Merge "Clean up configs around mergeability behavior"

Documentation/config-gerrit.txt

@@ -1171,15 +1171,6 @@ explicitly.
 +
 Default is `ALL`.
 
-[[change.api.excludeMergeableInChangeInfo]]change.api.excludeMergeableInChangeInfo::
-+
-If true, the mergeability bit in
-link:rest-api-changes.html#change-info[ChangeInfo] will never be set. It can
-be requested separately through the
-link:rest-api-changes.html#get-mergeable[get-mergeable] endpoint.
-+
-Default is false.
-
 [[change.cacheAutomerge]]change.cacheAutomerge::
 +
 When reviewing diff commits, the left-hand side shows the output of the
@@ -1248,6 +1239,34 @@ The following operations are allowed even when a change is at the limit:
 
 By default 1000.
 
+[[change.mergeabilityComputationBehavior]]change.mergeabilityComputationBehavior::
++
+This setting determines when Gerrit computes if a change is mergeable or not.
+This computation is expensive, especially when the repository is large or when
+there are many open changes.
++
+This config can have the following states:
++
+* `API_REF_UPDATED_AND_CHANGE_REINDEX`: Gerrit indexes `mergeability` enabling
+  the `is:mergeable` predicate in change search and allowing fast retrieval of
+  this bit in query responses. Gerrit will always serve `mergeable` in
+  link:rest-api-changes.html#change-info[ChangeInfo] objects.
+  Gerrit will reindex all open changes when the target ref advances (expensive).
+* `REF_UPDATED_AND_CHANGE_REINDEX`: Gerrit indexes `mergeability` enabling the
+  `is:mergeable` predicate in change search and allowing fast retrieval of this
+  bit in query responses. Gerrit will never serve `mergeable` in
+  link:rest-api-changes.html#change-info[ChangeInfo]
+  objects. This state can be a final state for instances that only want to
+  optimize the read path, but not the write path for speed or serve as an
+  intermediary step for instances that want to optimize both and need to migrate
+  callers of their API.
+  Gerrit will reindex all open changes when the target ref advances (expensive).
+* `NEVER`: Gerrit does not index `mergeable`, so `is:mergeable` is disabled as
+  query operator. Gerrit does not serve `mergeable` in
+  link:rest-api-changes.html#change-info[ChangeInfo].
+
+Default is `REF_UPDATED_AND_CHANGE_REINDEX`.
+
 [[change.move]]change.move::
 +
 Whether the link:rest-api-changes.html#move-change[Move Change] REST
@@ -1415,9 +1434,10 @@ the changes to auto-abandon.
 +
 By default `true`, meaning mergeable changes are auto-abandoned.
 +
-If link:#index.change.indexMergeable[`index.change.indexMergeable`]
+If
-is disabled, setting this option to `false` has no effect and it
+link:#change.mergeabilityComputationBehavior[`change.mergeabilityComputationBehavior`]
-behaves as though it were set to `true`.
+is set to `NEVER`, setting this option to `false` has no effect and it behaves
+as though it were set to `true`.
 
 [[changeCleanup.cleanupAccountPatchReview]]changeCleanup.cleanupAccountPatchReview::
 +
@@ -2791,22 +2811,6 @@ online schema upgrades.
 If not set or set to a zero, defaults to the number of logical CPUs as returned
 by the JVM. If set to a negative value, defaults to a direct executor.
 
-[[index.change.indexMergeable]]index.change.indexMergeable::
-+
-Specifies if `mergeable` should be index or not. Indexing this field enables
-queries that contain the mergeability operator (`is:mergeable`). If enabled,
-Gerrit will check if the change is mergeable into the target branch when
-reindexing a change. This is an expensive operation.
-+
-If true, Gerrit will reindex all open changes when the target ref advances.
-Depending on the frequency of updates to the ref and the number of open changes,
-this can be very expensive.
-+
-When this setting is changed from `false` to `true`, all changes need to be
-reindexed.
-+
-Defaults to true.
-
 [[index.onlineUpgrade]]index.onlineUpgrade::
 +
 Whether to upgrade to new index schema versions while the server is
@@ -3117,7 +3121,7 @@ Depending on the setup, these events might get serialized using stream
 events.
 +
 This can be set to the set of minimal options that consumers of Gerrit's
-events need. A minimal set would be (`SKIP_MERGEABLE`,`SKIP_DIFFSTAT`).
+events need. A minimal set would be (`SKIP_DIFFSTAT`).
 +
 Every option that gets added here will have a performance impact. The
 general recommendation is therefore to set this to a minimal set of

Documentation/rest-api-accounts.txt

@@ -2428,8 +2428,8 @@ that were deleted.
 |Field Name                 |Description
 |`change`                   |
 link:rest-api-changes.html#change-info[ChangeInfo] entity describing the change
-on which one or more comments was deleted. Populated with only the
+on which one or more comments was deleted. Populated with no change list
-link:rest-api-changes.html#skip_mergeable[SKIP_MERGEABLE] option.
+options.
 |`deleted`                  |
 List of link:rest-api-changes.html#comment-info[CommentInfo] entities for each
 comment that was deleted.

