ReleaseNotes/ReleaseNotes-2.5.txt - gerrit - Git at Google

 Release notes for Gerrit 2.5
 ============================

 Gerrit 2.5 is now available:

 link:http://code.google.com/p/gerrit/downloads/detail?name=gerrit-full-2.5.war[http://code.google.com/p/gerrit/downloads/detail?name=gerrit-full-2.5.war]

 Gerrit 2.5 includes the bug fixes done with
 link:ReleaseNotes-2.4.1.html[Gerrit 2.4.1] and
 link:ReleaseNotes-2.4.2.html[Gerrit 2.4.2]. These bug fixes are *not*
 listed in these release notes.

 Schema Change
 -------------
 *WARNING:* This release contains schema changes.  To upgrade:
 ----
   java -jar gerrit.war init -d site_path
 ----

 *WARNING:* Upgrading to 2.5.x requires the server be first upgraded to 2.1.7 (or
 a later 2.1.x version), and then to 2.5.x.  If you are upgrading from 2.2.x.x or
 newer, you may ignore this warning and upgrade directly to 2.5.x.

 Warning on upgrade to schema version 68
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 The migration to schema version 68, may result in a warning, which can
 be ignored when running init in the interactive mode.

 E.g. this warning may look like this:

 ----
 Upgrading database schema from version 67 to 68 ...
 warning: Cannot create index for submodule subscriptions
 Duplicate key name 'submodule_subscriptions_access_bySubscription'
 Ignore warning and proceed with schema upgrade [y/N]?
 ----

 This migration is creating an index for the
 link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/user-submodules.html[submodule feature] in
 Gerrit. When the submodule feature was introduced the index was only
 created when a new site was initialized, but not when Gerrit was
 upgraded. This migration tries to create the index, but it will only
 succeed if the index does not exist yet. If the index exists already,
 the creation of the index will fail. There was no database independent
 way to detect this case and this is why this migration leaves it to the
 user to decide if a failure should be ignored or not. If from the error
 message you can see that the migration failed because the index exists
 already (as in the example above), you can safely ignore this warning.

 Upgrade Warnings
 ----------------

 [[replication]]
 Replication
 ~~~~~~~~~~~

 Gerrit 2.5 no longer includes replication support out of the box.
 Servers that reply upon `replication.config` to copy Git repository
 data to other locations must also install the replication plugin.

 Cache Configuration
 ~~~~~~~~~~~~~~~~~~~

 Disk caches are now backed by individual H2 databases, rather than
 Ehcache's own private format. Administrators are encouraged to clear
 the `'$site_path'/cache` directory before starting the new server.

 The `cache.NAME.diskLimit` configuration variable is now expressed in
 bytes of disk used. This is a change from previous versions of Gerrit,
 which expressed the limit as the number of entries rather than bytes.
 Bytes of disk is a more accurate way to size what is held. Admins that
 set this variable must update their configurations, as the old values
 are too small. For example a setting of `diskLimit = 65535` will only
 store 64 KiB worth of data on disk and can no longer hold 65,000 patch
 sets. It is recommended to delete the diskLimit variable (if set) and
 rely on the built-in default of `128m`.

 The `cache.diff.memoryLimit` and `cache.diff_intraline.memoryLimit`
 configuration variables are now expressed in bytes of memory used,
 rather than number of entries in the cache. This is a change from
 previous versions of Gerrit and gives administrators more control over
 how memory is partioned within a server. Admins that set this variable
 must update their configurations, as the old values are too small.
 For example a setting of `memoryLimit = 1024` now means only 1 KiB of
 data (which may not even hold 1 patch set), not 1024 patch sets.  It
 is recommended to set these to `10m` for 10 MiB of memory, and
 increase as necessary.

 The `cache.NAME.maxAge` variable now means the maximum amount of time
 that can elapse between reads of the source data into the cache, no
 matter how often it is being accessed. In prior versions it meant how
 long an item could be held without being requested by a client before
 it was discarded. The new meaning of elapsed time before consulting
 the source data is more useful, as it enables a strict bound on how
 stale the cached data can be. This is especially useful for slave
 servers account and permission data, or the `ldap_groups` cache, where
 updates are often made to the source without telling Gerrit to reload
 the cache.

 New Features
 ------------

 Plugins
 ~~~~~~~

 The Gerrit server functionality can be extended by installing plugins.
 Depending on how tightly the extension code is coupled with the Gerrit
 server code, there is a distinction between
 link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/dev-plugins.html#plugin[plugins] and
 link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/dev-plugins.html#extension[extensions].

 * link:#replication[Move replication logic to replication plugin]
 +
 This splits all of the replication code out of the core server
 and moves it into a standard plugin.

 * link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/dev-plugins.html[Documentation about
   plugin development] including instructions for:
 ** link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/dev-plugins.html#getting-started[how to get
    started with plugin development]
 ** link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/dev-plugins.html#deployment[plugin
    deployment/installation]

 * link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/dev-plugins.html#API[API for plugins and
   extensions]

 * Support for link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/dev-plugins.html#ssh[SSH command
   plugins]
 +
 Allows plugin developers to declare additional SSH commands.

 * Enable link:#ssh-alias[aliases for SSH commands]
 +
 Site administrators can alias SSH commands from a plugin into the
 `gerrit` namespace.
 +
 The aliases are configured statically at server startup, but are
 resolved dynamically at invocation time to the currently loaded
 version of the plugin. If the plugin is not loaded, or does not
 define the command, "not found" is returned to the user.

 * Support for link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/dev-plugins.html#http[HTTP
   plugins]
 +
 Plugins may contribute to the /plugins/NAME/ URL space.

 * Automatic registration of plugin bindings
 +
 If a plugin has no modules declared in the manifest, automatically
 generate the modules for the plugin based on the class files that
 appear in the plugin and the `@Export` annotations that appear on
 these concrete classes.
 +
 For any non-abstract command that extends SshCommand, plugins may
 declare the command with `@Export("name")` to
 link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/dev-plugins.html#ssh[bind the implementation
 as that SSH command].
 +
 Likewise link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/dev-plugins.html#http[HTTP servlets
 can also be bound to URLs].

 * link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/dev-plugins.html#data-directory[Support a data
   directory for plugins on demand]

 * Support serving static/ and Documentation/ from plugins
 +
 The static/ and Documentation/ resource directories of a plugin can be
 served over HTTP for any loaded and running plugin, even if it has no
 other HTTP handlers. This permits a plugin to supply icons or other
 graphics for the web UI, or documentation content to help users learn
 how to use the plugin.

 * link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/dev-plugins.html#documentation[Auto-formatting
   of plugin HTTP pages from Markdown files]
 +
 If Gerrit detects that a requested plugin resource does not exist, but
 instead a file with a `.md` extension does exist, Gerrit opens the
 `.md` file and reformats it as html.

 * Support of link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/dev-plugins.html#macros[macros in
   Markdown plugin documentation]

 * link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/dev-plugins.html#auto-index[Automatic
   generation of an index for the plugin documentation]

 * Support for audit plugins
 +
 Plugins can implement an `AuditListener` to be informed about auditable
 actions:
 +
 ----
   @Listener
   public class MyAuditTrail extends AuditListener
 ----
 +
 The plugin must define a plugin module that binds the implementation of
 the audit listener in the `configure()` method:
 +
 ----
   DynamicSet.bind(binder(), AuditListener.class).to(MyAuditTrail.class);
 ----

 * Web UI for plugins
 +
 Administrators can see the list of installed plugins in the WebUI
 under `Admin` > `Plugins`. For each plugin the plugin status is shown
 and it is possible to navigate to the plugin documentation.

 * Servlet to list plugins
 +
 Administrators can retrieve plugin information from a REST interface
 by loading `<server-url>/a/plugins/`.

 * Support SSH commands to
 ** link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/cmd-plugin-ls.html[list the installed
    plugins]
 ** link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/cmd-plugin-install.html[install plugins]
 ** link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/cmd-plugin-enable.html[enable plugins]
 ** link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/cmd-plugin-remove.html[disable plugins]
 ** link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/cmd-plugin-reload.html[reload plugins]

 * Support installation of core plugin on site initialization

 * Automatically load/unload/reload plugins
 +
 The PluginScanner thread runs every 1 minute by default and loads any
 newly created plugins, unloads any deleted plugins, and reloads any
 plugins that have been modified.
 +
 The check frequency can be configured by setting
 link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/config-gerrit.html#plugins.checkFrequency[
 plugins.checkFrequency] in the Gerrit config file. By configuration
 the scanner can also be disabled.

 * link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/dev-plugins.html#classpath[Loading of plugins
   in own ClassLoader]

 * Plugin cleanup in the background
 +
 When a plugin is stopped, schedule a Plugin Cleaner task to run
 1 minute later to try and clean out the garbage and release the
 JAR from `$site_path/tmp`.

 * Export `LifecycleListener` as extension point
 +
 Extensions may need to know when they are starting or stopping.
 Export the interface that they can use to learn this information.

 * Support injection of `ServerInformation` into extensions and plugins
 +
 Plugins can take this value by injection and learn the current
 server state during their own LifecycleListener. This enables a
 plugin to determine if it is loading as part of server startup, or
 because it was dynamically installed or reloaded by an administrator.

 * link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/dev-plugins.html#getting-started[Maven
   archetype for creating gerrit plugin projects]

 * Enables the use of session management in Jetty
 +
 This enables plugins to make use of servlet sessions.

 REST API
 ~~~~~~~~
 Gerrit now supports a REST like API available over HTTP. The API is
 suitable for automated tools to build upon, as well as supporting some
 ad-hoc scripting use cases.

