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
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/ClientEnvironmentFunction.java b/src/main/java/com/google/devtools/build/lib/skyframe/ClientEnvironmentFunction.java
new file mode 100644
index 0000000..cc2c37a
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/ClientEnvironmentFunction.java
@@ -0,0 +1,38 @@
+// 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.SkyFunction;
+import com.google.devtools.build.skyframe.SkyKey;
+import com.google.devtools.build.skyframe.SkyValue;
+import java.util.Map;
+import javax.annotation.Nullable;
+
+/** The Skyframe function that generates values for variables of the client environment. */
+public final class ClientEnvironmentFunction implements SkyFunction {
+
+ @Nullable
+ @Override
+ public String extractTag(SkyKey skyKey) {
+ return null;
+ }
+
+ @Nullable
+ @Override
+ public SkyValue compute(SkyKey skyKey, Environment env) throws InterruptedException {
+ Map<String, String> clientEnv = PrecomputedValue.CLIENT_ENV.get(env);
+ return new ClientEnvironmentValue(clientEnv.get((String) skyKey.argument()));
+ }
+}