Documentation/rest-api-changes.txt

@@ -306,26 +306,6 @@ default. Optional fields are:
     from the change owner, i.e. this change would show up in the results of
     link:user-search.html#reviewedby[reviewedby:self].
 --
-
-[[skip_mergeable]]
---
-* `SKIP_MERGEABLE`: skip the `mergeable` field in
-link:#change-info[ChangeInfo]. For fast moving projects, this field must
-be recomputed often, which is slow for projects with big trees.
-+
-When link:config-gerrit.html#change.api.excludeMergeableInChangeInfo[
-`change.api.excludeMergeableInChangeInfo`] is set in the `gerrit.config`,
-the `mergeable` field will always be omitted and `SKIP_MERGEABLE` has no
-effect.
-+
-When link:config-gerrit.html#index.change.indexMergeable[
-`index.change.indexMergeable`] is set to `false` in the `gerrit.config`,
-the `mergeable` field will always be omitted when querying changes and
-`SKIP_MERGEABLE` has no effect.
-+
-A change's mergeability can be requested separately by calling the
-link:#get-mergeable[get-mergeable] endpoint.
---
 [[skip_diffstat]]
 --
 * `SKIP_DIFFSTAT`: skip the 'insertions' and 'deletions' field in link:#change-info[ChangeInfo].
@@ -5964,10 +5944,9 @@ The link:config-project-config.html#submit-type[submit type] of the change. +
 Not set for merged changes.
 |`mergeable`          |optional|
 Whether the change is mergeable. +
-Not set for merged changes, if the change has not yet been tested, or
+Only set for open changes if
-if the link:#skip_mergeable[skip_mergeable] option is set or when
+link:config-gerrit.html#change.mergeabilityComputationBehavior[change.mergeabilityComputationBehavior]
-link:config-gerrit.html#change.api.excludeMergeableInChangeInfo[change.api.excludeMergeableInChangeInfo]
+is `API_REF_UPDATED_AND_CHANGE_REINDEX`.
-is set.
 |`submittable`        |optional|
 Whether the change has been approved by the project submit rules. +
 Only set if link:#submittable[requested].

Documentation/rest-api-config.txt

@@ -1566,10 +1566,11 @@ link:config-gerrit.html#change.submitWholeTopic[A configuration if
 the whole topic is submitted].
 |`disable_private_changes` |not set if `false`|
 Returns true if private changes are disabled.
-|`exclude_mergeable_in_change_info` |not set if `false`|
+|`mergeability_computation_behavior` ||
-Value of the link:config-gerrit.html#change.api.excludeMergeableInChangeInfo[
+Value of the link:config-gerrit.html#change.mergeabilityComputationBehavior[
 configuration parameter] that controls whether the mergeability bit in
-link:rest-api-changes.html#change-info[ChangeInfo] will never be set.
+link:rest-api-changes.html#change-info[ChangeInfo] will never be set and if the
+bit is indexed.
 |=============================
 
 [[change-index-config-info]]

java/com/google/gerrit/acceptance/GerritServer.java

@@ -571,8 +571,8 @@ public class GerritServer implements AutoCloseable {
     cfg.setInt("sshd", null, "commandStartThreads", 1);
     cfg.setInt("receive", null, "threadPoolSize", 1);
     cfg.setInt("index", null, "threads", 1);
-    if (cfg.getString("index", "change", "indexMergeable") == null) {
+    if (cfg.getString("index", null, "mergeabilityComputationBehavior") == null) {
-      cfg.setBoolean("index", "change", "indexMergeable", false);
+      cfg.setString("index", null, "mergeabilityComputationBehavior", "NEVER");
     }
   }
 

java/com/google/gerrit/elasticsearch/ElasticChangeIndex.java

@@ -49,6 +49,7 @@ import com.google.gerrit.index.query.QueryParseException;
 import com.google.gerrit.server.ReviewerByEmailSet;
 import com.google.gerrit.server.ReviewerSet;
 import com.google.gerrit.server.StarredChangesUtil;
+import com.google.gerrit.server.change.MergeabilityComputationBehavior;
 import com.google.gerrit.server.config.GerritServerConfig;
 import com.google.gerrit.server.config.SitePaths;
 import com.google.gerrit.server.index.IndexUtils;
@@ -111,7 +112,7 @@ class ElasticChangeIndex extends AbstractElasticIndex<Change.Id, ChangeData>
     this.idField =
         this.schema.useLegacyNumericFields() ? ChangeField.LEGACY_ID : ChangeField.LEGACY_ID_STR;
     this.skipFields =
-        gerritConfig.getBoolean("index", "change", "indexMergeable", true)
+        MergeabilityComputationBehavior.fromConfig(gerritConfig).includeInIndex()
             ? ImmutableSet.of()
             : ImmutableSet.of(ChangeField.MERGEABLE.getName());
   }