 * link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/rest-api.html[Documentation of the REST API]

 * Support REST endpoints to
 ** link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/rest-api.html#changes[query changes]
 ** link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/rest-api.html#projects[list projects]
 ** link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/rest-api.html#suggest-projects[suggest
    projects]
 ** link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/rest-api.html#accounts_self_capabilities[query
    the global capabilities of the calling user]

 * Support link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/rest-api.html#authentication[anonymous
   and authenticated access] to the REST endpoints

 * Support link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/rest-api.html#output[JSON output
   format] for the REST endpoints

 The new REST API is used from the Gerrit WebUI.

 Some of the methods from the old internal JSON-RPC interface were
 completely replaced by the new REST API and got deleted:

 * `ProjectAdminService.visibleProjects(AsyncCallback<ProjectList>)`
 * `ProjectAdminService.suggestParentCandidates(AsyncCallback<List<Project>>)`
 * `ChangeListService.myStarredChangeIds(AsyncCallback<Set<Change.Id>>)`
 * `ChangeListService.allQueryNext(String, String, int, AsyncCallback<SingleListChangeInfo>)`
 * `ChangeListService.allQueryPrev(String, String, int, AsyncCallback<SingleListChangeInfo>)`
 * `ChangeListService.forAccount(Account.Id, AsyncCallback<AccountDashboardInfo>)`

 [[query-deprecation]]
 In addition the `/query` API has been deprecated. By default it is
 still available but server administrators may disable it by setting
 the link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/config-gerrit.html#site.enableDeprecatedQuery[
 `site.enableDeprecatedQuery`] parameter in the Gerrit config file. This
 allows to enforce tools to move to the new API.

 Web
 ~~~

 Change Screen
 ^^^^^^^^^^^^^

 * Display commit message in a box
 +
 The commit message on the change screen is now placed in a box with a
 title and emphasis on the commit summary. The star icon and the
 permalink are displayed in the box header. The header from the change
 screen is removed as it only held duplicate information.

 * Open the dependency section automatically when the change is needed
   by an open change

 * Only show a change as needed by if its current patch set depends on
   the change

 * Show only changes of the same project in the 'Depends On' section
 +
 If two projects share the same history it can happen that the same
 commit is pushed for both projects, resulting in two changes. If now
 a successor commit is pushed for one of the projects, the resulting
 successor change was wrongly listing both changes in the 'Depends On'
 section. Now only the predecessor change of the own project is listed.

 * link:http://code.google.com/p/gerrit/issues/detail?id=1383[issue 1383]:
   Display the approval table on the PublishCommentsScreen.
 +
 So far the approval table that shows the reviewers and their current
 votes was only shown on the ChangeScreen. Now it is also shown on the
 PublishCommentScreen. This allows the reviewer to see all existing
 votes and reviewers when doing their own voting and publishing of
 comments. Seeing the existing votes helps the reviewer in
 understanding which votes are still required before the change can be
 submitted.

 * link:http://code.google.com/p/gerrit/issues/detail?id=1380[issue 1380]:
   Display time next to change comments
 +
 When a comment was posted yesterday, or any time older than 1 day but
 less than 1 year ago, display the time too. Display "May 2 17:37" rather
 than just "May 2".

 * Only show "Can Merge" when the change is new or draft

 * Allow auto suggesting reviewers to draft changes
 +
 Auto completing users for draft changes did't work as the other
 users didn't have access to the drafts. The visibility check for
 the reviewer suggestion is now skipped.

 * link:http://code.google.com/p/gerrit/issues/detail?id=1294[issue 1294]:
   Shorten subject of parent commit for displaying in the UI
 +
 If the parent commit has a very long subject (> 80 characters) shorten
 the subject for displaying it in the Gerrit web UI on the change screen.
 This avoids that the 'Parent(s)' cell for the patch set becomes very
 wide.

 * If subject is shortened for displaying in the UI indicate this by '...'
 +
 If a commit has a very long subject line (> 80 characters) it is
 shortened when it is displayed in the Gerrit Web UI. Indicate to the
 user that the subject was shortened by appending '...' to the shortened
 subject.
 +
 Also the subject is now cropped after a whitespace if possible.

 * Insert Change-Id for revert commits
 +
 The 'Revert Change' action on a merged change allows to create a new
 change that reverts the merged change. The commit message of the revert
 commit now contains a Change-Id.
 +
 It is convenient if a Change-Id is automatically created and inserted
 into the commit message of the revert commit since it makes rebasing of
 the revert commit easier.

 * Use more gentle shade of red to highlight outdated dependencies

 Patch Screens
 ^^^^^^^^^^^^^

 * New patch screen header
 +
 A new patch screen header was added that is displayed above both the
 side-by-side and unified views. The new header contains actual links to
 the available patchsets and shows which patchset is being currently
 displayed.

 * link:http://code.google.com/p/gerrit/issues/detail?id=1192[issue 1192]:
   Add download links to the unified diff view

 * Improvement of the side-by-side viewer table
 +
 The line number column for the right side was moved to be on the far
 right of the table, so that the layout now looks like this:
 +
 ----
   1 |  foo       |       bar   | 1
   2 |  hello     |       hello | 2
 ----
 +
 This looks nicer when reading a lot of code, as the line numbers are
 less relevant than the code itself which is now in the center of the
 UI.
 +
 Line numbers are still links to create comment editors, but they
 use a light shade of gray and skip the underline decoration, making
 them less visually distracting.
 +
 Skip lines now use a paler shade of blue and also hide the fact they
 contain anchors, until you hover over them and the anchor shows up.
 +
 The expand before and after are changed to be arrows showing in
 which direction the lines will appear above or below the skip
 line.

 * link:http://code.google.com/p/gerrit/issues/detail?id=626[issue 626]:
   Option to display line endings
 +
 There is a new user preference that allows to display Windows EOL/Cr-Lf.
 '\r' is shown in a dotted-line box (similar to how '\r' is displayed in
 GitWeb).

 * Streamlined review workflow
 +
 A link was added next to the "Reviewed" checkbox that marks the current
 patch as reviewed and goes to the next unreviewed patch.

 * Add key commands to mark a patch as reviewed
 +
 Add key commands
 +
 . to toggle the reviewed flag for a patch ('m')
 +
 and
 +
 . to mark the patch as reviewed and navigate to the next unreviewed
 patch ('M').

 * Use download icons instead of the `Download` text links

 User Dashboard
 ^^^^^^^^^^^^^^
 * Support for link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/user-custom-dashboards.html[custom
   dashboards]

 * link:http://code.google.com/p/gerrit/issues/detail?id=1407[issue 1407]:
   Improve highlighting of unreviewed changes in the user's dashboard
 +
 A change will be highlighted as unreviewed if
 +
 . the user is reviewer of the change but hasn't published any change
   message for the current patch set
 . the user has published a change message for the current patch set,
   but afterwards the change owner has published a change message on
   the change

 * Sort outgoing reviews in the user dashboard by created date

 * Sort incoming reviews in the user dashboard by updated date
 +
 Sorting the incoming reviews by last updated date, descending, places
 the most recently updated reviews at the top of the list for a user,
 and the oldest stale at the bottom. This may help users to identify
 items to take immediate action on, as they appear closer to the top.

 Access Rights Screen
 ^^^^^^^^^^^^^^^^^^^^

 * Display error if modifying access rights for a ref is forbidden
 +
 If a user is owner of at least one ref he is able to edit the access
 rights on a project. If he adds access rights for other refs, these
 access rights were silently ignored on save. Instead of this now an
 error message is displayed to inform the user that he doesn't have
 permissions to do the update for these refs.
 +
 In case of such an error the project access screen stays in the edit
 mode so that the unsaved modifications are not lost. The user may now
 propose the changes to the access rights through code review.

 * Allow to propose changes to access rights through code review
 +
 Users that are able to upload changes for code review for the
 `refs/meta/config` branch can now propose changes to the project access
 rights through code review directly from the ProjectAccessScreen.
 +
 When editing the project access rights there is a new button
 'Save for Review' which will create a new change for the access
 rights modifications. Project owners are automatically added as
 reviewer to this change. If a project owner agrees to the access rights
 modifications he can simply approve and submit the change.

 * Show all access rights in WebUI if user can read `refs/meta/config`
 +
 Users who can read the `refs/meta/config` branch, can see all access
 rights by fetching this branch and looking at the `project.config`
 file. Now they can see the same information in the web UI.

 * Allow extra group suggestions for project owners
 +
 When suggesting groups to a user, only groups that are visible to the
 user are suggested. These are those group that the user is member of.
 For project owners now also groups to which they are not a member are
 suggested when editing the access rights of the project.

 Other
 ^^^^^

 * link:http://code.google.com/p/gerrit/issues/detail?id=1592[issue 1592]:
   Ask user to login if change is not found
 +
 Accessing a change URL was failing with 'Application Error - The page
 you requested was not found, or you do not have permission to view this
 page' if the user was not signed in and the change was not visible to
 `Anonymous Users`. Instead Gerrit now asks the user to login and
 afterwards shows the change to the user if it exists and is visible.
 If the change doesn't exist or is not visible, the user will still get
 the NotFoundScreen after sign in.

 * Link to owner query from user names
 +
 Instead of linking from a user name to the user's dashboards, link to
 a search for changes owned by that user.

 * link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/config-gerrit.html#gerrit.reportBugUrl[Allow
   configuring the `Report Bug` URL]
 +
 Let site administrators direct users to their own ticket queue, as for
 many servers most of the reported bugs are small internal problems like
 asking for a repository to be created or updating group memberships.

 * On project creation allow choosing the parent project from a popup
 +
 In the create project UI a user can now browse all projects and select
 one as parent for the new project.

 * Check for open changes on branch deletion
 +
 Check for open changes when deleting a branch in the Gerrit WebUI.
 Delete a branch only if there are no open changes for this branch.
 This makes users aware of open changes when deleting a branch.

 * Enable ProjectBranchesScreen for the `All-Projects` project
 +
 This allows to see the branches of the `All-Projects` project in the
 web UI.

 * Show for each project in the project list a link to the repository
   browser (e.g. GitWeb).

 * Move the project listing menu items to a new top-level item
 +
 Finding the project listing was very opaque to end users. Nobody
 expected to look under `Admin` and furthermore, anonymous users were
 unable to find that link at all.
 +
 Introduced a new top-level `Projects` menu that has `List` in it to
 take you to the project listing.
 +
 In addition the `Create new project` link from the top of that listing
 was moved to this new menu.

 * Move the Groups and Plugins menu items to the top level
 +
 The top-level Admin menu is removed as it is now unnecessary after the
 Projects, Groups and Plugins menu items were moved to the top-level.

 * Move form for group creation to own screen
 +
 Move the form for the group creation from the GroupListScreen to an
 own new CreateGroupScreen and add a link to this screen at the
 beginning of the GroupListScreen. The link to the CreateGroupScreen is
 only visible if the user has the permission to create new groups.

 * Drop the `Owners` column from the group list screen
 +
 The `Owners` column on the group list screen has been dropped in order
 to link:#performance-issue-on-showing-group-list[speed up the loading
 of the group list screen].

 * Drop the `Group Type` column from the group list screen
 +
 Since link:#migrate-ldap-groups[the LDAP group type was removed] there
 is no need to display the group type on the group list screen anymore.
 There are only 3 `SYSTEM` groups using well known names, and everything
 else has the type `INTERNAL`.

 * When adding a user to a group create an account for the user if needed
 +
 Trying to add a user to a group that doesn't have an account fails with
 '... is not a registered user.'. Now adding a user to a group does not
 immediately fail if there is no account for the user, but it tries to
 authenticate the user and if the authentication is successful a user
 account is automatically created, so that the user can be added to the
 group. This only works if LDAP is used as user backend.
 +
 This allows to add users to groups that did not log in into Gerrit
 before.

 * Differentiate between draft changes and draft comments
 +
 Show the draft changes of the user when he clicks on `My` > `Drafts`.
 The user's draft comments are now available under `My` >
 `Draft Comments`.

 * Show NotFoundScreen if a user that can't create projects tries to
   access the ProjectCreationScreen

 * Add Edit, Reload next to non-editable Full Name field
 +
 If the user database is actually an external system users might need go
 to another server to edit their account data, and then re-import their
 account data by going through a login cycle. This is highly similar to
 LDAP where the directory provides account data and its refreshed every
 time the user visits the `/login/` URL handler.
 +
 The URL for the external system can be configured for the
 link:#custom-extension[`CUSTOM_EXTENSION`] auth type.

 Access Rights
 ~~~~~~~~~~~~~

