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// 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.base.Preconditions;
import com.google.devtools.build.lib.cmdline.Label;
import com.google.devtools.build.lib.events.EventHandler;
import com.google.devtools.build.lib.packages.AdvertisedProviderSet;
import com.google.devtools.build.lib.packages.NoSuchPackageException;
import com.google.devtools.build.lib.packages.NoSuchTargetException;
import com.google.devtools.build.lib.packages.NoSuchThingException;
import com.google.devtools.build.lib.util.GroupedList;
import com.google.devtools.build.skyframe.SkyFunction;
import com.google.devtools.build.skyframe.SkyKey;
import com.google.devtools.build.skyframe.SkyValue;
import com.google.devtools.build.skyframe.ValueOrException2;
import java.util.Collection;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import javax.annotation.Nullable;
/**
* This class is like {@link TransitiveTargetFunction}, but the values it returns do not contain
* {@link com.google.devtools.build.lib.collect.nestedset.NestedSet}s. It performs the side-effects
* of {@link TransitiveTargetFunction} (i.e., ensuring that transitive targets and their packages
* have been loaded). It evaluates to a {@link TransitiveTraversalValue} that contains the first
* error message it encountered, and a set of names of providers if the target is a rule.
*/
public class TransitiveTraversalFunction
extends TransitiveBaseTraversalFunction<
TransitiveTraversalFunction.DeterministicErrorMessageAccumulator> {
@Override
Label argumentFromKey(SkyKey key) {
return (Label) key.argument();
}
@Override
SkyKey getKey(Label label) {
return TransitiveTraversalValue.key(label);
}
@Override
DeterministicErrorMessageAccumulator processTarget(TargetAndErrorIfAny targetAndErrorIfAny) {
NoSuchTargetException errorIfAny = targetAndErrorIfAny.getErrorLoadingTarget();
String errorMessageIfAny = errorIfAny == null ? null : errorIfAny.getMessage();
return DeterministicErrorMessageAccumulator.create(errorMessageIfAny);
}
@Override
void processDeps(
DeterministicErrorMessageAccumulator accumulator,
EventHandler eventHandler,
TargetAndErrorIfAny targetAndErrorIfAny,
Iterable<Map.Entry<SkyKey, ValueOrException2<NoSuchPackageException, NoSuchTargetException>>>
depEntries) {
for (Map.Entry<SkyKey, ValueOrException2<NoSuchPackageException, NoSuchTargetException>> entry :
depEntries) {
TransitiveTraversalValue transitiveTraversalValue;
try {
transitiveTraversalValue = (TransitiveTraversalValue) entry.getValue().get();
if (transitiveTraversalValue == null) {
continue;
}
} catch (NoSuchPackageException | NoSuchTargetException e) {
accumulator.maybeSet(e.getMessage());
continue;
}
String errorMessage = transitiveTraversalValue.getErrorMessage();
if (errorMessage != null) {
accumulator.maybeSet(errorMessage);
}
}
}
@Nullable
@Override
protected AdvertisedProviderSet getAdvertisedProviderSet(
Label toLabel,
@Nullable ValueOrException2<NoSuchPackageException, NoSuchTargetException> toVal,
Environment env) {
if (toVal == null) {
return null;
}
try {
return ((TransitiveTraversalValue) toVal.get()).getProviders();
} catch (NoSuchThingException e) {
// Do nothing interesting. This error was handled when we computed the corresponding
// TransitiveTargetValue.
return null;
}
}
@Override
SkyValue computeSkyValue(
TargetAndErrorIfAny targetAndErrorIfAny, DeterministicErrorMessageAccumulator accumulator) {
boolean targetLoadedSuccessfully = targetAndErrorIfAny.getErrorLoadingTarget() == null;
String errorMessage = accumulator.getErrorMessage();
return targetLoadedSuccessfully
? TransitiveTraversalValue.forTarget(targetAndErrorIfAny.getTarget(), errorMessage)
: TransitiveTraversalValue.unsuccessfulTransitiveTraversal(
errorMessage, targetAndErrorIfAny.getTarget());
}
@Override
Collection<SkyKey> getLabelDepKeys(
SkyFunction.Environment env, TargetAndErrorIfAny targetAndErrorIfAny)
throws InterruptedException {
// As a performance optimization we may already know the deps we are about to request from
// last time #compute was called. By requesting these from the environment, we can avoid
// repeating the label visitation step. For TransitiveTraversalFunction#compute, the label deps
// dependency group is requested immediately after the package.
