Small changes to skyframe package.

PiperOrigin-RevId: 162288376

src/main/java/com/google/devtools/build/skyframe/ConstantVersion.java

@@ -0,0 +1,26 @@
+// Copyright 2017 The Bazel Authors. All rights reserved.
+//
+// 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.devtools.build.skyframe;
+
+/** Use when only a single evaluation of the graph with a single constant version is expected. */
+public class ConstantVersion implements Version {
+  public static final ConstantVersion INSTANCE = new ConstantVersion();
+
+  private ConstantVersion() {}
+
+  @Override
+  public boolean atMost(Version other) {
+    return this.equals(other);
+  }
+}

src/main/java/com/google/devtools/build/skyframe/InMemoryGraph.java

@@ -17,7 +17,7 @@
 import javax.annotation.Nullable;
 
 /** {@link ProcessableGraph} that exposes the contents of the entire graph. */
-interface InMemoryGraph extends ProcessableGraph {
+public interface InMemoryGraph extends ProcessableGraph {
   @Override
   Map<SkyKey, ? extends NodeEntry> createIfAbsentBatch(
       @Nullable SkyKey requestor, Reason reason, Iterable<SkyKey> keys);