 * Restrict rebasing of a change in the web UI to the change owner and
   the submitter

 * Add a new link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/access-control.html#category_rebase[
   access right to permit rebasing changes in the web UI]

 * link:http://code.google.com/p/gerrit/issues/detail?id=930[issue 930]:
   Add new link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/access-control.html#category_abandon[
   access right for abandoning changes]

 * Check if user can upload in order to restore
 +
 Restoring a change is similar to uploading a new change. If a branch
 gets closed by removing the access rights to upload new changes it
 shouldn't be possible to restore changes for this branch.

 [[hide-config]]
 * Make read access to `refs/meta/config` by default exclusive to
   project owners
 +
 When initializing a new site a set of default access rights is
 configured on the `All-Projects` project. These default access rights
 include read access on `refs/*` for `Anonymous Users` and read access
 on `refs/meta/config` for `Project Owners`. Since the read access on
 `refs/meta/config` for `Project Owners` was not exclusive,
 `Anonymous users` were able to access the `refs/meta/config` branch
 which by default should only be accessible by the project owners.

 Search
 ~~~~~~
 * Offer suggestions for the search operators in the search panel
 +
 There are many search operators and it's difficult to remember all of
 them. Now the search operators are suggested as the user types the
 query.

 * Support alias `self` in queries
 +
 Writing an expression like "owner:self status:open" will now identify
 changes that the caller owns and are still open. This `self` alias
 is valid in contexts where a user is expected as an argument to a
 query operator.

 * Add parent(s) revision information to output of query command

 * Add owner username to output of query command

 * `/query` API has been link:#query-deprecation[deprecated]

 SSH
 ~~~
 * link:http://code.google.com/p/gerrit/issues/detail?id=1095[issue 1095]
   link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/cmd-set-account.html[SSH command to manage
   accounts]

 * On link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/cmd-create-account.html[account creation] a
   password for HTTP can be specified.

 * link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/cmd-set-project.html[SSH command to manage
   project settings]

 * link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/cmd-test-submit-rule.html[SSH command to test
   submit rules]
 +
 The command creates a fresh Prolog environment and loads a Prolog
 script from stdin. `can_submit` is then queried and the results are
 returned to the user.

 * link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/cmd-ban-commit.html[SSH command to ban
   commits]

 [[ssh-alias]]
 * Enable aliases for SSH commands
 +
 Site administrators can define aliases for SSH commands in the
 link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/config-gerrit.html#ssh-alias[`ssh-alias` section]
 of the Gerrit configuration.

 * Add submit records to the output of the
   link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/cmd-query.html[query] SSH command:
 +
 Add a command line option to the `query` SSH command to include submit
 records in the output.
 +
 This facilitates the querying of information relating to the submit
 status from the command line and by API clients, including information
 such as whether the change can be submitted as-is, and whether the
 submission criteria for each review label has been met.

 * Support JSON output format for the
   link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/cmd-ls-projects.html[ls-projects] SSH command

 * Support creation of multiple branches in
   link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/cmd-create-project.html[create-project] SSH
   command
 +
 In case if a project has some kind of waterfall automerging
 a->b->c it is convenient to create all these branches at the
 project creation time.
 +
 e.g. '.. gerrit create-project -b master -b foo -b bar ...'

 * Add verbose output option to
   link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/cmd-ls-groups.html[ls-groups] command
 +
 The verbose mode enabled by the new option makes the ls-groups
 command output a tab-separated table containing all available
 information about each group (though not its members).

