Replace ACCOUNT_DIFF_PREFERENCES table with Git backend (part1)

Replace the usage of AccountDiffPreference with a different class in
extension API package.

Data is saved optimized in Git backend: default values are discarded
during save operation and restored during read operation; so that
this optimization step is transparent for the callers.

For example when only one setting, theme in this case, differs from
the default value, only this value is written into diff section in
preferences.config file:

+[diff]
+       theme = eclipse

To support live migration, the upgrade is done in two steps:

* part1 (this change):
  o Always write to both git and db
  o Introduce new configuration option to indicate whether to read from
    git or db, initially set to read from db
  o First binary update: some servers are reading/writing just the db;
    some servers are additionally writing to git
  o After first update: all servers are reading from the db, writing to
    both
  o Batch copy data from db to git (only related to non open source
    Gerrit version)
  o Update all servers to read from git. During the update, some will
    still be reading from the db; that's ok, because everybody is
    writing to git
* part2 (next change):
  o Bump database version, migrate the data from db to git, delete the
    table (and the flag) from the code and update the servers.

Change-Id: I30a6d82f4a8d0c33ae9bb26d7f93c66bd0cb8bee

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/rest/account/DiffPreferencesIT.java

@@ -0,0 +1,160 @@
+// Copyright (C) 2015 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.acceptance.rest.account;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.assertEquals;
+
+import com.google.gerrit.acceptance.AbstractDaemonTest;
+import com.google.gerrit.acceptance.RestResponse;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo.Whitespace;
+import com.google.gerrit.extensions.client.Theme;
+import com.google.gerrit.testutil.ConfigSuite;
+
+import org.apache.http.HttpStatus;
+import org.eclipse.jgit.lib.Config;
+import org.junit.Test;
+
+public class DiffPreferencesIT extends AbstractDaemonTest {
+  @ConfigSuite.Config
+  public static Config readFromGitConfig() {
+    Config cfg = new Config();
+    cfg.setBoolean("user", null, "readPrefsFromGit", true);
+    return cfg;
+  }
+
+  @Test
+  public void getDiffPreferencesOfNonExistingAccount_NotFound()
+      throws Exception {
+    assertEquals(HttpStatus.SC_NOT_FOUND,
+        adminSession.get("/accounts/non-existing/preferences.diff")
+        .getStatusCode());
+  }
+
+  @Test
+  public void getDiffPreferences() throws Exception {
+    RestResponse r = adminSession.get("/accounts/" + admin.email
+        + "/preferences.diff");
+    assertEquals(HttpStatus.SC_OK, r.getStatusCode());
+    DiffPreferencesInfo d = DiffPreferencesInfo.defaults();
+    DiffPreferencesInfo o =
+        newGson().fromJson(r.getReader(), DiffPreferencesInfo.class);
+
+    assertThat(o.context).isEqualTo(d.context);
+    assertThat(o.tabSize).isEqualTo(d.tabSize);
+    assertThat(o.lineLength).isEqualTo(d.lineLength);
+    assertThat(o.expandAllComments).isNull();
+    assertThat(o.intralineDifference).isEqualTo(d.intralineDifference);
+    assertThat(o.manualReview).isNull();
+    assertThat(o.retainHeader).isNull();
+    assertThat(o.showLineEndings).isEqualTo(d.showLineEndings);
+    assertThat(o.showTabs).isEqualTo(d.showTabs);
+    assertThat(o.showWhitespaceErrors).isEqualTo(d.showWhitespaceErrors);
+    assertThat(o.skipDeleted).isNull();
+    assertThat(o.skipUncommented).isNull();
+    assertThat(o.syntaxHighlighting).isEqualTo(d.syntaxHighlighting);
+    assertThat(o.hideTopMenu).isNull();
+    assertThat(o.autoHideDiffTableHeader).isEqualTo(d.autoHideDiffTableHeader);
+    assertThat(o.hideLineNumbers).isNull();
+    assertThat(o.renderEntireFile).isNull();
+    assertThat(o.hideEmptyPane).isNull();
+    assertThat(o.ignoreWhitespace).isEqualTo(d.ignoreWhitespace);
+    assertThat(o.theme).isEqualTo(d.theme);
+  }
+
+  @Test
+  public void setDiffPreferences() throws Exception {
+    DiffPreferencesInfo i = DiffPreferencesInfo.defaults();
+
+    // change all default values
+    i.context *= -1;
+    i.tabSize *= -1;
+    i.lineLength *= -1;
+    i.theme = Theme.MIDNIGHT;
+    i.ignoreWhitespace = Whitespace.IGNORE_ALL;
+    i.expandAllComments ^= true;
+    i.intralineDifference ^= true;
+    i.manualReview ^= true;
+    i.retainHeader ^= true;
+    i.showLineEndings ^= true;
+    i.showTabs ^= true;
+    i.showWhitespaceErrors ^= true;
+    i.skipDeleted ^= true;
+    i.skipUncommented ^= true;
+    i.syntaxHighlighting ^= true;
+    i.hideTopMenu ^= true;
+    i.autoHideDiffTableHeader ^= true;
+    i.hideLineNumbers ^= true;
+    i.renderEntireFile ^= true;
+    i.hideEmptyPane ^= true;
+
+    RestResponse r = adminSession.put("/accounts/" + admin.email
+        + "/preferences.diff", i);
+    assertEquals(HttpStatus.SC_OK, r.getStatusCode());
+    DiffPreferencesInfo o = newGson().fromJson(r.getReader(),
+        DiffPreferencesInfo.class);
+
+    assertThat(o.context).isEqualTo(i.context);
+    assertThat(o.tabSize).isEqualTo(i.tabSize);
+    assertThat(o.lineLength).isEqualTo(i.lineLength);
+    assertThat(o.expandAllComments).isEqualTo(i.expandAllComments);
+    assertThat(o.intralineDifference).isNull();
+    assertThat(o.manualReview).isEqualTo(i.manualReview);
+    assertThat(o.retainHeader).isEqualTo(i.retainHeader);
+    assertThat(o.showLineEndings).isNull();
+    assertThat(o.showTabs).isNull();
+    assertThat(o.showWhitespaceErrors).isNull();
+    assertThat(o.skipDeleted).isEqualTo(i.skipDeleted);
+    assertThat(o.skipUncommented).isEqualTo(i.skipUncommented);
+    assertThat(o.syntaxHighlighting).isNull();
+    assertThat(o.hideTopMenu).isEqualTo(i.hideTopMenu);
+    assertThat(o.autoHideDiffTableHeader).isNull();
+    assertThat(o.hideLineNumbers).isEqualTo(i.hideLineNumbers);
+    assertThat(o.renderEntireFile).isEqualTo(i.renderEntireFile);
+    assertThat(o.hideEmptyPane).isEqualTo(i.hideEmptyPane);
+    assertThat(o.ignoreWhitespace).isEqualTo(i.ignoreWhitespace);
+    assertThat(o.theme).isEqualTo(i.theme);
+
+    // Partially fill input record
+    i = new DiffPreferencesInfo();
+    i.tabSize = 42;
+    r = adminSession.put("/accounts/" + admin.email
+        + "/preferences.diff", i);
+    DiffPreferencesInfo a = newGson().fromJson(r.getReader(),
+        DiffPreferencesInfo.class);
+
+    assertThat(a.context).isEqualTo(o.context);
+    assertThat(a.tabSize).isEqualTo(42);
+    assertThat(a.lineLength).isEqualTo(o.lineLength);
+    assertThat(a.expandAllComments).isEqualTo(o.expandAllComments);
+    assertThat(a.intralineDifference).isNull();
+    assertThat(a.manualReview).isEqualTo(o.manualReview);
+    assertThat(a.retainHeader).isEqualTo(o.retainHeader);
+    assertThat(a.showLineEndings).isNull();
+    assertThat(a.showTabs).isNull();
+    assertThat(a.showWhitespaceErrors).isNull();
+    assertThat(a.skipDeleted).isEqualTo(o.skipDeleted);
+    assertThat(a.skipUncommented).isEqualTo(o.skipUncommented);
+    assertThat(a.syntaxHighlighting).isNull();
+    assertThat(a.hideTopMenu).isEqualTo(o.hideTopMenu);
+    assertThat(a.autoHideDiffTableHeader).isNull();
+    assertThat(a.hideLineNumbers).isEqualTo(o.hideLineNumbers);
+    assertThat(a.renderEntireFile).isEqualTo(o.renderEntireFile);
+    assertThat(a.hideEmptyPane).isEqualTo(o.hideEmptyPane);
+    assertThat(a.ignoreWhitespace).isEqualTo(o.ignoreWhitespace);
+    assertThat(a.theme).isEqualTo(o.theme);
+  }
+}

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/rest/account/GetDiffPreferencesIT.java

@@ -1,67 +0,0 @@
-// Copyright (C) 2013 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.acceptance.rest.account;
-
-import static com.google.common.truth.Truth.assertThat;
-
-import com.google.gerrit.acceptance.AbstractDaemonTest;
-import com.google.gerrit.acceptance.RestResponse;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
-import com.google.gerrit.server.account.GetDiffPreferences.DiffPreferencesInfo;
-
-import org.apache.http.HttpStatus;
-import org.junit.Test;
-
-public class GetDiffPreferencesIT extends AbstractDaemonTest {
-  @Test
-  public void getDiffPreferencesOfNonExistingAccount_NotFound()
-      throws Exception {
-    assertThat(adminSession.get("/accounts/non-existing/preferences.diff").getStatusCode())
-      .isEqualTo(HttpStatus.SC_NOT_FOUND);
-  }
-
-  @Test
-  public void getDiffPreferences() throws Exception {
-    RestResponse r = adminSession.get("/accounts/" + admin.email + "/preferences.diff");
-    assertThat(r.getStatusCode()).isEqualTo(HttpStatus.SC_OK);
-    DiffPreferencesInfo diffPreferences =
-        newGson().fromJson(r.getReader(), DiffPreferencesInfo.class);
-    assertDiffPreferences(new AccountDiffPreference(admin.id), diffPreferences);
-  }
-
-  private static void assertDiffPreferences(AccountDiffPreference expected, DiffPreferencesInfo actual) {
-    assertThat(actual.context).isEqualTo(expected.getContext());
-    assertThat(toBoolean(actual.expandAllComments)).isEqualTo(expected.isExpandAllComments());
-    assertThat(actual.ignoreWhitespace).isEqualTo(expected.getIgnoreWhitespace());
-    assertThat(toBoolean(actual.intralineDifference)).isEqualTo(expected.isIntralineDifference());
-    assertThat(actual.lineLength).isEqualTo(expected.getLineLength());
-    assertThat(toBoolean(actual.manualReview)).isEqualTo(expected.isManualReview());
-    assertThat(toBoolean(actual.retainHeader)).isEqualTo(expected.isRetainHeader());
-    assertThat(toBoolean(actual.showLineEndings)).isEqualTo(expected.isShowLineEndings());
-    assertThat(toBoolean(actual.showTabs)).isEqualTo(expected.isShowTabs());
-    assertThat(toBoolean(actual.showWhitespaceErrors)).isEqualTo(expected.isShowWhitespaceErrors());
-    assertThat(toBoolean(actual.skipDeleted)).isEqualTo(expected.isSkipDeleted());
-    assertThat(toBoolean(actual.skipUncommented)).isEqualTo(expected.isSkipUncommented());
-    assertThat(toBoolean(actual.syntaxHighlighting)).isEqualTo(expected.isSyntaxHighlighting());
-    assertThat(actual.tabSize).isEqualTo(expected.getTabSize());
-  }
-
-  private static boolean toBoolean(Boolean b) {
-    if (b == null) {
-      return false;
-    }
-    return b.booleanValue();
-  }
-}

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/server/change/PatchListCacheIT.java

@@ -20,8 +20,8 @@ import static com.google.gerrit.acceptance.GitUtil.pushHead;
 
 import com.google.gerrit.acceptance.AbstractDaemonTest;
 import com.google.gerrit.acceptance.NoHttpd;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo.Whitespace;
 import com.google.gerrit.extensions.restapi.RestApiException;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference.Whitespace;
 import com.google.gerrit.reviewdb.client.Patch;
 import com.google.gerrit.reviewdb.client.Patch.ChangeType;
 import com.google.gerrit.server.patch.PatchListCache;

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

@@ -16,8 +16,8 @@ package com.google.gerrit.common.data;
 
 import com.google.gerrit.common.audit.Audit;
 import com.google.gerrit.common.auth.SignInRequired;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
 import com.google.gerrit.reviewdb.client.Account;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
 import com.google.gerrit.reviewdb.client.AccountProjectWatch;
 import com.google.gwtjsonrpc.common.AsyncCallback;
 import com.google.gwtjsonrpc.common.RemoteJsonService;
@@ -35,7 +35,7 @@ public interface AccountService extends RemoteJsonService {
 
   @Audit
   @SignInRequired
-  void changeDiffPreferences(AccountDiffPreference diffPref,
+  void changeDiffPreferences(DiffPreferencesInfo diffPref,
       AsyncCallback<VoidResult> callback);
 
   @SignInRequired

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

@@ -15,7 +15,7 @@
 package com.google.gerrit.common.data;
 
 import com.google.gerrit.common.audit.Audit;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
 import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gwtjsonrpc.common.AsyncCallback;
 import com.google.gwtjsonrpc.common.RemoteJsonService;
@@ -29,5 +29,5 @@ public interface ChangeDetailService extends RemoteJsonService {
 
   @Audit
   void patchSetDetail2(PatchSet.Id baseId, PatchSet.Id key,
-      AccountDiffPreference diffPrefs, AsyncCallback<PatchSetDetail> callback);
+      DiffPreferencesInfo diffPrefs, AsyncCallback<PatchSetDetail> callback);
 }

