// 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.MoreObjects;
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.AdvertisedProviderSet;
import com.google.devtools.build.lib.packages.Rule;
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.Objects;
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, the
* kind of target, 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 abstract class TransitiveTraversalValue implements SkyValue {
// A quick-lookup cache that allows us to get the value for a given target kind, assuming no error
// messages for the target. The number of built-in target kinds is limited, so memory bloat is not
// a concern.
private static final ConcurrentMap<String, TransitiveTraversalValue> VALUES_BY_TARGET_KIND =
new ConcurrentHashMap<>();
/**
* A strong interner of TransitiveTargetValue objects. Because we only wish to intern values for
* built-in non-skylark targets, 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<>();
private final String kind;
protected TransitiveTraversalValue(String kind) {
this.kind = Preconditions.checkNotNull(kind);
}
static TransitiveTraversalValue unsuccessfulTransitiveTraversal(
String firstErrorMessage, Target target) {
return new TransitiveTraversalValueWithError(
Preconditions.checkNotNull(firstErrorMessage), target.getTargetKind());
}
static TransitiveTraversalValue forTarget(Target target, @Nullable String firstErrorMessage) {
if (firstErrorMessage == null) {
if (target instanceof Rule && ((Rule) target).getRuleClassObject().isSkylark()) {
Rule rule = (Rule) target;
// Do not intern values for skylark rules.
return TransitiveTraversalValue.create(
rule.getRuleClassObject().getAdvertisedProviders(),
rule.getTargetKind(),
firstErrorMessage);
} else {
TransitiveTraversalValue value = VALUES_BY_TARGET_KIND.get(target.getTargetKind());
if (value != null) {
return value;
}
AdvertisedProviderSet providers =
target instanceof Rule
? ((Rule) target).getRuleClassObject().getAdvertisedProviders()
: AdvertisedProviderSet.EMPTY;
value = new TransitiveTraversalValueWithoutError(providers, target.getTargetKind());
// May already be there from another target or a concurrent put.
value = VALUE_INTERNER.intern(value);
// May already be there from a concurrent put.
VALUES_BY_TARGET_KIND.putIfAbsent(target.getTargetKind(), value);
return value;
}
} else {
return new TransitiveTraversalValueWithError(firstErrorMessage, target.getTargetKind());
}
}
public static TransitiveTraversalValue create(
AdvertisedProviderSet providers, String kind, @Nullable String firstErrorMessage) {
TransitiveTraversalValue value =
firstErrorMessage == null
? new TransitiveTraversalValueWithoutError(providers, kind)
: new TransitiveTraversalValueWithError(firstErrorMessage, kind);
if (firstErrorMessage == null) {
TransitiveTraversalValue oldValue = VALUE_INTERNER.getCanonical(value);
return oldValue == null ? value : oldValue;
}
return value;
}
/** Returns if the associated target can have any provider. True for "alias" rules. */
public abstract boolean canHaveAnyProvider();
/**
* Returns the set of provider names from the target, if the target is a {@link Rule}. Otherwise
* returns the empty set.
*/
public abstract AdvertisedProviderSet getProviders();
/** Returns the target kind. */
public String getKind() {
return kind;
}
/**
* Returns the first error message, if any, from loading the target and its transitive
* dependencies.
*/
@Nullable
public abstract String getFirstErrorMessage();
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (!(o instanceof TransitiveTraversalValue)) {
return false;
}
TransitiveTraversalValue that = (TransitiveTraversalValue) o;
return Objects.equals(this.getFirstErrorMessage(), that.getFirstErrorMessage())
&& Objects.equals(this.getKind(), that.getKind())
&& this.getProviders().equals(that.getProviders());
}
@Override
public int hashCode() {
return Objects.hash(getFirstErrorMessage(), getKind(), getProviders());
}
@ThreadSafe
public static SkyKey key(Label label) {
Preconditions.checkArgument(!label.getPackageIdentifier().getRepository().isDefault());
return label;
}
/** A transitive target reference without error. */
public static final class TransitiveTraversalValueWithoutError extends TransitiveTraversalValue {
private final AdvertisedProviderSet advertisedProviders;
private TransitiveTraversalValueWithoutError(
AdvertisedProviderSet providers, @Nullable String kind) {
super(kind);
this.advertisedProviders = Preconditions.checkNotNull(providers);
}
@Override
public boolean canHaveAnyProvider() {
return advertisedProviders.canHaveAnyProvider();
}
@Override
public AdvertisedProviderSet getProviders() {
return advertisedProviders;
}
@Override
@Nullable
public String getFirstErrorMessage() {
return null;
}
@Override
public String toString() {
return MoreObjects.toStringHelper(this)
.add("kind", getKind())
.add("providers", advertisedProviders)
.toString();
}
}
/** A transitive target reference with error. */
public static final class TransitiveTraversalValueWithError extends TransitiveTraversalValue {
private final String firstErrorMessage;
private TransitiveTraversalValueWithError(String firstErrorMessage, String kind) {
super(kind);
this.firstErrorMessage =
StringCanonicalizer.intern(Preconditions.checkNotNull(firstErrorMessage));
}
@Override
public boolean canHaveAnyProvider() {
return AdvertisedProviderSet.EMPTY.canHaveAnyProvider();
}
@Override
public AdvertisedProviderSet getProviders() {
return AdvertisedProviderSet.EMPTY;
}
@Override
@Nullable
public String getFirstErrorMessage() {
return firstErrorMessage;
}
@Override
public String toString() {
return MoreObjects.toStringHelper(this)
.add("error", firstErrorMessage)
.add("kind", getKind())
.toString();
}
}
}