//
// IMPORTANT: No other package values should be requested inside
// TransitiveTraversalFunction#compute from this point forward.
Collection<SkyKey> oldDepKeys = getDepsAfterLastPackageDep(env, /*offset=*/ 1);
return oldDepKeys == null ? super.getLabelDepKeys(env, targetAndErrorIfAny) : oldDepKeys;
}
@Override
Iterable<SkyKey> getStrictLabelAspectDepKeys(
SkyFunction.Environment env,
Map<SkyKey, ValueOrException2<NoSuchPackageException, NoSuchTargetException>> depMap,
TargetAndErrorIfAny targetAndErrorIfAny)
throws InterruptedException {
// As a performance optimization we may already know the deps we are about to request from
// last time #compute was called. By requesting these from the environment, we can avoid
// repeating the label visitation step. For TransitiveTraversalFunction#compute, the label
// aspect deps dependency group is requested two groups after the package.
Collection<SkyKey> oldAspectDepKeys = getDepsAfterLastPackageDep(env, /*offset=*/ 2);
return oldAspectDepKeys == null
? super.getStrictLabelAspectDepKeys(env, depMap, targetAndErrorIfAny)
: oldAspectDepKeys;
}
@Nullable
private static Collection<SkyKey> getDepsAfterLastPackageDep(
SkyFunction.Environment env, int offset) {
GroupedList<SkyKey> temporaryDirectDeps = env.getTemporaryDirectDeps();
if (temporaryDirectDeps == null) {
return null;
}
int lastPackageDepIndex = getLastPackageValueIndex(temporaryDirectDeps);
if (lastPackageDepIndex == -1
|| temporaryDirectDeps.listSize() <= lastPackageDepIndex + offset) {
return null;
}
return temporaryDirectDeps.get(lastPackageDepIndex + offset);
}
private static int getLastPackageValueIndex(GroupedList<SkyKey> directDeps) {
int directDepsNumGroups = directDeps.listSize();
for (int i = directDepsNumGroups - 1; i >= 0; i--) {
List<SkyKey> depGroup = directDeps.get(i);
if (depGroup.size() == 1 && depGroup.get(0).functionName().equals(SkyFunctions.PACKAGE)) {
return i;
}
}
return -1;
}
/**
* Keeps track of a deterministic error message encountered while traversing itself and its
* dependencies: either the error it was initialized with, or the shortest error it encounters,
* with ties broken alphabetically.
*
* <p>This preserves the behavior that the local target's error is the most important, and is
* cheap (constant-time) to compute the comparison between strings, unless they have the same
* length, which is unlikely.
*/
interface DeterministicErrorMessageAccumulator {
@Nullable
String getErrorMessage();
default void maybeSet(String errorMessage) {}
static DeterministicErrorMessageAccumulator create(@Nullable String errorMessage) {
if (errorMessage != null) {
return () -> errorMessage;
}
return new UpdateableErrorMessageAccumulator();
}
class UpdateableErrorMessageAccumulator implements DeterministicErrorMessageAccumulator {
private static final Comparator<String> LENGTH_THEN_ALPHABETICAL =
Comparator.nullsLast(
Comparator.comparingInt(String::length).thenComparing(Comparator.naturalOrder()));
@Nullable private String errorMessage;
@Override
public void maybeSet(String errorMessage) {
Preconditions.checkNotNull(errorMessage);
if (LENGTH_THEN_ALPHABETICAL.compare(this.errorMessage, errorMessage) > 0) {
this.errorMessage = errorMessage;
}
}
@Nullable
@Override
public String getErrorMessage() {
return errorMessage;
}
}
}
}