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

@@ -14,7 +14,7 @@
 
 package com.google.gerrit.common.data;
 
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
 
 import java.util.Date;
 import java.util.List;
@@ -22,7 +22,7 @@ import java.util.List;
 /** Data sent as part of the host page, to bootstrap the UI. */
 public class HostPageData {
   public String version;
-  public AccountDiffPreference accountDiffPref;
+  public DiffPreferencesInfo accountDiffPref;
   public String xGerritAuth;
   public Theme theme;
   public List<String> plugins;

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

@@ -15,7 +15,7 @@
 package com.google.gerrit.common.data;
 
 import com.google.gerrit.common.audit.Audit;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
 import com.google.gerrit.reviewdb.client.Patch;
 import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gwtjsonrpc.common.AsyncCallback;
@@ -27,5 +27,5 @@ import com.google.gwtjsonrpc.common.RpcImpl.Version;
 public interface PatchDetailService extends RemoteJsonService {
   @Audit
   void patchScript(Patch.Key key, PatchSet.Id a, PatchSet.Id b,
-      AccountDiffPreference diffPrefs, AsyncCallback<PatchScript> callback);
+      DiffPreferencesInfo diffPrefs, AsyncCallback<PatchScript> callback);
 }

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

@@ -14,10 +14,10 @@
 
 package com.google.gerrit.common.data;
 
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo.Whitespace;
 import com.google.gerrit.prettify.common.EditList;
 import com.google.gerrit.prettify.common.SparseFileContent;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference.Whitespace;
 import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.reviewdb.client.Patch;
 import com.google.gerrit.reviewdb.client.Patch.ChangeType;
@@ -42,7 +42,7 @@ public class PatchScript {
   protected FileMode oldMode;
   protected FileMode newMode;
   protected List<String> header;
-  protected AccountDiffPreference diffPrefs;
+  protected DiffPreferencesInfo diffPrefs;
   protected SparseFileContent a;
   protected SparseFileContent b;
   protected List<Edit> edits;
@@ -62,7 +62,7 @@ public class PatchScript {
 
   public PatchScript(final Change.Key ck, final ChangeType ct, final String on,
       final String nn, final FileMode om, final FileMode nm,
-      final List<String> h, final AccountDiffPreference dp,
+      final List<String> h, final DiffPreferencesInfo dp,
       final SparseFileContent ca, final SparseFileContent cb,
       final List<Edit> e, final DisplayMethod ma, final DisplayMethod mb,
       final String mta, final String mtb, final CommentDetail cd,
@@ -142,11 +142,11 @@ public class PatchScript {
     return history;
   }
 
-  public AccountDiffPreference getDiffPrefs() {
+  public DiffPreferencesInfo getDiffPrefs() {
     return diffPrefs;
   }
 
-  public void setDiffPrefs(AccountDiffPreference dp) {
+  public void setDiffPrefs(DiffPreferencesInfo dp) {
     diffPrefs = dp;
   }
 
@@ -155,7 +155,7 @@ public class PatchScript {
   }
 
   public boolean isIgnoreWhitespace() {
-    return diffPrefs.getIgnoreWhitespace() != Whitespace.IGNORE_NONE;
+    return diffPrefs.ignoreWhitespace != Whitespace.IGNORE_NONE;
   }
 
   public boolean hasIntralineDifference() {
@@ -171,7 +171,7 @@ public class PatchScript {
   }
 
   public boolean isExpandAllComments() {
-    return diffPrefs.isExpandAllComments();
+    return diffPrefs.expandAllComments;
   }
 
   public SparseFileContent getA() {
@@ -195,8 +195,8 @@ public class PatchScript {
   }
 
   public Iterable<EditList.Hunk> getHunks() {
-    int ctx = diffPrefs.getContext();
+    int ctx = diffPrefs.context;
-    if (ctx == AccountDiffPreference.WHOLE_FILE_CONTEXT) {
+    if (ctx == DiffPreferencesInfo.WHOLE_FILE_CONTEXT) {
       ctx = Math.max(a.size(), b.size());
     }
     return new EditList(edits, ctx, a.size(), b.size()).getHunks();

gerrit-extension-api/src/main/java/com/google/gerrit/extensions/client/DiffPreferencesInfo.java

@@ -0,0 +1,87 @@
+// Copyright (C) 2014 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.extensions.client;
+
+public class DiffPreferencesInfo {
+
+  /** Default number of lines of context. */
+  public static final int DEFAULT_CONTEXT = 10;
+
+  /** Default tab size. */
+  public static final int DEFAULT_TAB_SIZE = 8;
+
+  /** Default line length. */
+  public static final int DEFAULT_LINE_LENGTH = 100;
+
+  /** Context setting to display the entire file. */
+  public static final short WHOLE_FILE_CONTEXT = -1;
+
+  /** Typical valid choices for the default context setting. */
+  public static final short[] CONTEXT_CHOICES =
+      {3, 10, 25, 50, 75, 100, WHOLE_FILE_CONTEXT};
+
+  public static enum Whitespace {
+    IGNORE_NONE,
+    IGNORE_TRAILING,
+    IGNORE_LEADING_AND_TRAILING,
+    IGNORE_ALL;
+  }
+
+  public Integer context;
+  public Integer tabSize;
+  public Integer lineLength;
+  public Boolean expandAllComments;
+  public Boolean intralineDifference;
+  public Boolean manualReview;
+  public Boolean showLineEndings;
+  public Boolean showTabs;
+  public Boolean showWhitespaceErrors;
+  public Boolean syntaxHighlighting;
+  public Boolean hideTopMenu;
+  public Boolean autoHideDiffTableHeader;
+  public Boolean hideLineNumbers;
+  public Boolean renderEntireFile;
+  public Boolean hideEmptyPane;
+  public Theme theme;
+  public Whitespace ignoreWhitespace;
+  public Boolean retainHeader;
+  public Boolean skipDeleted;
+  public Boolean skipUncommented;
+
+  public static DiffPreferencesInfo defaults() {
+    DiffPreferencesInfo i = new DiffPreferencesInfo();
+    i.context = DEFAULT_CONTEXT;
+    i.tabSize = DEFAULT_TAB_SIZE;
+    i.lineLength = DEFAULT_LINE_LENGTH;
+    i.ignoreWhitespace = Whitespace.IGNORE_NONE;
+    i.theme = Theme.DEFAULT;
+    i.expandAllComments = false;
+    i.intralineDifference = true;
+    i.manualReview = false;
+    i.retainHeader = false;
+    i.showLineEndings = true;
+    i.showTabs = true;
+    i.showWhitespaceErrors = true;
+    i.skipDeleted = false;
+    i.skipUncommented = false;
+    i.syntaxHighlighting = true;
+    i.hideTopMenu = false;
+    i.autoHideDiffTableHeader = true;
+    i.hideLineNumbers = false;
+    i.renderEntireFile = false;
+    i.hideEmptyPane = false;
+    return i;
+  }
+}

gerrit-gwtui/src/main/java/com/google/gerrit/client/Gerrit.java

@@ -47,9 +47,9 @@ import com.google.gerrit.client.ui.Screen;
 import com.google.gerrit.common.PageLinks;
 import com.google.gerrit.common.data.HostPageData;
 import com.google.gerrit.common.data.SystemInfoService;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
 import com.google.gerrit.extensions.client.EditPreferencesInfo;
 import com.google.gerrit.extensions.client.GerritTopMenu;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gwt.aria.client.Roles;
 import com.google.gwt.core.client.EntryPoint;
@@ -119,7 +119,7 @@ public class Gerrit implements EntryPoint {
   private static String docUrl;
   private static HostPageData.Theme myTheme;
   private static String defaultScreenToken;
-  private static AccountDiffPreference myAccountDiffPref;
+  private static DiffPreferencesInfo myAccountDiffPref;
   private static EditPreferencesInfo editPrefs;
   private static String xGerritAuth;
   private static boolean isNoteDbEnabled;
@@ -321,12 +321,12 @@ public class Gerrit implements EntryPoint {
     return myPrefs;
   }
 
-  /** @return the currently signed in users's diff preferences; null if no diff preferences defined for the account */
+  /** @return the currently signed in users's diff preferences, or default values */
-  public static AccountDiffPreference getAccountDiffPreference() {
+  public static DiffPreferencesInfo getDiffPreferences() {
     return myAccountDiffPref;
   }
 
-  public static void setAccountDiffPreference(AccountDiffPreference accountDiffPref) {
+  public static void setDiffPreferences(DiffPreferencesInfo accountDiffPref) {
     myAccountDiffPref = accountDiffPref;
   }
 

gerrit-gwtui/src/main/java/com/google/gerrit/client/account/DiffPreferences.java

@@ -14,55 +14,58 @@
 
 package com.google.gerrit.client.account;
 
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
 import com.google.gerrit.extensions.client.Theme;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo.Whitespace;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference.Whitespace;
 import com.google.gwt.core.client.JavaScriptObject;
 
 public class DiffPreferences extends JavaScriptObject {
-  public static DiffPreferences create(AccountDiffPreference in) {
+  public static DiffPreferences create(DiffPreferencesInfo in) {
     DiffPreferences p = createObject().cast();
-    if (in == null) {
+    p.ignoreWhitespace(in.ignoreWhitespace);
-      in = AccountDiffPreference.createDefault(null);
+    p.tabSize(in.tabSize);
-    }
+    p.lineLength(in.lineLength);
-    p.ignoreWhitespace(in.getIgnoreWhitespace());
+    p.context(in.context);
-    p.tabSize(in.getTabSize());
+    p.intralineDifference(in.intralineDifference);
-    p.lineLength(in.getLineLength());
+    p.showLineEndings(in.showLineEndings);
-    p.context(in.getContext());
+    p.showTabs(in.showTabs);
-    p.intralineDifference(in.isIntralineDifference());
+    p.showWhitespaceErrors(in.showWhitespaceErrors);
-    p.showLineEndings(in.isShowLineEndings());
+    p.syntaxHighlighting(in.syntaxHighlighting);
-    p.showTabs(in.isShowTabs());
+    p.hideTopMenu(in.hideTopMenu);
-    p.showWhitespaceErrors(in.isShowWhitespaceErrors());
+    p.autoHideDiffTableHeader(in.autoHideDiffTableHeader);
-    p.syntaxHighlighting(in.isSyntaxHighlighting());
+    p.hideLineNumbers(in.hideLineNumbers);
-    p.hideTopMenu(in.isHideTopMenu());
+    p.expandAllComments(in.expandAllComments);
-    p.autoHideDiffTableHeader(in.isAutoHideDiffTableHeader());
+    p.manualReview(in.manualReview);
-    p.hideLineNumbers(in.isHideLineNumbers());
+    p.renderEntireFile(in.renderEntireFile);
-    p.expandAllComments(in.isExpandAllComments());
+    p.theme(in.theme);
-    p.manualReview(in.isManualReview());
+    p.hideEmptyPane(in.hideEmptyPane);
-    p.renderEntireFile(in.isRenderEntireFile());
+    p.retainHeader(in.retainHeader);
-    p.theme(in.getTheme());
+    p.skipUncommented(in.skipUncommented);
-    p.hideEmptyPane(in.isHideEmptyPane());
+    p.skipDeleted(in.skipDeleted);
     return p;
   }
 
-  public final void copyTo(AccountDiffPreference p) {
+  public final void copyTo(DiffPreferencesInfo p) {
-    p.setIgnoreWhitespace(ignoreWhitespace());
+    p.context = context();
-    p.setTabSize(tabSize());
+    p.tabSize = tabSize();
-    p.setLineLength(lineLength());
+    p.lineLength = lineLength();
-    p.setContext((short)context());
+    p.expandAllComments = expandAllComments();
-    p.setIntralineDifference(intralineDifference());
+    p.intralineDifference = intralineDifference();
-    p.setShowLineEndings(showLineEndings());
+    p.manualReview = manualReview();
-    p.setShowTabs(showTabs());
+    p.retainHeader = retainHeader();
-    p.setShowWhitespaceErrors(showWhitespaceErrors());
+    p.showLineEndings = showLineEndings();
-    p.setSyntaxHighlighting(syntaxHighlighting());
+    p.showTabs = showTabs();
-    p.setHideTopMenu(hideTopMenu());
+    p.showWhitespaceErrors = showWhitespaceErrors();
-    p.setAutoHideDiffTableHeader(autoHideDiffTableHeader());
+    p.skipDeleted = skipDeleted();
-    p.setHideLineNumbers(hideLineNumbers());
+    p.skipUncommented = skipUncommented();
-    p.setExpandAllComments(expandAllComments());
+    p.syntaxHighlighting = syntaxHighlighting();
-    p.setManualReview(manualReview());
+    p.hideTopMenu = hideTopMenu();
-    p.setRenderEntireFile(renderEntireFile());
+    p.autoHideDiffTableHeader = autoHideDiffTableHeader();
-    p.setTheme(theme());
+    p.hideLineNumbers = hideLineNumbers();
-    p.setHideEmptyPane(hideEmptyPane());
+    p.renderEntireFile = renderEntireFile();
+    p.hideEmptyPane = hideEmptyPane();
+    p.theme = theme();
+    p.ignoreWhitespace = ignoreWhitespace();
   }
 
   public final void ignoreWhitespace(Whitespace i) {
@@ -122,6 +125,9 @@ public class DiffPreferences extends JavaScriptObject {
   public final native void manualReview(boolean r) /*-{ this.manual_review = r }-*/;
   public final native void renderEntireFile(boolean r) /*-{ this.render_entire_file = r }-*/;
   public final native void hideEmptyPane(boolean s) /*-{ this.hide_empty_pane = s }-*/;
+  public final native void retainHeader(boolean r) /*-{ this.retain_header = r }-*/;
+  public final native void skipUncommented(boolean s) /*-{ this.skip_uncommented = s }-*/;
+  public final native void skipDeleted(boolean s) /*-{ this.skip_deleted = s }-*/;
   public final native boolean intralineDifference() /*-{ return this.intraline_difference || false }-*/;
   public final native boolean showLineEndings() /*-{ return this.show_line_endings || false }-*/;
   public final native boolean showTabs() /*-{ return this.show_tabs || false }-*/;
@@ -134,6 +140,9 @@ public class DiffPreferences extends JavaScriptObject {
   public final native boolean manualReview() /*-{ return this.manual_review || false }-*/;
   public final native boolean renderEntireFile() /*-{ return this.render_entire_file || false }-*/;
   public final native boolean hideEmptyPane() /*-{ return this.hide_empty_pane || false }-*/;
+  public final native boolean retainHeader() /*-{ return this.retain_header || false }-*/;
+  public final native boolean skipUncommented() /*-{ return this.skip_uncommented || false }-*/;
+  public final native boolean skipDeleted() /*-{ return this.skip_deleted || false }-*/;
 
   private final native void setThemeRaw(String i) /*-{ this.theme = i }-*/;
   private final native void setIgnoreWhitespaceRaw(String i) /*-{ this.ignore_whitespace = i }-*/;

gerrit-gwtui/src/main/java/com/google/gerrit/client/account/MyDiffPreferencesScreen.java

