Merge "Disable submit button if merge will fail"

Documentation/config-gerrit.txt

@@ -563,6 +563,22 @@ link:cmd-flush-caches.html[gerrit flush-caches].
 Default is 5 minutes.
 
 
+[[changeMerge]]Section changeMerge
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Controls whether or not the mergeability test of changes is
+enabled.  If enabled, when the change page is loaded, the test is
+triggered. The submit button will be enabled or disabled according to
+the result.
+
+----
+[changeMerge]
+  test = true
+----
+
++
+By default this is false (test is not enabled).
+
 [[commentlink]]Section commentlink
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Comment links are find/replace strings applied to change descriptions,

gerrit-common/src/main/java/com/google/gerrit/common/data/GerritConfig.java

@@ -41,6 +41,7 @@ public class GerritConfig implements Cloneable {
   protected Set<Account.FieldName> editableAccountFields;
   protected List<RegexFindReplace> commentLinks;
   protected boolean documentationAvailable;
+  protected boolean testChangeMerge;
 
   public String getRegisterUrl() {
     return registerUrl;
@@ -160,4 +161,12 @@ public class GerritConfig implements Cloneable {
   public void setDocumentationAvailable(final boolean available) {
     documentationAvailable = available;
   }
+
+  public boolean testChangeMerge() {
+    return testChangeMerge;
+  }
+
+  public void setTestChangeMerge(final boolean test) {
+    testChangeMerge = test;
+  }
 }

gerrit-gwtui/src/main/java/com/google/gerrit/client/changes/ApprovalTable.java

@@ -245,6 +245,15 @@ public class ApprovalTable extends Composite {
     }
 
     addReviewer.setVisible(Gerrit.isSignedIn());
+
+    if (Gerrit.getConfig().testChangeMerge()
+        && !detail.getChange().isMergeable()) {
+      Element li = DOM.createElement("li");
+      li.setClassName(Gerrit.RESOURCES.css().missingApproval());
+      DOM.setInnerText(li, Util.C.messageNeedsRebaseOrHasDependency());
+      DOM.appendChild(missingList, li);
+      missing.setVisible(true);
+    }
   }
 
   private void doAddReviewer() {

gerrit-gwtui/src/main/java/com/google/gerrit/client/changes/ChangeConstants.java

@@ -91,6 +91,9 @@ public interface ChangeConstants extends Constants {
   String changeInfoBlockUpdated();
   String changeInfoBlockStatus();
   String changePermalink();
+  String changeInfoBlockCanMerge();
+  String changeInfoBlockCanMergeYes();
+  String changeInfoBlockCanMergeNo();
 
   String includedInTableBranch();
   String includedInTableTag();
@@ -99,6 +102,7 @@ public interface ChangeConstants extends Constants {
   String messageExpandRecent();
   String messageExpandAll();
   String messageCollapseAll();
+  String messageNeedsRebaseOrHasDependency();
 
   String patchSetInfoAuthor();
   String patchSetInfoCommitter();
@@ -142,4 +146,4 @@ public interface ChangeConstants extends Constants {
 
   String buttonDiffAllSideBySide();
   String buttonDiffAllUnified();
-}
+}

gerrit-gwtui/src/main/java/com/google/gerrit/client/changes/ChangeConstants.properties

@@ -68,6 +68,9 @@ changeInfoBlockUploaded = Uploaded
 changeInfoBlockUpdated = Updated
 changeInfoBlockStatus = Status
 changePermalink = Permalink
+changeInfoBlockCanMerge = Can Merge
+changeInfoBlockCanMergeYes = Yes
+changeInfoBlockCanMergeNo = No
 
 includedInTableBranch = Branch Name
 includedInTableTag = Tag Name
@@ -76,6 +79,7 @@ messageNoAuthor = Gerrit Code Review
 messageExpandRecent = Expand Recent
 messageExpandAll = Expand All
 messageCollapseAll = Collapse All
+messageNeedsRebaseOrHasDependency = Need Rebase or Has Dependency
 
 patchSetInfoAuthor = Author
 patchSetInfoCommitter = Committer
@@ -122,4 +126,4 @@ submitFailed = Submit Failed
 buttonClose = Close
 
 buttonDiffAllSideBySide = Diff All Side-by-Side
-buttonDiffAllUnified = Diff All Unified
+buttonDiffAllUnified = Diff All Unified

