Merge changes Id255aa3d,I37f156cd

* changes:
  Introduce server.util.DelegateSystemReader
  AbstractChangeNotes: mark readRef @Nullable

java/com/google/gerrit/acceptance/BUILD

@@ -126,6 +126,7 @@ java_library2(
         "//java/com/google/gerrit/server/git/receive",
         "//java/com/google/gerrit/server/restapi",
         "//java/com/google/gerrit/server/schema",
+        "//java/com/google/gerrit/server/util/git",
         "//java/com/google/gerrit/server/util/time",
         "//java/com/google/gerrit/sshd",
         "//lib:args4j",

java/com/google/gerrit/acceptance/StandaloneSiteTest.java

@@ -30,6 +30,7 @@ import com.google.gerrit.server.config.SitePaths;
 import com.google.gerrit.server.util.ManualRequestContext;
 import com.google.gerrit.server.util.OneOffRequestContext;
 import com.google.gerrit.server.util.RequestContext;
+import com.google.gerrit.server.util.git.DelegateSystemReader;
 import com.google.gerrit.testing.ConfigSuite;
 import com.google.inject.Injector;
 import com.google.inject.Module;
@@ -134,22 +135,7 @@ public abstract class StandaloneSiteTest {
   private static SystemReader setFakeSystemReader(File tempDir) {
     SystemReader oldSystemReader = SystemReader.getInstance();
     SystemReader.setInstance(
-        new SystemReader() {
+        new DelegateSystemReader(oldSystemReader) {
-          @Override
-          public String getHostname() {
-            return oldSystemReader.getHostname();
-          }
-
-          @Override
-          public String getenv(String variable) {
-            return oldSystemReader.getenv(variable);
-          }
-
-          @Override
-          public String getProperty(String key) {
-            return oldSystemReader.getProperty(key);
-          }
-
           @Override
           public FileBasedConfig openUserConfig(Config parent, FS fs) {
             return new FileBasedConfig(parent, new File(tempDir, "user.config"), FS.detect());
@@ -159,16 +145,6 @@ public abstract class StandaloneSiteTest {
           public FileBasedConfig openSystemConfig(Config parent, FS fs) {
             return new FileBasedConfig(parent, new File(tempDir, "system.config"), FS.detect());
           }
-
-          @Override
-          public long getCurrentTime() {
-            return oldSystemReader.getCurrentTime();
-          }
-
-          @Override
-          public int getTimezone(long when) {
-            return oldSystemReader.getTimezone(when);
-          }
         });
     return oldSystemReader;
   }

java/com/google/gerrit/server/git/SystemReaderInstaller.java

@@ -17,6 +17,7 @@ package com.google.gerrit.server.git;
 import com.google.common.flogger.FluentLogger;
 import com.google.gerrit.extensions.events.LifecycleListener;
 import com.google.gerrit.server.config.SitePaths;
+import com.google.gerrit.server.util.git.DelegateSystemReader;
 import com.google.inject.Inject;
 import com.google.inject.Singleton;
 import org.eclipse.jgit.lib.Config;
@@ -47,41 +48,11 @@ public class SystemReaderInstaller implements LifecycleListener {
   private SystemReader customReader() {
     SystemReader current = SystemReader.getInstance();
 
-    return new SystemReader() {
+    return new DelegateSystemReader(current) {
-      @Override
-      public String getHostname() {
-        return current.getHostname();
-      }
-
-      @Override
-      public String getenv(String variable) {
-        return current.getenv(variable);
-      }
-
-      @Override
-      public String getProperty(String key) {
-        return current.getProperty(key);
-      }
-
-      @Override
-      public FileBasedConfig openUserConfig(Config parent, FS fs) {
-        return current.openUserConfig(parent, fs);
-      }
-
       @Override
       public FileBasedConfig openSystemConfig(Config parent, FS fs) {
         return new FileBasedConfig(parent, site.jgit_config.toFile(), FS.DETECTED);
       }
-
-      @Override
-      public long getCurrentTime() {
-        return current.getCurrentTime();
-      }
-
-      @Override
-      public int getTimezone(long when) {
-        return current.getTimezone(when);
-      }
     };
   }
 }

java/com/google/gerrit/server/notedb/AbstractChangeNotes.java

@@ -153,6 +153,7 @@ public abstract class AbstractChangeNotes<T> {
     return self();
   }
 
