Fix initial mirror sync if empty (#1842)

Fixes an error, when the initial synchronization of a git mirror had no branches.

gradle/changelog/initial_empty_mirror.yaml

@@ -0,0 +1,2 @@
+- type: fixed
+  descripion: Initial mirror with no accepted branch ([#1842](https://github.com/scm-manager/scm-manager/pull/1842))

scm-plugins/scm-git-plugin/src/main/java/sonia/scm/repository/spi/GitMirrorCommand.java

@@ -198,12 +198,18 @@ public class GitMirrorCommand extends AbstractGitCommand implements MirrorComman
       if (fetchResult.getTrackingRefUpdates().isEmpty()) {
         LOG.trace("No updates found for mirror repository {}", repository);
         mirrorLog.add("No updates found");
+        return new MirrorCommandResult(result, mirrorLog, stopwatch.stop().elapsed());
       } else {
         handleBranches();
         handleTags();
       }
 
-      defaultBranchSelector.newDefault().ifPresent(this::setNewDefaultBranch);
+      if (!defaultBranchSelector.isChanged()) {
+        mirrorLog.add("No effective changes detected");
+        return new MirrorCommandResult(result, mirrorLog, stopwatch.stop().elapsed());
+      }
+
+      defaultBranchSelector.newDefaultBranch().ifPresent(this::setNewDefaultBranch);
 
       String[] pushRefSpecs = generatePushRefSpecs().toArray(new String[0]);
       push(pushRefSpecs);
@@ -272,7 +278,7 @@ public class GitMirrorCommand extends AbstractGitCommand implements MirrorComman
     }
 
     private void handleBranch(LoggerWithHeader logger, TrackingRefUpdate ref) {
-      MirrorReferenceUpdateHandler refHandler = new MirrorReferenceUpdateHandler(logger, ref, "heads/", "branch");
+      MirrorReferenceUpdateHandler refHandler = new MirrorReferenceUpdateHandler(logger, ref, RefType.BRANCH);
       refHandler.handleRef(ref1 -> refHandler.testFilterForBranch());
     }
 
@@ -282,28 +288,26 @@ public class GitMirrorCommand extends AbstractGitCommand implements MirrorComman
     }
 
     private void handleTag(LoggerWithHeader logger, TrackingRefUpdate ref) {
-      MirrorReferenceUpdateHandler refHandler = new MirrorReferenceUpdateHandler(logger, ref, "tags/", "tag");
+      MirrorReferenceUpdateHandler refHandler = new MirrorReferenceUpdateHandler(logger, ref, RefType.TAG);
       refHandler.handleRef(ref1 -> refHandler.testFilterForTag());
     }
 
     private class MirrorReferenceUpdateHandler {
       private final LoggerWithHeader logger;
       private final TrackingRefUpdate ref;
-      private final String refType;
+      private final RefType refType;
-      private final String typeForLog;
 
-      public MirrorReferenceUpdateHandler(LoggerWithHeader logger, TrackingRefUpdate ref, String refType, String typeForLog) {
+      public MirrorReferenceUpdateHandler(LoggerWithHeader logger, TrackingRefUpdate ref, RefType refType) {
         this.logger = logger;
         this.ref = ref;
         this.refType = refType;
-        this.typeForLog = typeForLog;
       }
 
       private void handleRef(Function<TrackingRefUpdate, Result> filter) {
         LOG.trace("Handling {}", ref.getLocalName());
         Result filterResult = filter.apply(ref);
         try {
-          String referenceName = ref.getLocalName().substring("refs/".length() + refType.length());
+          String referenceName = ref.getLocalName().substring("refs/".length() + refType.refPath.length());
           if (filterResult.isAccepted()) {
             LOG.trace("Accepted ref {}", ref.getLocalName());
             handleAcceptedReference(referenceName);
@@ -332,7 +336,7 @@ public class GitMirrorCommand extends AbstractGitCommand implements MirrorComman
 