@@ -25,7 +25,7 @@ public class MyDiffPreferencesScreen extends SettingsScreen {
     super.onInitUI();
 
     PreferencesBox pb = new PreferencesBox(null);
-    pb.set(DiffPreferences.create(Gerrit.getAccountDiffPreference()));
+    pb.set(DiffPreferences.create(Gerrit.getDiffPreferences()));
     FlowPanel p = new FlowPanel();
     p.setStyleName(pb.getStyle().dialog());
     p.add(pb);

gerrit-gwtui/src/main/java/com/google/gerrit/client/diff/DiffApi.java

@@ -18,7 +18,7 @@ import com.google.gerrit.client.changes.ChangeApi;
 import com.google.gerrit.client.info.FileInfo;
 import com.google.gerrit.client.rpc.NativeMap;
 import com.google.gerrit.client.rpc.RestApi;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
 import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gwt.user.client.rpc.AsyncCallback;
 
@@ -69,7 +69,7 @@ public class DiffApi {
     return this;
   }
 
-  public DiffApi ignoreWhitespace(AccountDiffPreference.Whitespace w) {
+  public DiffApi ignoreWhitespace(DiffPreferencesInfo.Whitespace w) {
     switch (w) {
       default:
       case IGNORE_NONE:

gerrit-gwtui/src/main/java/com/google/gerrit/client/diff/PreferencesBox.java

@@ -29,9 +29,9 @@ import com.google.gerrit.client.patches.PatchUtil;
 import com.google.gerrit.client.rpc.GerritCallback;
 import com.google.gerrit.client.rpc.Natives;
 import com.google.gerrit.client.ui.NpIntTextBox;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo.Whitespace;
 import com.google.gerrit.extensions.client.Theme;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference.Whitespace;
 import com.google.gerrit.reviewdb.client.Patch;
 import com.google.gerrit.reviewdb.client.Patch.ChangeType;
 import com.google.gwt.core.client.GWT;
@@ -503,12 +503,9 @@ public class PreferencesBox extends Composite {
     AccountApi.putDiffPreferences(prefs, new GerritCallback<DiffPreferences>() {
       @Override
       public void onSuccess(DiffPreferences result) {
-        AccountDiffPreference p = Gerrit.getAccountDiffPreference();
+        DiffPreferencesInfo p = Gerrit.getDiffPreferences();
-        if (p == null) {
-          p = AccountDiffPreference.createDefault(Gerrit.getUserAccount().getId());
-        }
         result.copyTo(p);
-        Gerrit.setAccountDiffPreference(p);
+        Gerrit.setDiffPreferences(p);
       }
     });
     if (view != null) {

gerrit-gwtui/src/main/java/com/google/gerrit/client/diff/SideBySide.java

@@ -14,7 +14,8 @@
 
 package com.google.gerrit.client.diff;
 
-import static com.google.gerrit.reviewdb.client.AccountDiffPreference.WHOLE_FILE_CONTEXT;
+import static com.google.gerrit.extensions.client.DiffPreferencesInfo.WHOLE_FILE_CONTEXT;
+
 import static java.lang.Double.POSITIVE_INFINITY;
 
 import com.google.gerrit.client.Dispatcher;
@@ -151,7 +152,7 @@ public class SideBySide extends Screen {
     this.startSide = startSide;
     this.startLine = startLine;
 
-    prefs = DiffPreferences.create(Gerrit.getAccountDiffPreference());
+    prefs = DiffPreferences.create(Gerrit.getDiffPreferences());
     handlers = new ArrayList<>(6);
     keysNavigation = new KeyCommandSet(Gerrit.C.sectionNavigation());
     header = new Header(keysNavigation, base, revision, path);

gerrit-gwtui/src/main/java/com/google/gerrit/client/diff/SkipManager.java

@@ -16,7 +16,7 @@ package com.google.gerrit.client.diff;
 
 import com.google.gerrit.client.diff.DiffInfo.Region;
 import com.google.gerrit.client.patches.SkippedLine;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
 import com.google.gwt.core.client.JsArray;
 
 import net.codemirror.lib.CodeMirror;
@@ -39,7 +39,7 @@ class SkipManager {
   }
 
   void render(int context, DiffInfo diff) {
-    if (context == AccountDiffPreference.WHOLE_FILE_CONTEXT) {
+    if (context == DiffPreferencesInfo.WHOLE_FILE_CONTEXT) {
       return;
     }
 

gerrit-gwtui/src/main/java/com/google/gerrit/client/patches/AbstractPatchContentTable.java

@@ -28,11 +28,11 @@ import com.google.gerrit.common.data.AccountInfoCache;
 import com.google.gerrit.common.data.CommentDetail;
 import com.google.gerrit.common.data.PatchScript;
 import com.google.gerrit.common.data.PatchSetDetail;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
 import com.google.gerrit.prettify.client.ClientSideFormatter;
 import com.google.gerrit.prettify.client.PrettyFormatter;
 import com.google.gerrit.prettify.client.SparseHtmlFile;
 import com.google.gerrit.prettify.common.SparseFileContent;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
 import com.google.gerrit.reviewdb.client.Patch;
 import com.google.gerrit.reviewdb.client.PatchLineComment;
 import com.google.gerrit.reviewdb.client.PatchSet;
@@ -286,8 +286,8 @@ abstract class AbstractPatchContentTable extends NavigationTable<Object>
   }
 
   protected SparseHtmlFile getSparseHtmlFileA(PatchScript s) {
-    AccountDiffPreference dp = new AccountDiffPreference(s.getDiffPrefs());
+    DiffPreferencesInfo dp = s.getDiffPrefs();
-    dp.setShowWhitespaceErrors(false);
+    dp.showWhitespaceErrors = false;
 
     PrettyFormatter f = ClientSideFormatter.FACTORY.get();
     f.setDiffPrefs(dp);
@@ -299,7 +299,7 @@ abstract class AbstractPatchContentTable extends NavigationTable<Object>
   }
 
   protected SparseHtmlFile getSparseHtmlFileB(PatchScript s) {
-    AccountDiffPreference dp = new AccountDiffPreference(s.getDiffPrefs());
+    DiffPreferencesInfo dp = s.getDiffPrefs();
 
     SparseFileContent b = s.getB();
     PrettyFormatter f = ClientSideFormatter.FACTORY.get();

gerrit-gwtui/src/main/java/com/google/gerrit/client/patches/PatchScriptSettingsPanel.java

@@ -20,8 +20,8 @@ import com.google.gerrit.client.account.Util;
 import com.google.gerrit.client.rpc.GerritCallback;
 import com.google.gerrit.client.ui.ListenableAccountDiffPreference;
 import com.google.gerrit.client.ui.NpIntTextBox;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference.Whitespace;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo.Whitespace;
 import com.google.gwt.core.client.GWT;
 import com.google.gwt.dom.client.NodeList;
 import com.google.gwt.dom.client.OptionElement;
@@ -156,7 +156,7 @@ public class PatchScriptSettingsPanel extends Composite {
   public void setEnableSmallFileFeatures(final boolean on) {
     enableSmallFileFeatures = on;
     if (enableSmallFileFeatures) {
-      syntaxHighlighting.setValue(getValue().isSyntaxHighlighting());
+      syntaxHighlighting.setValue(getValue().syntaxHighlighting);
     } else {
       syntaxHighlighting.setValue(false);
     }
@@ -181,7 +181,7 @@ public class PatchScriptSettingsPanel extends Composite {
   public void setEnableIntralineDifference(final boolean on) {
     enableIntralineDifference = on;
     if (enableIntralineDifference) {
-      intralineDifference.setValue(getValue().isIntralineDifference());
+      intralineDifference.setValue(getValue().intralineDifference);
     } else {
       intralineDifference.setValue(false);
     }
@@ -197,36 +197,36 @@ public class PatchScriptSettingsPanel extends Composite {
     syntaxHighlighting.setTitle(title);
   }
 
-  public AccountDiffPreference getValue() {
+  public DiffPreferencesInfo getValue() {
     return listenablePrefs.get();
   }
 
-  public void setValue(final AccountDiffPreference dp) {
+  public void setValue(final DiffPreferencesInfo dp) {
     listenablePrefs.set(dp);
     display();
   }
 
   protected void display() {
-    final AccountDiffPreference dp = getValue();
+    final DiffPreferencesInfo dp = getValue();
-    setIgnoreWhitespace(dp.getIgnoreWhitespace());
+    setIgnoreWhitespace(dp.ignoreWhitespace);
     if (enableSmallFileFeatures) {
-      syntaxHighlighting.setValue(dp.isSyntaxHighlighting());
+      syntaxHighlighting.setValue(dp.syntaxHighlighting);
     } else {
       syntaxHighlighting.setValue(false);
     }
-    setContext(dp.getContext());
+    setContext(dp.context);
 
-    tabWidth.setIntValue(dp.getTabSize());
+    tabWidth.setIntValue(dp.tabSize);
-    colWidth.setIntValue(dp.getLineLength());
+    colWidth.setIntValue(dp.lineLength);
-    intralineDifference.setValue(dp.isIntralineDifference());
+    intralineDifference.setValue(dp.intralineDifference);
-    whitespaceErrors.setValue(dp.isShowWhitespaceErrors());
+    whitespaceErrors.setValue(dp.showWhitespaceErrors);
-    showLineEndings.setValue(dp.isShowLineEndings());
+    showLineEndings.setValue(dp.showLineEndings);
-    showTabs.setValue(dp.isShowTabs());
+    showTabs.setValue(dp.showTabs);
-    skipDeleted.setValue(dp.isSkipDeleted());
+    skipDeleted.setValue(dp.skipDeleted);
-    skipUncommented.setValue(dp.isSkipUncommented());
+    skipUncommented.setValue(dp.skipUncommented);
-    expandAllComments.setValue(dp.isExpandAllComments());
+    expandAllComments.setValue(dp.expandAllComments);
-    retainHeader.setValue(dp.isRetainHeader());
+    retainHeader.setValue(dp.retainHeader);
-    manualReview.setValue(dp.isManualReview());
+    manualReview.setValue(dp.manualReview);
   }
 
   @UiHandler("update")
@@ -244,22 +244,21 @@ public class PatchScriptSettingsPanel extends Composite {
       new ErrorDialog(PatchUtil.C.illegalNumberOfColumns()).center();
       return;
     }
-
+    DiffPreferencesInfo dp = getValue();
-    AccountDiffPreference dp = new AccountDiffPreference(getValue());
+    dp.ignoreWhitespace = getIgnoreWhitespace();
-    dp.setIgnoreWhitespace(getIgnoreWhitespace());
+    dp.context = getContext();
-    dp.setContext(getContext());
+    dp.tabSize = tabWidth.getIntValue();
-    dp.setTabSize(tabWidth.getIntValue());
+    dp.lineLength = colWidth.getIntValue();
-    dp.setLineLength(colWidth.getIntValue());
+    dp.syntaxHighlighting = syntaxHighlighting.getValue();
-    dp.setSyntaxHighlighting(syntaxHighlighting.getValue());
+    dp.intralineDifference = intralineDifference.getValue();
-    dp.setIntralineDifference(intralineDifference.getValue());
+    dp.showWhitespaceErrors = whitespaceErrors.getValue();
-    dp.setShowWhitespaceErrors(whitespaceErrors.getValue());
+    dp.showLineEndings = showLineEndings.getValue();
-    dp.setShowLineEndings(showLineEndings.getValue());
+    dp.showTabs = showTabs.getValue();
-    dp.setShowTabs(showTabs.getValue());
+    dp.skipDeleted = skipDeleted.getValue();
-    dp.setSkipDeleted(skipDeleted.getValue());
+    dp.skipUncommented = skipUncommented.getValue();
-    dp.setSkipUncommented(skipUncommented.getValue());
+    dp.expandAllComments = expandAllComments.getValue();
-    dp.setExpandAllComments(expandAllComments.getValue());
+    dp.retainHeader = retainHeader.getValue();
-    dp.setRetainHeader(retainHeader.getValue());
+    dp.manualReview = manualReview.getValue();
-    dp.setManualReview(manualReview.getValue());
 
     listenablePrefs.set(dp);
   }
@@ -298,9 +297,9 @@ public class PatchScriptSettingsPanel extends Composite {
   }
 
   private void initContext(ListBox context) {
-    for (final short v : AccountDiffPreference.CONTEXT_CHOICES) {
+    for (final short v : DiffPreferencesInfo.CONTEXT_CHOICES) {
       final String label;
-      if (v == AccountDiffPreference.WHOLE_FILE_CONTEXT) {
+      if (v == DiffPreferencesInfo.WHOLE_FILE_CONTEXT) {
         label = Util.C.contextWholeFile();
       } else {
         label = Util.M.lines(v);
@@ -314,7 +313,7 @@ public class PatchScriptSettingsPanel extends Composite {
     if (0 <= sel) {
       return Whitespace.valueOf(ignoreWhitespace.getValue(sel));
     }
-    return getValue().getIgnoreWhitespace();
+    return getValue().ignoreWhitespace;
   }
 
   private void setIgnoreWhitespace(Whitespace s) {
@@ -327,12 +326,12 @@ public class PatchScriptSettingsPanel extends Composite {
     ignoreWhitespace.setSelectedIndex(0);
   }
 