 Documentation
 ~~~~~~~~~~~~~

 Commands
 ^^^^^^^^

 * document for the link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/cmd-create-group.html[`create-group`]
   command that for unknown users an account is automatically created if
   the LDAP authentication succeeds

 * Update documentation and help text for the
   link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/cmd-review.html[`review`] SSH command
 +
 The review command can be applied to multiple changes, but the
 help text was written in singular tense.
 +
 Add a paragraph in the documentation explaining that the
 `--force-message` option will not be effective if the `review` command
 fails because the user is not permitted to change the label.

 * Clarify that `init --batch` doesn't drop old database objects

 * Update the list of unsupported slave commands

 * Fix link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/cmd-stream-events.html[`stream-events`]
   documentation
 +
 Some attributes contained in the events were not described, for a few
 others the name was given in a wrong case.

 * Fix and complete synopsis of commands

 Access Control
 ^^^^^^^^^^^^^^

 * Clarify the ref format for
   link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/access-control.html#category_push_merge[`Push
   Merge Commit`]
 +
 Elaborate on the required format of the ref used for `Push Merge Commit`
 access right entries to avoid user confusion when granting access to
 `refs/heads/*` still doesn't allow them to push any merge commits.

 * Document the
   link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/access-control.html#capability_emailReviewers[
   `emailReviewers`] capability

 Error
 ^^^^^
 * Improve documentation of link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/error-change-closed.html[
   `change closed` error]
 +
 The `change closed` error can also occur when trying to submit a
 review label with the SSH review command onto a change that has
 been closed (submitted and merged, or abandoned) or onto a patchset
 that has been replaced by a newer patchset.

 * Correct documentation of `invalid author` and `invalid committer`
   errors
 +
 The error messages `you are not committer ...` and `you are not
 author ...` were replaced with `invalid author` and `invalid
 committer`.

 * Describe that the `prohibited by Gerrit` error is returned if pushing
   a tag fails because the tagger is somebody else and the `Forge
   Committer` access right is not assigned.

 Dev
 ^^^

 * Update push URL in link:../SUBMITTING_PATCHES[SUBMITTING_PATCHES]
 +
 Pushes are now accepted at the same address as clone/fetch/pull.

 * Update link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/dev-contributing.html[contributor
   document]
 +
 We now prefer to use Guava (previously known as Google Collections).

 * Fixed broken link to source code
 +
 Updated the documentation source code links to point to:
 http://code.google.com/p/gerrit/source/checkout

 * State link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/dev-eclipse.html#known-problems[known issues]
   when debugging Gerrit with Eclipse

 * Improved the section on
   link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/dev-eclipse.html#hosted-mode[hosted mode
   debugging]
 +
 The existing section on hosted mode debugging left out a couple of
 steps, and the requirement to use `DEVELOPMENT_BECOME_ANY_ACCOUNT`
 instead of `OpenID` was not mentioned anywhere.

 * Add a link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/dev-release.html[release preparation
   document]
 +
 Document what it takes to make a Gerrit stable or stable-fix release,
 and how to release Gerrit subprojects.

 Other
 ^^^^^
 * Add link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/prolog-cookbook.html[Cookbook for Prolog
   submit rules]
 +
 A new document providing a step by step introduction into implementing
 specific submit policies using Prolog based submit rules was added.

 * Describe link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/refs-notes-review.html[
   `refs/notes/review` and its contents]

 * link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/config-mail.html[Document `RebasedPatchSet.vm`
   and `Reverted.vm` mail templates]

 * Specify output file for curl commands in documentation
 +
 For downloading the `commit-msg` hook and the `gerrit-cherry-pick`
 script users can either use scp or curl. Specify the output file for
 each curl command so that the result is equal to the matching scp
 command.

 * Document that user must be in repository root to install `commit-msg`
   hook

 * Add some clarifications to the
   link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/install-quick.html[quick installation guide]

 * Add missing documentation about
   link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/config-gerrit.html#hooks[hook configuration]
 +
 Add documentation of hook config for `change-restored`, `ref-updated`
 and `cla-signed` hooks.

 * Document that the commit message hook file should be executable

 * Mention that also MySQL supports replication, not just Postgres

 * Make sorting of release notes consistent so that the release notes
   for the newest release is always on top

 * Various corrections
 +
 Correct typos, spelling mistakes, and grammatical errors.

 Dev
 ~~~
 * Add link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/dev-release.html#plugin-api[script for
   releasing plugin API jars]

 * Pushes are now accepted at the same address as clone/fetch/pull
 +
 To submit patches commits can be pushed to
 https://gerrit.googlesource.com/gerrit

 * Add `-Pchrome`, `-Pwebkit`, `-Pfirefox` aliases for building
 +
 This makes it easier to build for the browser you want to
 test on, rather than remembering what its GWT name is.

 * Disable assertions for KeyCommandSet when running in gwtdebug mode
 +
 The assertions in the KeyCommandSet class cause exceptions when a
 KeyCommand is registered several times.

 * Add the run profiles to the favorites menu

 * Add Intellij IDEA files to ignore list

 * Move local Maven repository to Google Cloud Storage

 * Make sure asciidoc uses unix line endings in generated HTML.
 +
 Use an explicit asciidoc attribute to make sure the produced HTML will
 always contain unix line endings.  This will help in producing build
 results that are better comparable by size.

 * Remove timestamp from all `org.eclipse.core.resources.prefs` files
 +
 Eclipse overwrites these files when we import projects using m2e.
 Eclipse 3 writes a timestamp at the top of these files making the Git
 working tree dirty.  Eclipse 4 (Juno) still overwrites these files but
 doesn't write the timestamp.  This should help to keep the working tree
 clean.  However, since the timestamp is currently present in these
 files, Eclispe 4 would still make them dirty by overwriting and
 effectively removing the timestamp.
 +
 This change removes the timestamp from these files. This helps those
 using Eclipse 4 and doesn't make it worse for those still using Eclispe
 3.

 * Add Maven profile to skip build of plugin modules
 +
 Building the plugin modules ('Plugin API' and 'Plugin Archetype') may
 take a significant amount of time (since many jars are downloaded).
 During development it is not needed to build the plugin modules. A new
 Maven profile was added that skips the build of the plugin modules,
 so that developers have a faster turnaround. This profile is called
 `no-plugins` and it's active by default. To include the plugin modules
 into the build activate the `all` profile:
 +
 ----
   mvn clean package -P all
 ----
 +
 The script to make release builds has been adapted to activate the
 `all` profile so that the plugin modules are always built for release
 builds.

 Mail
 ~~~~

 * Add unified diff to newchange mail template
 +
 Add `$email.UnifiedDiff` as new macro to the `NewChange.vm` mail
 template. This macro is expanded to a unified diff of the patch.

 * link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/config-gerrit.html#sendemail.includeDiff[
   sendemail.includeDiff]: Enable `$email.UnifiedDiff` in `NewChange.vm`
 +
 Instead of making site administrators hack the email template, allow
 admins to enable the diff feature by setting a configuration variable
 in `gerrit.config`.

 * link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/config-gerrit.html#sendemail.maximumDiffSize[
   sendemail.maximumDiffSize]: Limit the size of diffs sent by email
 +
 If a unified diff included in an email will exceed the limit configured
 by the system administrator, only the affected file paths are listed in
 the email instead. This gives interested parties some context on the
 size and scope of the change, without killing their inbox.

 * Catch all exceptions when emailing change update

 * Allow unique from address generation
 +
 Allow the from email address to be a ParameterizedString that handles
 the `${userHash}` variable. The value of the variable is the md5 hash
 of the user name. This allows unique generation of email addresses, so
 GMAIL threads names of users in conversations correctly. For example,
 the from pattern for gerrit-review defined in the Gerrit configuration
 looks like this:
 +
 ----
   [sendemail]
     from = ${user} <noreply-gerritcodereview+${userHash}@google.com>
 ----

 * Show new change URLs in the body of the new change email
 +
 Some email clients hide the signature section of an email
 automatically.  If there are no reviewers listed on a new change,
 such as when a change is pushed over HTTP and a notification is
 automatically sent out to any subscribed watchers, the URL was
 hidden inside of the signature and not readily available.
 +
 Show the URL right away in the body.

 Miscellaneous
 ~~~~~~~~~~~~~
 * Back in-memory caches with Guava, disk caches with H2
 +
 Instead of using Ehcache for in-memory caches, use Guava. The Guava
 cache code has been more completely tested by Google in high load
 production environments, and it tends to have fewer bugs. It enables
 caches to be built at any time, rather than only at server startup.
 +
 By creating a Guava cache as soon as it is declared, rather than
 during the LifecycleListener.start() for the CachePool, we can promise
 any downstream consumer of the cache that the cache is ready to
 execute requests the moment it is supplied by Guice. This fixes a
 startup ordering problem in the GroupCache and the ProjectCache, where
 code wants to use one of these caches during startup to resolve a
 group or project by name.
 +
 Tracking the Gauva backend caches with a DynamicMap makes it possible
 for plugins to define their own in-memory caches using CacheModule's
 cache() function to declare the cache. It allows the core server to
 make the cache available to administrators over SSH with the gerrit
 show-caches and gerrit `flush-caches` commands.
 +
 Persistent caches store in a private H2 database per cache, with a
 simple one-table schema that stores each entry in a table row as a
 pair of serialized objects (key and value). Database reads are gated
 by a BloomFilter, to reduce the number of calls made to H2 during
 cache misses. In theory less than 3% of cache misses will reach H2 and
 find nothing. Stores happen on a background thread quickly after the
 put is made to the cache, reducing the risk that a diff or web_session
 record is lost during an ungraceful shutdown.
 +
 Cache databases are capped around 128M worth of stored data by running
 a prune cycle each day at 1 AM local server time. Records are removed
 from the database by ordering on the last access time, where last
 accessed is the last time the record was moved from disk to memory.