gerrit-gwtui/src/main/java/com/google/gerrit/client/changes/ChangeInfoBlock.java

@@ -39,13 +39,20 @@ public class ChangeInfoBlock extends Composite {
   private static final int R_UPLOADED = 5;
   private static final int R_UPDATED = 6;
   private static final int R_STATUS = 7;
-  private static final int R_PERMALINK = 8;
-  private static final int R_CNT = 9;
+  private static final int R_MERGE_TEST = 8;
+  private final int R_PERMALINK;
+  private static final int R_CNT = 10;
 
   private final Grid table;
 
   public ChangeInfoBlock() {
-    table = new Grid(R_CNT, 2);
+    if (Gerrit.getConfig().testChangeMerge()) {
+      table = new Grid(R_CNT, 2);
+      R_PERMALINK = 9;
+    } else {
+      table = new Grid(R_CNT - 1, 2);
+      R_PERMALINK = 8;
+    }
     table.setStyleName(Gerrit.RESOURCES.css().infoBlock());
     table.addStyleName(Gerrit.RESOURCES.css().changeInfoBlock());
 
@@ -57,6 +64,9 @@ public class ChangeInfoBlock extends Composite {
     initRow(R_UPLOADED, Util.C.changeInfoBlockUploaded());
     initRow(R_UPDATED, Util.C.changeInfoBlockUpdated());
     initRow(R_STATUS, Util.C.changeInfoBlockStatus());
+    if (Gerrit.getConfig().testChangeMerge()) {
+      initRow(R_MERGE_TEST, Util.C.changeInfoBlockCanMerge());
+    }
 
     final CellFormatter fmt = table.getCellFormatter();
     fmt.addStyleName(0, 0, Gerrit.RESOURCES.css().topmost());
@@ -91,6 +101,10 @@ public class ChangeInfoBlock extends Composite {
     table.setText(R_UPLOADED, 1, mediumFormat(chg.getCreatedOn()));
     table.setText(R_UPDATED, 1, mediumFormat(chg.getLastUpdatedOn()));
     table.setText(R_STATUS, 1, Util.toLongString(chg.getStatus()));
+    if (Gerrit.getConfig().testChangeMerge()) {
+      table.setText(R_MERGE_TEST, 1, chg.isMergeable() ? Util.C
+          .changeInfoBlockCanMergeYes() : Util.C.changeInfoBlockCanMergeNo());
+    }
 
     if (chg.getStatus().isClosed()) {
       table.getCellFormatter().addStyleName(R_STATUS, 1, Gerrit.RESOURCES.css().closedstate());

gerrit-gwtui/src/main/java/com/google/gerrit/client/changes/PatchSetComplexDisclosurePanel.java

@@ -405,6 +405,10 @@ class PatchSetComplexDisclosurePanel extends ComplexDisclosurePanel implements O
       final Button b =
           new Button(Util.M
               .submitPatchSet(detail.getPatchSet().getPatchSetId()));
+      if (Gerrit.getConfig().testChangeMerge()) {
+        b.setEnabled(changeDetail.getChange().isMergeable());
+      }
+
       b.addClickHandler(new ClickHandler() {
         @Override
         public void onClick(final ClickEvent event) {
@@ -640,4 +644,4 @@ class PatchSetComplexDisclosurePanel extends ComplexDisclosurePanel implements O
       }
     };
   }
-}
+}

gerrit-gwtui/src/main/java/com/google/gerrit/client/changes/PublishCommentScreen.java

@@ -41,11 +41,11 @@ import com.google.gwt.event.dom.client.ClickHandler;
 import com.google.gwt.user.client.ui.Button;
 import com.google.gwt.user.client.ui.FlowPanel;
 import com.google.gwt.user.client.ui.FormPanel;
-import com.google.gwt.user.client.ui.FormPanel.SubmitEvent;
 import com.google.gwt.user.client.ui.Panel;
 import com.google.gwt.user.client.ui.RadioButton;
 import com.google.gwt.user.client.ui.VerticalPanel;
 import com.google.gwt.user.client.ui.Widget;
+import com.google.gwt.user.client.ui.FormPanel.SubmitEvent;
 import com.google.gwtexpui.globalkey.client.NpTextArea;
 import com.google.gwtjsonrpc.client.VoidResult;
 
