Add attention set to index

Change-Id: I22d2aa7b73cbbdf0d24cc4e49a0263705ea0229d

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

@@ -0,0 +1,41 @@
+// 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.query.change;
+
+import static com.google.gerrit.server.util.AttentionSetUtil.additionsOnly;
+
+import com.google.gerrit.entities.Account;
+import com.google.gerrit.server.index.change.ChangeField;
+
+/** Simple predicate for searching by attention set. */
+public class AttentionSetPredicate extends ChangeIndexPredicate {
+  protected final Account.Id id;
+
+  AttentionSetPredicate(Account.Id id) {
+    super(ChangeField.ATTENTION_SET_USERS, id.toString());
+    this.id = id;
+  }
+
+  @Override
+  public boolean match(ChangeData changeData) {
+    return additionsOnly(changeData.attentionSet()).stream()
+        .anyMatch(update -> update.account().equals(id));
+  }
+
+  @Override
+  public int getCost() {
+    return 1;
+  }
+}

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

@@ -611,6 +611,21 @@ public class ChangeData {
     return attentionSet;
   }
 
+  /**
+   * Sets the specified attention set. If two or more entries refer to the same user, throws an
+   * {@link IllegalStateException}.
+   */
+  public void setAttentionSet(ImmutableSet<AttentionSetUpdate> attentionSet) {
+    if (attentionSet.stream().map(AttentionSetUpdate::account).distinct().count()
+        != attentionSet.size()) {
+      throw new IllegalStateException(
+          String.format(
+              "Stored attention set for change %d contains duplicate update",
+              change.getId().get()));
+    }
+    this.attentionSet = attentionSet;
+  }
+
   /** @return patches for the change, in patch set ID order. */
   public Collection<PatchSet> patchSets() {
     if (patchSets == null) {

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

@@ -14,6 +14,7 @@
 
 package com.google.gerrit.server.query.change;
 
+import static com.google.common.collect.ImmutableSet.toImmutableSet;
 import static com.google.gerrit.entities.Change.CHANGE_ID_PATTERN;
 import static com.google.gerrit.server.account.AccountResolver.isSelf;
 import static com.google.gerrit.server.query.change.ChangeData.asChanges;
@@ -136,6 +137,8 @@ public class ChangeQueryBuilder extends QueryBuilder<ChangeData, ChangeQueryBuil
 
   public static final String FIELD_ADDED = "added";
   public static final String FIELD_AGE = "age";
+  public static final String FIELD_ATTENTION_SET_USERS = "attentionusers";
+  public static final String FIELD_ATTENTION_SET_FULL = "attentionfull";
   public static final String FIELD_ASSIGNEE = "assignee";
   public static final String FIELD_AUTHOR = "author";
   public static final String FIELD_EXACTAUTHOR = "exactauthor";
@@ -1056,6 +1059,20 @@ public class ChangeQueryBuilder extends QueryBuilder<ChangeData, ChangeQueryBuil
     return owner(accounts);
   }
 
+  @Operator
+  public Predicate<ChangeData> attention(String who)
+      throws QueryParseException, IOException, ConfigInvalidException {
+    if (!args.index.getSchema().hasField(ChangeField.ATTENTION_SET_USERS)) {
+      throw new QueryParseException(
+          "'attention' operator is not supported by change index version");
+    }
+    return attention(parseAccount(who, (AccountState s) -> true));
+  }
+
+  private Predicate<ChangeData> attention(Set<Account.Id> who) {
+    return Predicate.or(who.stream().map(AttentionSetPredicate::new).collect(toImmutableSet()));
+  }
+
   @Operator
   public Predicate<ChangeData> assignee(String who)
       throws QueryParseException, IOException, ConfigInvalidException {