// 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.skyframe; import com.google.common.collect.ImmutableList; import com.google.devtools.build.lib.events.Event; import com.google.devtools.build.skyframe.EmptySkyValue; import com.google.devtools.build.skyframe.SkyFunction; import com.google.devtools.build.skyframe.SkyKey; import com.google.devtools.build.skyframe.SkyValue; /** * Given a "cycle" of objects of type {@param S}, emits an error message for this cycle. * The keys for this SkyFunction are assumed to deduplicate cycles that differ only in which element * of the cycle they start at, so multiple paths to the cycle will be reported by a single execution * of this function. * *
The cycle need not actually be a cycle -- any iterable exhibiting an error that is independent
* of the iterable's starting point can be an argument to this function.
*/
abstract class AbstractChainUniquenessFunction implements SkyFunction {
protected abstract String getConciseDescription();
protected abstract String getHeaderMessage();
protected abstract String getFooterMessage();
protected abstract String elementToString(S elt);
@Override
public SkyValue compute(SkyKey skyKey, Environment env) {
StringBuilder errorMessage = new StringBuilder();
errorMessage.append(getConciseDescription() + " detected\n");
errorMessage.append(getHeaderMessage() + "\n");
@SuppressWarnings("unchecked")
ImmutableList chain = (ImmutableList) skyKey.argument();
for (S elt : chain) {
errorMessage.append(elementToString(elt) + "\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 error.
env.getListener().handle(Event.error(errorMessage.toString()));
return EmptySkyValue.INSTANCE;
}
@Override
public String extractTag(SkyKey skyKey) {
return null;
}
}