@@ -311,6 +311,9 @@ public class PublishCommentScreen extends AccountScreen implements
     }
 
     submit.setVisible(r.canSubmit());
+    if (Gerrit.getConfig().testChangeMerge()) {
+      submit.setEnabled(r.getChange().isMergeable());
+    }
   }
 
   private void onSend(final boolean submit) {

gerrit-httpd/src/main/java/com/google/gerrit/httpd/GerritConfigProvider.java

@@ -102,6 +102,8 @@ class GerritConfigProvider implements Provider<GerritConfig> {
     config.setApprovalTypes(approvalTypes);
     config.setDocumentationAvailable(servletContext
         .getResource("/Documentation/index.html") != null);
+    config.setTestChangeMerge(cfg.getBoolean("changeMerge",
+        "test", false));
 
     final Set<Account.FieldName> fields = new HashSet<Account.FieldName>();
     for (final Account.FieldName n : Account.FieldName.values()) {

gerrit-httpd/src/main/java/com/google/gerrit/httpd/rpc/changedetail/ChangeDetailFactory.java

@@ -31,8 +31,11 @@ import com.google.gerrit.reviewdb.PatchSetApproval;
 import com.google.gerrit.reviewdb.RevId;
 import com.google.gerrit.reviewdb.ReviewDb;
 import com.google.gerrit.server.AnonymousUser;
+import com.google.gerrit.server.ChangeUtil;
 import com.google.gerrit.server.IdentifiedUser;
 import com.google.gerrit.server.account.AccountInfoCacheFactory;
+import com.google.gerrit.server.config.GerritServerConfig;
+import com.google.gerrit.server.git.MergeOp;
 import com.google.gerrit.server.patch.PatchSetInfoNotAvailableException;
 import com.google.gerrit.server.project.ChangeControl;
 import com.google.gerrit.server.project.NoSuchChangeException;
@@ -42,6 +45,8 @@ import com.google.gwtorm.client.OrmException;
 import com.google.inject.Inject;
 import com.google.inject.assistedinject.Assisted;
 
+import org.eclipse.jgit.lib.Config;
+
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
@@ -70,6 +75,9 @@ public class ChangeDetailFactory extends Handler<ChangeDetail> {
   private ChangeDetail detail;
   private ChangeControl control;
 
+  private final MergeOp.Factory opFactory;
+  private boolean testMerge;
+
   @Inject
   ChangeDetailFactory(final ApprovalTypes approvalTypes,
       final FunctionState.Factory functionState,
@@ -77,6 +85,8 @@ public class ChangeDetailFactory extends Handler<ChangeDetail> {
       final ChangeControl.Factory changeControlFactory,
       final AccountInfoCacheFactory.Factory accountInfoCacheFactory,
       final AnonymousUser anonymousUser,
+      final MergeOp.Factory opFactory,
+      @GerritServerConfig final Config cfg,
       @Assisted final Change.Id id) {
     this.approvalTypes = approvalTypes;
     this.functionState = functionState;
@@ -86,6 +96,9 @@ public class ChangeDetailFactory extends Handler<ChangeDetail> {
     this.anonymousUser = anonymousUser;
     this.aic = accountInfoCacheFactory.create();
 
+    this.opFactory = opFactory;
+    this.testMerge = cfg.getBoolean("changeMerge", "test", false);
+
     this.changeId = id;
   }
 
@@ -148,7 +161,11 @@ public class ChangeDetailFactory extends Handler<ChangeDetail> {
     }
   }
 
-  private void load() throws OrmException {
+  private void load() throws OrmException, NoSuchChangeException {
+    if (detail.getChange().getStatus().equals(Change.Status.NEW) && testMerge) {
+      ChangeUtil.testMerge(opFactory, detail.getChange());
+    }
+
     final PatchSet.Id psId = detail.getChange().currentPatchSetId();
     final List<PatchSetApproval> allApprovals =
         db.patchSetApprovals().byChange(changeId).toList();

gerrit-httpd/src/main/java/com/google/gerrit/httpd/rpc/changedetail/RestoreChange.java

@@ -18,7 +18,9 @@ import com.google.gerrit.common.ChangeHookRunner;
 import com.google.gerrit.common.data.ChangeDetail;
 import com.google.gerrit.common.errors.NoSuchEntityException;
 import com.google.gerrit.httpd.rpc.Handler;
-import com.google.gerrit.reviewdb.*;
+import com.google.gerrit.reviewdb.Change;
+import com.google.gerrit.reviewdb.PatchSet;
+import com.google.gerrit.reviewdb.ReviewDb;
 import com.google.gerrit.server.ChangeUtil;
 import com.google.gerrit.server.IdentifiedUser;
 import com.google.gerrit.server.mail.EmailException;

gerrit-reviewdb/src/main/java/com/google/gerrit/reviewdb/Change.java

@@ -355,6 +355,17 @@ public final class Change {
   @Column(id = 14, notNull = false)
   protected String topic;
 
