Correctly close the repository

license-maven-plugin-git/src/main/java/com/mycila/maven/plugin/license/git/CopyrightAuthorProvider.java

@@ -52,10 +52,8 @@ public CopyrightAuthorProvider() {
   public Map<String, String> getAdditionalProperties(AbstractLicenseMojo mojo, Properties properties,
                                                      Document document) {
 
-    try {
+    try (GitLookup gitLookup = getGitLookup(mojo, document.getFile(), properties)) {
       Map<String, String> result = new HashMap<>(3);
-      GitLookup gitLookup = getGitLookup(mojo, document.getFile(), properties);
-
       result.put(COPYRIGHT_CREATION_AUTHOR_NAME_KEY, gitLookup.getAuthorNameOfCreation(document.getFile()));
       result.put(COPYRIGHT_CREATION_AUTHOR_EMAIL_KEY, gitLookup.getAuthorEmailOfCreation(document.getFile()));
       return Collections.unmodifiableMap(result);
@@ -64,6 +62,4 @@ public Map<String, String> getAdditionalProperties(AbstractLicenseMojo mojo, Pro
           + document.getFile().getAbsolutePath(), e);
     }
   }
-
-
 }

license-maven-plugin-git/src/main/java/com/mycila/maven/plugin/license/git/CopyrightRangeProvider.java

@@ -54,7 +54,7 @@ public CopyrightRangeProvider() {
    * returned; otherwise, the two values are combined using dash, so that the result is e.g. {@code "2000-2010"}.</li>
    * <li>{@value #COPYRIGHT_CREATION_YEAR_KEY} key stores the year from the committer date of the first git commit for
    * the supplied {@code document}.</li>
-   * <li>{@value #COPYRIGHT_EXISTENCE_YEARS_KEY} key stores the range from {@value #COPYRIGHT_CREATION_YEAR_KEY} value to 
+   * <li>{@value #COPYRIGHT_EXISTENCE_YEARS_KEY} key stores the range from {@value #COPYRIGHT_CREATION_YEAR_KEY} value to
    * {@value #COPYRIGHT_LAST_YEAR_KEY} value.  If both values are equal only the {@value #COPYRIGHT_CREATION_YEAR_KEY} is returned;
    * otherwise, the two values are combined using dash, so that the result is e.g. {@code "2005-2010"}.</li>
    * </ul>
@@ -75,9 +75,9 @@ public Map<String, String> getAdditionalProperties(AbstractLicenseMojo mojo, Pro
       throw new RuntimeException("'" + INCEPTION_YEAR_KEY + "' must be an integer ; found = " + inceptionYear + " file: "
           + document.getFile().getAbsolutePath());
     }
-    try {
+    try (GitLookup gitLookup = getGitLookup(mojo, document.getFile(), properties)) {
       Map<String, String> result = new HashMap<>(4);
-      GitLookup gitLookup = getGitLookup(mojo, document.getFile(), properties);
+
       int copyrightEnd = gitLookup.getYearOfLastChange(document.getFile());
       result.put(COPYRIGHT_LAST_YEAR_KEY, Integer.toString(copyrightEnd));
       final String copyrightYears;
@@ -90,15 +90,15 @@ public Map<String, String> getAdditionalProperties(AbstractLicenseMojo mojo, Pro
 
       int copyrightStart = gitLookup.getYearOfCreation(document.getFile());
       result.put(COPYRIGHT_CREATION_YEAR_KEY, Integer.toString(copyrightStart));
-      
+
       final String copyrightExistenceYears;
       if (copyrightStart >= copyrightEnd) {
-          copyrightExistenceYears = Integer.toString(copyrightStart);
+        copyrightExistenceYears = Integer.toString(copyrightStart);
       } else {
-          copyrightExistenceYears = copyrightStart + "-" + copyrightEnd;
+        copyrightExistenceYears = copyrightStart + "-" + copyrightEnd;
       }
       result.put(COPYRIGHT_EXISTENCE_YEARS_KEY, copyrightExistenceYears);
-      
+
       return Collections.unmodifiableMap(result);
     } catch (Exception e) {
       throw new RuntimeException("Could not compute the year of the last git commit for file "

license-maven-plugin-git/src/main/java/com/mycila/maven/plugin/license/git/GitLookup.java

