}
	}

	/** Quick method to find owner emails of every file. */
	Map<String, Set<String>> findOwners(Collection<String> files) {
	return findOwners(files, null, new ArrayList<>());
	}

	/** Returns owner emails of every file and set up ownerWeights. */
	Map<String, Set<String>> findOwners(
	Collection<String> files, Map<String, OwnerWeights> ownerWeights, List<String> logs) {
	return findOwners(files.toArray(new String[0]), ownerWeights, logs);
	}

	/** Returns owner emails of every file and set up ownerWeights. */
	Map<String, Set<String>> findOwners(
	String[] files, Map<String, OwnerWeights> ownerWeights, List<String> logs) {
	// Returns a map of file to set of owner emails.
	// If ownerWeights is not null, add to it owner to distance-from-dir;
	// a distance of 1 is the lowest/closest possible distance
	// (which makes the subsequent math easier).
	logs.add("findOwners");
	Arrays.sort(files); // Force an ordered search sequence.
	Map<String, Set<String>> file2Owners = new HashMap<>();
	for (String fileName : files) {
	fileName = Util.addDotPrefix(fileName);
	logs.add("checkFile:" + fileName);
	String dirPath = Util.getParentDir(fileName);
	String baseName = fileName.substring(dirPath.length() + 1);
	int distance = 1;
	FileSystem fileSystem = FileSystems.getDefault();
	// Collect all matched (path, distance) in all OWNERS files for
	// fileName. Add them only if there is no special "*" owner.
	ArrayList<String> paths = new ArrayList<>();
	ArrayList<Integer> distances = new ArrayList<>();
	boolean foundStar = false;
	while (true) {
	int savedSizeOfPaths = paths.size();
	logs.add("checkDir:" + dirPath);
	if (dir2Globs.containsKey(dirPath + "/")) {
	Set<String> patterns = dir2Globs.get(dirPath + "/");
	for (String pat : patterns) {
	PathMatcher matcher = fileSystem.getPathMatcher("glob:" + pat);
	if (matcher.matches(Paths.get(dirPath + "/" + baseName))) {
	foundStar \|= findStarOwner(pat, distance, paths, distances);
	// Do not break here, a file could match multiple globs
	// with different owners.
	// OwnerWeights.add won't add duplicated files.
	}
	}
	// NOTE: A per-file directive can only specify owner emails,
	// not "set noparent".
	}
	// If baseName does not match per-file glob, paths is not changed.
	// Then we should check the general non-per-file owners.
	if (paths.size() == savedSizeOfPaths) {
	foundStar \|= findStarOwner(dirPath + "/", distance, paths, distances);
	}
	if (foundStar // This file can be approved by anyone, no owner.
	\|\| stopLooking.contains(dirPath + "/") // stop looking parent
	\|\| !dirPath.contains("/") /* root */) {
	break;
	}
	if (paths.size() != savedSizeOfPaths) {
	distance++; // increase distance for each found OWNERS
	}
	dirPath = Util.getDirName(dirPath); // go up one level
	}
	if (!foundStar) {
	addOwnerWeights(paths, distances, fileName, file2Owners, ownerWeights, logs);
	} else {
	logs.add("found * in:" + fileName);
	}
	}
	return file2Owners;
	}

	/** Returns true if path has '' owner. /
	private boolean findStarOwner(
	String path, int distance, ArrayList<String> paths, ArrayList<Integer> distances) {
	Set<String> owners = path2Owners.get(path);
	if (owners != null) {
	paths.add(path);
	distances.add(distance);
	if (owners.contains("*")) {
	return true;
	}
	}
	return false;
	}

	/** Returns ObjectId of the given branch, or null. */
	private static ObjectId getBranchId(
	Repository repo, String branch, ChangeData changeData, List<String> logs) {
	String header = "getBranchId:" + branch;
	try {
	ObjectId id = repo.resolve(branch);
	if (id == null && changeData != null && !Checker.isExemptFromOwnerApproval(changeData)) {
	logger.atSevere().log(
	"cannot find branch %s for %s", branch, Config.getChangeId(changeData));
	logs.add(header + " (NOT FOUND)");
	} else {
	logs.add(header + " (FOUND)");
	}
	return id;
	} catch (Exception e) {
	logger.atSevere().withCause(e).log(
	"cannot find branch %s for %s", branch, Config.getChangeId(changeData));
	logException(logs, header, e);
	}
	return null;
	}

	/** Returns file content or empty string; uses project+branch+file names. */
	public static String getRepoFile(GitRepositoryManager repoManager,
	String project, String branch, String file, List<String> logs) {
	// 'file' must be an absolute path from the root of 'project'.
	logs.add("getRepoFile:" + project + ":" + branch + ":" + file);
	try (Repository repo = repoManager.openRepository(new Project.NameKey(project))) {
	ObjectId id = repo.resolve(branch);
	if (id != null) {
	return getFile(repo, id, file, logs);
	}
	logs.add("getRepoFile not found branch " + branch);
	} catch (Exception e) {
	logger.atSevere().withCause(e).log(
	"Fail to find repository of project %s", project);
	logException(logs, "getRepoFile", e);
	}
	return "";
	}

	/** Returns file content or empty string; uses Repository. */
	private static String getFile(
	Repository repo, ObjectId id, String file, List<String> logs) {
	file = Util.gitRepoFilePath(file);
	String header = "getFile:" + file;
	try (RevWalk revWalk = new RevWalk(repo)) {
	RevTree tree = revWalk.parseCommit(id).getTree();
	ObjectReader reader = revWalk.getObjectReader();
	TreeWalk treeWalk = TreeWalk.forPath(reader, file, tree);
	if (treeWalk != null) {
	String content = new String(reader.open(treeWalk.getObjectId(0)).getBytes(), UTF_8);
	logs.add(header + ":" + content);
	return content;
	}
	logs.add(header + " (NOT FOUND)");
	} catch (Exception e) {
	logger.atSevere().withCause(e).log("get file %s", file);
	logException(logs, "getFile", e);
	}
	return "";
	}

	/** Adds a header + exception message to the logs. */
	private static void logException(List<String> logs, String header, Exception e) {
	logs.add(header + " Exception:" + e.getMessage());
	}
	}