-  private short getContext() {
+  private int getContext() {
     final int sel = context.getSelectedIndex();
     if (0 <= sel) {
       return Short.parseShort(context.getValue(sel));
     }
-    return getValue().getContext();
+    return getValue().context;
   }
 
   private void setContext(int ctx) {

gerrit-gwtui/src/main/java/com/google/gerrit/client/patches/PatchTable.java

@@ -65,9 +65,9 @@ class PatchTable extends Composite {
       new PatchValidator() {
         @Override
         public boolean isValid(Patch patch) {
-          return !((listenablePrefs.get().isSkipDeleted()
+          return !((listenablePrefs.get().skipDeleted
               && patch.getChangeType().equals(ChangeType.DELETED))
-              || (listenablePrefs.get().isSkipUncommented()
+              || (listenablePrefs.get().skipUncommented
               && patch.getCommentCount() == 0));
         }
 

gerrit-gwtui/src/main/java/com/google/gerrit/client/patches/UnifiedDiffTable.java

@@ -294,7 +294,7 @@ public class UnifiedDiffTable extends AbstractPatchContentTable {
   private void appendImageDifferences(final PatchScript script,
       final SafeHtmlBuilder nc) {
     final boolean syntaxHighlighting =
-        script.getDiffPrefs().isSyntaxHighlighting();
+        script.getDiffPrefs().syntaxHighlighting;
     if (script.getDisplayMethodA() == DisplayMethod.IMG) {
       final String url = getUrlA();
       appendImageLine(nc, url, syntaxHighlighting, false);
@@ -310,7 +310,7 @@ public class UnifiedDiffTable extends AbstractPatchContentTable {
     final SparseHtmlFile a = getSparseHtmlFileA(script);
     final SparseHtmlFile b = getSparseHtmlFileB(script);
     final boolean syntaxHighlighting =
-        script.getDiffPrefs().isSyntaxHighlighting();
+        script.getDiffPrefs().syntaxHighlighting;
     for (final EditList.Hunk hunk : script.getHunks()) {
       appendHunkHeader(nc, hunk);
       while (hunk.next()) {

gerrit-gwtui/src/main/java/com/google/gerrit/client/patches/UnifiedPatchScreen.java

@@ -31,9 +31,9 @@ import com.google.gerrit.client.ui.ListenableAccountDiffPreference;
 import com.google.gerrit.client.ui.Screen;
 import com.google.gerrit.common.data.PatchScript;
 import com.google.gerrit.common.data.PatchSetDetail;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
 import com.google.gerrit.prettify.client.ClientSideFormatter;
 import com.google.gerrit.prettify.client.PrettyFactory;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
 import com.google.gerrit.reviewdb.client.Patch;
 import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gwt.core.client.Scheduler;
@@ -125,10 +125,10 @@ public class UnifiedPatchScreen extends Screen implements
     lastScript = null;
   }
 
-  private void update(AccountDiffPreference dp) {
+  private void update(DiffPreferencesInfo dp) {
     // Did the user just turn on auto-review?
-    if (!reviewedPanels.getValue() && prefs.getOld().isManualReview()
+    if (!reviewedPanels.getValue() && prefs.getOld().manualReview
-        && !dp.isManualReview()) {
+        && !dp.manualReview) {
       reviewedPanels.setValue(true);
       reviewedPanels.setReviewedByCurrentUser(true);
     }
@@ -152,25 +152,25 @@ public class UnifiedPatchScreen extends Screen implements
     }
   }
 
-  private boolean canReuse(AccountDiffPreference dp, PatchScript last) {
+  private boolean canReuse(DiffPreferencesInfo dp, PatchScript last) {
-    if (last.getDiffPrefs().getIgnoreWhitespace() != dp.getIgnoreWhitespace()) {
+    if (last.getDiffPrefs().ignoreWhitespace != dp.ignoreWhitespace) {
       // Whitespace ignore setting requires server computation.
       return false;
     }
 
-    final int ctx = dp.getContext();
+    final int ctx = dp.context;
-    if (ctx == AccountDiffPreference.WHOLE_FILE_CONTEXT && !last.getA().isWholeFile()) {
+    if (ctx == DiffPreferencesInfo.WHOLE_FILE_CONTEXT
+        && !last.getA().isWholeFile()) {
       // We don't have the entire file here, so we can't render it.
       return false;
     }
 
-    if (last.getDiffPrefs().getContext() < ctx && !last.getA().isWholeFile()) {
+    if (last.getDiffPrefs().context < ctx && !last.getA().isWholeFile()) {
       // We don't have sufficient context.
       return false;
     }
 
-    if (dp.isSyntaxHighlighting()
+    if (dp.syntaxHighlighting && !last.getA().isWholeFile()) {
-        && !last.getA().isWholeFile()) {
       // We need the whole file to syntax highlight accurately.
       return false;
     }
@@ -425,15 +425,15 @@ public class UnifiedPatchScreen extends Screen implements
     }
 
     if (script.isHugeFile()) {
-      AccountDiffPreference dp = script.getDiffPrefs();
+      DiffPreferencesInfo dp = script.getDiffPrefs();
-      int context = dp.getContext();
+      int context = dp.context;
-      if (context == AccountDiffPreference.WHOLE_FILE_CONTEXT) {
+      if (context == DiffPreferencesInfo.WHOLE_FILE_CONTEXT) {
         context = Short.MAX_VALUE;
       } else if (context > Short.MAX_VALUE) {
         context = Short.MAX_VALUE;
       }
-      dp.setContext((short) Math.min(context, LARGE_FILE_CONTEXT));
+      dp.context = Math.min(context, LARGE_FILE_CONTEXT);
-      dp.setSyntaxHighlighting(false);
+      dp.syntaxHighlighting = false;
       script.setDiffPrefs(dp);
     }
 
@@ -453,7 +453,7 @@ public class UnifiedPatchScreen extends Screen implements
 
     if (Gerrit.isSignedIn()) {
       boolean isReviewed = false;
-      if (isFirst && !prefs.get().isManualReview()) {
+      if (isFirst && !prefs.get().manualReview) {
         isReviewed = true;
         reviewedPanels.setReviewedByCurrentUser(isReviewed);
       } else {
@@ -476,9 +476,9 @@ public class UnifiedPatchScreen extends Screen implements
     super.onShowView();
     if (prefsHandler == null) {
       prefsHandler = prefs.addValueChangeHandler(
-          new ValueChangeHandler<AccountDiffPreference>() {
+          new ValueChangeHandler<DiffPreferencesInfo>() {
             @Override
-            public void onValueChange(ValueChangeEvent<AccountDiffPreference> event) {
+            public void onValueChange(ValueChangeEvent<DiffPreferencesInfo> event) {
               update(event.getValue());
             }
           });
@@ -491,7 +491,7 @@ public class UnifiedPatchScreen extends Screen implements
       new ErrorDialog(PatchUtil.C.intralineTimeout()).setText(
           Gerrit.C.warnTitle()).show();
     }
-    if (topView != null && prefs.get().isRetainHeader()) {
+    if (topView != null && prefs.get().retainHeader) {
       setTopView(topView);
     }
   }

gerrit-gwtui/src/main/java/com/google/gerrit/client/ui/ListenableAccountDiffPreference.java

@@ -17,11 +17,11 @@ package com.google.gerrit.client.ui;
 import com.google.gerrit.client.Gerrit;
 import com.google.gerrit.client.account.Util;
 import com.google.gerrit.client.rpc.GerritCallback;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
 import com.google.gwtjsonrpc.common.VoidResult;
 
 public class ListenableAccountDiffPreference
-    extends ListenableOldValue<AccountDiffPreference> {
+    extends ListenableOldValue<DiffPreferencesInfo> {
 
   public ListenableAccountDiffPreference() {
     reset();
@@ -33,7 +33,7 @@ public class ListenableAccountDiffPreference
           new GerritCallback<VoidResult>() {
         @Override
         public void onSuccess(VoidResult result) {
-          Gerrit.setAccountDiffPreference(get());
+          Gerrit.setDiffPreferences(get());
           cb.onSuccess(result);
         }
 
@@ -46,10 +46,10 @@ public class ListenableAccountDiffPreference
   }
 
   public void reset() {
-    if (Gerrit.isSignedIn() && Gerrit.getAccountDiffPreference() != null) {
+    if (Gerrit.isSignedIn() && Gerrit.getDiffPreferences() != null) {
-      set(Gerrit.getAccountDiffPreference());
+      set(Gerrit.getDiffPreferences());
     } else {
-      set(AccountDiffPreference.createDefault(null));
+      set(DiffPreferencesInfo.defaults());
     }
   }
 }

gerrit-httpd/src/main/java/com/google/gerrit/httpd/raw/HostPageServlet.java

@@ -24,13 +24,18 @@ import com.google.common.hash.Hashing;
 import com.google.common.primitives.Bytes;
 import com.google.gerrit.common.Version;
 import com.google.gerrit.common.data.HostPageData;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
 import com.google.gerrit.extensions.registration.DynamicItem;
 import com.google.gerrit.extensions.registration.DynamicSet;
+import com.google.gerrit.extensions.restapi.AuthException;
 import com.google.gerrit.extensions.systemstatus.MessageOfTheDay;
 import com.google.gerrit.extensions.webui.WebUiPlugin;
 import com.google.gerrit.httpd.HtmlDomUtil;
 import com.google.gerrit.httpd.WebSession;
 import com.google.gerrit.server.CurrentUser;
+import com.google.gerrit.server.IdentifiedUser;
+import com.google.gerrit.server.account.AccountResource;
+import com.google.gerrit.server.account.GetDiffPreferences;
 import com.google.gerrit.server.config.ConfigUtil;
 import com.google.gerrit.server.config.GerritServerConfig;
 import com.google.gerrit.server.config.SitePaths;
@@ -38,10 +43,12 @@ import com.google.gerrit.server.notedb.NotesMigration;
 import com.google.gwtexpui.server.CacheHeaders;
 import com.google.gwtjsonrpc.server.JsonServlet;
 import com.google.gwtjsonrpc.server.RPCServletUtils;
+import com.google.gwtorm.server.OrmException;
 import com.google.inject.Inject;
 import com.google.inject.Provider;
 import com.google.inject.Singleton;
 
+import org.eclipse.jgit.errors.ConfigInvalidException;
 import org.eclipse.jgit.lib.Config;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -87,6 +94,7 @@ public class HostPageServlet extends HttpServlet {
   private final StaticServlet staticServlet;
   private final boolean isNoteDbEnabled;
   private final Integer pluginsLoadTimeout;
+  private final GetDiffPreferences getDiff;
   private volatile Page page;
 
   @Inject
@@ -100,7 +108,8 @@ public class HostPageServlet extends HttpServlet {
       DynamicSet<MessageOfTheDay> motd,
       @GerritServerConfig Config cfg,
       StaticServlet ss,
-      NotesMigration migration)
+      NotesMigration migration,
+      GetDiffPreferences diffPref)
       throws IOException, ServletException {
     currentUser = cu;
     session = w;
@@ -113,6 +122,7 @@ public class HostPageServlet extends HttpServlet {
     staticServlet = ss;
     isNoteDbEnabled = migration.enabled();
     pluginsLoadTimeout = getPluginsLoadTimeout(cfg);
+    getDiff = diffPref;
 
     final String pageName = "HostPage.html";
     template = HtmlDomUtil.parseFile(getClass(), pageName);
@@ -187,7 +197,7 @@ public class HostPageServlet extends HttpServlet {
       w.write(";");
 
       w.write(HPD_ID + ".accountDiffPref=");
-      json(user.asIdentifiedUser().getAccountDiffPreference(), w);
+      json(getDiffPreferences(user.asIdentifiedUser()), w);
       w.write(";");
 
       w.write(HPD_ID + ".theme=");
@@ -220,6 +230,16 @@ public class HostPageServlet extends HttpServlet {
     }
   }
 
+  private DiffPreferencesInfo getDiffPreferences(IdentifiedUser user) {
+    try {
+      return getDiff.apply(new AccountResource(user));
+    } catch (AuthException | OrmException | ConfigInvalidException
+        | IOException e) {
+      log.warn("Cannot query account diff preferences", e);
+    }
+    return DiffPreferencesInfo.defaults();
+  }
+
   private void plugins(StringWriter w) {
     List<String> urls = Lists.newArrayList();
     for (WebUiPlugin u : plugins) {

gerrit-httpd/src/main/java/com/google/gerrit/httpd/rpc/account/AccountServiceImpl.java

