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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
package com.google.devtools.build.skyframe;
import com.google.common.base.Preconditions;
import com.google.devtools.build.lib.collect.nestedset.NestedSet;
import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
import com.google.devtools.build.lib.collect.nestedset.Order;
import java.util.Objects;
import javax.annotation.Nullable;
/**
* Encapsulation of data stored by {@link NodeEntry} when the value has finished building.
*
* <p>This is intended only for use in alternative {@code MemoizingEvaluator} implementations.
*/
public abstract class ValueWithMetadata implements SkyValue {
protected final SkyValue value;
private static final NestedSet<TaggedEvents> NO_EVENTS =
NestedSetBuilder.<TaggedEvents>emptySet(Order.STABLE_ORDER);
public ValueWithMetadata(SkyValue value) {
this.value = value;
}
/** Builds a value entry value that has an error (and no value value).
*
* <p>This is intended only for use in alternative {@code MemoizingEvaluator} implementations.
*/
public static ValueWithMetadata error(ErrorInfo errorInfo,
NestedSet<TaggedEvents> transitiveEvents) {
return new ErrorInfoValue(errorInfo, null, transitiveEvents);
}
/**
* Builds a value entry value that has a value value, and possibly an error (constructed from its
* children's errors).
*
* <p>This is intended only for use in alternative {@code MemoizingEvaluator} implementations.
*/
static SkyValue normal(@Nullable SkyValue value, @Nullable ErrorInfo errorInfo,
NestedSet<TaggedEvents> transitiveEvents) {
Preconditions.checkState(value != null || errorInfo != null,
"Value and error cannot both be null");
if (errorInfo == null) {
return transitiveEvents.isEmpty()
? value
: new ValueWithEvents(value, transitiveEvents);
}
return new ErrorInfoValue(errorInfo, value, transitiveEvents);
}
@Nullable SkyValue getValue() {
return value;
}
@Nullable
abstract ErrorInfo getErrorInfo();
abstract NestedSet<TaggedEvents> getTransitiveEvents();
static final class ValueWithEvents extends ValueWithMetadata {
private final NestedSet<TaggedEvents> transitiveEvents;
ValueWithEvents(SkyValue value, NestedSet<TaggedEvents> transitiveEvents) {
super(Preconditions.checkNotNull(value));
this.transitiveEvents = Preconditions.checkNotNull(transitiveEvents);
}
@Nullable
@Override
ErrorInfo getErrorInfo() { return null; }
@Override
NestedSet<TaggedEvents> getTransitiveEvents() { return transitiveEvents; }
/**
* We override equals so that if the same value is written to a {@link NodeEntry} twice, it can
* verify that the two values are equal, and avoid incrementing its version.
*/
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
ValueWithEvents that = (ValueWithEvents) o;
// Shallow equals is a middle ground between using default equals, which might miss
// nested sets with the same elements, and deep equality checking, which would be expensive.
// All three choices are sound, since shallow equals and default equals are more
// conservative than deep equals. Using shallow equals means that we may unnecessarily
// consider some values unequal that are actually equal, but this is still a net win over
// deep equals.
return value.equals(that.value) && transitiveEvents.shallowEquals(that.transitiveEvents);
}
@Override
public int hashCode() {
return 31 * value.hashCode() + transitiveEvents.hashCode();
}
@Override
public String toString() { return value.toString(); }
}
static final class ErrorInfoValue extends ValueWithMetadata {
private final ErrorInfo errorInfo;
private final NestedSet<TaggedEvents> transitiveEvents;
ErrorInfoValue(ErrorInfo errorInfo, @Nullable SkyValue value,
NestedSet<TaggedEvents> transitiveEvents) {
super(value);
this.errorInfo = Preconditions.checkNotNull(errorInfo);
this.transitiveEvents = Preconditions.checkNotNull(transitiveEvents);
}
@Nullable
@Override
ErrorInfo getErrorInfo() { return errorInfo; }
@Override
NestedSet<TaggedEvents> getTransitiveEvents() { return transitiveEvents; }
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
ErrorInfoValue that = (ErrorInfoValue) o;
// Shallow equals is a middle ground between using default equals, which might miss
// nested sets with the same elements, and deep equality checking, which would be expensive.
// All three choices are sound, since shallow equals and default equals are more
// conservative than deep equals. Using shallow equals means that we may unnecessarily
// consider some values unequal that are actually equal, but this is still a net win over
// deep equals.
return Objects.equals(this.value, that.value)
&& Objects.equals(this.errorInfo, that.errorInfo)
&& transitiveEvents.shallowEquals(that.transitiveEvents);
}
@Override
public int hashCode() {
return 31 * Objects.hash(value, errorInfo) + transitiveEvents.shallowHashCode();
}
@Override
public String toString() {
StringBuilder result = new StringBuilder();
if (value != null) {
result.append("Value: ").append(value);
}
if (errorInfo != null) {
if (result.length() > 0) {
result.append("; ");
}
result.append("Error: ").append(errorInfo);
}
return result.toString();
}
}
static SkyValue justValue(SkyValue value) {
if (value instanceof ValueWithMetadata) {
return ((ValueWithMetadata) value).getValue();
}
return value;
}
static ValueWithMetadata wrapWithMetadata(SkyValue value) {
if (value instanceof ValueWithMetadata) {
return (ValueWithMetadata) value;
}
return new ValueWithEvents(value, NO_EVENTS);
}
@Nullable
public static ErrorInfo getMaybeErrorInfo(SkyValue value) {
if (value.getClass() == ErrorInfoValue.class) {
return ((ValueWithMetadata) value).getErrorInfo();
}
return null;
}
}
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