Remove unconditional force push

This removes the unconditional force mode used while pushing changes made by the modify or the merge command in git repositories. The force mode led to the "deletion" of other changes on the same branch made between the creation of the working copy and the push to the core repository inside SCM-Manager.

Committed-by: Konstantin Schaper <konstantin.schaper@cloudogu.com>

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

@@ -42,6 +42,8 @@ import org.eclipse.jgit.transport.RefSpec;
 import org.eclipse.jgit.transport.RemoteRefUpdate;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import sonia.scm.ConcurrentModificationException;
+import sonia.scm.ContextEntry;
 import sonia.scm.repository.GitWorkingCopyFactory;
 import sonia.scm.repository.InternalRepositoryException;
 import sonia.scm.repository.Person;
@@ -62,6 +64,7 @@ import static java.util.Optional.of;
 import static java.util.stream.Collectors.toList;
 import static org.eclipse.jgit.transport.RemoteRefUpdate.Status.NON_EXISTING;
 import static org.eclipse.jgit.transport.RemoteRefUpdate.Status.OK;
+import static org.eclipse.jgit.transport.RemoteRefUpdate.Status.REJECTED_NONFASTFORWARD;
 import static org.eclipse.jgit.transport.RemoteRefUpdate.Status.UP_TO_DATE;
 import static sonia.scm.ContextEntry.ContextBuilder.entity;
 import static sonia.scm.NotFoundException.notFound;
@@ -247,13 +250,21 @@ class AbstractGitCommand {
     }
 
     void push(String... refSpecs) {
+      push(false, refSpecs);
+    }
+
+    void forcePush(String... refSpecs) {
+      push(true, refSpecs);
+    }
+
+    private void push(boolean force, String... refSpecs) {
       logger.trace("Pushing mirror result to repository {} with refspec '{}'", repository, refSpecs);
       try {
         Iterable<PushResult> pushResults =
           clone
             .push()
             .setRefSpecs(stream(refSpecs).map(RefSpec::new).collect(toList()))
-            .setForce(true)
+            .setForce(force)
             .call();
         Iterator<PushResult> pushResultIterator = pushResults.iterator();
         if (!pushResultIterator.hasNext()) {
@@ -269,8 +280,13 @@ class AbstractGitCommand {
           .filter(remoteRefUpdate -> !ACCEPTED_UPDATE_STATUS.contains(remoteRefUpdate.getStatus()))
           .findAny()
           .ifPresent(remoteRefUpdate -> {
-            logger.info("message for unexpected push result {} for remote {}: {}", remoteRefUpdate.getStatus(), remoteRefUpdate.getRemoteName(), pushResult.getMessages());
-            throw forMessage(repository, pushResult.getMessages());
+            if (remoteRefUpdate.getStatus() == REJECTED_NONFASTFORWARD) {
+              logger.debug("non fast-forward change detected; probably the remote {} has been changed during the modification: {}", remoteRefUpdate.getRemoteName(), pushResult.getMessages());
+              throw new ConcurrentModificationException(ContextEntry.ContextBuilder.entity("Branch", remoteRefUpdate.getRemoteName()).in(repository).build());
+            } else {
+              logger.info("message for unexpected push result {} for remote {}: {}", remoteRefUpdate.getStatus(), remoteRefUpdate.getRemoteName(), pushResult.getMessages());
+              throw forMessage(repository, pushResult.getMessages());
+            }
           });
       } catch (GitAPIException e) {
         throw new InternalRepositoryException(repository, "could not push changes into central repository", e);

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

@@ -219,7 +219,7 @@ public class GitMirrorCommand extends AbstractGitCommand implements MirrorComman
       defaultBranchSelector.newDefaultBranch().ifPresent(this::setNewDefaultBranch);
 
       String[] pushRefSpecs = generatePushRefSpecs().toArray(new String[0]);
-      push(pushRefSpecs);
+      forcePush(pushRefSpecs);
       ResultType finalResult = lfsUpdateResult.hasFailures()? FAILED: result;
       return new MirrorCommandResult(finalResult, mirrorLog, stopwatch.stop().elapsed(), lfsUpdateResult);
     }

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

@@ -0,0 +1,132 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020-present Cloudogu GmbH and Contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package sonia.scm.repository.spi;
+
+import io.micrometer.core.instrument.simple.SimpleMeterRegistry;
+import org.awaitility.Awaitility;
+import org.eclipse.jgit.api.Git;
+import org.eclipse.jgit.api.errors.GitAPIException;
+import org.eclipse.jgit.lib.Repository;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+import sonia.scm.ConcurrentModificationException;
+import sonia.scm.repository.work.NoneCachingWorkingCopyPool;
+import sonia.scm.repository.work.WorkdirProvider;
+
+import java.io.IOException;
+import java.util.concurrent.CountDownLatch;
+
+public class AbstractGitCommandTest extends AbstractGitCommandTestBase {
+
+  @Rule
+  public BindTransportProtocolRule transportProtocolRule = new BindTransportProtocolRule();
+  @Rule
+  public TemporaryFolder cloneFolder = new TemporaryFolder();
+
+  private final CountDownLatch createdWorkingCopyLatch = new CountDownLatch(1);
+  private final CountDownLatch createdConflictingCommitLatch = new CountDownLatch(1);
+  private boolean gotConflict = false;
+
+  @Override
+  protected String getZippedRepositoryResource() {
+    return "sonia/scm/repository/spi/scm-git-spi-test.zip";
+  }
+
+  @Test
+  public void shouldNotOverwriteConcurrentCommit() throws GitAPIException, IOException, InterruptedException {
+    GitContext context = createContext();
+    SimpleGitCommand command = new SimpleGitCommand(context);
+    Repository repo = context.open();
+
+    new Thread(() -> {
+      try {
+        command.doSomething();
+      } catch (Exception e) {
+        throw new RuntimeException(e);
+      }
+    }).start();
+
+    Git clone = Git
+      .cloneRepository()
+      .setURI(repo.getDirectory().toString())
+      .setDirectory(cloneFolder.newFolder())
+      .call();
+
+    // somehow we have to wait here, though we don't know why
+    Thread.sleep(1000);
+
+    createdWorkingCopyLatch.await();
+    createCommit(clone);
+    clone.push().call();
+    createdConflictingCommitLatch.countDown();
+
+    Awaitility.await().until(() -> gotConflict);
+  }
+
+  private class SimpleGitCommand extends AbstractGitCommand {
+
+    SimpleGitCommand(GitContext context) {
+      super(context);
+    }
+
+    void doSomething() {
+      inClone(
+        git -> new Worker(context, repository, git),
+        new SimpleGitWorkingCopyFactory(new NoneCachingWorkingCopyPool(new WorkdirProvider(repositoryLocationResolver)), new SimpleMeterRegistry()),
+        "master"
+      );
+    }
+  }
+
+  private synchronized void createCommit(Git git) throws GitAPIException {
+    git.commit().setMessage("Add new commit").call();
+  }
+
+  private class Worker extends AbstractGitCommand.GitCloneWorker<Void> {
+
+    private final Git git;
+
+    private Worker(GitContext context, sonia.scm.repository.Repository repository, Git git) {
+      super(git, context, repository);
+      this.git = git;
+    }
+
+    @Override
+    Void run() {
+      try {
+        createCommit(git);
+        createdWorkingCopyLatch.countDown();
+        createdConflictingCommitLatch.await();
+        push("master");
+      } catch (ConcurrentModificationException e) {
+        gotConflict = true;
+      } catch (Exception e) {
+        throw new RuntimeException(e);
+      }
+      return null;
+    }
+  }
+}