@@ -19,13 +19,17 @@ import com.google.gerrit.common.data.AccountService;
 import com.google.gerrit.common.data.AgreementInfo;
 import com.google.gerrit.common.errors.InvalidQueryException;
 import com.google.gerrit.common.errors.NoSuchEntityException;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
+import com.google.gerrit.extensions.restapi.AuthException;
+import com.google.gerrit.extensions.restapi.BadRequestException;
 import com.google.gerrit.httpd.rpc.BaseServiceImplementation;
 import com.google.gerrit.reviewdb.client.Account;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
 import com.google.gerrit.reviewdb.client.AccountProjectWatch;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.IdentifiedUser;
+import com.google.gerrit.server.account.AccountResource;
+import com.google.gerrit.server.account.SetDiffPreferences;
 import com.google.gerrit.server.project.NoSuchProjectException;
 import com.google.gerrit.server.project.ProjectControl;
 import com.google.gerrit.server.query.QueryParseException;
@@ -37,6 +41,9 @@ import com.google.gwtorm.server.OrmException;
 import com.google.inject.Inject;
 import com.google.inject.Provider;
 
+import org.eclipse.jgit.errors.ConfigInvalidException;
+
+import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
@@ -49,18 +56,21 @@ class AccountServiceImpl extends BaseServiceImplementation implements
   private final ProjectControl.Factory projectControlFactory;
   private final AgreementInfoFactory.Factory agreementInfoFactory;
   private final ChangeQueryBuilder queryBuilder;
+  private final SetDiffPreferences setDiff;
 
   @Inject
   AccountServiceImpl(final Provider<ReviewDb> schema,
       final Provider<IdentifiedUser> identifiedUser,
       final ProjectControl.Factory projectControlFactory,
       final AgreementInfoFactory.Factory agreementInfoFactory,
-      final ChangeQueryBuilder queryBuilder) {
+      final ChangeQueryBuilder queryBuilder,
+      SetDiffPreferences setDiff) {
     super(schema, identifiedUser);
     this.currentUser = identifiedUser;
     this.projectControlFactory = projectControlFactory;
     this.agreementInfoFactory = agreementInfoFactory;
     this.queryBuilder = queryBuilder;
+    this.setDiff = setDiff;
   }
 
   @Override
@@ -74,17 +84,21 @@ class AccountServiceImpl extends BaseServiceImplementation implements
   }
 
   @Override
-  public void changeDiffPreferences(final AccountDiffPreference diffPref,
+  public void changeDiffPreferences(final DiffPreferencesInfo diffPref,
       AsyncCallback<VoidResult> callback) {
     run(callback, new Action<VoidResult>(){
       @Override
       public VoidResult run(ReviewDb db) throws OrmException {
-        if (!diffPref.getAccountId().equals(getAccountId())) {
+        if (!getUser().isIdentifiedUser()) {
-          throw new IllegalArgumentException("diffPref.getAccountId() "
+          throw new IllegalArgumentException("Not authenticated");
-              + diffPref.getAccountId() + " doesn't match"
+        }
-              + " the accountId of the signed in user " + getAccountId());
+        IdentifiedUser me = getUser().asIdentifiedUser();
+        try {
+          setDiff.apply(new AccountResource(me), diffPref);
+        } catch (AuthException | BadRequestException | ConfigInvalidException
+            | IOException e) {
+          throw new OrmException("Cannot save diff preferences", e);
         }
-        db.accountDiffPreferences().upsert(Collections.singleton(diffPref));
         return VoidResult.INSTANCE;
       }
     });

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

@@ -16,7 +16,7 @@ package com.google.gerrit.httpd.rpc.changedetail;
 
 import com.google.gerrit.common.data.ChangeDetailService;
 import com.google.gerrit.common.data.PatchSetDetail;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
 import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gwtjsonrpc.common.AsyncCallback;
 import com.google.inject.Inject;
@@ -38,7 +38,7 @@ class ChangeDetailServiceImpl implements ChangeDetailService {
 
   @Override
   public void patchSetDetail2(PatchSet.Id baseId, PatchSet.Id id,
-      AccountDiffPreference diffPrefs, AsyncCallback<PatchSetDetail> callback) {
+      DiffPreferencesInfo diffPrefs, AsyncCallback<PatchSetDetail> callback) {
     patchSetDetail.create(baseId, id, diffPrefs).to(callback);
   }
 }

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

@@ -18,11 +18,11 @@ import com.google.common.base.Optional;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.common.data.PatchSetDetail;
 import com.google.gerrit.common.errors.NoSuchEntityException;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo.Whitespace;
 import com.google.gerrit.extensions.restapi.AuthException;
 import com.google.gerrit.httpd.rpc.Handler;
 import com.google.gerrit.reviewdb.client.Account;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference.Whitespace;
 import com.google.gerrit.reviewdb.client.AccountPatchReview;
 import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.reviewdb.client.Patch;
@@ -67,7 +67,7 @@ class PatchSetDetailFactory extends Handler<PatchSetDetail> {
     PatchSetDetailFactory create(
         @Assisted("psIdBase") @Nullable PatchSet.Id psIdBase,
         @Assisted("psIdNew") PatchSet.Id psIdNew,
-        @Nullable AccountDiffPreference diffPrefs);
+        @Nullable DiffPreferencesInfo diffPrefs);
   }
 
   private final PatchSetInfoFactory infoFactory;
@@ -81,7 +81,7 @@ class PatchSetDetailFactory extends Handler<PatchSetDetail> {
   private Project.NameKey project;
   private final PatchSet.Id psIdBase;
   private final PatchSet.Id psIdNew;
-  private final AccountDiffPreference diffPrefs;
+  private final DiffPreferencesInfo diffPrefs;
   private ObjectId oldId;
   private ObjectId newId;
 
@@ -98,7 +98,7 @@ class PatchSetDetailFactory extends Handler<PatchSetDetail> {
       ChangeEditUtil editUtil,
       @Assisted("psIdBase") @Nullable final PatchSet.Id psIdBase,
       @Assisted("psIdNew") final PatchSet.Id psIdNew,
-      @Assisted @Nullable final AccountDiffPreference diffPrefs) {
+      @Assisted @Nullable final DiffPreferencesInfo diffPrefs) {
     this.infoFactory = psif;
     this.db = db;
     this.patchListCache = patchListCache;
@@ -145,7 +145,7 @@ class PatchSetDetailFactory extends Handler<PatchSetDetail> {
           newId = toObjectId(psIdNew);
         }
 
-        list = listFor(keyFor(diffPrefs.getIgnoreWhitespace()));
+        list = listFor(keyFor(diffPrefs.ignoreWhitespace));
       } else { // OK, means use base to compare
         list = patchListCache.get(control.getChange(), patchSet);
       }

gerrit-httpd/src/main/java/com/google/gerrit/httpd/rpc/patch/PatchDetailServiceImpl.java

@@ -17,9 +17,9 @@ package com.google.gerrit.httpd.rpc.patch;
 import com.google.gerrit.common.data.PatchDetailService;
 import com.google.gerrit.common.data.PatchScript;
 import com.google.gerrit.common.errors.NoSuchEntityException;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
 import com.google.gerrit.httpd.rpc.BaseServiceImplementation;
 import com.google.gerrit.httpd.rpc.Handler;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
 import com.google.gerrit.reviewdb.client.Patch;
 import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gerrit.reviewdb.server.ReviewDb;
@@ -48,7 +48,7 @@ class PatchDetailServiceImpl extends BaseServiceImplementation implements
 
   @Override
   public void patchScript(final Patch.Key patchKey, final PatchSet.Id psa,
-      final PatchSet.Id psb, final AccountDiffPreference dp,
+      final PatchSet.Id psb, final DiffPreferencesInfo dp,
       final AsyncCallback<PatchScript> callback) {
     if (psb == null) {
       callback.onFailure(new NoSuchEntityException());

gerrit-prettify/BUCK

@@ -15,6 +15,7 @@ gwt_module(
     '//gerrit-gwtexpui:SafeHtml',
   ],
   exported_deps = [
+    '//gerrit-extension-api:client',
     '//gerrit-patch-jgit:client',
     '//gerrit-reviewdb:client',
     '//lib:gwtjsonrpc',

gerrit-prettify/src/main/java/com/google/gerrit/prettify/client/PrettyFormatter.java

@@ -14,8 +14,8 @@
 
 package com.google.gerrit.prettify.client;
 
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
 import com.google.gerrit.prettify.common.SparseFileContent;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
 import com.google.gwtexpui.safehtml.client.SafeHtml;
 import com.google.gwtexpui.safehtml.client.SafeHtmlBuilder;
 
@@ -73,7 +73,7 @@ public abstract class PrettyFormatter implements SparseHtmlFile {
   protected SparseFileContent content;
   protected EditFilter side;
   protected List<Edit> edits;
-  protected AccountDiffPreference diffPrefs;
+  protected DiffPreferencesInfo diffPrefs;
   protected String fileName;
   protected Set<Integer> trailingEdits;
 
@@ -110,7 +110,7 @@ public abstract class PrettyFormatter implements SparseHtmlFile {
     edits = all;
   }
 
-  public void setDiffPrefs(AccountDiffPreference how) {
+  public void setDiffPrefs(DiffPreferencesInfo how) {
     diffPrefs = how;
   }
 
@@ -132,7 +132,7 @@ public abstract class PrettyFormatter implements SparseHtmlFile {
     String html = toHTML(src);
 
     html = expandTabs(html);
-    if (diffPrefs.isSyntaxHighlighting() && getFileType() != null
+    if (diffPrefs.syntaxHighlighting && getFileType() != null
         && src.isWholeFile()) {
       // The prettify parsers don't like &#39; as an entity for the
       // single quote character. Replace them all out so we don't
@@ -233,7 +233,7 @@ public abstract class PrettyFormatter implements SparseHtmlFile {
       cleanText(txt, pos, start);
       pos = txt.indexOf(';', start + 1) + 1;
 
-      if (diffPrefs.getLineLength() <= col) {
+      if (diffPrefs.lineLength <= col) {
         buf.append("<br />");
         col = 0;
       }
@@ -247,14 +247,14 @@ public abstract class PrettyFormatter implements SparseHtmlFile {
 
   private void cleanText(String txt, int pos, int end) {
     while (pos < end) {
-      int free = diffPrefs.getLineLength() - col;
+      int free = diffPrefs.lineLength - col;
       if (free <= 0) {
         // The current line is full. Throw an explicit line break
         // onto the end, and we'll continue on the next line.
         //
         buf.append("<br />");
         col = 0;
-        free = diffPrefs.getLineLength();
+        free = diffPrefs.lineLength;
       }
 
       int n = Math.min(end - pos, free);
@@ -326,7 +326,7 @@ public abstract class PrettyFormatter implements SparseHtmlFile {
   private String toHTML(SparseFileContent src) {
     SafeHtml html;
 
-    if (diffPrefs.isIntralineDifference()) {
+    if (diffPrefs.intralineDifference) {
       html = colorLineEdits(src);
     } else {
       SafeHtmlBuilder b = new SafeHtmlBuilder();
@@ -342,7 +342,7 @@ public abstract class PrettyFormatter implements SparseHtmlFile {
       html = html.replaceAll("\r([^\n])", r);
     }
 
-    if (diffPrefs.isShowWhitespaceErrors()) {
+    if (diffPrefs.showWhitespaceErrors) {
       // We need to do whitespace errors before showing tabs, because
       // these patterns rely on \t as a literal, before it expands.
       //
@@ -350,12 +350,12 @@ public abstract class PrettyFormatter implements SparseHtmlFile {
       html = showTrailingWhitespace(html);
     }
 
-    if (diffPrefs.isShowLineEndings()){
+    if (diffPrefs.showLineEndings){
       html = showLineEndings(html);
     }
 
-    if (diffPrefs.isShowTabs()) {
+    if (diffPrefs.showTabs) {
-      String t = 1 < diffPrefs.getTabSize() ? "\t" : "";
+      String t = 1 < diffPrefs.tabSize ? "\t" : "";
       html = html.replaceAll("\t", "<span class=\"vt\">\u00BB</span>" + t);
     }
 
@@ -528,10 +528,10 @@ public abstract class PrettyFormatter implements SparseHtmlFile {
   private String expandTabs(String html) {
     StringBuilder tmp = new StringBuilder();
     int i = 0;
-    if (diffPrefs.isShowTabs()) {
+    if (diffPrefs.showTabs) {
       i = 1;
     }
-    for (; i < diffPrefs.getTabSize(); i++) {
+    for (; i < diffPrefs.tabSize; i++) {
       tmp.append("&nbsp;");
     }
     return html.replaceAll("\t", tmp.toString());

gerrit-reviewdb/src/main/java/com/google/gerrit/reviewdb/client/Account.java

@@ -16,6 +16,7 @@ package com.google.gerrit.reviewdb.client;
 
 import static com.google.gerrit.reviewdb.client.RefNames.REFS_USERS;
 
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
 import com.google.gwtorm.client.Column;
 import com.google.gwtorm.client.IntKey;
 
@@ -51,7 +52,7 @@ import java.sql.Timestamp;
  * notifications of updates on that change, or just book-marking it for faster
  * future reference. One record per starred change.</li>
  *
- * <li>{@link AccountDiffPreference}: user's preferences for rendering side-to-side
+ * <li>{@link DiffPreferencesInfo}: user's preferences for rendering side-to-side
  * and unified diff</li>
  *
  * </ul>

gerrit-server/src/main/java/com/google/gerrit/rules/StoredValues.java

@@ -17,8 +17,8 @@ package com.google.gerrit.rules;
 import static com.google.gerrit.rules.StoredValue.create;
 
 import com.google.common.collect.Maps;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo.Whitespace;
 import com.google.gerrit.reviewdb.client.Account;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference.Whitespace;
 import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gerrit.reviewdb.client.PatchSetInfo;