       private void handleRejectedRef(String referenceName, Result filterResult) throws IOException {
         result = REJECTED_UPDATES;
-        LOG.trace("{} ref rejected in {}: {}", typeForLog, GitMirrorCommand.this.repository, ref.getLocalName());
+        LOG.trace("{} ref rejected in {}: {}", refType.typeForLog, GitMirrorCommand.this.repository, ref.getLocalName());
         if (ref.getResult() == NEW) {
           deleteReference(ref.getLocalName());
         } else {
@@ -342,16 +346,16 @@ public class GitMirrorCommand extends AbstractGitCommand implements MirrorComman
       }
 
       private void handleAcceptedReference(String referenceName) throws IOException {
-        String targetRef = "refs/" + refType + referenceName;
+        String targetRef = "refs/" + refType.refPath + referenceName;
         if (isDeletedReference(ref)) {
-          LOG.trace("deleting {} ref in {}: {}", typeForLog, GitMirrorCommand.this.repository, targetRef);
+          LOG.trace("deleting {} ref in {}: {}", refType.typeForLog, GitMirrorCommand.this.repository, targetRef);
-          defaultBranchSelector.deleted(referenceName);
+          defaultBranchSelector.deleted(refType, referenceName);
           logger.logChange(ref, referenceName, "deleted");
           deleteReference(targetRef);
           deletedRefs.add(targetRef);
         } else {
-          LOG.trace("updating {} ref in {}: {}", typeForLog, GitMirrorCommand.this.repository, targetRef);
+          LOG.trace("updating {} ref in {}: {}", refType.typeForLog, GitMirrorCommand.this.repository, targetRef);
-          defaultBranchSelector.accepted(referenceName);
+          defaultBranchSelector.accepted(refType, referenceName);
           logger.logChange(ref, referenceName, getUpdateType(ref));
         }
       }
@@ -665,6 +669,8 @@ public class GitMirrorCommand extends AbstractGitCommand implements MirrorComman
     private final Set<String> remainingBranches;
     private final Set<String> newBranches = new HashSet<>();
 
+    private boolean changed = false;
+
     DefaultBranchSelector(String initialDefaultBranch, Collection<String> initialBranches) {
       this.initialDefaultBranch = initialBranches.isEmpty() ? null : initialDefaultBranch;
       this.initialBranches = new HashSet<>(initialBranches);
@@ -706,25 +712,50 @@ public class GitMirrorCommand extends AbstractGitCommand implements MirrorComman
       }
     }
 
-    public void accepted(String branch) {
+    public void accepted(RefType refType, String ref) {
-      newBranches.add(branch);
+      changed = true;
+      if (refType == RefType.BRANCH) {
+        newBranches.add(ref);
+      }
     }
 
-    public void deleted(String branch) {
+    public void deleted(RefType refType, String ref) {
-      remainingBranches.remove(branch);
+      changed = true;
+      if (refType == RefType.BRANCH) {
+        remainingBranches.remove(ref);
+      }
     }
 
-    public Optional<String> newDefault() {
+    public boolean isChanged() {
+      return changed;
+    }
+
+    public Optional<String> newDefaultBranch() {
       if (initialDefaultBranch == null && newBranches.contains("master") || remainingBranches.contains(initialDefaultBranch)) {
         return empty();
       } else if (!newBranches.isEmpty() && initialBranches.isEmpty()) {
         return of(newBranches.iterator().next());
+      } else if (initialDefaultBranch == null && newBranches.isEmpty()) {
+        LOG.info("Could not mirror repository with tags only.");
+        throw new IllegalStateException("No branch could be mirrored. Initial mirror without accepted branch is not supported. Make sure that at least one branch can be mirrored.");
       } else if (remainingBranches.isEmpty()) {
-        LOG.warn("Could not compute new default branch.");
+        LOG.info("Could not compute new default branch.");
         throw new IllegalStateException("Deleting all existing branches is not supported. Please restore branch '" + initialDefaultBranch + "' or recreate the mirror.");
       } else {
         return of(remainingBranches.iterator().next());
       }
     }
   }
+
+  enum RefType {
+    BRANCH("heads/", "branch"), TAG("tags/", "tag");
+
+    private final String refPath;
+    private final String typeForLog;
+
+    RefType(String refPath, String typeForLog) {
+      this.refPath = refPath;
+      this.typeForLog = typeForLog;
+    }
+  }
 }

scm-plugins/scm-git-plugin/src/test/java/sonia/scm/repository/spi/GitMirrorCommandTest.java