 * Add OpenID SSO support.
 +
 Setting `OPENID_SSO` for
 link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/config-gerrit.html#auth.type[`auth.type`] in the
 `gerrit.config` will allow the admin to specify an SSO entry point URL
 so that users clicking on "Sign In" are sent directly to that URL.

 * Git over HTTP BasicAuth against Gerrit basic auth.
 +
 Allows the configuration of native Gerrit username/password
 authentication scheme used for Git over HTTP BasicAuth, as alternative
 of the default DigestAuth scheme against the random generated password
 on Gerrit DB.
 +
 Example setting for link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/config-gerrit.html#auth.type[
 `auth.type`] and link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/config-gerrit.html#auth.gitBasicAuth[
 `auth.gitBasicAuth`]:
 +
 ----
   [auth]
     type = LDAP
     gitBasicAuth = true
 ----
 +
 With this configuration Git over HTTP protocol will be authenticated
 using `HTTP-BasicAuth` and credentials checked on LDAP.

 * Abstract group systems into GroupBackend interface
 +
 Group backends are supposed to use unique prefixes to isolate the
 namespaces. E.g. the group backend for LDAP is using `ldap/` as prefix
 for the group names.
 +
 This means that to refer to an LDAP group in the WebUI the group name
 needs to be prefixed with the `ldap/` string. E.g. if there is a group
 in LDAP which is called "Developers", Gerrit will suggest this group
 when the user types `ldap/De`.
 +
 WARNING: External groups are not anymore allowed to be members of
 internal groups.

 [[migrate-ldap-groups]]
 * Migrate existing internal LDAP groups
 +
 Previously, LDAP groups were mirrored in the AccountGroup table and
 given an Id and UUID the same as internal groups. Update these groups
 to be backed by only a GroupReference, with a special "ldap:" UUID
 prefix. Migrate all existing references to the UUID in ownerGroupUUID
 and any `project.config`.
 +
 This made the LDAP group type obsolete and it was removed.

 * link:https://code.google.com/p/gerrit/issues/detail?id=548[issue 548]:
   Make commands to download patch sets
   link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/config-gerrit.html#download.command[configurable]
 +
 For patch sets on the ChangeScreen different commands for downloading
 the patch sets are offered. For some installations not all commands are
 needed. Allow Gerrit administrators to configure which download
 commands should be offered.

 * Add more link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/config-gerrit.html#theme[theme color
   options]
 +
 ** Add a theme option to change outdated background color
 ** Add odd/even row background color for tables such as list of open
 reviews.  This makes them more visible without clicking on them.

 * link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/user-notify.html[Add `notify` section in
   `project.config`]
 +
 The notify section allows project owners to include emails to users
 directly from `project.config`. This removes the need to create fake
 user accounts to always BCC a group mailing list.

 * Include the contributor agreements in the `project.config` and
   migrate contributor agreements to `All-Projects`
 +
 Update the parsing of `project.config` to support the contributor
 agreements.
 +
 Add a new schema to move the ContributorAgreement, AccountAgreement,
 and AccountGroupAgreement information into the `All-Projects`
 `project.config`.

 * Add `sameGroupVisibility` to `All-Projects` `project.config`
 +
 The `sameGroupVisiblity` is needed to restrict the visibility of
 accounts when `accountVisibility` is `SAME_GROUP`. Namely, this is a
 way to make sure the `autoVerify` group in a `contributor-agreements`
 section is never suggested.

 * Add change topic in hook arguments
 +
 It was not possible for hook scripts to include topic-specific
 behaviour because the topic name was not included in the arguments.

 * Add `--is-draft` argument on `patchset-created` hook
 +
 The `--is-draft` argument will be passed with either `true` if
 the patchset is a draft, or `false` otherwise.
 +
 This can be used by hooks that need to behave differently if the
 change is a draft.

 * Log sign in failures on info level
 +
 If for a user signing in into the Gerrit web UI fails, this can have
 many reasons, e.g. username is wrong, password is wrong, user is marked
 as inactive, user is locked in the user backend etc. In all cases the
 user just gets a generic error message 'Incorrect username or
 password.'. Gerrit administrators had trouble to find the exact reason
 for the sign in problem because the corresponding AccountException was
 not logged.

 * Do not log 'Object too large' as error with full stacktrace
 +
 If a user pushes an object which is larger than the configured
 `receive.maxObjectSizeLimit` parameter, the push is rejected with an
 'Object too large' error. In addition an error log entry with the full
 stacktrace was written into the error log.
 +
 This is not really a server error, but just a user doing something that
 is not allowed, and thus it should not be logged as error. For a Gerrit
 administrator it might still be interesting how often the limit is hit.
 This is why it makes sense to still log this on info level.
 +
 For the user pushing a too large object we now do not print the
 'fatal: Unpack error, check server log' message anymore, but only the
 'Object too large' error message.

 * Add better explanations to rejection messages
 +
 Provide information to the user why a certain push was rejected.

 * Automatic schema upgrade on Gerrit startup
 +
 In case when Gerrit administrator(s) don't have a direct access to the
 file system where the review site is located it gets difficult to
 perform a schema upgrade (run the init program). For such cases it is
 convenient if Gerrit performs schema upgrade automatically on its
 startup.
 +
 Since this is a potentially dangerous operation, by default it will not
 be performed. The configuration parameter
 link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/config-gerrit.html#site.upgradeSchemaOnStartup[
 site.upgradeSchemaOnStartup] is used to switch on automatic schema
 upgrade.

 * Shorten column names that are longer than 30 characters
 +
 Some databases can't deal with column names that are longer than 30
 characters. Examples are MaxDB and
 link:http://groups.google.com/group/repo-discuss/browse_thread/thread/ecb713d42c04ae8a/cc963525d8247a17?lnk=gst#cc963525d8247a17[Oracle].
 +
 Gerrit had two column names in the `accounts` table that exceeded the
 30 characters: `displayPatchSetsInReverseOrder`,
 `displayPersonNameInReviewCategory`
 +
 These 2 columns were renamed so that their names fit within the 30
 character range.

 * Increase the maximum length for tracking ID's to 32 characters
 +
 So far tracking ID's had a maximum length of only 20 characters.

 * Set `GERRIT_SITE` in Gerrit hooks as environment variable
 +
 Allows development of hooks parametrised on Gerrit location. This can
 be useful to allow hooks to load the Gerrit configuration when needed
 (from `$GERRIT_SITE`) or even store their additional config files under
 `$GERRIT_SITE/etc` and retrieve them at startup.

 * Add an exponentially rolling garbage collection script
 +
 `git-exproll.sh` is a git garbage collection script aimed specifically
 at reducing exccessive garbage collection and particularly large
 packfile churn for Gerrit installations.
 +
 Excessive garbage collection on "dormant" repos is wasteful of both CPU
 and disk IO.  Large packfile churn can lead to heavy RAM and FS usage
 on Gerrit servers when the Gerrit process continues to hold open the
 old delete packfiles.  This situation is most detrimental when jgit is
 configured with large caching parameters.  Aside from these downsides,
 running git gc often can be very beneficial to performance on servers.
 This script attempts to implement a git gc policy which avoids the
 downsides mentioned above so that git gc can be comfortably run very
 regularly.
 +
 `git-exproll.sh` uses keep files to manage which files will get
 repacked.  It also uses timestamps on the repos to detect dormant repos
 to avoid repacking them at all.  The primary packfile objective is to
 keep around a series of packfiles with sizes spaced out exponentially
 from each other, and to roll smaller packfiles into larger ones once
 the smaller ones have grown.  This strategy attempts to balance disk
 space usage with avoiding rewriting large packfiles most of the time.
 +
 The exponential packing objective above does not save a large amount of
 time or CPU, but it does prevent the packfile churn.  Depending on repo
 usage, however the dormant repo detection and avoidance can result in a
 very large time savings.