+  @Nullable
   protected ObjectId readRef(Repository repo) throws IOException {
     Ref ref = repo.getRefDatabase().exactRef(getRefName());
     return ref != null ? ref.getObjectId() : null;

java/com/google/gerrit/server/util/git/DelegateSystemReader.java

@@ -0,0 +1,63 @@
+// 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.server.util.git;
+
+import org.eclipse.jgit.lib.Config;
+import org.eclipse.jgit.storage.file.FileBasedConfig;
+import org.eclipse.jgit.util.FS;
+import org.eclipse.jgit.util.SystemReader;
+
+public class DelegateSystemReader extends SystemReader {
+  private final SystemReader delegate;
+
+  public DelegateSystemReader(SystemReader delegate) {
+    this.delegate = delegate;
+  }
+
+  @Override
+  public String getHostname() {
+    return delegate.getHostname();
+  }
+
+  @Override
+  public String getenv(String variable) {
+    return delegate.getenv(variable);
+  }
+
+  @Override
+  public String getProperty(String key) {
+    return delegate.getProperty(key);
+  }
+
+  @Override
+  public FileBasedConfig openUserConfig(Config parent, FS fs) {
+    return delegate.openUserConfig(parent, fs);
+  }
+
+  @Override
+  public FileBasedConfig openSystemConfig(Config parent, FS fs) {
+    return delegate.openSystemConfig(parent, fs);
+  }
+
+  @Override
+  public long getCurrentTime() {
+    return delegate.getCurrentTime();
+  }
+
+  @Override
+  public int getTimezone(long when) {
+    return delegate.getTimezone(when);
+  }
+}

java/com/google/gerrit/server/util/time/BUILD

@@ -4,6 +4,7 @@ java_library(
     visibility = ["//visibility:public"],
     deps = [
         "//java/com/google/gerrit/common:annotations",
+        "//java/com/google/gerrit/server/util/git",
         "//lib:guava",
         "//lib/jgit/org.eclipse.jgit:jgit",
     ],

java/com/google/gerrit/server/util/time/TimeUtil.java

@@ -17,12 +17,10 @@ package com.google.gerrit.server.util.time;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.gerrit.common.UsedAt;
 import com.google.gerrit.common.UsedAt.Project;
+import com.google.gerrit.server.util.git.DelegateSystemReader;
 import java.sql.Timestamp;
 import java.time.Instant;
 import java.util.function.LongSupplier;
-import org.eclipse.jgit.lib.Config;
-import org.eclipse.jgit.storage.file.FileBasedConfig;
-import org.eclipse.jgit.util.FS;
 import org.eclipse.jgit.util.SystemReader;
 
 /** Static utility methods for dealing with dates and times. */
@@ -76,47 +74,15 @@ public class TimeUtil {
     SystemReader.setInstance(null);
   }
 
-  private static class GerritSystemReader extends SystemReader {
+  static class GerritSystemReader extends DelegateSystemReader {
-    SystemReader delegate;
+    GerritSystemReader(SystemReader reader) {
-
+      super(reader);
-    GerritSystemReader(SystemReader delegate) {
-      this.delegate = delegate;
-    }
-
-    @Override
-    public String getHostname() {
-      return delegate.getHostname();
-    }
-
-    @Override
-    public String getenv(String variable) {
-      return delegate.getenv(variable);
-    }
-
-    @Override
-    public String getProperty(String key) {
-      return delegate.getProperty(key);
-    }
-
-    @Override
-    public FileBasedConfig openUserConfig(Config parent, FS fs) {
-      return delegate.openUserConfig(parent, fs);
-    }
-
-    @Override
-    public FileBasedConfig openSystemConfig(Config parent, FS fs) {
-      return delegate.openSystemConfig(parent, fs);
     }
 
     @Override
     public long getCurrentTime() {
       return currentMillisSupplier.getAsLong();
     }
-
-    @Override
-    public int getTimezone(long when) {
-      return delegate.getTimezone(when);
-    }
   }
 
   private TimeUtil() {}