java/com/google/gerrit/extensions/api/changes/ChangeApi.java

@@ -259,17 +259,12 @@ public interface ChangeApi {
    *
    * <ul>
    *   <li>{@code CHECK} is omitted, to skip consistency checks.
-   *   <li>{@code SKIP_MERGEABLE} is omitted, so the {@code mergeable} bit <em>is</em> set.
    *   <li>{@code SKIP_DIFFSTAT} is omitted to ensure diffstat calculations.
    * </ul>
    */
   default ChangeInfo get() throws RestApiException {
     return get(
-        EnumSet.complementOf(
+        EnumSet.complementOf(EnumSet.of(ListChangesOption.CHECK, ListChangesOption.SKIP_DIFFSTAT)));
-            EnumSet.of(
-                ListChangesOption.CHECK,
-                ListChangesOption.SKIP_MERGEABLE,
-                ListChangesOption.SKIP_DIFFSTAT)));
   }
 
   /** {@link #get(ListChangesOption...)} with no options included. */

java/com/google/gerrit/extensions/client/ListChangesOption.java

@@ -74,7 +74,11 @@ public enum ListChangesOption implements ListOption {
   /** If tracking Ids are included, include detailed tracking Ids info. */
   TRACKING_IDS(21),
 
-  /** Skip mergeability data */
+  /**
+   * Use {@code gerrit.config} instead to turn this off for your instance. See {@code
+   * change.mergeabilityComputationBehavior}.
+   */
+  @Deprecated
   SKIP_MERGEABLE(22),
 
   /**

java/com/google/gerrit/extensions/common/ChangeConfigInfo.java

@@ -24,5 +24,5 @@ public class ChangeConfigInfo {
   public String replyTooltip;
   public int updateDelay;
   public Boolean submitWholeTopic;
-  public Boolean excludeMergeableInChangeInfo;
+  public String mergeabilityComputationBehavior;
 }

java/com/google/gerrit/extensions/common/ChangeIndexConfigInfo.java

@@ -1,22 +0,0 @@
-// Copyright (C) 2019 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.common;
-
-/**
- * API response containing values from the {@code index.change} section of {@code gerrit.config}.
- */
-public class ChangeIndexConfigInfo {
-  public Boolean indexMergeable;
-}

java/com/google/gerrit/extensions/common/IndexConfigInfo.java

@@ -1,20 +0,0 @@
-// Copyright (C) 2019 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.common;
-
-/** API response containing values from the {@code index} section of {@code gerrit.config}. */
-public class IndexConfigInfo {
-  public ChangeIndexConfigInfo change;
-}

java/com/google/gerrit/extensions/common/ServerInfo.java

@@ -21,7 +21,6 @@ public class ServerInfo {
   public ChangeConfigInfo change;
   public DownloadInfo download;
   public GerritInfo gerrit;
-  public IndexConfigInfo index;
   public Boolean noteDbEnabled;
   public PluginConfigInfo plugin;
   public SshdInfo sshd;

java/com/google/gerrit/lucene/LuceneChangeIndex.java

@@ -55,6 +55,7 @@ import com.google.gerrit.index.query.QueryParseException;
 import com.google.gerrit.index.query.ResultSet;
 import com.google.gerrit.proto.Protos;
 import com.google.gerrit.server.StarredChangesUtil;
+import com.google.gerrit.server.change.MergeabilityComputationBehavior;
 import com.google.gerrit.server.config.GerritServerConfig;
 import com.google.gerrit.server.config.SitePaths;
 import com.google.gerrit.server.index.IndexExecutor;
@@ -182,7 +183,7 @@ public class LuceneChangeIndex implements ChangeIndex {
     this.changeDataFactory = changeDataFactory;
     this.schema = schema;
     this.skipFields =
-        cfg.getBoolean("index", "change", "indexMergeable", true)
+        MergeabilityComputationBehavior.fromConfig(cfg).includeInIndex()
             ? ImmutableSet.of()
             : ImmutableSet.of(ChangeField.MERGEABLE.getName());
 

java/com/google/gerrit/server/change/ChangeJson.java

@@ -29,7 +29,6 @@ import static com.google.gerrit.extensions.client.ListChangesOption.MESSAGES;
 import static com.google.gerrit.extensions.client.ListChangesOption.REVIEWED;
 import static com.google.gerrit.extensions.client.ListChangesOption.REVIEWER_UPDATES;
 import static com.google.gerrit.extensions.client.ListChangesOption.SKIP_DIFFSTAT;
-import static com.google.gerrit.extensions.client.ListChangesOption.SKIP_MERGEABLE;
 import static com.google.gerrit.extensions.client.ListChangesOption.SUBMITTABLE;
 import static com.google.gerrit.extensions.client.ListChangesOption.TRACKING_IDS;
 import static com.google.gerrit.server.ChangeMessagesUtil.createChangeMessageInfo;
@@ -219,7 +218,7 @@ public class ChangeJson {
   private final Metrics metrics;
   private final RevisionJson revisionJson;
   private final Optional<PluginDefinedAttributesFactory> pluginDefinedAttributesFactory;
-  private final boolean excludeMergeableInChangeInfo;
+  private final boolean includeMergeable;
   private final boolean lazyLoad;
 
