InlineEdit: Allow to upload change edit with git push

Edits can already be pulled with download commands. This change allows
edit to be pushed to gerrit by using magic branch %edit option.

Change must already exist for edit to be created/replaced. One use case
where edit might need to be replaced with git operations is rebasing of
edits on new patch set, in which case two refs are affected: old ref is
deleted and new ref is created:

  $ git push g HEAD:refs/for/master%e
  Counting objects: 14, done.
  [...]
  remote: Processing changes: updated: 1, refs: 2, done
  remote:
  remote: Updated Changes:
  remote:   http://localhost:8080/42 Fix typo in the doc [EDIT]

Change-Id: I3dbf66f1700c212ab90acfa77a5bd1e774b94555

Documentation/user-upload.txt

@@ -169,6 +169,23 @@ apply multiple review labels.
 The value is optional.  If not specified, it defaults to +1 (if
 the label range allows it).
 
+[[change_edit]]
+A change edit can be pushed by specifying the `edit` (or `e`) option on
+the reference:
+
+====
+  git push ssh://john.doe@git.example.com:29418/kernel/common HEAD:refs/for/master%edit
+====
+
+There is at most one change edit per user and change. In order to push
+a change edit the change must already exist.
+
+[NOTE]
+When a change edit already exists for a change then pushing with
+`%edit` replaces the existing change edit. This option is useful to
+rebase a change edit on the newest patch set when the rebase of the
+change edit in the web UI fails due to conflicts.
+
 If you are frequently uploading changes to the same Gerrit server,
 consider adding an SSH host block in `~/.ssh/config` to remember
 your username, hostname and port number.  This permits the use of

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/AbstractDaemonTest.java

@@ -31,6 +31,7 @@ import com.google.gerrit.extensions.api.GerritApi;
 import com.google.gerrit.extensions.api.changes.RevisionApi;
 import com.google.gerrit.extensions.client.ListChangesOption;
 import com.google.gerrit.extensions.common.ChangeInfo;
+import com.google.gerrit.extensions.common.EditInfo;
 import com.google.gerrit.extensions.restapi.RestApiException;
 import com.google.gerrit.reviewdb.client.AccountGroup;
 import com.google.gerrit.reviewdb.client.Project;
@@ -222,11 +223,16 @@ public abstract class AbstractDaemonTest {
       Chars.asList(new char[]{'a','b','c','d','e','f','g','h'});
   protected PushOneCommit.Result amendChange(String changeId)
       throws GitAPIException, IOException {
+    return amendChange(changeId, "refs/for/master");
+  }
+
+  protected PushOneCommit.Result amendChange(String changeId, String ref)
+      throws GitAPIException, IOException {
     Collections.shuffle(RANDOM);
     PushOneCommit push =
         pushFactory.create(db, admin.getIdent(), PushOneCommit.SUBJECT,
             PushOneCommit.FILE_NAME, new String(Chars.toArray(RANDOM)), changeId);
-    return push.to(git, "refs/for/master");
+    return push.to(git, ref);
   }
 
   protected ChangeInfo getChange(String changeId, ListChangesOption... options)
@@ -252,6 +258,11 @@ public abstract class AbstractDaemonTest {
     return gApi.changes().id(id).get();
   }
 
+  protected EditInfo getEdit(String id)
+      throws RestApiException {
+    return gApi.changes().id(id).getEdit();
+  }
+
   protected ChangeInfo get(String id, ListChangesOption... options)
       throws RestApiException {
     EnumSet<ListChangesOption> s = EnumSet.noneOf(ListChangesOption.class);

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/git/AbstractPushForReview.java

@@ -23,6 +23,7 @@ import com.google.gerrit.acceptance.AbstractDaemonTest;
 import com.google.gerrit.acceptance.PushOneCommit;
 import com.google.gerrit.acceptance.TestAccount;
 import com.google.gerrit.extensions.common.ChangeInfo;
+import com.google.gerrit.extensions.common.EditInfo;
 import com.google.gerrit.extensions.common.LabelInfo;
 import com.google.gerrit.extensions.restapi.RestApiException;
 import com.google.gerrit.reviewdb.client.Change;
@@ -162,6 +163,21 @@ public abstract class AbstractPushForReview extends AbstractDaemonTest {
     r.assertChange(Change.Status.DRAFT, null);
   }
 