 * Automatically flush persistent H2 cache if the existing cache entries
   are incompatible with the cache entry class and thus can't be
   deserialized

 * Unpack JARs for running servers in `$site_path/tmp`
 +
 Instead of unpacking a running server into `~/.gerritcodereview/tmp`
 only use that location for commands like init where there is no active
 site. From gerrit.sh always use `$site_path/tmp` for the JARs to
 isolate servers that run on the same host under the same UNIX user
 account.

 [[custom-extension]]
 * Allow for the `CUSTOM_EXTENSION` `auth.type` to configure URLs for
   editing the user name and obtaining an HTTP password
 +
 Allow `CUSTOM_EXTENSION` auth type to supply by `auth.editFullNameUrl`
 a URL in the web UI that links users to the other account system,
 where they can edit their name, and then use another reload URL to
 cycle through the `/login/` step and refresh the data cached by Gerrit.
 +
 Allow `CUSTOM_EXTENSION` auth type to supply by `auth.httpPasswordUrl`
 a URL in the web UI that allows users to obtain an HTTP password.
 +
 Like the rest of the `CUSTOM_EXTENSION` stuff, this is hack that will
 eventually go away when there is proper support for authentication
 plugins.

 Performance
 ~~~~~~~~~~~
 [[performance-issue-on-showing-group-list]]
 * Fix performance issues on showing the list of groups in the Gerrit
   WebUI
 +
 Loading `Admin` > `Groups` on large servers was very slow. The entire
 group membership database was downloaded to the browser when showing
 just the list of groups.
 +
 Now the amount of data that needs to be downloaded to the browser is
 reduced by using the more leightweight `AccountGroup` type instead of
 the `GroupDetail` type when showing the groups in a list format. As a
 consequence the `Owners` column that showed the name of the owner group
 had been dropped.

 * Add LDAP-cache to minimize number of queries when unnesting groups
 +
 A new cache named "ldap_groups_byinclude" is introduced to help lessen
 the number of queries needed to resolve nested LDAP-groups.

 * Add index for accessing change messages by patch set
 +
 This improves the performance of loading the dashboards.

 * Add a fast path to avoid checking every commit on push
 +
 If a user can forge author, committer and gerrit server identity, and
 can upload merges, don't bother checking the commit history of what is
 being uploaded. This can save time on servers that are trying to accept
 a large project import using the push permission.

 * Improve performance of `ReceiveCommits` by reducing `RevWalk` load
 +
 JGit RevWalk does not perform well when a large number of objects are
 added to the start set by `markStart` or `markUninteresting`. Avoid
 putting existing `refs/changes/` or `refs/tags/` into the `RevWalk` and
 instead use only the `refs/heads` namespace and the name of the branch
 used in the `refs/for/` push line.
 +
 Catch existing changes by looking for their exact commit SHA-1, rather
 than complete ancestory. This should have roughly the same outcome for
 anyone pushing a new commit on top of an existing open change, but
 with lower computional cost at the server.

 * Lookup changes in parallel during `ReceiveCommits`
 +
 If the database has high query latency, the loop that locates existing
 changes on the destination branch given Change-Id can be slow. Start
 all of the queries as commits are discovered, but don't block on
 results until all queries were started.
 +
 If the database can build the `ResultSet` in the background, this may
 hide some of the query latency by allowing the queries to overlap when
 more than one lookup must be performed for a push.

 * Perform change update on multiple threads
 +
 When multiple changes need to be created or updated for a single push
 operation they are now inserted into the database by parallel threads,
 up to the maximum allowed thread count. The current thread is used
 when the thread pool is already fully in use, falling back to the
 prior behavior where each concurrent push operation can do its own
 concurrent database update. The thread pool exists to reduce latency
 so long as there are sufficient threads available.
 +
 This helps push times on databases that are high latency, such as
 database servers that are running on a different machine from the
 Gerrit server itself, e.g. gerrit.googlesource.com.
 +
 The new thread pool is
 link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/config-gerrit.html#receive.changeUpdateThreads[
 disabled by default], limiting the overhead to servers that have good
 latency with their database, such as using in-process H2 database, or
 a MySQL or PostgreSQL on the same host.

 * Use `BatchRefUpdate` to execute reference changes
 +
 Some storage backends for JGit are able to update multiple references
 in a single pass efficiently. Take advantage of this by pushing
 any normal reference updates (such as direct push or branch create)
 into a single `BatchRefUpdate` object.

 * Assume labels are correct in ListChanges
 +
 To reduce end-user latency when displaying changes in a search result
 or user dashboard, assume the labels are accurate in the database at
 display time and don't recompute the access privileges of a reviewer.

 * Notify the cache that the git_tags was modified
 +
 The tag cache was updated in-place, which prevented the H2 based
 storage from writing out the updated tag information. This meant
 servers almost never had the right data stored on disk and had to
 recompute it at startup.
 +
 Anytime the value is now modified in place, put it back into the
 cache so it can be saved for use on the next startup.

 * Special case hiding `refs/meta/config` from Git clients
 +
 VisibleRefFilter requires a lot of server CPU to accurately provide
 the correct listing to clients when they cannot read `refs/*`.
 +
 Since the default configuration is now to link:#hide-config[
 hide `refs/meta/config`], use a special case in VisibleRefFilter that
 permits showing every reference except `refs/meta/config` if a user can
 read every other reference in the repository.

 * Avoid second remote call to lookup approvals when loading change
   results
 +
 By using the new link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/rest-api.html#changes[`/changes/`]
 REST endpoint the web UI client now obtains the label information
 during the query and avoids a second round trip to lookup the current
 approvals for each displayed change. For most users this should improve
 the way the page renders. The verified and code review columns will be
 populated before the table is made visible, preventing the layout from
 "jumping" the way the old UI did when the 2nd RPC finally finished and
 supplied the label data.

 * Load patch set approvals in parallel
 +
 ResultSet is a future-like interface, the database system is free to
 execute each result set asynchronously in the background if it
 supports that. gwtorm's default SQL backend always runs queries
 immediately and then returns a ListResultSet, so for most installs this
 has no real impact in ordering.
 +
 For the system that runs gerrit-review, each query has a high cost in
 network latency, the system treats ResultSet as a future promise to
 supply the matching rows. Getting all of the necessary ResultSets up
 front allows the database to send all requests to the backend as early
 as possible, allowing the network latency to overlap.

 Upgrades
 --------
 * Update Gson to 2.1
 * Update GWT to 2.4.0
 * Update JGit to 2.0.0.201206130900-r.23-gb3dbf19

 * Use gwtexpui 1.2.6
 +
 ** Hide superfluous status text from clippy flash widget
 ** Fix diappearance of text in CopyableLabel when clicking on it

 * Update Guava to 12.0.1
 +
 This fixes a performance problem with LoadingCache where the cache's
 inner table did not dynamically resize to handle a larger number
 of cached items, causing O(N) lookup performance for most objects.

 Bug Fixes
 ---------

 Security
 ~~~~~~~~
 * Ensure that only administrators can change the global capabilities
 +
 Only Gerrit server administrators (members of the groups that have
 the `administrateServer` capability) should be able to edit the
 global capabilities because being able to edit the global capabilities
 means being able to assign the `administrateServer` capability.
 +
 Because of this on the `All-Projects` project it is disallowed to assign
 +
 . the `owner` access rights on `refs/*`
 +
 Project owners (members of groups to which the `owner` access right
 is assigned) are able to edit the access control list of the projects
 they own. Hence being owner of the `All-Projects` project would allow
 to edit the global capabilities and assign the `administrateServer`
 capabilitiy without being Gerrit administrator.
 +
 In earlier Gerrit versions (2.1.x) it was already implemented like
 this but the corresponding checks got lost.
 +
 . the 'push' access right on `refs/meta/config`
 +
 Being able to push configuration changes to the `All-Projects` project
 allows to edit the global capabilities and hence a user with this
 access right could assign the `administrateServer` capability without
 being Gerrit administrator.
 +
 From the Gerrit WebUI (ProjectAccessScreen) it is not possible anymore
 to assign on the `All-Projects` project the `owner` access right on
 `refs/*` and the `push` access right on `refs/meta/config`.
 +
 In addition it is ensured that an `owner` access right that is assigned
 for `refs/*` on the `All-Projects` project has no effect and that only
 Gerrit administrators with the `push` access right can push
 configuration changes to the `All-Projects` project.
 +
 It is still possible to assign both access rights (`owner` on `refs/*`
 and `push` on `refs/meta/config`) on the `All-Projects` project by directly
 editing its `project.config` file and pushing to `refs/meta/config`.
 To fix this it would be needed to reject assigning these access rights
 on the `All-Projects` project as invalid configuration, however doing this
 would mean to break existing configurations of the `All-Projects` project
 that assign these access rights. At the moment there is no migration
 framework in place that would allow to migrate `project.config` files.
 Hence this check is currently not done and these access rights in this
 case have simply no effect.