   private AccountLoader accountLoader;
@@ -257,8 +256,7 @@ public class ChangeJson {
     this.metrics = metrics;
     this.revisionJson = revisionJsonFactory.create(options);
     this.options = Sets.immutableEnumSet(options);
-    this.excludeMergeableInChangeInfo =
+    this.includeMergeable = MergeabilityComputationBehavior.fromConfig(cfg).includeInApi();
-        cfg.getBoolean("change", "api", "excludeMergeableInChangeInfo", false);
     this.lazyLoad = containsAnyOf(this.options, REQUIRE_LAZY_LOAD);
     this.pluginDefinedAttributesFactory = pluginDefinedAttributesFactory;
 
@@ -525,7 +523,7 @@ public class ChangeJson {
       if (str.isOk()) {
         out.submitType = str.type;
       }
-      if (!excludeMergeableInChangeInfo && !has(SKIP_MERGEABLE)) {
+      if (includeMergeable) {
         out.mergeable = cd.isMergeable();
       }
       if (has(SUBMITTABLE)) {

java/com/google/gerrit/server/change/MergeabilityComputationBehavior.java

@@ -0,0 +1,58 @@
+// Copyright (C) 2020 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.server.change;
+
+import org.eclipse.jgit.lib.Config;
+
+/**
+ * State that is used to decide if {@code mergeable} should be included in the REST API or the
+ * change index.
+ *
+ * <p>Computing mergeability of a change is an expensive operation - especially for Gerrit
+ * installations with a large number of open changes or large repositories. Therefore, we want to
+ * control when this computation is performed.
+ */
+public enum MergeabilityComputationBehavior {
+  NEVER(false, false),
+  REF_UPDATED_AND_CHANGE_REINDEX(true, false),
+  API_REF_UPDATED_AND_CHANGE_REINDEX(true, true);
+
+  private final boolean includeInIndex;
+  private final boolean includeInApi;
+
+  MergeabilityComputationBehavior(boolean includeInIndex, boolean includeInApi) {
+    this.includeInIndex = includeInIndex;
+    this.includeInApi = includeInApi;
+  }
+
+  /** Returns a {@link MergeabilityComputationBehavior} constructed from a Gerrit server config. */
+  public static MergeabilityComputationBehavior fromConfig(Config cfg) {
+    return cfg.getEnum(
+        "change",
+        null,
+        "mergeabilityComputationBehavior",
+        MergeabilityComputationBehavior.API_REF_UPDATED_AND_CHANGE_REINDEX);
+  }
+
+  /** Whether {@code mergeable} should be included in the change API. */
+  public boolean includeInApi() {
+    return includeInApi;
+  }
+
+  /** Whether {@code mergeable} should be included in the change index. */
+  public boolean includeInIndex() {
+    return includeInIndex;
+  }
+}

java/com/google/gerrit/server/config/ChangeCleanupConfig.java

@@ -17,6 +17,7 @@ package com.google.gerrit.server.config;
 import com.google.common.base.Strings;
 import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.extensions.registration.DynamicItem;
+import com.google.gerrit.server.change.MergeabilityComputationBehavior;
 import com.google.gerrit.server.config.ScheduleConfig.Schedule;
 import com.google.inject.Inject;
 import com.google.inject.Singleton;
@@ -51,7 +52,7 @@ public class ChangeCleanupConfig {
     this.urlFormatter = urlFormatter;
     schedule = ScheduleConfig.createSchedule(cfg, SECTION);
     abandonAfter = readAbandonAfter(cfg);
-    boolean indexMergeable = cfg.getBoolean("index", "change", "indexMergeable", true);
+    boolean indexMergeable = MergeabilityComputationBehavior.fromConfig(cfg).includeInIndex();
     if (!indexMergeable) {
       if (!readAbandonIfMergeable(cfg)) {
         logger.atWarning().log(

java/com/google/gerrit/server/index/change/ReindexAfterRefUpdate.java

@@ -28,6 +28,7 @@ import com.google.gerrit.entities.Project;
 import com.google.gerrit.entities.RefNames;
 import com.google.gerrit.extensions.events.GitReferenceUpdatedListener;
 import com.google.gerrit.server.account.AccountCache;
+import com.google.gerrit.server.change.MergeabilityComputationBehavior;
 import com.google.gerrit.server.config.AllUsersName;
 import com.google.gerrit.server.config.GerritServerConfig;
 import com.google.gerrit.server.git.QueueProvider.QueueType;
@@ -85,7 +86,7 @@ public class ReindexAfterRefUpdate implements GitReferenceUpdatedListener {
     this.accountCache = accountCache;
     this.indexer = indexer;
     this.executor = executor;
-    this.enabled = cfg.getBoolean("index", "change", "indexMergeable", true);
+    this.enabled = MergeabilityComputationBehavior.fromConfig(cfg).includeInIndex();
   }
 