+  /**
+   * Null if the change has never been tested.
+   * Empty if it has been tested but against a branch that does
+   * not exist.
+   */
+  @Column(id = 15, notNull = false)
+  protected RevId lastSha1MergeTested;
+
+  @Column(id = 16)
+  protected boolean mergeable;
+
   protected Change() {
   }
 
@@ -367,6 +378,7 @@ public final class Change {
     owner = ownedBy;
     dest = forBranch;
     setStatus(Status.NEW);
+    setLastSha1MergeTested(null);
   }
 
   /** Legacy 32 bit integer identity for a change. */
@@ -466,4 +478,20 @@ public final class Change {
   public void setTopic(String topic) {
     this.topic = topic;
   }
-}
+
+  public RevId getLastSha1MergeTested() {
+    return lastSha1MergeTested;
+  }
+
+  public void setLastSha1MergeTested(RevId lastSha1MergeTested) {
+    this.lastSha1MergeTested = lastSha1MergeTested;
+  }
+
+  public boolean isMergeable() {
+    return mergeable;
+  }
+
+  public void setMergeable(boolean mergeable) {
+    this.mergeable = mergeable;
+  }
+}

gerrit-server/src/main/java/com/google/gerrit/server/ChangeUtil.java

@@ -25,27 +25,25 @@ import com.google.gerrit.reviewdb.PatchSetInfo;
 import com.google.gerrit.reviewdb.RevId;
 import com.google.gerrit.reviewdb.ReviewDb;
 import com.google.gerrit.reviewdb.TrackingId;
-import com.google.gerrit.server.IdentifiedUser;
 import com.google.gerrit.server.config.TrackingFooter;
 import com.google.gerrit.server.config.TrackingFooters;
 import com.google.gerrit.server.git.GitRepositoryManager;
 import com.google.gerrit.server.git.MergeOp;
 import com.google.gerrit.server.git.MergeQueue;
 import com.google.gerrit.server.git.ReplicationQueue;
-import com.google.gerrit.server.patch.PatchSetInfoFactory;
-import com.google.gerrit.server.patch.PatchSetInfoNotAvailableException;
-import com.google.gerrit.server.project.InvalidChangeOperationException;
-import com.google.gerrit.server.project.NoSuchChangeException;
 import com.google.gerrit.server.mail.AbandonedSender;
 import com.google.gerrit.server.mail.EmailException;
 import com.google.gerrit.server.mail.ReplyToChangeSender;
 import com.google.gerrit.server.mail.RestoredSender;
 import com.google.gerrit.server.mail.RevertedSender;
+import com.google.gerrit.server.patch.PatchSetInfoFactory;
+import com.google.gerrit.server.patch.PatchSetInfoNotAvailableException;
+import com.google.gerrit.server.project.InvalidChangeOperationException;
+import com.google.gerrit.server.project.NoSuchChangeException;
 import com.google.gwtorm.client.AtomicUpdate;
 import com.google.gwtorm.client.OrmConcurrencyException;
 import com.google.gwtorm.client.OrmException;
 
-
 import org.eclipse.jgit.errors.IncorrectObjectTypeException;
 import org.eclipse.jgit.errors.MissingObjectException;
 import org.eclipse.jgit.errors.RepositoryNotFoundException;
@@ -165,6 +163,10 @@ public class ChangeUtil {
     db.trackingIds().delete(toDelete);
   }
 
+  public static void testMerge(MergeOp.Factory opFactory, Change change) {
+    opFactory.create(change.getDest()).verifyMergeability(change);
+  }
+
   public static void submit(final PatchSet.Id patchSetId,
       final IdentifiedUser user, final ReviewDb db,
       final MergeOp.Factory opFactory, final MergeQueue merger)

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

@@ -16,32 +16,50 @@ package com.google.gerrit.server.git;
 
 enum CommitMergeStatus {
   /** */
-  CLEAN_MERGE,
+  CLEAN_MERGE("Change has been successfully merged into the git repository."),
 
   /** */
-  CLEAN_PICK,
+  CLEAN_PICK("Change has been successfully cherry-picked"),
 