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

@@ -21,7 +21,6 @@ import com.google.common.collect.Sets;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.common.data.AccountInfo;
 import com.google.gerrit.reviewdb.client.Account;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
 import com.google.gerrit.reviewdb.client.AccountProjectWatch;
 import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.reviewdb.client.StarredChange;
@@ -110,14 +109,16 @@ public class IdentifiedUser extends CurrentUser {
     public IdentifiedUser create(SocketAddress remotePeer, Account.Id id) {
       return new IdentifiedUser(capabilityControlFactory, authConfig, realm,
           anonymousCowardName, canonicalUrl, accountCache, groupBackend,
-          disableReverseDnsLookup, Providers.of(remotePeer), null, id, null);
+          disableReverseDnsLookup, Providers.of(remotePeer), null,
+          id, null);
     }
 
     public CurrentUser runAs(SocketAddress remotePeer, Account.Id id,
         @Nullable CurrentUser caller) {
       return new IdentifiedUser(capabilityControlFactory, authConfig, realm,
           anonymousCowardName, canonicalUrl, accountCache, groupBackend,
-          disableReverseDnsLookup, Providers.of(remotePeer), null, id, caller);
+          disableReverseDnsLookup, Providers.of(remotePeer), null,
+          id, caller);
     }
   }
 
@@ -151,7 +152,6 @@ public class IdentifiedUser extends CurrentUser {
         final AccountCache accountCache,
         final GroupBackend groupBackend,
         @DisableReverseDnsLookup final Boolean disableReverseDnsLookup,
-
         @RemotePeer final Provider<SocketAddress> remotePeerProvider,
         final Provider<ReviewDb> dbProvider) {
       this.capabilityControlFactory = capabilityControlFactory;
@@ -162,7 +162,6 @@ public class IdentifiedUser extends CurrentUser {
       this.accountCache = accountCache;
       this.groupBackend = groupBackend;
       this.disableReverseDnsLookup = disableReverseDnsLookup;
-
       this.remotePeerProvider = remotePeerProvider;
       this.dbProvider = dbProvider;
     }
@@ -170,13 +169,15 @@ public class IdentifiedUser extends CurrentUser {
     public IdentifiedUser create(Account.Id id) {
       return new IdentifiedUser(capabilityControlFactory, authConfig, realm,
           anonymousCowardName, canonicalUrl, accountCache, groupBackend,
-          disableReverseDnsLookup, remotePeerProvider, dbProvider, id, null);
+          disableReverseDnsLookup, remotePeerProvider, dbProvider,
+          id, null);
     }
 
     public IdentifiedUser runAs(Account.Id id, CurrentUser caller) {
       return new IdentifiedUser(capabilityControlFactory, authConfig, realm,
           anonymousCowardName, canonicalUrl, accountCache, groupBackend,
-          disableReverseDnsLookup, remotePeerProvider, dbProvider, id, caller);
+          disableReverseDnsLookup, remotePeerProvider, dbProvider,
+          id, caller);
     }
   }
 
@@ -274,20 +275,6 @@ public class IdentifiedUser extends CurrentUser {
     return state().getAccount();
   }
 
-  public AccountDiffPreference getAccountDiffPreference() {
-    AccountDiffPreference diffPref;
-    try {
-      diffPref = dbProvider.get().accountDiffPreferences().get(getAccountId());
-      if (diffPref == null) {
-        diffPref = AccountDiffPreference.createDefault(getAccountId());
-      }
-    } catch (OrmException e) {
-      log.warn("Cannot query account diff preferences", e);
-      diffPref = AccountDiffPreference.createDefault(getAccountId());
-    }
-    return diffPref;
-  }
-
   public boolean hasEmailAddress(String email) {
     if (validEmails.contains(email)) {
       return true;

gerrit-server/src/main/java/com/google/gerrit/server/account/GetDiffPreferences.java

@@ -14,91 +14,140 @@
 
 package com.google.gerrit.server.account;
 
-import com.google.gerrit.extensions.client.Theme;
+import static com.google.gerrit.server.config.ConfigUtil.loadSection;
+
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
 import com.google.gerrit.extensions.restapi.AuthException;
 import com.google.gerrit.extensions.restapi.RestReadView;
 import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.reviewdb.client.AccountDiffPreference;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference.Whitespace;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.CurrentUser;
+import com.google.gerrit.server.config.AllUsersName;
+import com.google.gerrit.server.config.GerritServerConfig;
+import com.google.gerrit.server.git.GitRepositoryManager;
+import com.google.gerrit.server.git.UserConfigSections;
+import com.google.gerrit.server.patch.PatchListKey;
 import com.google.gwtorm.server.OrmException;
 import com.google.inject.Inject;
 import com.google.inject.Provider;
 import com.google.inject.Singleton;
 
+import org.eclipse.jgit.errors.ConfigInvalidException;
+import org.eclipse.jgit.errors.RepositoryNotFoundException;
+import org.eclipse.jgit.lib.Config;
+import org.eclipse.jgit.lib.Repository;
+
+import java.io.IOException;
+
 @Singleton
 public class GetDiffPreferences implements RestReadView<AccountResource> {
   private final Provider<CurrentUser> self;
   private final Provider<ReviewDb> db;
+  private final Provider<AllUsersName> allUsersName;
+  private final GitRepositoryManager gitMgr;
+  private final boolean readFromGit;
 
   @Inject
-  GetDiffPreferences(Provider<CurrentUser> self, Provider<ReviewDb> db) {
+  GetDiffPreferences(Provider<CurrentUser> self,
+      Provider<ReviewDb> db,
+      @GerritServerConfig Config cfg,
+      Provider<AllUsersName> allUsersName,
+      GitRepositoryManager gitMgr) {
     this.self = self;
     this.db = db;
+    this.allUsersName = allUsersName;
+    this.gitMgr = gitMgr;
+    readFromGit = cfg.getBoolean("user", null, "readPrefsFromGit", false);
   }
 
   @Override
   public DiffPreferencesInfo apply(AccountResource rsrc)
-      throws AuthException, OrmException {
+      throws AuthException, OrmException, ConfigInvalidException, IOException {
     if (self.get() != rsrc.getUser()
         && !self.get().getCapabilities().canAdministrateServer()) {
       throw new AuthException("restricted to administrator");
     }
 
     Account.Id userId = rsrc.getUser().getAccountId();
-    AccountDiffPreference a = db.get().accountDiffPreferences().get(userId);
+    return readFromGit
-    if (a == null) {
+        ? readFromGit(userId, gitMgr, allUsersName.get(), null)
-      a = new AccountDiffPreference(userId);
+        : readFromDb(userId);
-    }
-    return DiffPreferencesInfo.parse(a);
   }
 
-  public static class DiffPreferencesInfo {
+  static DiffPreferencesInfo readFromGit(Account.Id id,
-    static DiffPreferencesInfo parse(AccountDiffPreference p) {
+      GitRepositoryManager gitMgr, AllUsersName allUsersName,
-      DiffPreferencesInfo info = new DiffPreferencesInfo();
+      DiffPreferencesInfo in)
-      info.context = p.getContext();
+      throws IOException, ConfigInvalidException, RepositoryNotFoundException {
-      info.expandAllComments = p.isExpandAllComments() ? true : null;
+    try (Repository git = gitMgr.openRepository(allUsersName)) {
-      info.ignoreWhitespace = p.getIgnoreWhitespace();
+      VersionedAccountPreferences p =
-      info.intralineDifference = p.isIntralineDifference() ? true : null;
+          VersionedAccountPreferences.forUser(id);
-      info.lineLength = p.getLineLength();
+      p.load(git);
-      info.manualReview = p.isManualReview() ? true : null;
+      DiffPreferencesInfo prefs = new DiffPreferencesInfo();
-      info.retainHeader = p.isRetainHeader() ? true : null;
+      loadSection(p.getConfig(), UserConfigSections.DIFF, null, prefs,
-      info.showLineEndings = p.isShowLineEndings() ? true : null;
+          DiffPreferencesInfo.defaults(), in);
-      info.showTabs = p.isShowTabs() ? true : null;
+      return prefs;
-      info.showWhitespaceErrors = p.isShowWhitespaceErrors() ? true : null;
+    }
-      info.skipDeleted = p.isSkipDeleted() ? true : null;
+  }
-      info.skipUncommented = p.isSkipUncommented() ? true : null;
+
-      info.hideTopMenu = p.isHideTopMenu() ? true : null;
+  private DiffPreferencesInfo readFromDb(Account.Id id)
-      info.autoHideDiffTableHeader = p.isAutoHideDiffTableHeader() ? true : null;
+      throws OrmException {
-      info.hideLineNumbers = p.isHideLineNumbers() ? true : null;
+    AccountDiffPreference a = db.get().accountDiffPreferences().get(id);
-      info.syntaxHighlighting = p.isSyntaxHighlighting() ? true : null;
+    return nullify(initFromDb(a));
-      info.tabSize = p.getTabSize();
+  }
-      info.renderEntireFile = p.isRenderEntireFile() ? true : null;
+
-      info.hideEmptyPane = p.isHideEmptyPane() ? true : null;
+  static DiffPreferencesInfo initFromDb(AccountDiffPreference a) {
-      info.theme = p.getTheme();
+    DiffPreferencesInfo prefs = DiffPreferencesInfo.defaults();
-      return info;
+    if (a != null) {
+      prefs.context = (int)a.getContext();
+      prefs.expandAllComments = a.isExpandAllComments();
+      prefs.hideLineNumbers = a.isHideLineNumbers();
+      prefs.hideTopMenu = a.isHideTopMenu();
+      prefs.ignoreWhitespace = PatchListKey.WHITESPACE_TYPES.inverse().get(
+          a.getIgnoreWhitespace().getCode());
+      prefs.intralineDifference = a.isIntralineDifference();
+      prefs.lineLength = a.getLineLength();
+      prefs.manualReview = a.isManualReview();
+      prefs.renderEntireFile = a.isRenderEntireFile();
+      prefs.retainHeader = a.isRetainHeader();
+      prefs.showLineEndings = a.isShowLineEndings();
+      prefs.showTabs = a.isShowTabs();
+      prefs.showWhitespaceErrors = a.isShowWhitespaceErrors();
+      prefs.skipDeleted = a.isSkipDeleted();
+      prefs.skipUncommented = a.isSkipUncommented();
+      prefs.syntaxHighlighting = a.isSyntaxHighlighting();
+      prefs.tabSize = a.getTabSize();
+      prefs.theme = a.getTheme();
+      prefs.hideEmptyPane = a.isHideEmptyPane();
+      prefs.autoHideDiffTableHeader = a.isAutoHideDiffTableHeader();
     }
 
-    public short context;
+    return prefs;
-    public Boolean expandAllComments;
+  }
-    public Whitespace ignoreWhitespace;
+
-    public Boolean intralineDifference;
+  private static DiffPreferencesInfo nullify(DiffPreferencesInfo prefs) {
-    public int lineLength;
+    prefs.expandAllComments = b(prefs.expandAllComments);
-    public Boolean manualReview;
+    prefs.hideLineNumbers = b(prefs.hideLineNumbers);
-    public Boolean retainHeader;
+    prefs.hideTopMenu = b(prefs.hideTopMenu);
-    public Boolean showLineEndings;
+    prefs.intralineDifference = b(prefs.intralineDifference);
-    public Boolean showTabs;
+    prefs.manualReview = b(prefs.manualReview);
-    public Boolean showWhitespaceErrors;
+    prefs.renderEntireFile = b(prefs.renderEntireFile);
-    public Boolean skipDeleted;
+    prefs.retainHeader = b(prefs.retainHeader);
-    public Boolean skipUncommented;
+    prefs.showLineEndings = b(prefs.showLineEndings);
-    public Boolean syntaxHighlighting;
+    prefs.showTabs = b(prefs.showTabs);
-    public Boolean hideTopMenu;
+    prefs.showWhitespaceErrors = b(prefs.showWhitespaceErrors);
-    public Boolean autoHideDiffTableHeader;
+    prefs.skipDeleted = b(prefs.skipDeleted);
-    public Boolean hideLineNumbers;
+    prefs.skipUncommented = b(prefs.skipUncommented);
-    public Boolean renderEntireFile;
+    prefs.syntaxHighlighting = b(prefs.syntaxHighlighting);
-    public Boolean hideEmptyPane;
+    prefs.hideEmptyPane = b(prefs.hideEmptyPane);
-    public int tabSize;
+    prefs.autoHideDiffTableHeader = b(prefs.autoHideDiffTableHeader);
-    public Theme theme;
+    return prefs;
+  }
+
+  private static Boolean b(Boolean b) {
+    if (b == null) {
+      return null;
+    }
+    return b ? Boolean.TRUE : null;
   }
 }

gerrit-server/src/main/java/com/google/gerrit/server/account/SetDiffPreferences.java

@@ -14,144 +14,224 @@
 
 package com.google.gerrit.server.account;
 
-import com.google.gerrit.extensions.client.Theme;
+import static com.google.gerrit.server.account.GetDiffPreferences.initFromDb;
+import static com.google.gerrit.server.account.GetDiffPreferences.readFromGit;
+import static com.google.gerrit.server.config.ConfigUtil.loadSection;
+import static com.google.gerrit.server.config.ConfigUtil.storeSection;
+
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
 import com.google.gerrit.extensions.restapi.AuthException;
+import com.google.gerrit.extensions.restapi.BadRequestException;
 import com.google.gerrit.extensions.restapi.RestModifyView;
 import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.reviewdb.client.AccountDiffPreference;
 import com.google.gerrit.reviewdb.client.AccountDiffPreference.Whitespace;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.CurrentUser;
-import com.google.gerrit.server.account.GetDiffPreferences.DiffPreferencesInfo;
+import com.google.gerrit.server.config.AllUsersName;
-import com.google.gerrit.server.account.SetDiffPreferences.Input;
+import com.google.gerrit.server.config.GerritServerConfig;
+import com.google.gerrit.server.git.GitRepositoryManager;
+import com.google.gerrit.server.git.MetaDataUpdate;
+import com.google.gerrit.server.git.UserConfigSections;
+import com.google.gerrit.server.patch.PatchListKey;
 import com.google.gwtorm.server.OrmException;
 import com.google.inject.Inject;
 import com.google.inject.Provider;
 import com.google.inject.Singleton;
 
