Make environment dependency of actions factor through individual values

With actions depending on the (white-listed part) of the environment
as a whole, even though they are only re-executed if the used parts of
the environment change, each action has to be reconsidered on any change
of the environment. For large dependency graphs, this can be a considerable
amount of effort; therefore add intermediate values for the individual
variables and make actions only depend on those actually used.

--
Change-Id: I283d289da3e0782dc4f9ac084a41425166cfede0
Reviewed-on: https://bazel-review.googlesource.com/#/c/5494
MOS_MIGRATED_REVID=133255911

1 files changed, 33 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/ClientEnvironmentValue.java b/src/main/java/com/google/devtools/build/lib/skyframe/ClientEnvironmentValue.java
new file mode 100644
index 0000000000..bb005339fd
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/ClientEnvironmentValue.java
@@ -0,0 +1,33 @@
+// Copyright 2016 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.lib.skyframe;
+
+import com.google.devtools.build.skyframe.SkyValue;
+import javax.annotation.Nullable;
+
+/** An aspect in the context of the Skyframe graph. */
+public final class ClientEnvironmentValue implements SkyValue {
+  private final String value;
+
+  public ClientEnvironmentValue(@Nullable String value) {
+    this.value = value;
+  }
+
+  /** @return the value in the client environment or null if unset in the environment. */
+  @Nullable
+  public String getValue() {
+    return value;
+  }
+}