   /** */
-  ALREADY_MERGED,
+  ALREADY_MERGED(""),
 
   /** */
-  PATH_CONFLICT,
+  PATH_CONFLICT("Your change could not be merged due to a path conflict.\n"
+                  + "\n"
+                  + "Please merge (or rebase) the change locally and upload the resolution for review."),
 
   /** */
-  MISSING_DEPENDENCY,
+  MISSING_DEPENDENCY(""),
 
   /** */
-  NO_PATCH_SET,
+  NO_PATCH_SET(""),
 
   /** */
-  REVISION_GONE,
+  REVISION_GONE(""),
 
   /** */
-  CRISS_CROSS_MERGE,
+  CRISS_CROSS_MERGE("Your change requires a recursive merge to resolve.\n"
+                  + "\n"
+                  + "Please merge (or rebase) the change locally and upload the resolution for review."),
 
   /** */
-  CANNOT_CHERRY_PICK_ROOT,
+  CANNOT_CHERRY_PICK_ROOT("Cannot cherry-pick an initial commit onto an existing branch.\n"
+                  + "\n"
+                  + "Please merge the change locally and upload the merge commit for review."),
 
   /** */
-  NOT_FAST_FORWARD;
-}
+  NOT_FAST_FORWARD("Project policy requires all submissions to be a fast-forward.\n"
+                  + "\n"
+                  + "Please rebase the change locally and upload again for review.");
+
+  private String message;
+
+  CommitMergeStatus(String message){
+    this.message = message;
+  }
+
+  public String getMessage(){
+    return message;
+  }
+}

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

@@ -20,6 +20,7 @@ import static java.util.concurrent.TimeUnit.MINUTES;
 import com.google.gerrit.common.ChangeHookRunner;
 import com.google.gerrit.common.data.ApprovalType;
 import com.google.gerrit.common.data.ApprovalTypes;
+import com.google.gerrit.common.data.Capable;
 import com.google.gerrit.reviewdb.Account;
 import com.google.gerrit.reviewdb.ApprovalCategory;
 import com.google.gerrit.reviewdb.Branch;
@@ -174,8 +175,7 @@ public class MergeOp {
       @GerritPersonIdent final PersonIdent myIdent,
       final MergeQueue mergeQueue, @Assisted final Branch.NameKey branch,
       final ChangeHookRunner hooks, final AccountCache accountCache,
-      final TagCache tagCache,
-      final CreateCodeReviewNotes.Factory crnf) {
+      final TagCache tagCache, final CreateCodeReviewNotes.Factory crnf) {
     repoManager = grm;
     schemaFactory = sf;
     functionState = fs;
@@ -200,20 +200,76 @@ public class MergeOp {
     commits = new HashMap<Change.Id, CodeReviewCommit>();
   }
 
-  public void merge() throws MergeException {
+  public void verifyMergeability(Change change) {
+    try {
+      setDestProject();
+      openRepository();
+      final Ref destBranchRef = db.getRef(destBranch.get());
+      submitted = new ArrayList<Change>();
+      submitted.add(change);
+
+      // Test mergeability of the change if the last merged sha1
+      // in the branch is different from the last sha1
+      // the change was tested against.
+      if ((destBranchRef == null && change.getLastSha1MergeTested() == null)
+          || change.getLastSha1MergeTested() == null
+          || (destBranchRef != null && !destBranchRef.getObjectId().getName()
+              .equals(change.getLastSha1MergeTested().get()))) {
+        openSchema();
+        preMerge();
+
+        // update sha1 tested merge.
+        if (destBranchRef != null) {
+          change.setLastSha1MergeTested(new RevId(destBranchRef
+              .getObjectId().getName()));
+        } else {
+          change.setLastSha1MergeTested(new RevId(""));
+        }
+        change.setMergeable(isMergeable(change));
+        schema.changes().update(Collections.singleton(change));
+      }
+    } catch (MergeException e) {
+      log.error("Test merge attempt for change: " + change.getId()
+          + " failed", e);
+    } catch (OrmException e) {
+      log.error("Test merge attempt for change: " + change.getId()
+          + " failed: Not able to query the database", e);
+    } catch (IOException e) {
+      log.error("Test merge attempt for change: " + change.getId()
+          + " failed", e);
+    } finally {
+      if (schema != null) {
+        schema.close();
+      }
+      schema = null;
+    }
+  }
+
+  private void setDestProject() throws MergeException {
     final ProjectState pe = projectCache.get(destBranch.getParentKey());
     if (pe == null) {
       throw new MergeException("No such project: " + destBranch.getParentKey());
     }
     destProject = pe.getProject();
+  }
 
