src/main/java/com/google/devtools/build/lib/skyframe/AbstractFileSymlinkExceptionUniquenessFunction.java

// 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.lib.skyframe;

import com.google.common.collect.ImmutableList;
import com.google.devtools.build.lib.events.Event;
import com.google.devtools.build.lib.vfs.RootedPath;
import com.google.devtools.build.skyframe.SkyFunction;
import com.google.devtools.build.skyframe.SkyKey;
import com.google.devtools.build.skyframe.SkyValue;

abstract class AbstractFileSymlinkExceptionUniquenessFunction implements SkyFunction {
  protected abstract String getConciseDescription();
  protected abstract String getHeaderMessage();
  protected abstract String getFooterMessage();
  protected abstract SkyValue getDummyValue();

  @Override
  public SkyValue compute(SkyKey skyKey, Environment env) {
    StringBuilder errorMessage = new StringBuilder();
    errorMessage.append(getConciseDescription() + " detected\n");
    errorMessage.append(getHeaderMessage() + "\n");
    @SuppressWarnings("unchecked")
    ImmutableList<RootedPath> chain = (ImmutableList<RootedPath>) skyKey.argument();
    for (RootedPath rootedPath : chain) {
      errorMessage.append(rootedPath.asPath() + "\n");
    }
    errorMessage.append(getFooterMessage() + "\n");
    // The purpose of this SkyFunction is the side effect of emitting an error message exactly
    // once per build per unique symlink error.
    env.getListener().handle(Event.error(errorMessage.toString()));
    return getDummyValue();
  }

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