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// 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.base.Function;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.devtools.build.lib.events.Event;
import com.google.devtools.build.lib.events.EventHandler;
import com.google.devtools.build.lib.packages.NoSuchThingException;
import com.google.devtools.build.lib.packages.Target;
import com.google.devtools.build.lib.pkgcache.LoadedPackageProvider;
import com.google.devtools.build.lib.syntax.Label;
import com.google.devtools.build.skyframe.CycleInfo;
import com.google.devtools.build.skyframe.CyclesReporter;
import com.google.devtools.build.skyframe.SkyKey;
/** Reports cycles between skyframe values whose keys contains {@link Label}s. */
abstract class AbstractLabelCycleReporter implements CyclesReporter.SingleCycleReporter {
private final LoadedPackageProvider loadedPackageProvider;
AbstractLabelCycleReporter(LoadedPackageProvider loadedPackageProvider) {
this.loadedPackageProvider = loadedPackageProvider;
}
/** Returns the String representation of the {@code SkyKey}. */
protected abstract String prettyPrint(SkyKey key);
/** Returns the associated Label of the SkyKey. */
protected abstract Label getLabel(SkyKey key);
protected abstract boolean canReportCycle(SkyKey topLevelKey, CycleInfo cycleInfo);
protected String getAdditionalMessageAboutCycle(SkyKey topLevelKey, CycleInfo cycleInfo) {
return "";
}
@Override
public boolean maybeReportCycle(SkyKey topLevelKey, CycleInfo cycleInfo,
boolean alreadyReported, EventHandler eventHandler) {
Preconditions.checkNotNull(eventHandler);
if (!canReportCycle(topLevelKey, cycleInfo)) {
return false;
}
if (alreadyReported) {
Label label = getLabel(topLevelKey);
Target target = getTargetForLabel(label);
eventHandler.handle(Event.error(target.getLocation(),
"in " + target.getTargetKind() + " " + label +
": cycle in dependency graph: target depends on an already-reported cycle"));
} else {
StringBuilder cycleMessage = new StringBuilder("cycle in dependency graph:");
ImmutableList<SkyKey> pathToCycle = cycleInfo.getPathToCycle();
ImmutableList<SkyKey> cycle = cycleInfo.getCycle();
for (SkyKey value : pathToCycle) {
cycleMessage.append("\n ");
cycleMessage.append(prettyPrint(value));
}
SkyKey cycleValue = printCycle(cycle, cycleMessage, new Function<SkyKey, String>() {
@Override
public String apply(SkyKey input) {
return prettyPrint(input);
}
});
cycleMessage.append(getAdditionalMessageAboutCycle(topLevelKey, cycleInfo));
Label label = getLabel(cycleValue);
Target target = getTargetForLabel(label);
eventHandler.handle(
Event.error(target.getLocation(), "in " + target.getTargetKind() + " " + label
+ ": " + cycleMessage.toString()));
}
return true;
}
/**
* Prints the SkyKey-s in cycle into cycleMessage using the print function.
*/
static SkyKey printCycle(ImmutableList<SkyKey> cycle, StringBuilder cycleMessage,
Function<SkyKey, String> printFunction) {
Iterable<SkyKey> valuesToPrint = cycle.size() > 1
? Iterables.concat(cycle, ImmutableList.of(cycle.get(0))) : cycle;
SkyKey cycleValue = null;
for (SkyKey value : valuesToPrint) {
if (cycleValue == null) {
cycleValue = value;
}
if (value == cycleValue) {
cycleMessage.append("\n * ");
} else {
cycleMessage.append("\n ");
}
cycleMessage.append(printFunction.apply(value));
}
if (cycle.size() == 1) {
cycleMessage.append(" [self-edge]");
}
return cycleValue;
}
protected final Target getTargetForLabel(Label label) {
try {
return loadedPackageProvider.getLoadedTarget(label);
} catch (NoSuchThingException e) {
// This method is used for getting the target from a label in a circular dependency.
// If we have a cycle that means that we need to have accessed the target (to get its
// dependencies). So all the labels in a dependency cycle need to exist.
throw new IllegalStateException(e);
}
}
}
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