@@ -82,6 +82,7 @@ import static org.mockito.Mockito.when;
 import static sonia.scm.repository.api.MirrorCommandResult.ResultType.FAILED;
 import static sonia.scm.repository.api.MirrorCommandResult.ResultType.OK;
 import static sonia.scm.repository.api.MirrorCommandResult.ResultType.REJECTED_UPDATES;
+import static sonia.scm.repository.spi.GitMirrorCommand.RefType.BRANCH;
 
 public class GitMirrorCommandTest extends AbstractGitCommandTestBase {
 
@@ -164,6 +165,58 @@ public class GitMirrorCommandTest extends AbstractGitCommandTestBase {
     }
   }
 
+  @Test
+  public void shouldAcceptEmptyInitialMirror() throws IOException, GitAPIException {
+    MirrorCommandResult result = callMirrorCommand(repositoryDirectory.getAbsolutePath(), c -> {
+      c.setFilter(new MirrorFilter() {
+        @Override
+        public Filter getFilter(FilterContext context) {
+          return new Filter() {
+            @Override
+            public Result acceptBranch(BranchUpdate branch) {
+              return Result.reject("nothing accepted");
+            }
+
+            @Override
+            public Result acceptTag(TagUpdate tag) {
+              return Result.reject("nothing accepted");
+            }
+          };
+        }
+      });
+    });
+
+    assertThat(result.getResult()).isEqualTo(REJECTED_UPDATES);
+    assertThat(result.getLog()).contains("Branches:")
+      .contains("- 000000000..fcd0ef183 master (nothing accepted)")
+      .contains("- 000000000..3f76a12f0 test-branch (nothing accepted)")
+      .contains("Tags:")
+      .contains("- 000000000..86a6645ec test-tag (nothing accepted)");
+
+    try (Git createdMirror = Git.open(clone)) {
+      assertThat(createdMirror.branchList().call()).isEmpty();
+      assertThat(createdMirror.tagList().call()).isEmpty();
+    }
+  }
+
+  @Test
+  public void shouldAcceptOnlyTagInInitialMirror() {
+    assertThrows(IllegalStateException.class, () ->
+      callMirrorCommand(repositoryDirectory.getAbsolutePath(), c -> {
+        c.setFilter(new MirrorFilter() {
+          @Override
+          public Filter getFilter(FilterContext context) {
+            return new Filter() {
+              @Override
+              public Result acceptBranch(BranchUpdate branch) {
+                return Result.reject("nothing accepted");
+              }
+            };
+          }
+        });
+      }));
+  }
+
   @Test
   public void shouldFilterMasterBranchWhenFilteredOnInitialMirror() throws IOException, GitAPIException {
     MirrorCommandResult result = callMirrorCommand(repositoryDirectory.getAbsolutePath(), c -> {
@@ -356,7 +409,8 @@ public class GitMirrorCommandTest extends AbstractGitCommandTestBase {
     assertThat(result.getResult()).isEqualTo(REJECTED_UPDATES);
     assertThat(result.getLog()).containsExactly(
       "Branches:",
-      "- 000000000..fcd0ef183 added-branch (rejected due to filter)"
+      "- 000000000..fcd0ef183 added-branch (rejected due to filter)",
+      "No effective changes detected"
     );
 
     try (Git updatedMirror = Git.open(clone)) {
@@ -378,7 +432,8 @@ public class GitMirrorCommandTest extends AbstractGitCommandTestBase {
     assertThat(result.getResult()).isEqualTo(REJECTED_UPDATES);
     assertThat(result.getLog()).containsExactly(
       "Branches:",
-      "- 3f76a12f0..9e93d8631 test-branch (rejected due to filter)"
+      "- 3f76a12f0..9e93d8631 test-branch (rejected due to filter)",
+      "No effective changes detected"
     );
 
