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/*
* Copyright (c) 2010-2022. Axon Framework
*
* 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 org.axonframework.tracing.opentelemetry;
import io.opentelemetry.context.propagation.TextMapGetter;
import org.axonframework.messaging.Message;
import javax.annotation.Nonnull;
/**
* This {@link TextMapGetter} implementation is able to extract the parent OpenTelemetry span context from a
* {@link Message}.
*
* The trace parent is part of the message's {@link org.axonframework.messaging.MetaData}, if it was set when
* dispatching by the {@link MetadataContextSetter}. This is done using the
* {@link org.axonframework.tracing.SpanFactory#propagateContext(Message)} method for the message.
*
* @author Mitchell Herrijgers
* @since 4.6.0
*/
public class MetadataContextGetter implements TextMapGetter> {
/**
* Singleton instance of the {@link MetadataContextGetter}, used by the {@link OpenTelemetrySpanFactory}.
*/
public static final MetadataContextGetter INSTANCE = new MetadataContextGetter();
private MetadataContextGetter() {
// Should not be initialized directly, use the public static INSTANCE.
}
@Override
public Iterable keys(Message message) {
return message.getMetaData().keySet();
}
@Override
public String get(Message message, @Nonnull String key) {
if (message == null) {
return null;
}
return (String) message.getMetaData().get(key);
}
}