Update from Google.
--
MOE_MIGRATED_REVID=85702957
diff --git a/src/main/java/com/google/devtools/build/skyframe/SkyKey.java b/src/main/java/com/google/devtools/build/skyframe/SkyKey.java
new file mode 100644
index 0000000..cc1dd1f
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/skyframe/SkyKey.java
@@ -0,0 +1,86 @@
+// Copyright 2014 Google Inc. 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;
+
+import com.google.common.base.Function;
+import com.google.common.base.Preconditions;
+
+import java.io.Serializable;
+
+/**
+ * A {@link SkyKey} is effectively a pair (type, name) that identifies a Skyframe value.
+ */
+public final class SkyKey implements Serializable {
+ private final SkyFunctionName functionName;
+
+ /**
+ * The name of the value.
+ *
+ * <p>This is deliberately an untyped Object so that we can use arbitrary value types (e.g.,
+ * Labels, PathFragments, BuildConfigurations, etc.) as value names without incurring
+ * serialization costs in the in-memory implementation of the graph.
+ */
+ private final Object argument;
+
+ /**
+ * Cache the hash code for this object. It might be expensive to compute.
+ */
+ private final int hashCode;
+
+ public SkyKey(SkyFunctionName functionName, Object valueName) {
+ this.functionName = Preconditions.checkNotNull(functionName);
+ this.argument = Preconditions.checkNotNull(valueName);
+ this.hashCode = 31 * functionName.hashCode() + argument.hashCode();
+ }
+
+ public SkyFunctionName functionName() {
+ return functionName;
+ }
+
+ public Object argument() {
+ return argument;
+ }
+
+ @Override
+ public String toString() {
+ return functionName + ":" + argument;
+ }
+
+ @Override
+ public int hashCode() {
+ return hashCode;
+ }
+
+ @Override
+ public boolean equals(Object obj) {
+ if (this == obj) {
+ return true;
+ }
+ if (obj == null) {
+ return false;
+ }
+ if (getClass() != obj.getClass()) {
+ return false;
+ }
+ SkyKey other = (SkyKey) obj;
+ return argument.equals(other.argument) && functionName.equals(other.functionName);
+ }
+
+ public static final Function<SkyKey, Object> NODE_NAME = new Function<SkyKey, Object>() {
+ @Override
+ public Object apply(SkyKey input) {
+ return input.argument();
+ }
+ };
+}
