Add test to ensure change details don't require an index

With the new URL schema (project name + change number) we don't rely on
a working change index for serving change details anymore. This has the
benefit that we can still serve change details pages in case of an index
failure.

This commit adds a test for this case to ensure this functionality is
working as intended.

Change-Id: Id34af71d218e98989709dd1e7baa409da6ff7200

java/com/google/gerrit/acceptance/AbstractDaemonTest.java

@@ -825,6 +825,25 @@ public abstract class AbstractDaemonTest {
     }
   }
 
+  protected AutoCloseable disableChangeIndex() {
+    disableChangeIndexWrites();
+    ChangeIndex searchIndex = changeIndexes.getSearchIndex();
+    if (!(searchIndex instanceof DisabledChangeIndex)) {
+      changeIndexes.setSearchIndex(new DisabledChangeIndex(searchIndex), false);
+    }
+
+    return new AutoCloseable() {
+      @Override
+      public void close() throws Exception {
+        enableChangeIndexWrites();
+        ChangeIndex searchIndex = changeIndexes.getSearchIndex();
+        if (searchIndex instanceof DisabledChangeIndex) {
+          changeIndexes.setSearchIndex(((DisabledChangeIndex) searchIndex).unwrap(), false);
+        }
+      }
+    };
+  }
+
   protected static Gson newGson() {
     return OutputFormat.JSON_COMPACT.newGson();
   }

java/com/google/gerrit/acceptance/DisabledChangeIndex.java

@@ -0,0 +1,86 @@
+// Copyright (C) 2017 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.acceptance;
+
+import com.google.gerrit.index.QueryOptions;
+import com.google.gerrit.index.Schema;
+import com.google.gerrit.index.query.DataSource;
+import com.google.gerrit.index.query.Predicate;
+import com.google.gerrit.index.query.QueryParseException;
+import com.google.gerrit.reviewdb.client.Change;
+import com.google.gerrit.reviewdb.client.Change.Id;
+import com.google.gerrit.server.index.change.ChangeIndex;
+import com.google.gerrit.server.query.change.ChangeData;
+import java.io.IOException;
+import java.util.Optional;
+
+/**
+ * This class wraps an index and assumes the search index can't handle any queries. However, it does
+ * return the current schema as the assumption is that we need a search index for starting Gerrit in
+ * the first place and only later lose the index connection (making it so that we can't send
+ * requests there anymore).
+ */
+public class DisabledChangeIndex implements ChangeIndex {
+  private final ChangeIndex index;
+
+  public DisabledChangeIndex(ChangeIndex index) {
+    this.index = index;
+  }
+
+  public ChangeIndex unwrap() {
+    return index;
+  }
+
+  @Override
+  public Schema<ChangeData> getSchema() {
+    return index.getSchema();
+  }
+
+  @Override
+  public void close() {
+    index.close();
+  }
+
+  @Override
+  public void replace(ChangeData obj) throws IOException {
+    throw new UnsupportedOperationException("ChangeIndex is disabled");
+  }
+
+  @Override
+  public void delete(Id key) throws IOException {
+    throw new UnsupportedOperationException("ChangeIndex is disabled");
+  }
+
+  @Override
+  public void deleteAll() throws IOException {
+    throw new UnsupportedOperationException("ChangeIndex is disabled");
+  }
+
+  @Override
+  public DataSource<ChangeData> getSource(Predicate<ChangeData> p, QueryOptions opts)
+      throws QueryParseException {
+    throw new UnsupportedOperationException("ChangeIndex is disabled");
+  }
+
+  @Override
+  public void markReady(boolean ready) throws IOException {
+    throw new UnsupportedOperationException("ChangeIndex is disabled");
+  }
+
+  @Override
+  public Optional<ChangeData> get(Change.Id key, QueryOptions opts) throws IOException {
+    throw new UnsupportedOperationException("ChangeIndex is disabled");
+  }
+}

java/com/google/gerrit/index/IndexCollection.java

@@ -14,6 +14,7 @@
 
 package com.google.gerrit.index;
 
+import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.Lists;
 import com.google.gerrit.extensions.events.LifecycleListener;
 import java.util.Collection;
@@ -37,8 +38,13 @@ public abstract class IndexCollection<K, V, I extends Index<K, V>> implements Li
   }
 
   public void setSearchIndex(I index) {
+    setSearchIndex(index, true);
+  }
+
+  @VisibleForTesting
+  public void setSearchIndex(I index, boolean closeOld) {
     I old = searchIndex.getAndSet(index);
-    if (old != null && old != index && !writeIndexes.contains(old)) {
+    if (closeOld && old != null && old != index && !writeIndexes.contains(old)) {
       old.close();
     }
   }

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

@@ -3631,6 +3631,17 @@ public class ChangeIT extends AbstractDaemonTest {
     gApi.accounts().self().setStars(changeId, new StarsInput(ImmutableSet.of(invalidLabel)));
   }
 
+  @Test
+  public void changeDetailsDoesNotRequireIndex() throws Exception {
+    PushOneCommit.Result change = createChange();
+    int number = gApi.changes().id(change.getChangeId()).get()._number;
+
+    try (AutoCloseable ctx = disableChangeIndex()) {
+      assertThat(gApi.changes().id(project.get(), number).get(ImmutableSet.of()).changeId)
+          .isEqualTo(change.getChangeId());
+    }
+  }
+
   private static class ChangeIndexedCounter implements ChangeIndexedListener {
     private final AtomicLongMap<Integer> countsByChange = AtomicLongMap.create();