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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.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.devtools.build.lib.cmdline.Label;
import com.google.devtools.build.lib.concurrent.ThreadSafety.Immutable;
import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
import com.google.devtools.build.lib.packages.Rule;
import com.google.devtools.build.lib.packages.RuleClass;
import com.google.devtools.build.lib.packages.Target;
import com.google.devtools.build.lib.util.Preconditions;
import com.google.devtools.build.lib.util.StringCanonicalizer;
import com.google.devtools.build.skyframe.SkyKey;
import com.google.devtools.build.skyframe.SkyValue;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Objects;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import javax.annotation.Nullable;
/**
* A <i>transitive</i> target reference that, when built in skyframe, loads the entire transitive
* closure of a target. Retains the first error message found during the transitive traversal, and a
* set of names of providers if the target is a {@link Rule}.
*
* <p>Interns values for error-free traversal nodes that correspond to built-in rules.
*/
@Immutable
@ThreadSafe
public class TransitiveTraversalValue implements SkyValue {
private static final TransitiveTraversalValue EMPTY_VALUE =
new TransitiveTraversalValue(false, ImmutableSet.<String>of(), null);
// A quick-lookup cache that allows us to get the value for a given RuleClass, assuming no error
// messages for the target. Only stores built-in RuleClass objects to avoid memory bloat.
private static final ConcurrentMap<RuleClass, TransitiveTraversalValue> VALUES_BY_RULE_CLASS =
new ConcurrentHashMap<>();
/**
* A strong interner of TransitiveTargetValue objects. Because we only wish to intern values for
* built-in rules, we need an interner with an additional method to return the canonical
* representative if it is present without interning our sample. This is only mutated in {@link
* #forTarget}, and read in {@link #forTarget} and {@link #create}.
*/
private static final InternerWithPresenceCheck<TransitiveTraversalValue> VALUE_INTERNER =
new InternerWithPresenceCheck<>();
static {
VALUE_INTERNER.intern(EMPTY_VALUE);
}
private final boolean canHaveAnyProvider;
private final ImmutableSet<String> providers;
@Nullable private final String firstErrorMessage;
private TransitiveTraversalValue(
boolean canHaveAnyProvider,
ImmutableSet<String> providers,
@Nullable String firstErrorMessage) {
this.canHaveAnyProvider = canHaveAnyProvider;
this.providers = Preconditions.checkNotNull(providers);
this.firstErrorMessage =
(firstErrorMessage == null) ? null : StringCanonicalizer.intern(firstErrorMessage);
}
static TransitiveTraversalValue unsuccessfulTransitiveTraversal(String firstErrorMessage) {
return new TransitiveTraversalValue(
false, ImmutableSet.<String>of(), Preconditions.checkNotNull(firstErrorMessage));
}
static TransitiveTraversalValue forTarget(Target target, @Nullable String firstErrorMessage) {
if (target instanceof Rule) {
Rule rule = (Rule) target;
RuleClass ruleClass = rule.getRuleClassObject();
if (firstErrorMessage == null && !ruleClass.isSkylark()) {
TransitiveTraversalValue value = VALUES_BY_RULE_CLASS.get(ruleClass);
if (value != null) {
return value;
}
ImmutableSet<String> providers = canonicalSet(toList(ruleClass.getAdvertisedProviders()));
value = new TransitiveTraversalValue(ruleClass.canHaveAnyProvider(), providers, null);
// May already be there from another RuleClass or a concurrent put.
value = VALUE_INTERNER.intern(value);
// May already be there from a concurrent put.
VALUES_BY_RULE_CLASS.putIfAbsent(ruleClass, value);
return value;
} else {
// If this is a Skylark rule, we may still get a cache hit from another RuleClass with the
// same providers.
return TransitiveTraversalValue.create(
ruleClass.canHaveAnyProvider(),
toList(rule.getRuleClassObject().getAdvertisedProviders()),
firstErrorMessage);
}
}
if (firstErrorMessage == null) {
return EMPTY_VALUE;
} else {
return new TransitiveTraversalValue(false, ImmutableSet.<String>of(), firstErrorMessage);
}
}
public static TransitiveTraversalValue create(
boolean canHaveAnyProvider,
Collection<String> providers,
@Nullable String firstErrorMessage) {
TransitiveTraversalValue value =
new TransitiveTraversalValue(
canHaveAnyProvider, canonicalSet(providers), firstErrorMessage);
if (firstErrorMessage == null) {
TransitiveTraversalValue oldValue = VALUE_INTERNER.getCanonical(value);
return oldValue == null ? value : oldValue;
}
return value;
}
private static ImmutableSet<String> canonicalSet(Iterable<String> strIterable) {
ImmutableSet.Builder<String> builder = new ImmutableSet.Builder<>();
for (String str : strIterable) {
builder.add(StringCanonicalizer.intern(str));
}
return builder.build();
}
private static List<String> toList(Collection<Class<?>> providers) {
if (providers == null) {
return ImmutableList.of();
}
List<String> strings = new ArrayList<>(providers.size());
for (Class<?> clazz : providers) {
strings.add(clazz.getName());
}
return strings;
}
/**
* Returns if the associated target can have any provider. True for "alias" rules.
*/
public boolean canHaveAnyProvider() {
return canHaveAnyProvider;
}
/**
* Returns the set of provider names from the target, if the target is a {@link Rule}. Otherwise
* returns the empty set.
*/
public Set<String> getProviders() {
return providers;
}
/**
* Returns the first error message, if any, from loading the target and its transitive
* dependencies.
*/
@Nullable
public String getFirstErrorMessage() {
return firstErrorMessage;
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (!(o instanceof TransitiveTraversalValue)) {
return false;
}
TransitiveTraversalValue that = (TransitiveTraversalValue) o;
return this.canHaveAnyProvider == that.canHaveAnyProvider
&& Objects.equals(this.firstErrorMessage, that.firstErrorMessage)
&& this.providers.equals(that.providers);
}
@Override
public int hashCode() {
return Objects.hash(firstErrorMessage, providers, canHaveAnyProvider);
}
@ThreadSafe
public static SkyKey key(Label label) {
Preconditions.checkArgument(!label.getPackageIdentifier().getRepository().isDefault());
return SkyKey.create(SkyFunctions.TRANSITIVE_TRAVERSAL, label);
}
}
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