-    try {
+  private void openSchema() throws OrmException {
+    if (schema == null) {
       schema = schemaFactory.open();
-    } catch (OrmException e) {
-      throw new MergeException("Cannot open database", e);
     }
+  }
+
+  public void merge() throws MergeException {
+    setDestProject();
     try {
-      mergeImpl();
+      openSchema();
+      openRepository();
+      submitted = schema.changes().submitted(destBranch).toList();
+      preMerge();
+      updateBranch();
+      updateChangeStatus();
+    } catch (OrmException e) {
+      throw new MergeException("Cannot query the database", e);
     } finally {
       if (rw != null) {
         rw.release();
@@ -226,10 +282,8 @@ public class MergeOp {
     }
   }
 
-  private void mergeImpl() throws MergeException {
-    openRepository();
+  private void preMerge() throws MergeException {
     openBranch();
-    listPendingSubmits();
     validateChangeList();
     mergeTip = branchTip;
     switch (destProject.getSubmitType()) {
@@ -246,8 +300,6 @@ public class MergeOp {
         markCleanMerges();
         break;
     }
-    updateBranch();
-    updateChangeStatus();
   }
 
   private void openRepository() throws MergeException {
@@ -298,14 +350,6 @@ public class MergeOp {
     }
   }
 
-  private void listPendingSubmits() throws MergeException {
-    try {
-      submitted = schema.changes().submitted(destBranch).toList();
-    } catch (OrmException e) {
-      throw new MergeException("Cannot query the database", e);
-    }
-  }
-
   private void validateChangeList() throws MergeException {
     final Set<ObjectId> tips = new HashSet<ObjectId>();
     for (final Ref r : db.getAllRefs().values()) {
@@ -942,6 +986,20 @@ public class MergeOp {
     }
   }
 
+  private boolean isMergeable(Change c) throws OrmException {
+    final CodeReviewCommit commit = commits.get(c.getId());
+    final CommitMergeStatus s = commit != null ? commit.statusCode : null;
+    boolean isMergeable = false;
+    if (s != null
+        && (s.equals(CommitMergeStatus.CLEAN_MERGE)
+            || s.equals(CommitMergeStatus.CLEAN_PICK) || s
+            .equals(CommitMergeStatus.ALREADY_MERGED))) {
+      isMergeable = true;
+    }
+
+    return isMergeable;
+  }
+
   private void updateChangeStatus() throws MergeException {
     List<CodeReviewCommit> merged = new ArrayList<CodeReviewCommit>();
 
@@ -955,19 +1013,16 @@ public class MergeOp {
         continue;
       }
 
+      final String txt = s.getMessage();
+
       switch (s) {
         case CLEAN_MERGE: {
-          final String txt =
-              "Change has been successfully merged into the git repository.";
           setMerged(c, message(c, txt));
           merged.add(commit);
           break;
         }
 
         case CLEAN_PICK: {
-          final String txt =
-              "Change has been successfully cherry-picked as " + commit.name()
-                  + ".";
           setMerged(c, message(c, txt));
           merged.add(commit);
           break;
@@ -978,44 +1033,19 @@ public class MergeOp {
           merged.add(commit);
           break;
 
-        case PATH_CONFLICT: {
-          final String txt =
-              "Your change could not be merged due to a path conflict.\n"
-                  + "\n"
-                  + "Please merge (or rebase) the change locally and upload the resolution for review.";
-          setNew(c, message(c, txt));
-          break;
-        }
-
-        case CRISS_CROSS_MERGE: {
-          final String txt =
-              "Your change requires a recursive merge to resolve.\n"
-                  + "\n"
-                  + "Please merge (or rebase) the change locally and upload the resolution for review.";
-          setNew(c, message(c, txt));
-          break;
-        }
-
-        case CANNOT_CHERRY_PICK_ROOT: {
-          final String txt =
-              "Cannot cherry-pick an initial commit onto an existing branch.\n"
-                  + "\n"
-                  + "Please merge the change locally and upload the merge commit for review.";
-          setNew(c, message(c, txt));
-          break;
-        }
-
+        case PATH_CONFLICT:
+        case CRISS_CROSS_MERGE:
+        case CANNOT_CHERRY_PICK_ROOT:
         case NOT_FAST_FORWARD: {
-          final String txt =
-              "Project policy requires all submissions to be a fast-forward.\n"
-                  + "\n"
-                  + "Please rebase the change locally and upload again for review.";
           setNew(c, message(c, txt));
           break;
         }
 
         case MISSING_DEPENDENCY: {
-          dependencyError(commit);
+          final Capable capable = isSubmitStillPossible(commit);
+          if (capable != Capable.OK) {
+            sendMergeFail(c, message(c, capable.getMessage()), false);
+          }
           break;
         }
 