   @Override

java/com/google/gerrit/server/query/change/ChangeQueryBuilder.java

@@ -63,6 +63,7 @@ import com.google.gerrit.server.account.GroupMembers;
 import com.google.gerrit.server.account.VersionedAccountDestinations;
 import com.google.gerrit.server.account.VersionedAccountQueries;
 import com.google.gerrit.server.change.ChangeTriplet;
+import com.google.gerrit.server.change.MergeabilityComputationBehavior;
 import com.google.gerrit.server.config.AllProjectsName;
 import com.google.gerrit.server.config.AllUsersName;
 import com.google.gerrit.server.config.GerritServerConfig;
@@ -293,7 +294,7 @@ public class ChangeQueryBuilder extends QueryBuilder<ChangeData, ChangeQueryBuil
           groupMembers,
           anonymousUserProvider,
           operatorAliasConfig,
-          gerritConfig.getBoolean("index", "change", "indexMergeable", true));
+          MergeabilityComputationBehavior.fromConfig(gerritConfig).includeInIndex());
     }
 
     private Arguments(

java/com/google/gerrit/server/restapi/account/DeleteDraftComments.java

@@ -27,7 +27,6 @@ import com.google.gerrit.entities.PatchSet;
 import com.google.gerrit.entities.Project;
 import com.google.gerrit.extensions.api.accounts.DeleteDraftCommentsInput;
 import com.google.gerrit.extensions.api.accounts.DeletedDraftCommentInfo;
-import com.google.gerrit.extensions.client.ListChangesOption;
 import com.google.gerrit.extensions.common.CommentInfo;
 import com.google.gerrit.extensions.restapi.AuthException;
 import com.google.gerrit.extensions.restapi.BadRequestException;
@@ -190,9 +189,7 @@ public class DeleteDraftComments
       if (dirty) {
         result = new DeletedDraftCommentInfo();
         result.change =
-            changeJsonFactory
+            changeJsonFactory.noOptions().format(changeDataFactory.create(ctx.getNotes()));
-                .create(ListChangesOption.SKIP_MERGEABLE)
-                .format(changeDataFactory.create(ctx.getNotes()));
         result.deleted = comments.build();
       }
       return dirty;

java/com/google/gerrit/server/restapi/config/GetServerInfo.java

@@ -23,11 +23,9 @@ import com.google.gerrit.common.data.ContributorAgreement;
 import com.google.gerrit.extensions.common.AccountsInfo;
 import com.google.gerrit.extensions.common.AuthInfo;
 import com.google.gerrit.extensions.common.ChangeConfigInfo;
-import com.google.gerrit.extensions.common.ChangeIndexConfigInfo;
 import com.google.gerrit.extensions.common.DownloadInfo;
 import com.google.gerrit.extensions.common.DownloadSchemeInfo;
 import com.google.gerrit.extensions.common.GerritInfo;
-import com.google.gerrit.extensions.common.IndexConfigInfo;
 import com.google.gerrit.extensions.common.PluginConfigInfo;
 import com.google.gerrit.extensions.common.ReceiveInfo;
 import com.google.gerrit.extensions.common.ServerInfo;
@@ -45,6 +43,7 @@ import com.google.gerrit.server.account.AccountVisibilityProvider;
 import com.google.gerrit.server.account.Realm;
 import com.google.gerrit.server.avatar.AvatarProvider;
 import com.google.gerrit.server.change.ArchiveFormat;
+import com.google.gerrit.server.change.MergeabilityComputationBehavior;
 import com.google.gerrit.server.config.AllProjectsName;
 import com.google.gerrit.server.config.AllUsersName;
 import com.google.gerrit.server.config.AnonymousCowardName;
@@ -143,7 +142,6 @@ public class GetServerInfo implements RestReadView<ConfigResource> {
     info.change = getChangeInfo();
     info.download = getDownloadInfo();
     info.gerrit = getGerritInfo();
-    info.index = getIndexInfo();
     info.noteDbEnabled = true;
     info.plugin = getPluginInfo();
     info.defaultTheme = getDefaultTheme();
@@ -230,10 +228,10 @@ public class GetServerInfo implements RestReadView<ConfigResource> {
     info.updateDelay =
         (int) ConfigUtil.getTimeUnit(config, "change", null, "updateDelay", 300, TimeUnit.SECONDS);
     info.submitWholeTopic = toBoolean(MergeSuperSet.wholeTopicEnabled(config));
-    info.excludeMergeableInChangeInfo =
-        toBoolean(this.config.getBoolean("change", "api", "excludeMergeableInChangeInfo", false));
     info.disablePrivateChanges =
         toBoolean(this.config.getBoolean("change", null, "disablePrivateChanges", false));
+    info.mergeabilityComputationBehavior =
+        MergeabilityComputationBehavior.fromConfig(config).name();
     return info;
   }
 