@@ -15,6 +15,7 @@
  */
 package com.mycila.maven.plugin.license.git;
 
+import java.io.Closeable;
 import java.io.File;
 import java.io.IOException;
 import java.util.Arrays;
@@ -44,7 +45,7 @@
  *
  * @author <a href="mailto:[email protected]">Peter Palaga</a>
  */
-public class GitLookup {
+public class GitLookup implements Closeable {
   public static final TimeZone DEFAULT_ZONE = TimeZone.getTimeZone("GMT");
 
   public enum DateSource {
@@ -71,10 +72,13 @@ public enum DateSource {
    * @throws IOException
    */
   public GitLookup(File anyFile, DateSource dateSource, TimeZone timeZone, int checkCommitsCount) throws IOException {
-    super();
     this.repository = new FileRepositoryBuilder().findGitDir(anyFile).build();
     /* A workaround for  https://bugs.eclipse.org/bugs/show_bug.cgi?id=457961 */
     // Also contains contents of .git/shallow and can detect shallow repo
+    // the line below reads and caches the entries in the FileObjectDatabase of the repository to
+    // avoid concurrent modifications during RevWalk
+    // Closing the repository will close the FileObjectDatabase.
+    // Here the newReader() is a WindowCursor which delegates the getShallowCommits() to the FileObjectDatabase.
     this.shallow = !this.repository.getObjectDatabase().newReader().getShallowCommits().isEmpty();
 
     this.pathResolver = new GitPathResolver(repository.getWorkTree().getAbsolutePath());
@@ -148,12 +152,12 @@ int getYearOfCreation(File file) throws IOException, GitAPIException {
       commitYear = getYearFromCommit(commit);
     }
     walk.dispose();
-    
+
     // If we couldn't find a creation year from Git assume newly created file
     if (commitYear == 0) {
-        return getCurrentYear();
-      }
-    
+      return getCurrentYear();
+    }
+
     return commitYear;
   }
 
@@ -182,7 +186,7 @@ String getAuthorEmailOfCreation(File file) throws IOException {
     walk.dispose();
     return authorEmail;
   }
-  
+
   boolean isShallowRepository() {
     return this.shallow;
   }
@@ -245,4 +249,9 @@ private String getAuthorEmailFromCommit(RevCommit commit) {
     PersonIdent id = commit.getAuthorIdent();
     return id.getEmailAddress();
   }
+
+  @Override
+  public void close() {
+    repository.close();
+  }
 }

license-maven-plugin-git/src/main/java/com/mycila/maven/plugin/license/git/GitPropertiesProvider.java

@@ -16,6 +16,7 @@
 package com.mycila.maven.plugin.license.git;
 
 import com.mycila.maven.plugin.license.AbstractLicenseMojo;
+
 import java.io.File;
 import java.io.IOException;
 import java.util.Locale;
@@ -27,66 +28,51 @@
  */
 public class GitPropertiesProvider {
 
-  private GitLookup gitLookup;
   public static final String MAX_COMMITS_LOOKUP_KEY = "license.git.maxCommitsLookup";
   // keep for compatibility
   private static final String COPYRIGHT_LAST_YEAR_MAX_COMMITS_LOOKUP_KEY = "license.git.copyrightLastYearMaxCommitsLookup";
   public static final String COPYRIGHT_LAST_YEAR_SOURCE_KEY = "license.git.copyrightLastYearSource";
   public static final String COPYRIGHT_LAST_YEAR_TIME_ZONE_KEY = "license.git.copyrightLastYearTimeZone";
 