@@ -1036,7 +1066,8 @@ public class MergeOp {
         GitRepositoryManager.REFS_NOTES_REVIEW);
   }
 
-  private void dependencyError(final CodeReviewCommit commit) {
+  private Capable isSubmitStillPossible(final CodeReviewCommit commit) {
+    final Capable capable;
     final Change c = commit.change;
     if (commit.missing == null) {
       commit.missing = new ArrayList<CodeReviewCommit>();
@@ -1071,7 +1102,7 @@ public class MergeOp {
       // this change submitted. Reschedule an attempt in a bit.
       //
       mergeQueue.recheckAfter(destBranch, waitUntil - now, MILLISECONDS);
-
+      capable = Capable.OK;
     } else if (submitStillPossible) {
       // It would be possible to submit the change if the missing
       // dependencies are also submitted. Perhaps the user just
@@ -1095,9 +1126,7 @@ public class MergeOp {
         }
         txt = m.toString();
       }
-
-      sendMergeFail(c, message(c, txt), false);
-
+      capable = new Capable(txt);
     } else {
       // It is impossible to submit this change as-is. The author
       // needs to rebase it in order to work around the missing
@@ -1127,9 +1156,10 @@ public class MergeOp {
       }
       m.append("\n");
       m.append("Please rebase the change and upload a replacement commit.");
-
-      setNew(c, message(c, m.toString()));
+      capable = new Capable(m.toString());
     }
+
+    return capable;
   }
 
   private void loadChangeInfo(final CodeReviewCommit commit) {
@@ -1215,6 +1245,10 @@ public class MergeOp {
         @Override
         public Change update(Change c) {
           c.setStatus(Change.Status.MERGED);
+          // It could be possible that the change being merged
+          // has never had its mergeability tested. So we insure
+          // merged changes has mergeable field true.
+          c.setMergeable(true);
           if (!merged.equals(c.currentPatchSetId())) {
             // Uncool; the patch set changed after we merged it.
             // Go back to the patch set that was actually merged.

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

@@ -1169,6 +1169,7 @@ public class ReceiveCommits implements PreReceiveHook, PostReceiveHook {
           public Change update(Change change) {
             if (change.getStatus().isOpen()) {
               change.nextPatchSetId();
+              change.setLastSha1MergeTested(null);
               return change;
             } else {
               return null;

gerrit-server/src/main/java/com/google/gerrit/server/schema/SchemaVersion.java

@@ -32,7 +32,7 @@ import java.util.List;
 /** A version of the database schema. */
 public abstract class SchemaVersion {
   /** The current schema version. */
-  private static final Class<? extends SchemaVersion> C = Schema_58.class;
+  private static final Class<? extends SchemaVersion> C = Schema_59.class;
 
   public static class Module extends AbstractModule {
     @Override

gerrit-server/src/main/java/com/google/gerrit/server/schema/Schema_59.java

@@ -0,0 +1,42 @@
+// Copyright (C) 2011 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.google.gerrit.server.schema;
+
+import com.google.gerrit.reviewdb.Change;
+import com.google.gerrit.reviewdb.ReviewDb;
+import com.google.gwtorm.client.OrmException;
+import com.google.inject.Inject;
+import com.google.inject.Provider;
+
+import java.sql.SQLException;
+import java.util.List;
+
+public class Schema_59 extends SchemaVersion {
+  @Inject
+  Schema_59(Provider<Schema_58> prior) {
+    super(prior);
+  }
+
+  @Override
+  protected void migrateData(ReviewDb db, UpdateUI ui) throws OrmException,
+      SQLException {
+    List<Change> allChanges = db.changes().all().toList();
+    for (Change change : allChanges) {
+      change.setMergeable(true);
+      change.setLastSha1MergeTested(null);
+    }
+    db.changes().update(allChanges);
+  }
+}