     try (Git updatedMirror = Git.open(clone)) {
@@ -400,7 +455,8 @@ public class GitMirrorCommandTest extends AbstractGitCommandTestBase {
     assertThat(result.getResult()).isEqualTo(REJECTED_UPDATES);
     assertThat(result.getLog()).containsExactly(
       "Branches:",
-      "- 3f76a12f0..000000000 test-branch (rejected due to filter)"
+      "- 3f76a12f0..000000000 test-branch (rejected due to filter)",
+      "No effective changes detected"
     );
 
     try (Git updatedMirror = Git.open(clone)) {
@@ -423,7 +479,8 @@ public class GitMirrorCommandTest extends AbstractGitCommandTestBase {
     assertThat(result.getResult()).isEqualTo(REJECTED_UPDATES);
     assertThat(result.getLog()).containsExactly(
       "Tags:",
-      "- 000000000..9e93d8631 added-tag (rejected due to filter)"
+      "- 000000000..9e93d8631 added-tag (rejected due to filter)",
+      "No effective changes detected"
     );
 
     try (Git updatedMirror = Git.open(clone)) {
@@ -446,7 +503,8 @@ public class GitMirrorCommandTest extends AbstractGitCommandTestBase {
     assertThat(result.getResult()).isEqualTo(REJECTED_UPDATES);
     assertThat(result.getLog()).containsExactly(
       "Tags:",
-      "- 86a6645ec..9e93d8631 test-tag (rejected due to filter)"
+      "- 86a6645ec..9e93d8631 test-tag (rejected due to filter)",
+      "No effective changes detected"
     );
 
     try (Git updatedMirror = Git.open(clone)) {
@@ -468,7 +526,8 @@ public class GitMirrorCommandTest extends AbstractGitCommandTestBase {
     assertThat(result.getResult()).isEqualTo(REJECTED_UPDATES);
     assertThat(result.getLog()).containsExactly(
       "Tags:",
-      "- 86a6645ec..000000000 test-tag (rejected due to filter)"
+      "- 86a6645ec..000000000 test-tag (rejected due to filter)",
+      "No effective changes detected"
     );
 
     try (Git updatedMirror = Git.open(clone)) {
@@ -490,7 +549,8 @@ public class GitMirrorCommandTest extends AbstractGitCommandTestBase {
     assertThat(result.getResult()).isEqualTo(REJECTED_UPDATES);
     assertThat(result.getLog()).containsExactly(
       "Tags:",
-      "- 86a6645ec..000000000 test-tag (thou shalt not pass)"
+      "- 86a6645ec..000000000 test-tag (thou shalt not pass)",
+      "No effective changes detected"
     );
   }
 
@@ -508,7 +568,8 @@ public class GitMirrorCommandTest extends AbstractGitCommandTestBase {
     assertThat(result.getLog()).containsExactly(
       "! got error checking filter for update: this tag creates an exception",
       "Tags:",
-      "- 86a6645ec..000000000 test-tag (exception in filter)"
+      "- 86a6645ec..000000000 test-tag (exception in filter)",
+      "No effective changes detected"
     );
   }
 
@@ -777,10 +838,10 @@ public class GitMirrorCommandTest extends AbstractGitCommandTestBase {
       GitMirrorCommand.DefaultBranchSelector selector =
         new GitMirrorCommand.DefaultBranchSelector("master", emptyList());
 
-      selector.accepted("master");
+      selector.accepted(BRANCH, "master");
-      selector.accepted("something");
+      selector.accepted(BRANCH, "something");
 
-      assertThat(selector.newDefault()).isEmpty();
+      assertThat(selector.newDefaultBranch()).isEmpty();
     }
 
     @Test
@@ -788,10 +849,10 @@ public class GitMirrorCommandTest extends AbstractGitCommandTestBase {
       GitMirrorCommand.DefaultBranchSelector selector =
         new GitMirrorCommand.DefaultBranchSelector("master", BRANCHES);
 
-      selector.accepted("new");
+      selector.accepted(BRANCH, "new");
-      selector.deleted("two");
+      selector.deleted(BRANCH, "two");
 