 Web
 ~~~

 * Do not show "Session cookie not available" on sign in
 +
 When LDAP is used for authentication, clicking on the 'Sign In' link
 opens a user/password dialog. In this dialog the "Session cookie not
 available." message was always shown as warning. This warning was
 pretty useless since the user was about to sign in because he had no
 current session.
 +
 This problem was discussed on the
 link:https://groups.google.com/forum/#!topic/repo-discuss/j-t77m8-7I0/discussion[
 Gerrit mailing list].

 * Reject restoring a change if its destination branch does not exist
   anymore

 * Reject submitting a change if its destination branch does not exist
   anymore
 +
 If a branch got deleted and there was an open change for this branch,
 it was still possible to submit this open change. As result the
 destination branch was implicitly recreated, even if the user
 submitting the change had no privileges to create branches.

 * link:http://code.google.com/p/gerrit/issues/detail?id=1352[issue 1352]:
   Don't display "Download" link for `/COMMIT_MSG`
 +
 The commit message file is special, it doesn't actually exist and
 cannot be downloaded. Don't offer the download link in the side by
 side viewer.

 * Dependencies were lost in the ChangeScreen's "Needed By" table
 +
 Older patchsets are now iterated for decendents, so that the dependency
 chain does not break on new upstream patchsets.

 * link:http://code.google.com/p/gerrit/issues/detail?id=1442[issue 1442]:
   Only show draft change dependency if current user is owner or reviewer
 +
 In the change screen, the dependencies panel was showing draft changes
 in the "Depends On" and "Needed By" lists for all users, and when there
 was no user logged in.

 * link:http://code.google.com/p/gerrit/issues/detail?id=1558[issue 1558]:
   Create a draft patch set when a draft patch set is rebased
 +
 Rebasing a draft patch set created a non-draft patch set. It was
 unexpected that rebasing a draft patch set published the modifications
 done in the draft patch set.

 * link:http://code.google.com/p/gerrit/issues/detail?id=1176[issue 1176]:
   Fix disappearance of download command in Firefox
 +
 Clicking on the download command for a patch set in Firefox made the
 download command disappear.

 * link:http://code.google.com/p/gerrit/issues/detail?id=1587[issue 1587]:
   Fix disappearance of action buttons when selecting the last patch set
   as `Old Version History`

 * Fix updating patch list when `Old Version History` is changed
 +
 If a collapsed patch set panel was expanded and re-closed it's patch
 list wasn't updated anymore when the selection for `Old Version History`
 was changed.

 * link:http://code.google.com/p/gerrit/issues/detail?id=1523[issue 1523]:
   Update diff base to match old version history
 +
 When changing the diff base in the `Old Version History` on the change
 screen and then entering the Side-By-Side view for a file, clicking on
 the back button in the browser (reentering the change screen) was
 causing the files to be wrongly compared with `Base` again.

 * Don't NPE if current patch set is not available
 +
 Broken changes may have the current patch set field incorrectly
 specified, causing currentPatchSet to be unable to locate the
 correct data and return it. When this happens don't NPE, just
 claim the change is not reviewed.

 * link:https://code.google.com/p/gerrit/issues/detail?id=1555[issue 1555]:
   Fix displaying of file diff if draft patch has been deleted
 +
 Displaying any file diff for a patch set failed if the change had any
 gaps in its patch set history. Patch sets can be missing, if they
 have been drafts and were deleted.

 * link:https://code.google.com/p/gerrit/issues/detail?id=856[issue 856]:
   Fix displaying of comments on deleted files
 +
 Published and draft comments that are posted on deleted files were not
 loaded and displayed.

 * link:https://code.google.com/p/gerrit/issues/detail?id=735[issue 735]:
   Fix `ArrayIndexOutOfBoundsException` on navigation to next/previous
   patch
 +
 An `ArrayIndexOutOfBoundsException` could occur when navigating from
 one patch to the next/previous patch if the next/previous patch was a
 newly added binary file. The exception occurred if the user was not
 signed in or if the user was signed in and had `Syntax Coloring` in the
 preferences enabled.

 * link:https://code.google.com/p/gerrit/issues/detail?id=816[issue 816]:
   Fix wrong file indention in Side-by-Sie diff viewer on right side

 * Only set reviewed attribute on open changes
 +
 If a change is merged or abandoned, do not consider the reviewed
 property for the calling user, so that the change is not highlighted
 as unreviewed on the user's dashboard.

 * Change PatchTable pointer when loading patch
 +
 This patch fixes an issue with the "file list" table displayed by
 clicking on the "Files" sub-menu when viewing a diff.
 +
 Originally when navigating between patch screens the highlighted row
 (pointer) of the file list table would not change when not directly
 interacting with the table e.g. by clicking on the previous or next
 file link.
 +
 This patch updates the file list table whenever a new patch screen is loaded
 so that the pointer corresponds to the current patch being displayed.

 * Don't hyperlink non-internal groups
 +
 When an external group (such as LDAP) is used in a permission rule,
 don't attempt to link to the group in the internal account system UI.
 The group won't load successfully. Instead just display the name and
 put the UUID into a tooltip to show the full DN.

 * Fix: Popup jumps back to original position when resizing screen
 +
 On 'Watched Projects' screen, the 'Browse' button displays a popup
 window. If the user moves it and then resizes the screen, it won't snap
 back to the original position.

 * link:http://code.google.com/p/gerrit/issues/detail?id=1457[issue 1457]:
   Prevent groups from being renamed to empty string

 * Fixed AccountGroupInfoScreen search callback
 +
 If the search returned no results, the search button would not be
 enabled and the status panel was not shown. Fixed the panel and button
 to always be enabled.

 * Fix NullPointerException on `/p/`
 +
 Requesting just `/p/` caused a NullPointerException as the redirection
 logic had no project name to form a URL from. Detect requests for `/p/`
 and redirect to 'Admin' > 'Projects' to show the projects the caller
 has access to.

 Mail
 ~~~~

 * Fix: Rebase did not mail all reviewers

 * Fix email showing in AccountLink instead of names
 +
 Prefer the full name for the display text of the link.

 * Fix signature delimiter for e-mail messages
 +
 Make sure the signature delimiter is "-- " (two dashes and a space).

 * link:http://code.google.com/p/gerrit/issues/detail?id=1397[issue 1397]:
   Don't wait for banner message from SMTP server after STARTTLS
   negotiation
 +
 According to RFC 2847 section 5.2, SMTP server won't send the banner
 message again after STARTTLS negotiation. The original code will hang
 until SMTP server kicks it off due to timeout and can't send email with
 STARTTLS enabled, aka. `sendemail.smtpEncryption = tls`.

 * Extract all mail templates during site init
 +
 The example mail templates `RebasedPatchSet.vm`, `Restored.vm` and
 `Reverted.vm` were not extracted during the initialization of a new
 site.

 SSH
 ~~~
 * Fix reject message if bypassing code review is not allowed
 +
 If a user is not allowed to bypass code review, but tries to push a
 commit directly, Gerrit rejected this push with the error message
 "can not update the reference as a fast forward". This message was
 confusing to the user since the push only failed due to missing
 access rights. Go back to the old message that says "prohibited
 by Gerrit".

 * Fix reject message if pushing tag is rejected because tagger is
   somebody else
 +
 Pushing a tag that has somebody else as tagger requires the `Forge
 Committer` access right. If this access right was missing Gerrit
 was rejecting the push with "can not create new references". This error
 message was misleading because the user may have thought that the
 `Create Reference` access right was missing which was actually assigned.
 +
 The same reject message was also returned on push of an annotated tag
 if the `Push Annotated Tag` access right was missing. Also in this case
 the error message was not ideal.
 +
 Go back to the old more generic message which says `prohibited by
 Gerrit`.

 * link:http://code.google.com/p/gerrit/issues/detail?id=1437[issue 1437]:
   Send event to stream when draft change is published
 +
 When a change is uploaded as a draft, a `patchset-created` event is
 sent to the event stream, but since drafts are private to the owner,
 the event is not publicly visible.  When the draft is later published,
 no publicly visible event was sent. As result of this external tools
 that rely on the event stream to detect new changes didn't receive
 events for any changes that were first uploaded as draft.
 +
 There is now a new event, `draft-published`, which is sent to the
 event stream when a draft change is published.  The content of this
 event is the same as `patchset-created`.

 * Fix: Wrong ps/rev in `change-merged` stream-event
 +
 When using cherry-pick as merge strategy, the wrong ref was set in the
 `change-merged` stream-event.
 +
 The issue stems from Gerrit would not acknowledge the resulting new
 pachset (the actual cherry-pick).

 * Fix NullPointerException in `query` SSH command
 +
 Running the `query` SSH command with the options `--comments` and
 `--format=JSON` failed with a NullPointerException if a change had a
 message without author. Change messages have no author if they were
 created by Gerrit. For such messages now the Gerrit Server identity is
 returned as author.

 * Fix the `export-review-notes` command's Guice bindings
 +
 The `export-review-notes` command was broken becasue of the CachePool
 class being bound twice. The startup of the command failed because of
 that.

 * Fix sorting of SSH help text
 +
 Commands were displaying in random order, sort commands before output.

 * `replicate` command: Do not log errors for wrong user input
 +
 If the user provided an invalid combination of command options or an
 non existing project name this was logged in the `error.log` but
 printing the error out to the user is sufficient.

 Authentication
 ~~~~~~~~~~~~~~

 * Fix NPE in LdapRealm caused by non-LDAP users
 +
 Servers that are connected to LDAP but have non-LDAP user accounts
 created by `gerrit create-account` (e.g. batch role accounts for
 build systems) were crashing with a NullPointerException when the
 LdapRealm tried to discover which LDAP groups the non-LDAP user
 was a member of in the directory.