+  @Test
+  public void testPushForMasterAsEdit() throws GitAPIException,
+      IOException, RestApiException {
+    PushOneCommit.Result r = pushTo("refs/for/master");
+    r.assertOkStatus();
+    EditInfo edit = getEdit(r.getChangeId());
+    assertThat(edit).isNull();
+
+    // specify edit as option
+    r = amendChange(r.getChangeId(), "refs/for/master%edit");
+    r.assertOkStatus();
+    edit = getEdit(r.getChangeId());
+    assertThat(edit).isNotNull();
+  }
+
   @Test
   public void testPushForMasterWithApprovals() throws GitAPIException,
       IOException, RestApiException {

gerrit-server/src/main/java/com/google/gerrit/server/edit/ChangeEditUtil.java

@@ -91,12 +91,26 @@ public class ChangeEditUtil {
    */
   public Optional<ChangeEdit> byChange(Change change)
       throws AuthException, IOException {
-    if (!user.get().isIdentifiedUser()) {
+    CurrentUser currentUser = user.get();
+    if (!currentUser.isIdentifiedUser()) {
       throw new AuthException("Authentication required");
     }
+    return byChange(change, (IdentifiedUser)currentUser);
+  }
+
+  /**
+   * Retrieve edits for a change and user. Max. one change edit can
+   * exist per user and change.
+   *
+   * @param change
+   * @param user to retrieve change edits for
+   * @return edit for this change for this user, if present.
+   * @throws IOException
+   */
+  public Optional<ChangeEdit> byChange(Change change, IdentifiedUser me)
+      throws IOException {
     Repository repo = gitManager.openRepository(change.getProject());
     try {
-      IdentifiedUser me = (IdentifiedUser) user.get();
       String editRefPrefix = editRefPrefix(me.getAccountId(), change.getId());
       Map<String, Ref> refs = repo.getRefDatabase().getRefs(editRefPrefix);
       if (refs.isEmpty()) {
@@ -201,7 +215,7 @@ public class ChangeEditUtil {
    * @param psId patch set number
    * @return reference for this change edit
    */
-  static String editRefName(Account.Id accountId, Change.Id changeId,
+  public static String editRefName(Account.Id accountId, Change.Id changeId,
       PatchSet.Id psId) {
     return editRefPrefix(accountId, changeId) + psId.get();
   }

gerrit-server/src/main/java/com/google/gerrit/server/git/ReceiveCommits.java

@@ -30,6 +30,7 @@ import static org.eclipse.jgit.transport.ReceiveCommand.Result.REJECTED_OTHER_RE
 
 import com.google.common.base.Function;
 import com.google.common.base.Joiner;
+import com.google.common.base.Optional;
 import com.google.common.base.Predicate;
 import com.google.common.base.Splitter;
 import com.google.common.base.Strings;
@@ -90,6 +91,8 @@ import com.google.gerrit.server.config.AllProjectsName;
 import com.google.gerrit.server.config.CanonicalWebUrl;
 import com.google.gerrit.server.config.PluginConfig;
 import com.google.gerrit.server.config.ProjectConfigEntry;
+import com.google.gerrit.server.edit.ChangeEdit;
+import com.google.gerrit.server.edit.ChangeEditUtil;
 import com.google.gerrit.server.events.CommitReceivedEvent;
 import com.google.gerrit.server.extensions.events.GitReferenceUpdated;
 import com.google.gerrit.server.git.MultiProgressMonitor.Task;
@@ -326,6 +329,7 @@ public class ReceiveCommits {
   private final MergeQueue mergeQueue;
   private final DynamicMap<ProjectConfigEntry> pluginConfigEntries;
   private final NotesMigration notesMigration;
+  private final ChangeEditUtil editUtil;
 
   private final List<CommitValidationMessage> messages = new ArrayList<>();
   private ListMultimap<Error, String> errors = LinkedListMultimap.create();
@@ -375,7 +379,8 @@ public class ReceiveCommits {
       final MergeQueue mergeQueue,
       final ChangeKindCache changeKindCache,
       final DynamicMap<ProjectConfigEntry> pluginConfigEntries,
-      final NotesMigration notesMigration) throws IOException {
+      final NotesMigration notesMigration,
+      final ChangeEditUtil editUtil) throws IOException {
     this.currentUser = (IdentifiedUser) projectControl.getCurrentUser();
     this.db = db;
     this.queryProvider = queryProvider;
@@ -422,6 +427,8 @@ public class ReceiveCommits {
     this.pluginConfigEntries = pluginConfigEntries;
     this.notesMigration = notesMigration;
 
+    this.editUtil = editUtil;
+
     this.messageSender = new ReceivePackMessageSender();
 
     ProjectState ps = projectControl.getProjectState();
@@ -560,6 +567,7 @@ public class ReceiveCommits {
 
     if (!batch.getCommands().isEmpty()) {
       try {
+        batch.setAllowNonFastForwards(magicBranch != null && magicBranch.edit);
         batch.execute(rp.getRevWalk(), commandProgress);
       } catch (IOException err) {
         int cnt = 0;
@@ -658,7 +666,7 @@ public class ReceiveCommits {
       addMessage("");
       addMessage("New Changes:");
       for (CreateRequest c : created) {
-        addMessage(formatChangeUrl(canonicalWebUrl, c.change));
+        addMessage(formatChangeUrl(canonicalWebUrl, c.change, false));
       }
       addMessage("");
     }
@@ -681,14 +689,16 @@ public class ReceiveCommits {
     if (!updated.isEmpty()) {
       addMessage("");
       addMessage("Updated Changes:");
+      boolean edit = magicBranch != null && magicBranch.edit;
       for (ReplaceRequest u : updated) {
-        addMessage(formatChangeUrl(canonicalWebUrl, u.change));
+        addMessage(formatChangeUrl(canonicalWebUrl, u.change, edit));
       }
       addMessage("");
     }
   }
 