-  public GitPropertiesProvider() {}
-
-  ;
-
   /**
    * Lazily initializes #gitLookup assuming that all subsequent calls to this method will be related to the same
    * git repository.
-   *
-   * @param file
-   * @return
-   * @throws IOException
    */
-  GitLookup getGitLookup(AbstractLicenseMojo mojo, File file, Properties props) throws IOException {
-    if (gitLookup == null) {
-      synchronized (this) {
-        if (gitLookup == null) {
-          String dateSourceString = props.getProperty(COPYRIGHT_LAST_YEAR_SOURCE_KEY,
-              GitLookup.DateSource.AUTHOR.name());
-          GitLookup.DateSource dateSource = GitLookup.DateSource.valueOf(dateSourceString.toUpperCase(Locale.US));
-          String checkCommitsCountString = props.getProperty(MAX_COMMITS_LOOKUP_KEY);
-          // Backwads compatibility
-          if (checkCommitsCountString == null) {
-              checkCommitsCountString = props.getProperty(COPYRIGHT_LAST_YEAR_MAX_COMMITS_LOOKUP_KEY);              
-          }
-          int checkCommitsCount = Integer.MAX_VALUE;
-          if (checkCommitsCountString != null) {
-            checkCommitsCountString = checkCommitsCountString.trim();
-            checkCommitsCount = Integer.parseInt(checkCommitsCountString);
-          }
-          final TimeZone timeZone;
-          String tzString = props.getProperty(COPYRIGHT_LAST_YEAR_TIME_ZONE_KEY);
-          switch (dateSource) {
-            case COMMITER:
-              timeZone = tzString == null ? GitLookup.DEFAULT_ZONE : TimeZone.getTimeZone(tzString);
-              break;
-            case AUTHOR:
-              if (tzString != null) {
-                throw new RuntimeException(COPYRIGHT_LAST_YEAR_TIME_ZONE_KEY + " must not be set with "
-                    + COPYRIGHT_LAST_YEAR_SOURCE_KEY + " = " + GitLookup.DateSource.AUTHOR.name()
-                    + " because git author name already contrains time zone information.");
-              }
-              timeZone = null;
-              break;
-            default:
-              throw new IllegalStateException("Unexpected " + GitLookup.DateSource.class.getName() + " " + dateSource);
-          }
-          gitLookup = new GitLookup(file, dateSource, timeZone, checkCommitsCount);
-          // One-time warning for shallow repo
-          if (mojo.warnIfShallow && gitLookup.isShallowRepository()) {
-            mojo.warn("Shallow git repository detected. Year and author property values may not be accurate.");
-          }
+  static GitLookup getGitLookup(AbstractLicenseMojo mojo, File file, Properties props) throws IOException {
+    String dateSourceString = props.getProperty(COPYRIGHT_LAST_YEAR_SOURCE_KEY,
+        GitLookup.DateSource.AUTHOR.name());
+    GitLookup.DateSource dateSource = GitLookup.DateSource.valueOf(dateSourceString.toUpperCase(Locale.US));
+    String checkCommitsCountString = props.getProperty(MAX_COMMITS_LOOKUP_KEY);
+    // Backwads compatibility
+    if (checkCommitsCountString == null) {
+      checkCommitsCountString = props.getProperty(COPYRIGHT_LAST_YEAR_MAX_COMMITS_LOOKUP_KEY);
+    }
+    int checkCommitsCount = Integer.MAX_VALUE;
+    if (checkCommitsCountString != null) {
+      checkCommitsCountString = checkCommitsCountString.trim();
+      checkCommitsCount = Integer.parseInt(checkCommitsCountString);
+    }
+    final TimeZone timeZone;
+    String tzString = props.getProperty(COPYRIGHT_LAST_YEAR_TIME_ZONE_KEY);
+    switch (dateSource) {
+      case COMMITER:
+        timeZone = tzString == null ? GitLookup.DEFAULT_ZONE : TimeZone.getTimeZone(tzString);
+        break;
+      case AUTHOR:
+        if (tzString != null) {
+          throw new RuntimeException(COPYRIGHT_LAST_YEAR_TIME_ZONE_KEY + " must not be set with "
+              + COPYRIGHT_LAST_YEAR_SOURCE_KEY + " = " + GitLookup.DateSource.AUTHOR.name()
+              + " because git author name already contrains time zone information.");
         }
-      }
+        timeZone = null;
+        break;
+      default:
+        throw new IllegalStateException("Unexpected " + GitLookup.DateSource.class.getName() + " " + dateSource);
+    }
+    GitLookup gitLookup = new GitLookup(file, dateSource, timeZone, checkCommitsCount);
+    // One-time warning for shallow repo
+    if (mojo.warnIfShallow && gitLookup.isShallowRepository()) {
+      mojo.warn("Shallow git repository detected. Year and author property values may not be accurate.");
     }
     return gitLookup;
   }