+import org.eclipse.jgit.errors.ConfigInvalidException;
+import org.eclipse.jgit.errors.RepositoryNotFoundException;
+import org.eclipse.jgit.lib.Config;
+
+import java.io.IOException;
 import java.util.Collections;
 
 @Singleton
-public class SetDiffPreferences implements RestModifyView<AccountResource, Input> {
+public class SetDiffPreferences implements
-  static class Input {
+    RestModifyView<AccountResource, DiffPreferencesInfo> {
-    Short context;
-    Boolean expandAllComments;
-    Whitespace ignoreWhitespace;
-    Boolean intralineDifference;
-    Integer lineLength;
-    Boolean manualReview;
-    Boolean retainHeader;
-    Boolean showLineEndings;
-    Boolean showTabs;
-    Boolean showWhitespaceErrors;
-    Boolean skipDeleted;
-    Boolean skipUncommented;
-    Boolean syntaxHighlighting;
-    Boolean hideTopMenu;
-    Boolean autoHideDiffTableHeader;
-    Boolean hideLineNumbers;
-    Boolean renderEntireFile;
-    Integer tabSize;
-    Theme theme;
-    Boolean hideEmptyPane;
-  }
-
   private final Provider<CurrentUser> self;
   private final Provider<ReviewDb> db;
+  private final Provider<MetaDataUpdate.User> metaDataUpdateFactory;
+  private final AllUsersName allUsersName;
+  private final GitRepositoryManager gitMgr;
+  private final boolean readFromGit;
 
   @Inject
-  SetDiffPreferences(Provider<CurrentUser> self, Provider<ReviewDb> db) {
+  SetDiffPreferences(Provider<CurrentUser> self,
+      Provider<ReviewDb> db,
+      @GerritServerConfig Config cfg,
+      Provider<MetaDataUpdate.User> metaDataUpdateFactory,
+      AllUsersName allUsersName,
+      GitRepositoryManager gitMgr) {
     this.self = self;
     this.db = db;
+    this.metaDataUpdateFactory = metaDataUpdateFactory;
+    this.allUsersName = allUsersName;
+    this.gitMgr = gitMgr;
+    readFromGit = cfg.getBoolean("user", null, "readPrefsFromGit", false);
   }
 
   @Override
-  public DiffPreferencesInfo apply(AccountResource rsrc, Input input)
+  public DiffPreferencesInfo apply(AccountResource rsrc, DiffPreferencesInfo in)
-      throws AuthException, OrmException {
+      throws AuthException, BadRequestException, ConfigInvalidException,
+      RepositoryNotFoundException, IOException, OrmException {
     if (self.get() != rsrc.getUser()
         && !self.get().getCapabilities().canModifyAccount()) {
       throw new AuthException("restricted to members of Modify Accounts");
     }
-    if (input == null) {
+
-      input = new Input();
+    if (in == null) {
+      throw new BadRequestException("input must be provided");
     }
 
-    Account.Id accountId = rsrc.getUser().getAccountId();
+    Account.Id userId = rsrc.getUser().getAccountId();
-    AccountDiffPreference p;
+    DiffPreferencesInfo n = readFromGit
+        ? readFromGit(userId, gitMgr, allUsersName, in)
+        : merge(initFromDb(db.get().accountDiffPreferences().get(userId)), in);
+    DiffPreferencesInfo out = writeToGit(n, userId);
+    writeToDb(n, userId);
+    return out;
+  }
 
-    db.get().accounts().beginTransaction(accountId);
+  private void writeToDb(DiffPreferencesInfo in, Account.Id id)
+      throws OrmException {
+    db.get().accounts().beginTransaction(id);
     try {
-      p = db.get().accountDiffPreferences().get(accountId);
+      AccountDiffPreference p = db.get().accountDiffPreferences().get(id);
-      if (p == null) {
+      p = initAccountDiffPreferences(p, in, id);
-        p = new AccountDiffPreference(accountId);
-      }
-
-      if (input.context != null) {
-        p.setContext(input.context);
-      }
-      if (input.ignoreWhitespace != null) {
-        p.setIgnoreWhitespace(input.ignoreWhitespace);
-      }
-      if (input.expandAllComments != null) {
-        p.setExpandAllComments(input.expandAllComments);
-      }
-      if (input.intralineDifference != null) {
-        p.setIntralineDifference(input.intralineDifference);
-      }
-      if (input.lineLength != null) {
-        p.setLineLength(input.lineLength);
-      }
-      if (input.manualReview != null) {
-        p.setManualReview(input.manualReview);
-      }
-      if (input.retainHeader != null) {
-        p.setRetainHeader(input.retainHeader);
-      }
-      if (input.showLineEndings != null) {
-        p.setShowLineEndings(input.showLineEndings);
-      }
-      if (input.showTabs != null) {
-        p.setShowTabs(input.showTabs);
-      }
-      if (input.showWhitespaceErrors != null) {
-        p.setShowWhitespaceErrors(input.showWhitespaceErrors);
-      }
-      if (input.skipDeleted != null) {
-        p.setSkipDeleted(input.skipDeleted);
-      }
-      if (input.skipUncommented != null) {
-        p.setSkipUncommented(input.skipUncommented);
-      }
-      if (input.syntaxHighlighting != null) {
-        p.setSyntaxHighlighting(input.syntaxHighlighting);
-      }
-      if (input.hideTopMenu != null) {
-        p.setHideTopMenu(input.hideTopMenu);
-      }
-      if (input.autoHideDiffTableHeader != null) {
-        p.setAutoHideDiffTableHeader(input.autoHideDiffTableHeader);
-      }
-      if (input.hideLineNumbers != null) {
-        p.setHideLineNumbers(input.hideLineNumbers);
-      }
-      if (input.renderEntireFile != null) {
-        p.setRenderEntireFile(input.renderEntireFile);
-      }
-      if (input.tabSize != null) {
-        p.setTabSize(input.tabSize);
-      }
-      if (input.theme != null) {
-        p.setTheme(input.theme);
-      }
-      if (input.hideEmptyPane != null) {
-        p.setHideEmptyPane(input.hideEmptyPane);
-      }
-
       db.get().accountDiffPreferences().upsert(Collections.singleton(p));
       db.get().commit();
     } finally {
       db.get().rollback();
     }
-    return DiffPreferencesInfo.parse(p);
+  }
+
+  private DiffPreferencesInfo writeToGit(DiffPreferencesInfo in,
+      Account.Id useId) throws RepositoryNotFoundException, IOException,
+          ConfigInvalidException {
+    MetaDataUpdate md = metaDataUpdateFactory.get().create(allUsersName);
+
+    VersionedAccountPreferences prefs;
+    DiffPreferencesInfo out = new DiffPreferencesInfo();
+    try {
+      prefs = VersionedAccountPreferences.forUser(useId);
+      prefs.load(md);
+      storeSection(prefs.getConfig(), UserConfigSections.DIFF, null, in,
+          DiffPreferencesInfo.defaults());
+      prefs.commit(md);
+      loadSection(prefs.getConfig(), UserConfigSections.DIFF, null, out,
+          DiffPreferencesInfo.defaults(), null);
+    } finally {
+      md.close();
+    }
+    return out;
+  }
+
+  // TODO(davido): Remove manual merging in follow-up change
+  private DiffPreferencesInfo merge(DiffPreferencesInfo n,
+      DiffPreferencesInfo i) {
+    if (i.context != null) {
+      n.context = i.context;
+    }
+    if (i.expandAllComments != null) {
+      n.expandAllComments = i.expandAllComments;
+    }
+    if (i.hideLineNumbers != null) {
+      n.hideLineNumbers = i.hideLineNumbers;
+    }
+    if (i.hideTopMenu != null) {
+      n.hideTopMenu = i.hideTopMenu;
+    }
+    if (i.ignoreWhitespace != null) {
+      n.ignoreWhitespace = i.ignoreWhitespace;
+    }
+    if (i.intralineDifference != null) {
+      n.intralineDifference = i.intralineDifference;
+    }
+    if (i.lineLength != null) {
+      n.lineLength = i.lineLength;
+    }
+    if (i.manualReview != null) {
+      n.manualReview = i.manualReview;
+    }
+    if (i.renderEntireFile != null) {
+      n.renderEntireFile = i.renderEntireFile;
+    }
+    if (i.retainHeader != null) {
+      n.retainHeader = i.retainHeader;
+    }
+    if (i.showLineEndings != null) {
+      n.showLineEndings = i.showLineEndings;
+    }
+    if (i.showTabs != null) {
+      n.showTabs = i.showTabs;
+    }
+    if (i.showWhitespaceErrors != null) {
+      n.showWhitespaceErrors = i.showWhitespaceErrors;
+    }
+    if (i.skipDeleted != null) {
+      n.skipDeleted = i.skipDeleted;
+    }
+    if (i.skipUncommented != null) {
+      n.skipUncommented = i.skipUncommented;
+    }
+    if (i.syntaxHighlighting != null) {
+      n.syntaxHighlighting = i.syntaxHighlighting;
+    }
+    if (i.tabSize != null) {
+      n.tabSize = i.tabSize;
+    }
+    if (i.theme != null) {
+      n.theme = i.theme;
+    }
+    if (i.hideEmptyPane != null) {
+      n.hideEmptyPane = i.hideEmptyPane;
+    }
+    if (i.autoHideDiffTableHeader != null) {
+      n.autoHideDiffTableHeader = i.autoHideDiffTableHeader;
+    }
+    return n;
+  }
+
+  private static AccountDiffPreference initAccountDiffPreferences(
+      AccountDiffPreference a, DiffPreferencesInfo i, Account.Id id) {
+    if (a == null) {
+      a = AccountDiffPreference.createDefault(id);
+    }
+    int context = i.context == null
+        ? DiffPreferencesInfo.DEFAULT_CONTEXT
+        :  i.context;
+    a.setContext((short)context);
+    a.setExpandAllComments(b(i.expandAllComments));
+    a.setHideLineNumbers(b(i.hideLineNumbers));
+    a.setHideTopMenu(b(i.hideTopMenu));
+    a.setIgnoreWhitespace(i.ignoreWhitespace == null
+        ? Whitespace.IGNORE_NONE
+        : Whitespace.forCode(
+            PatchListKey.WHITESPACE_TYPES.get(i.ignoreWhitespace)));
+    a.setIntralineDifference(b(i.intralineDifference));
+    a.setLineLength(i.lineLength == null
+        ? DiffPreferencesInfo.DEFAULT_LINE_LENGTH
+        : i.lineLength);
+    a.setManualReview(b(i.manualReview));
+    a.setRenderEntireFile(b(i.renderEntireFile));
+    a.setRetainHeader(b(i.retainHeader));
+    a.setShowLineEndings(b(i.showLineEndings));
+    a.setShowTabs(b(i.showTabs));
+    a.setShowWhitespaceErrors(b(i.showWhitespaceErrors));
+    a.setSkipDeleted(b(i.skipDeleted));
+    a.setSkipUncommented(b(i.skipUncommented));
+    a.setSyntaxHighlighting(b(i.syntaxHighlighting));
+    a.setTabSize(i.tabSize == null
+        ? DiffPreferencesInfo.DEFAULT_TAB_SIZE
+        : i.tabSize);
+    a.setTheme(i.theme);
+    a.setHideEmptyPane(b(i.hideEmptyPane));
+    a.setAutoHideDiffTableHeader(b(i.autoHideDiffTableHeader));
+    return a;
+  }
+
+  private static boolean b(Boolean b) {
+    return b == null ? false : b;
   }
 }

gerrit-server/src/main/java/com/google/gerrit/server/change/FileInfoJson.java

@@ -16,8 +16,8 @@ package com.google.gerrit.server.change;
 
 import com.google.common.collect.Maps;
 import com.google.gerrit.common.Nullable;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo.Whitespace;
 import com.google.gerrit.extensions.common.FileInfo;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference.Whitespace;
 import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.reviewdb.client.Patch;
 import com.google.gerrit.reviewdb.client.PatchSet;

gerrit-server/src/main/java/com/google/gerrit/server/change/GetDiff.java

@@ -24,6 +24,7 @@ import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
 import com.google.gerrit.common.data.PatchScript;
 import com.google.gerrit.common.data.PatchScript.DisplayMethod;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
 import com.google.gerrit.extensions.common.ChangeType;
 import com.google.gerrit.extensions.common.DiffInfo;
 import com.google.gerrit.extensions.common.DiffInfo.ContentEntry;
@@ -39,8 +40,6 @@ import com.google.gerrit.extensions.restapi.ResourceNotFoundException;
 import com.google.gerrit.extensions.restapi.Response;
 import com.google.gerrit.extensions.restapi.RestReadView;
 import com.google.gerrit.prettify.common.SparseFileContent;
-import com.google.gerrit.reviewdb.client.Account;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
 import com.google.gerrit.reviewdb.client.Patch;
 import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gerrit.reviewdb.client.Project;
@@ -52,7 +51,6 @@ import com.google.gerrit.server.project.NoSuchChangeException;
 import com.google.gerrit.server.project.ProjectCache;
 import com.google.gerrit.server.project.ProjectState;
 import com.google.gwtorm.server.OrmException;
-import com.google.inject.Inject;
 
 import org.eclipse.jgit.diff.Edit;
 import org.eclipse.jgit.diff.ReplaceEdit;
@@ -69,6 +67,8 @@ import java.io.IOException;
 import java.util.List;
 import java.util.concurrent.TimeUnit;
 