 * Fix domain field of HTTP digest authentication
 +
 Per RFC 2617 the domain field is optional. If it is not present,
 the digest token is valid on any URL on the server. When set it
 must be a path prefix describing the URLs that the password would
 be valid against.
 +
 When a canonical URL is known, supply that as the only domain that
 is valid. When the URL is missing (e.g. because the provider is
 still broken) rely on the context path of the application instead.

 Replication
 ~~~~~~~~~~~

 * Fix inconsistent behaviour when replicating `refs/meta/config`
 +
 In `replication.config`, if `authGroup` is set to be used together with
 `mirror = true`, refs blocked through the `authGroup` are deleted from
 the slave/mirror. The same correctly applies if the `authGroup` is used
 to block `refs/meta/config`.
 +
 However, if `replicatePermission` was set to `false`, Gerrit was
 refusing to clean up `refs/meta/config` on the slave/mirror.

 * Fix bug with member assignment order in PushReplication.
 +
 The groupCache was being used before it was set in the class. Fix the
 ordering of the assignment.

 Approval Categories
 ~~~~~~~~~~~~~~~~~~~

 * Make `NoBlock` and `NoOp` approval category functions work
 +
 The approval category functions `NoBlock` and `NoOp` have not worked
 since the integration of Prolog.
 +
 `MAY` was introduced as a new submit record status to complement `OK`,
 `REJECT`, `NEED`, and `IMPOSSIBLE`. This allows the expression of
 approval categories (labels) that are optional, i.e. could either be
 set or unset without ever influencing whether the change could be
 submitted. Previously there was no way to express this property in
 the submit record.
 +
 This enables the `NoBlock` and `NoOp` approval category functions to
 work as they now emit may() terms from the Prolog rules. Previously
 they returned ok() terms lacking a nested user term, leading to
 exceptions in code that expected a user context if the label was `OK`.

 * Fix category block status without negative score
 +
 Categories without blocking or approval scores will result in the
 blocking/approved image appearing in the category column after changes
 are merged should the score by the reviewer match the minimum or
 maximum value respectively.
 +
 A check to ignore "No Score" values of 0 was added.

 * Don't remove dashes from approval category name
 +
 If an approval category name contained a dash, it was removed by
 Gerrit. On the other side a space in an approval category name is
 converted to a dash. This was confusing for writing Prolog submit
 rules. If, for example, one defined a new category named `X-Y`, then in
 the Prolog code the proper name for that category would have been `XY`
 which was unintuitive.

 * Fix NPE in `PRED__load_commit_labels_1`
 +
 If a change query uses reviewer information and loads the approvals
 map, but there are no approvals for a given patch set available, the
 collection came out null, which cannot be iterated. Make it always be
 an empty list.

 Other
 ~~~~~

 * link:http://code.google.com/p/gerrit/issues/detail?id=1554[issue 1554]:
   Fix cloning of new projects from slave servers
 +
 If a new project is created in Gerrit the replication creates the
 repository for this new project directly in the filesystem of the slave
 server. The slave server was not discovering this new repository and as
 result any attempt to clone the corresponding project from the slave
 server failed.

 * link:http://code.google.com/p/gerrit/issues/detail?id=1548[issue 1548]:
   Create a ref for the patch set that is created when a change is
   cherry-picked and trigger the replication for it:
 +
 If Cherry Pick is chosen as submit type, on submit a new commit is
 created by the cherry-pick. For this commit a new patch set is created
 which is added to the change. Using any of the download commands to
 fetch this new patch set failed with 'Couldn't find remote ref' because
 no ref for the new patch set was created.

 * link:http://code.google.com/p/gerrit/issues/detail?id=1626[issue 1626]:
   Fix NullPointerException on cherry-pick if `changeMerge.test` is enabled

 * link:http://code.google.com/p/gerrit/issues/detail?id=1491[issue 1491]:
   Fix nested submodule updates

 * Set link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/config-gerrit.html#transfer.timeout[transfer
   timeout] for pushes through HTTP
 +
 The transfer timeout was only set when pushing via SSH.

 * link:http://gerrit-documentation.googlecode.com/svn/Documentation/2.5/config-gerrit.html#receive.maxObjectSizeLimit[
   Limit maximum Git object size] when pushing through HTTP
 +
 The limit for the maximum object size was only set when pushing via SSH.

 * Fix units of `httpd.maxwait`
 +
 The default unit here is minutes, but Jetty wants to get milliseconds
 from the maxWait field. Convert the minutes returned by getTimeUnit to
 be milliseconds, matching what Jetty expects.
 +
 This should resolve a large number of 503 errors for Git over HTTP.

 * link:http://code.google.com/p/gerrit/issues/detail?id=1493[issue 1493]:
   Fix wrong "change ... closed" message on direct push
 +
 Pushing a commit directly into the central repository with bypassing
 code review wrongly resulted in a "change ... closed" message if the
 commit was already pushed for review and if a Change-Id was included in
 the commit message. Despite of the error message the push succeeded and
 the corresponding change got closed. Now the message is not printed
 anymore.

 * Fix NPE that can hide guice CreationException on site init
 +
 Note that the `--show-stack-trace` option is needed to print the stack
 trace when a program stops with a Die exception.

 * Do not automatically add author/committer as reviewer to drafts

 * Do not automatically add reviewers from footer lines to drafts

 * Fix NullPointerException in MergeOp
 +
 The body of the commit object may have been discarded earlier to
 save memory, so ensure it exists before asking for the author.

 * link:http://code.google.com/p/gerrit/issues/detail?id=1396[issue 1396]:
   Initialize the submodule commit message buffer

 * Fix file name matching in `commit_delta` to perform substring
   matching
 +
 The `commit_delta` predicate was matching the entire file name against
 the given regular expression while other predicates (`commit_edits`,
 `commit_message_matches`) performed substring matching. It was
 inconsistent that for `commit_delta` it was needed to write something
 like:
 +
 ----
   commit_delta('.*\.java')
 ----
 +
 to match all `*.java` files, while for `commit_edits` it was:
 +
 ----
   commit_edits('\.java$', '...')
 ----
 +
 to match the same set of (Java) files.

 * Create index for submodule subscriptions on site upgrade

 * Fix URL to Jetty XML DTDs so they can be properly validated

 * Fix resource leak when `changeMerge.test` is `true`

 * Fix possible synchronization issue in TaskThunk

 * Fix possible NPEs in `ReplaceRequest.cmd` usage in `ReceiveCommits`
 +
 The `cmd` field is populated by `validate(boolean)`. If this method
 fails, results on some `ReplaceRequests` may not be set. Guard the
 attempt to access the field with a null check.

 * Match no labels if current patch set is not available
 +
 If the current patch set cannot be loaded from `ChangeData`, assume no
 label information. This works around an NullPointerException inside of
 `ChangeControl` where the `PatchSet` is otherwise required.

 * Create new patch set references before database records
 +
 Ensure the commit used by a new change or replacement patch set
 always exists in the Git repository by writing the reference first
 as part of the overall `BatchRefUpdate`, then inserting the database
 records if all of the references stored successfully.

 * Fix rebase patch set and revert change to update Git first
 +
 Update the Git reference before writing to the database. This way the
 repository cannot be corrupted if the server goes down between the two
 actions.

 * Make sure we use only one type of NoteMerger for review notes creation

 * Fix generation of owner group in GroupDetail
 +
 Set the GroupDetail.ownerGroup to the AccountGroup.ownerGroupUUID
 instead of the groupUUID.

 * Ensure that ObjectOutputStream in H2CacheImpl is closed

 * Ensure that RevWalk in SubmoduleOp is released