-  private static String formatChangeUrl(String url, Change change) {
+  private static String formatChangeUrl(String url, Change change,
+      boolean edit) {
     StringBuilder m = new StringBuilder()
         .append("  ")
         .append(url)
@@ -698,6 +708,9 @@ public class ReceiveCommits {
     if (change.getStatus() == Change.Status.DRAFT) {
       m.append(" [DRAFT]");
     }
+    if (edit) {
+      m.append(" [EDIT]");
+    }
     return m.toString();
   }
 
@@ -1118,6 +1131,9 @@ public class ReceiveCommits {
     @Option(name = "--draft", usage = "mark new/updated changes as draft")
     boolean draft;
 
+    @Option(name = "--edit", aliases = {"-e"}, usage = "upload as change edit")
+    boolean edit;
+
     @Option(name = "--submit", usage = "immediately submit the change")
     boolean submit;
 
@@ -1583,6 +1599,10 @@ public class ReceiveCommits {
       reject(magicBranch.cmd, "no new changes");
       return;
     }
+    if (!newChanges.isEmpty() && magicBranch.edit) {
+      reject(magicBranch.cmd, "edit is not supported for new changes");
+      return;
+    }
     for (CreateRequest create : newChanges) {
       batch.addCommand(create.cmd);
     }
@@ -1776,6 +1796,9 @@ public class ReceiveCommits {
 
     for (ReplaceRequest req : replaceByChange.values()) {
       if (req.inputCommand.getResult() == NOT_ATTEMPTED && req.cmd != null) {
+        if (req.prev != null) {
+          batch.addCommand(req.prev);
+        }
         batch.addCommand(req.cmd);
       }
     }
@@ -1816,6 +1839,7 @@ public class ReceiveCommits {
     ChangeControl changeCtl;
     BiMap<RevCommit, PatchSet.Id> revisions;
     PatchSet newPatchSet;
+    ReceiveCommand prev;
     ReceiveCommand cmd;
     PatchSetInfo info;
     ChangeMessage msg;
@@ -1938,6 +1962,59 @@ public class ReceiveCommits {
         }
       }
 
+      if (magicBranch != null && magicBranch.edit) {
+        return newEdit();
+      }
+
+      newPatchSet();
+      return true;
+    }
+
+    private boolean newEdit() {
+      newPatchSet = new PatchSet(change.currentPatchSetId());
+      Optional<ChangeEdit> edit = null;
+
+      try {
+        edit = editUtil.byChange(change, currentUser);
+      } catch (IOException e) {
+        log.error("Cannt retrieve edit", e);
+        return false;
+      }
+
+      if (edit.isPresent()) {
+        if (edit.get().getBasePatchSet().getId().equals(newPatchSet.getId())) {
+          // replace edit
+          cmd = new ReceiveCommand(
+              edit.get().getRef().getObjectId(),
+              newCommit,
+              edit.get().getRefName());
+        } else {
+          // delete old edit ref on rebase
+          prev = new ReceiveCommand(
+              edit.get().getRef().getObjectId(),
+              ObjectId.zeroId(),
+              edit.get().getRefName());
+          createEditCommand();
+        }
+      } else {
+        createEditCommand();
+      }
+
+      return true;
+    }
+
+    private void createEditCommand() {
+      // create new edit
+      cmd = new ReceiveCommand(
+          ObjectId.zeroId(),
+          newCommit,
+          ChangeEditUtil.editRefName(
+              currentUser.getAccountId(),
+              change.getId(),
+              newPatchSet.getId()));
+    }
+
+    private void newPatchSet() {
       PatchSet.Id id =
           ChangeUtil.nextPatchSetId(allRefs, change.currentPatchSetId());
       newPatchSet = new PatchSet(id);
@@ -1952,7 +2029,6 @@ public class ReceiveCommits {
           ObjectId.zeroId(),
           newCommit,
           newPatchSet.getRefName());
-      return true;
     }
 
     CheckedFuture<PatchSet.Id, InsertException> insertPatchSet()
@@ -1965,7 +2041,9 @@ public class ReceiveCommits {
         @Override
         public PatchSet.Id call() throws OrmException, IOException, NoSuchChangeException {
           try {
-            if (caller == Thread.currentThread()) {
+            if (magicBranch.edit) {
+              return upsertEdit();
+            } else if (caller == Thread.currentThread()) {
               return insertPatchSet(db);
             } else {
               ReviewDb db = schemaFactory.open();
@@ -2007,6 +2085,13 @@ public class ReceiveCommits {
       return msg;
     }
 
+    PatchSet.Id upsertEdit() {
+      if (cmd.getResult() == NOT_ATTEMPTED) {
+        cmd.execute(rp);
+      }
+      return newPatchSet.getId();
+    }
+
     PatchSet.Id insertPatchSet(ReviewDb db) throws OrmException, IOException {
       final Account.Id me = currentUser.getAccountId();
       final List<FooterLine> footerLines = newCommit.getFooterLines();