@@ -299,14 +297,6 @@ public class GetServerInfo implements RestReadView<ConfigResource> {
     return info;
   }
 
-  private IndexConfigInfo getIndexInfo() {
-    ChangeIndexConfigInfo change = new ChangeIndexConfigInfo();
-    change.indexMergeable = toBoolean(config.getBoolean("index", "change", "indexMergeable", true));
-    IndexConfigInfo index = new IndexConfigInfo();
-    index.change = change;
-    return index;
-  }
-
   private String getDocUrl() {
     String docUrl = config.getString("gerrit", null, "docUrl");
     if (Strings.isNullOrEmpty(docUrl)) {

java/com/google/gerrit/testing/IndexConfig.java

@@ -14,6 +14,7 @@
 
 package com.google.gerrit.testing;
 
+import com.google.gerrit.server.change.MergeabilityComputationBehavior;
 import org.eclipse.jgit.lib.Config;
 
 public class IndexConfig {
@@ -23,9 +24,10 @@ public class IndexConfig {
 
   public static Config createFromExistingConfig(Config cfg) {
     cfg.setInt("index", null, "maxPages", 10);
-    // To avoid this flakiness indexMergeable is switched off for the tests as it incurs background
+    // To avoid this flakiness indexing mergeable is disabled for the tests as it incurs background
     // reindex calls.
-    cfg.setBoolean("index", "change", "indexMergeable", false);
+    cfg.setEnum(
+        "change", null, "mergeabilityComputationBehavior", MergeabilityComputationBehavior.NEVER);
     cfg.setString("trackingid", "query-bug", "footer", "Bug:");
     cfg.setString("trackingid", "query-bug", "match", "QUERY\\d{2,8}");
     cfg.setString("trackingid", "query-bug", "system", "querytests");

javatests/com/google/gerrit/acceptance/api/change/AbandonIT.java

@@ -143,7 +143,9 @@ public class AbandonIT extends AbstractDaemonTest {
   @UseClockStep
   @GerritConfig(name = "changeCleanup.abandonAfter", value = "1w")
   @GerritConfig(name = "changeCleanup.abandonIfMergeable", value = "false")
-  @GerritConfig(name = "index.change.indexMergeable", value = "true")
+  @GerritConfig(
+      name = "change.mergeabilityComputationBehavior",
+      value = "API_REF_UPDATED_AND_CHANGE_REINDEX")
   public void notAbandonedIfMergeableWhenMergeableOperatorIsEnabled() throws Exception {
     ObjectId initial = repo().exactRef(HEAD).getLeaf().getObjectId();
 
@@ -180,14 +182,14 @@ public class AbandonIT extends AbstractDaemonTest {
   }
 
   /**
-   * When indexMergeable is disabled then the abandonIfMergeable option is ineffective and the auto
+   * When indexing mergeable is disabled then the abandonIfMergeable option is ineffective and the
-   * abandon behaves as though it were set to its default value (true).
+   * auto abandon behaves as though it were set to its default value (true).
    */
   @Test
   @UseClockStep
   @GerritConfig(name = "changeCleanup.abandonAfter", value = "1w")
   @GerritConfig(name = "changeCleanup.abandonIfMergeable", value = "false")
-  @GerritConfig(name = "index.change.indexMergeable", value = "false")
+  @GerritConfig(name = "change.mergeabilityComputationBehavior", value = "NEVER")
   public void abandonedIfMergeableWhenMergeableOperatorIsDisabled() throws Exception {
     ObjectId initial = repo().exactRef(HEAD).getLeaf().getObjectId();
 

javatests/com/google/gerrit/acceptance/api/change/ChangeIT.java

@@ -295,19 +295,7 @@ public class ChangeIT extends AbstractDaemonTest {
   }
 
   @Test
-  public void skipMergeable() throws Exception {
+  @GerritConfig(name = "change.mergeabilityComputationBehavior", value = "NEVER")
-    PushOneCommit.Result r = createChange();
-    String triplet = project.get() + "~master~" + r.getChangeId();
-    ChangeInfo c =
-        gApi.changes().id(triplet).get(ImmutableList.of(ListChangesOption.SKIP_MERGEABLE));
-    assertThat(c.mergeable).isNull();
-
-    c = gApi.changes().id(triplet).get();
-    assertThat(c.mergeable).isTrue();
-  }
-
-  @Test
-  @GerritConfig(name = "change.api.excludeMergeableInChangeInfo", value = "true")
   public void excludeMergeableInChangeInfo() throws Exception {
     PushOneCommit.Result r = createChange();
     ChangeInfo c = gApi.changes().id(r.getChangeId()).get();
@@ -4425,7 +4413,6 @@ public class ChangeIT extends AbstractDaemonTest {
             ListChangesOption.MESSAGES,
             ListChangesOption.SUBMITTABLE,
             ListChangesOption.WEB_LINKS,
-            ListChangesOption.SKIP_MERGEABLE,
             ListChangesOption.SKIP_DIFFSTAT);
 