-      assertThat(selector.newDefault()).isEmpty();
+      assertThat(selector.newDefaultBranch()).isEmpty();
     }
 
     @Test
@@ -799,9 +860,9 @@ public class GitMirrorCommandTest extends AbstractGitCommandTestBase {
       GitMirrorCommand.DefaultBranchSelector selector =
         new GitMirrorCommand.DefaultBranchSelector("master", BRANCHES);
 
-      selector.deleted("master");
+      selector.deleted(BRANCH, "master");
 
-      assertThat(selector.newDefault()).get().isIn("one", "two", "three");
+      assertThat(selector.newDefaultBranch()).get().isIn("one", "two", "three");
     }
 
     @Test
@@ -809,11 +870,11 @@ public class GitMirrorCommandTest extends AbstractGitCommandTestBase {
       GitMirrorCommand.DefaultBranchSelector selector =
         new GitMirrorCommand.DefaultBranchSelector("master", BRANCHES);
 
-      selector.deleted("master");
+      selector.deleted(BRANCH, "master");
-      selector.deleted("one");
+      selector.deleted(BRANCH, "one");
-      selector.deleted("three");
+      selector.deleted(BRANCH, "three");
 
-      assertThat(selector.newDefault()).get().isEqualTo("two");
+      assertThat(selector.newDefaultBranch()).get().isEqualTo("two");
     }
 
     @Test
@@ -821,11 +882,11 @@ public class GitMirrorCommandTest extends AbstractGitCommandTestBase {
       GitMirrorCommand.DefaultBranchSelector selector =
         new GitMirrorCommand.DefaultBranchSelector("master", BRANCHES);
 
-      selector.deleted("master");
+      selector.deleted(BRANCH, "master");
-      selector.deleted("one");
+      selector.deleted(BRANCH, "one");
-      selector.deleted("three");
+      selector.deleted(BRANCH, "three");
 
-      assertThat(selector.newDefault()).get().isEqualTo("two");
+      assertThat(selector.newDefaultBranch()).get().isEqualTo("two");
     }
 
     @Test
@@ -833,13 +894,13 @@ public class GitMirrorCommandTest extends AbstractGitCommandTestBase {
       GitMirrorCommand.DefaultBranchSelector selector =
         new GitMirrorCommand.DefaultBranchSelector("master", BRANCHES);
 
-      selector.deleted("master");
+      selector.deleted(BRANCH, "master");
-      selector.deleted("one");
+      selector.deleted(BRANCH, "one");
-      selector.deleted("two");
+      selector.deleted(BRANCH, "two");
-      selector.accepted("new");
+      selector.accepted(BRANCH, "new");
-      selector.deleted("three");
+      selector.deleted(BRANCH, "three");
 
-      assertThrows(IllegalStateException.class, selector::newDefault);
+      assertThrows(IllegalStateException.class, selector::newDefaultBranch);
     }
 
     @Test
@@ -847,10 +908,10 @@ public class GitMirrorCommandTest extends AbstractGitCommandTestBase {
       GitMirrorCommand.DefaultBranchSelector selector =
         new GitMirrorCommand.DefaultBranchSelector("master", emptyList());
 
-      selector.accepted("main");
+      selector.accepted(BRANCH, "main");
-      selector.deleted("master");
+      selector.deleted(BRANCH, "master");
 
-      assertThat(selector.newDefault()).get().isEqualTo("main");
+      assertThat(selector.newDefaultBranch()).get().isEqualTo("main");
     }
 
     @Test
@@ -858,9 +919,9 @@ public class GitMirrorCommandTest extends AbstractGitCommandTestBase {
       GitMirrorCommand.DefaultBranchSelector selector =
         new GitMirrorCommand.DefaultBranchSelector("master", emptyList());
 
-      selector.accepted("main");
+      selector.accepted(BRANCH, "main");
 
-      assertThat(selector.newDefault()).get().isEqualTo("main");
+      assertThat(selector.newDefaultBranch()).get().isEqualTo("main");
     }
   }