src/main/java/com/google/devtools/build/lib/rules/cpp/CcSupportFunction.java

// Copyright 2014 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.rules.cpp;

import com.google.common.base.Preconditions;
import com.google.devtools.build.lib.analysis.BlazeDirectories;
import com.google.devtools.build.lib.vfs.Path;
import com.google.devtools.build.skyframe.SkyFunction;
import com.google.devtools.build.skyframe.SkyKey;
import com.google.devtools.build.skyframe.SkyValue;
import javax.annotation.Nullable;

/**
 * A {@link SkyFunction} that does things for FDO that a regular configured target is not allowed
 * to.
 *
 * <p>This only exists because the value of {@code --fdo_optimize} can be a workspace-relative path
 * and thus we need to depend on {@link BlazeDirectories} somehow, which neither the configuration
 * nor the analysis phase can "officially" do.
 *
 * <p>The fix is probably to make it possible for {@link
 * com.google.devtools.build.lib.analysis.actions.SymlinkAction} to create workspace-relative
 * symlinks because action execution can hopefully depend on {@link BlazeDirectories}.
 *
 * <p>There is also the awful and incorrect {@link Path#exists()} call in {@link
 * com.google.devtools.build.lib.view.proto.CcProtoProfileProvider#getProfile(
 * com.google.devtools.build.lib.analysis.RuleContext)} which needs a {@link Path}.
 */
public class CcSupportFunction implements SkyFunction {
  private final BlazeDirectories directories;

  public CcSupportFunction(BlazeDirectories directories) {
    this.directories = Preconditions.checkNotNull(directories);
  }

  @Nullable
  @Override
  public SkyValue compute(SkyKey skyKey, Environment env) throws InterruptedException {
    CcSkyframeSupportValue.Key key = (CcSkyframeSupportValue.Key) skyKey.argument();
    Path resolvedPath =
        key.getFilePath() == null
            ? null
            : directories.getWorkspace().getRelative(key.getFilePath());
    return new CcSkyframeSupportValue(resolvedPath);
  }

  @Nullable
  @Override
  public String extractTag(SkyKey skyKey) {
    return null;
  }
}