     PushOneCommit.Result change = createChange();
@@ -4438,14 +4425,16 @@ public class ChangeIT extends AbstractDaemonTest {
   }
 
   @Test
-  @GerritConfig(name = "index.change.indexMergeable", value = "true")
+  @GerritConfig(
+      name = "change.mergeabilityComputationBehavior",
+      value = "API_REF_UPDATED_AND_CHANGE_REINDEX")
   public void changeQueryReturnsMergeableWhenGerritIndexMergeable() throws Exception {
     String changeId = createChange().getChangeId();
     assertThat(gApi.changes().query(changeId).get().get(0).mergeable).isTrue();
   }
 
   @Test
-  @GerritConfig(name = "index.change.indexMergeable", value = "false")
+  @GerritConfig(name = "change.mergeabilityComputationBehavior", value = "NEVER")
   public void changeQueryDoesNotReturnMergeableWhenGerritDoesNotIndexMergeable() throws Exception {
     String changeId = createChange().getChangeId();
     assertThat(gApi.changes().query(changeId).get().get(0).mergeable).isNull();

javatests/com/google/gerrit/acceptance/api/revision/RevisionIT.java

@@ -1102,7 +1102,9 @@ public class RevisionIT extends AbstractDaemonTest {
   }
 
   @Test
-  @GerritConfig(name = "index.change.indexMergeable", value = "true")
+  @GerritConfig(
+      name = "change.mergeabilityComputationBehavior",
+      value = "API_REF_UPDATED_AND_CHANGE_REINDEX")
   public void mergeable() throws Exception {
     ObjectId initial = repo().exactRef(HEAD).getLeaf().getObjectId();
 

javatests/com/google/gerrit/acceptance/rest/change/AbstractSubmit.java

@@ -1205,7 +1205,9 @@ public abstract class AbstractSubmit extends AbstractDaemonTest {
   }
 
   @Test
-  @GerritConfig(name = "index.change.indexMergeable", value = "true")
+  @GerritConfig(
+      name = "change.mergeabilityComputationBehavior",
+      value = "API_REF_UPDATED_AND_CHANGE_REINDEX")
   public void submitSchedulesOpenChangesOfSameBranchForReindexing() throws Throwable {
     // Create a merged change.
     PushOneCommit push =

javatests/com/google/gerrit/acceptance/rest/change/IndexChangeIT.java

@@ -59,7 +59,9 @@ public class IndexChangeIT extends AbstractDaemonTest {
   }
 
   @Test
-  @GerritConfig(name = "index.change.indexMergeable", value = "true")
+  @GerritConfig(
+      name = "change.mergeabilityComputationBehavior",
+      value = "API_REF_UPDATED_AND_CHANGE_REINDEX")
   public void indexChangeAfterOwnerLosesVisibility() throws Exception {
     // Create a test group with 2 users as members
     TestAccount user2 = accountCreator.user2();

javatests/com/google/gerrit/acceptance/rest/config/ServerInfoIT.java

@@ -169,7 +169,8 @@ public class ServerInfoIT extends AbstractDaemonTest {
     assertThat(i.change.updateDelay).isEqualTo(300);
     assertThat(i.change.disablePrivateChanges).isNull();
     assertThat(i.change.submitWholeTopic).isNull();
-    assertThat(i.change.excludeMergeableInChangeInfo).isNull();
+    assertThat(i.change.mergeabilityComputationBehavior)
+        .isEqualTo("API_REF_UPDATED_AND_CHANGE_REINDEX");
 
     // download
     assertThat(i.download.archives).containsExactly("tar", "tbz2", "tgz", "txz");
@@ -180,9 +181,6 @@ public class ServerInfoIT extends AbstractDaemonTest {
     assertThat(i.gerrit.allUsers).isEqualTo(AllUsersNameProvider.DEFAULT);
     assertThat(i.gerrit.reportBugUrl).isNull();
 
-    // index
-    assertThat(i.index.change.indexMergeable).isNull(); // false in all tests
-
     // plugin
     assertThat(i.plugin.jsResourcePaths).isEmpty();
 