+import javax.inject.Inject;
+
 public class GetDiff implements RestReadView<FileResource> {
   private static final ImmutableMap<Patch.ChangeType, ChangeType> CHANGE_TYPE =
       Maps.immutableEnumMap(
@@ -93,7 +93,7 @@ public class GetDiff implements RestReadView<FileResource> {
   IgnoreWhitespace ignoreWhitespace = IgnoreWhitespace.NONE;
 
   @Option(name = "--context", handler = ContextOptionHandler.class)
-  short context = AccountDiffPreference.DEFAULT_CONTEXT;
+  int context = DiffPreferencesInfo.DEFAULT_CONTEXT;
 
   @Option(name = "--intraline")
   boolean intraline;
@@ -122,10 +122,10 @@ public class GetDiff implements RestReadView<FileResource> {
           resource.getRevision().getChangeResource(), IdString.fromDecoded(base));
       basePatchSet = baseResource.getPatchSet();
     }
-    AccountDiffPreference prefs = new AccountDiffPreference(new Account.Id(0));
+    DiffPreferencesInfo prefs = new DiffPreferencesInfo();
-    prefs.setIgnoreWhitespace(ignoreWhitespace.whitespace);
+    prefs.ignoreWhitespace = ignoreWhitespace.whitespace;
-    prefs.setContext(context);
+    prefs.context = context;
-    prefs.setIntralineDifference(intraline);
+    prefs.intralineDifference = intraline;
 
     try {
       PatchScriptFactory psf = patchScriptFactoryFactory.create(
@@ -135,7 +135,7 @@ public class GetDiff implements RestReadView<FileResource> {
           resource.getPatchKey().getParentKey(),
           prefs);
       psf.setLoadHistory(false);
-      psf.setLoadComments(context != AccountDiffPreference.WHOLE_FILE_CONTEXT);
+      psf.setLoadComments(context != DiffPreferencesInfo.WHOLE_FILE_CONTEXT);
       PatchScript ps = psf.call();
       Content content = new Content(ps);
       for (Edit edit : ps.getEdits()) {
@@ -369,14 +369,14 @@ public class GetDiff implements RestReadView<FileResource> {
   }
 
   enum IgnoreWhitespace {
-    NONE(AccountDiffPreference.Whitespace.IGNORE_NONE),
+    NONE(DiffPreferencesInfo.Whitespace.IGNORE_NONE),
-    TRAILING(AccountDiffPreference.Whitespace.IGNORE_TRAILING),
+    TRAILING(DiffPreferencesInfo.Whitespace.IGNORE_TRAILING),
-    CHANGED(AccountDiffPreference.Whitespace.IGNORE_LEADING_AND_TRAILING),
+    CHANGED(DiffPreferencesInfo.Whitespace.IGNORE_LEADING_AND_TRAILING),
-    ALL(AccountDiffPreference.Whitespace.IGNORE_ALL);
+    ALL(DiffPreferencesInfo.Whitespace.IGNORE_ALL);
 
-    private final AccountDiffPreference.Whitespace whitespace;
+    private final DiffPreferencesInfo.Whitespace whitespace;
 
-    private IgnoreWhitespace(AccountDiffPreference.Whitespace whitespace) {
+    private IgnoreWhitespace(DiffPreferencesInfo.Whitespace whitespace) {
       this.whitespace = whitespace;
     }
   }
@@ -393,7 +393,7 @@ public class GetDiff implements RestReadView<FileResource> {
       final String value = params.getParameter(0);
       short context;
       if ("all".equalsIgnoreCase(value)) {
-        context = AccountDiffPreference.WHOLE_FILE_CONTEXT;
+        context = DiffPreferencesInfo.WHOLE_FILE_CONTEXT;
       } else {
         try {
           context = Short.parseShort(value, 10);

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

@@ -22,6 +22,9 @@ public class UserConfigSections {
   /** The edit user preferences. */
   public static final String EDIT = "edit";
 
+  /** The diff user preferences. */
+  public static final String DIFF = "diff";
+
   private UserConfigSections() {
   }
 }

gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchListCacheImpl.java

@@ -16,7 +16,7 @@
 package com.google.gerrit.server.patch;
 
 import com.google.common.cache.Cache;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference.Whitespace;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo.Whitespace;
 import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.reviewdb.client.PatchSet;
 import com.google.gerrit.reviewdb.client.Project;

gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchListKey.java

@@ -14,15 +14,16 @@
 
 package com.google.gerrit.server.patch;
 
-import static com.google.gerrit.server.ioutil.BasicSerialization.readEnum;
+import static com.google.common.base.Preconditions.checkState;
-import static com.google.gerrit.server.ioutil.BasicSerialization.writeEnum;
 import static org.eclipse.jgit.lib.ObjectIdSerialization.readCanBeNull;
 import static org.eclipse.jgit.lib.ObjectIdSerialization.readNotNull;
 import static org.eclipse.jgit.lib.ObjectIdSerialization.writeCanBeNull;
 import static org.eclipse.jgit.lib.ObjectIdSerialization.writeNotNull;
 
+import com.google.common.collect.BiMap;
+import com.google.common.collect.ImmutableBiMap;
 import com.google.gerrit.common.Nullable;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference.Whitespace;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo.Whitespace;
 
 import org.eclipse.jgit.lib.AnyObjectId;
 import org.eclipse.jgit.lib.ObjectId;
@@ -35,6 +36,16 @@ import java.io.Serializable;
 public class PatchListKey implements Serializable {
   static final long serialVersionUID = 18L;
 
+  public static final BiMap<Whitespace, Character> WHITESPACE_TYPES = ImmutableBiMap.of(
+      Whitespace.IGNORE_NONE, 'N',
+      Whitespace.IGNORE_TRAILING, 'E',
+      Whitespace.IGNORE_LEADING_AND_TRAILING, 'S',
+      Whitespace.IGNORE_ALL, 'A');
+
+  static {
+    checkState(WHITESPACE_TYPES.size() == Whitespace.values().length);
+  }
+
   private transient ObjectId oldId;
   private transient ObjectId newId;
   private transient Whitespace whitespace;
@@ -108,12 +119,20 @@ public class PatchListKey implements Serializable {
   private void writeObject(final ObjectOutputStream out) throws IOException {
     writeCanBeNull(out, oldId);
     writeNotNull(out, newId);
-    writeEnum(out, whitespace);
+    Character c = WHITESPACE_TYPES.get(whitespace);
+    if (c == null) {
+      throw new IOException("Invalid whitespace type: " + whitespace);
+    }
+    out.writeChar(c);
   }
 
   private void readObject(final ObjectInputStream in) throws IOException {
     oldId = readCanBeNull(in);
     newId = readNotNull(in);
-    whitespace = readEnum(in, Whitespace.values());
+    char t = in.readChar();
+    whitespace = WHITESPACE_TYPES.inverse().get(t);
+    if (whitespace == null) {
+      throw new IOException("Invalid whitespace type code: " + t);
+    }
   }
 }

gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchListLoader.java

@@ -21,7 +21,7 @@ import static org.eclipse.jgit.lib.Constants.OBJ_BLOB;
 import com.google.common.base.Function;
 import com.google.common.base.Throwables;
 import com.google.common.collect.FluentIterable;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference.Whitespace;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo.Whitespace;
 import com.google.gerrit.reviewdb.client.Patch;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.reviewdb.client.RefNames;

gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchScriptBuilder.java

@@ -17,10 +17,10 @@ package com.google.gerrit.server.patch;
 import com.google.gerrit.common.data.CommentDetail;
 import com.google.gerrit.common.data.PatchScript;
 import com.google.gerrit.common.data.PatchScript.DisplayMethod;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo.Whitespace;
 import com.google.gerrit.prettify.common.EditList;
 import com.google.gerrit.prettify.common.SparseFileContent;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference.Whitespace;
 import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.reviewdb.client.Patch;
 import com.google.gerrit.reviewdb.client.PatchLineComment;
@@ -65,7 +65,7 @@ class PatchScriptBuilder {
   private Project.NameKey projectKey;
   private ObjectReader reader;
   private Change change;
-  private AccountDiffPreference diffPrefs;
+  private DiffPreferencesInfo diffPrefs;
   private boolean againstParent;
   private ObjectId aId;
   private ObjectId bId;
@@ -95,11 +95,11 @@ class PatchScriptBuilder {
     this.change = c;
   }
 
-  void setDiffPrefs(final AccountDiffPreference dp) {
+  void setDiffPrefs(final DiffPreferencesInfo dp) {
     diffPrefs = dp;
 
-    context = diffPrefs.getContext();
+    context = diffPrefs.context;
-    if (context == AccountDiffPreference.WHOLE_FILE_CONTEXT) {
+    if (context == DiffPreferencesInfo.WHOLE_FILE_CONTEXT) {
       context = MAX_CONTEXT;
     } else if (context > MAX_CONTEXT) {
       context = MAX_CONTEXT;
@@ -140,12 +140,12 @@ class PatchScriptBuilder {
 
     if (!isModify(content)) {
       intralineDifferenceIsPossible = false;
-    } else if (diffPrefs.isIntralineDifference()) {
+    } else if (diffPrefs.intralineDifference) {
       IntraLineDiff d =
           patchListCache.getIntraLineDiff(
               new IntraLineDiffKey(
                 a.id, b.id,
-                diffPrefs.getIgnoreWhitespace() != Whitespace.IGNORE_NONE),
+                diffPrefs.ignoreWhitespace != Whitespace.IGNORE_NONE),
               IntraLineDiffArgs.create(
                 a.src, b.src, edits, projectKey, bId, b.path));
       if (d != null) {
@@ -208,7 +208,7 @@ class PatchScriptBuilder {
       //
       context = MAX_CONTEXT;
 
-      packContent(diffPrefs.getIgnoreWhitespace() != Whitespace.IGNORE_NONE);
+      packContent(diffPrefs.ignoreWhitespace != Whitespace.IGNORE_NONE);
     }
 
     return new PatchScript(change.getKey(), content.getChangeType(),

gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchScriptFactory.java

@@ -18,10 +18,10 @@ import com.google.common.base.Optional;
 import com.google.gerrit.common.Nullable;
 import com.google.gerrit.common.data.CommentDetail;
 import com.google.gerrit.common.data.PatchScript;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo;
+import com.google.gerrit.extensions.client.DiffPreferencesInfo.Whitespace;
 import com.google.gerrit.extensions.restapi.AuthException;
 import com.google.gerrit.reviewdb.client.Account;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference;
-import com.google.gerrit.reviewdb.client.AccountDiffPreference.Whitespace;
 import com.google.gerrit.reviewdb.client.Change;
 import com.google.gerrit.reviewdb.client.Patch;
 import com.google.gerrit.reviewdb.client.Patch.ChangeType;
@@ -66,7 +66,7 @@ public class PatchScriptFactory implements Callable<PatchScript> {
         String fileName,
         @Assisted("patchSetA") PatchSet.Id patchSetA,
         @Assisted("patchSetB") PatchSet.Id patchSetB,
-        AccountDiffPreference diffPrefs);
+        DiffPreferencesInfo diffPrefs);
   }
 
   private static final Logger log =
@@ -83,7 +83,7 @@ public class PatchScriptFactory implements Callable<PatchScript> {
   @Nullable
   private final PatchSet.Id psa;
   private final PatchSet.Id psb;
-  private final AccountDiffPreference diffPrefs;
+  private final DiffPreferencesInfo diffPrefs;
   private final ChangeEditUtil editReader;
   private Optional<ChangeEdit> edit;
 
@@ -110,7 +110,7 @@ public class PatchScriptFactory implements Callable<PatchScript> {
       @Assisted final String fileName,
       @Assisted("patchSetA") @Nullable final PatchSet.Id patchSetA,
       @Assisted("patchSetB") final PatchSet.Id patchSetB,
-      @Assisted final AccountDiffPreference diffPrefs) {
+      @Assisted DiffPreferencesInfo diffPrefs) {
     this.repoManager = grm;
     this.builderFactory = builderFactory;
     this.patchListCache = patchListCache;
@@ -156,7 +156,7 @@ public class PatchScriptFactory implements Callable<PatchScript> {
 
     try (Repository git = repoManager.openRepository(project)) {
       try {
-        final PatchList list = listFor(keyFor(diffPrefs.getIgnoreWhitespace()));
+        final PatchList list = listFor(keyFor(diffPrefs.ignoreWhitespace));
         final PatchScriptBuilder b = newBuilder(list, git);
         final PatchListEntry content = list.get(fileName);
 
@@ -192,11 +192,10 @@ public class PatchScriptFactory implements Callable<PatchScript> {
   }
 
   private PatchScriptBuilder newBuilder(final PatchList list, Repository git) {
-    final AccountDiffPreference dp = new AccountDiffPreference(diffPrefs);
     final PatchScriptBuilder b = builderFactory.get();
     b.setRepository(git, project);
     b.setChange(change);
-    b.setDiffPrefs(dp);
+    b.setDiffPrefs(diffPrefs);
     b.setTrees(list.isAgainstParent(), list.getOldId(), list.getNewId());
     return b;
   }

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

@@ -19,6 +19,7 @@ import com.google.gerrit.reviewdb.client.SystemConfig;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.GerritPersonIdent;
 import com.google.gerrit.server.config.AllProjectsName;
+import com.google.gerrit.server.config.AllUsersName;
 import com.google.gerrit.server.config.AnonymousCowardName;
 import com.google.gerrit.server.config.SitePaths;
 import com.google.gerrit.server.git.GitRepositoryManager;
@@ -76,6 +77,7 @@ public class SchemaUpdater {
         for (Class<?> c : new Class<?>[] {
             AllProjectsName.class,
             AllUsersCreator.class,
+            AllUsersName.class,
             GitRepositoryManager.class,
             SitePaths.class,
             }) {