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/*
* Copyright 2017, OpenCensus Authors
*
* 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 io.opencensus.trace;
import com.google.auto.value.AutoValue;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import javax.annotation.concurrent.Immutable;
/**
* A link to a {@link Span} from a different trace.
*
* <p>It requires a {@link Type} which describes the relationship with the linked {@code Span} and
* the identifiers of the linked {@code Span}.
*
* <p>Used (for example) in batching operations, where a single batch handler processes multiple
* requests from different traces.
*
* @since 0.5
*/
@Immutable
@AutoValue
public abstract class Link {
private static final Map<String, AttributeValue> EMPTY_ATTRIBUTES = Collections.emptyMap();
/**
* The relationship with the linked {@code Span} relative to the current {@code Span}.
*
* @since 0.5
*/
public enum Type {
/**
* When the linked {@code Span} is a child of the current {@code Span}.
*
* @since 0.5
*/
CHILD_LINKED_SPAN,
/**
* When the linked {@code Span} is a parent of the current {@code Span}.
*
* @since 0.5
*/
PARENT_LINKED_SPAN
}
/**
* Returns a new {@code Link}.
*
* @param context the context of the linked {@code Span}.
* @param type the type of the relationship with the linked {@code Span}.
* @return a new {@code Link}.
* @since 0.5
*/
public static Link fromSpanContext(SpanContext context, Type type) {
return new AutoValue_Link(context.getTraceId(), context.getSpanId(), type, EMPTY_ATTRIBUTES);
}
/**
* Returns a new {@code Link}.
*
* @param context the context of the linked {@code Span}.
* @param type the type of the relationship with the linked {@code Span}.
* @param attributes the attributes of the {@code Link}.
* @return a new {@code Link}.
* @since 0.5
*/
public static Link fromSpanContext(
SpanContext context, Type type, Map<String, AttributeValue> attributes) {
return new AutoValue_Link(
context.getTraceId(),
context.getSpanId(),
type,
Collections.unmodifiableMap(new HashMap<String, AttributeValue>(attributes)));
}
/**
* Returns the {@code TraceId}.
*
* @return the {@code TraceId}.
* @since 0.5
*/
public abstract TraceId getTraceId();
/**
* Returns the {@code SpanId}.
*
* @return the {@code SpanId}
* @since 0.5
*/
public abstract SpanId getSpanId();
/**
* Returns the {@code Type}.
*
* @return the {@code Type}.
* @since 0.5
*/
public abstract Type getType();
/**
* Returns the set of attributes.
*
* @return the set of attributes.
* @since 0.5
*/
public abstract Map<String, AttributeValue> getAttributes();
Link() {}
}
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