@@ -204,16 +202,9 @@ public class ServerInfoIT extends AbstractDaemonTest {
   }
 
   @Test
-  @GerritConfig(name = "change.api.excludeMergeableInChangeInfo", value = "true")
+  @GerritConfig(name = "change.mergeabilityComputationBehavior", value = "NEVER")
-  public void serverConfigWithExcludeMergeableInChangeInfo() throws Exception {
+  public void mergeabilityComputationBehavior_neverCompute() throws Exception {
     ServerInfo i = gApi.config().server().getInfo();
-    assertThat(i.change.excludeMergeableInChangeInfo).isTrue();
+    assertThat(i.change.mergeabilityComputationBehavior).isEqualTo("NEVER");
-  }
-
-  @Test
-  @GerritConfig(name = "index.change.indexMergeable", value = "true")
-  public void indexMergeableIsTrueWhenTrueInConfig() throws Exception {
-    ServerInfo i = gApi.config().server().getInfo();
-    assertThat(i.index.change.indexMergeable).isTrue();
   }
 }

javatests/com/google/gerrit/acceptance/server/event/EventPayloadIT.java

@@ -32,32 +32,26 @@ public class EventPayloadIT extends AbstractDaemonTest {
   @Test
   public void defaultOptions() throws Exception {
     RevisionCreatedListener listener =
-        new RevisionCreatedListener() {
+        event -> {
-          @Override
-          public void onRevisionCreated(Event event) {
           assertThat(event.getChange().submittable).isNotNull();
           assertThat(event.getRevision().files).isNotEmpty();
-          }
         };
-    try (Registration registration = extensionRegistry.newRegistration().add(listener)) {
+    try (Registration ignored = extensionRegistry.newRegistration().add(listener)) {
       createChange();
     }
   }
 
   @Test
-  @GerritConfig(name = "event.payload.listChangeOptions", value = "SKIP_MERGEABLE")
+  @GerritConfig(name = "event.payload.listChangeOptions", value = "SKIP_DIFFSTAT")
   public void configuredOptions() throws Exception {
     RevisionCreatedListener listener =
-        new RevisionCreatedListener() {
+        event -> {
-          @Override
-          public void onRevisionCreated(Event event) {
           assertThat(event.getChange().submittable).isNull();
-            assertThat(event.getChange().mergeable).isNull();
+          assertThat(event.getChange().insertions).isNull();
           assertThat(event.getRevision().files).isNull();
           assertThat(event.getChange().subject).isNotEmpty();
-          }
         };
-    try (Registration registration = extensionRegistry.newRegistration().add(listener)) {
+    try (Registration ignored = extensionRegistry.newRegistration().add(listener)) {
       createChange();
     }
   }

javatests/com/google/gerrit/server/query/change/AbstractQueryChangesTest.java

@@ -2025,7 +2025,9 @@ public abstract class AbstractQueryChangesTest extends GerritServerTests {
   }
 
   @Test
-  @GerritConfig(name = "index.change.indexMergeable", value = "true")
+  @GerritConfig(
+      name = "change.mergeabilityComputationBehavior",
+      value = "API_REF_UPDATED_AND_CHANGE_REINDEX")
   public void mergeable() throws Exception {
     TestRepository<Repo> repo = createProject("repo");
     RevCommit commit1 = repo.parseBody(repo.commit().add("file1", "contents1").create());
@@ -2043,7 +2045,7 @@ public abstract class AbstractQueryChangesTest extends GerritServerTests {
     // If a change gets submitted, the remaining open changes get reindexed asynchronously to update
     // their mergeability information. If the further assertions in this test are done before the
     // asynchronous reindex completed they fail because the mergeability information in the index
-    // was not updated yet. To avoid this flakiness indexMergeable is switched off for the
+    // was not updated yet. To avoid this flakiness indexing mergeable is switched off for the
     // tests and we index change2 synchronously here.
     gApi.changes().id(change2.getChangeId()).index();
 
@@ -3083,7 +3085,7 @@ public abstract class AbstractQueryChangesTest extends GerritServerTests {
   }
 
   @Test
-  @GerritConfig(name = "index.change.indexMergeable", value = "false")
+  @GerritConfig(name = "change.mergeabilityComputationBehavior", value = "NEVER")
   public void mergeableFailsWhenNotIndexed() throws Exception {
     TestRepository<Repo> repo = createProject("repo");
     RevCommit commit1 = repo.parseBody(repo.commit().add("file1", "contents1").create());

polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface.js

@@ -1001,7 +1001,6 @@
         this.ListChangesOption.MESSAGES,
         this.ListChangesOption.SUBMITTABLE,
         this.ListChangesOption.WEB_LINKS,
-        this.ListChangesOption.SKIP_MERGEABLE,
         this.ListChangesOption.SKIP_DIFFSTAT,
       ];
       return this.getConfig(false).then(config => {
@@ -1024,7 +1023,6 @@
       const optionsHex = this.listChangesOptionsToHex(
           this.ListChangesOption.ALL_COMMITS,
           this.ListChangesOption.ALL_REVISIONS,
-          this.ListChangesOption.SKIP_MERGEABLE,
           this.ListChangesOption.SKIP_DIFFSTAT
       );
       return this._getChangeDetail(changeNum, optionsHex, opt_errFn,