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/*
* Copyright (c) 2016, Uber Technologies, Inc
*
* 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.jaegertracing.spi;
import io.jaegertracing.internal.JaegerSpanContext;
import io.jaegertracing.internal.propagation.B3TextMapCodec;
import io.jaegertracing.internal.propagation.TextMapCodec;
/**
* You should implement this class if you want to add possibility to extract information about
* JaegerSpanContext that is provided in your custom propagation scheme. Otherwise you should probably use
* built-in {@link TextMapCodec} or {@link B3TextMapCodec}
*
* @see B3TextMapCodec
* @see TextMapCodec
* @see Codec
*/
public interface Extractor {
/**
* Called when {@link io.opentracing.Tracer#extract(io.opentracing.propagation.Format, Object)}
* is used. It should handle the logic behind extracting propagation-scheme
* specific information from carrier (e.g. http request headers, amqp message headers, etc.).
*
* This method must not modify the carrier
*
* All exceptions thrown from this method will be caught and logged on {@code WARN} level so
* that business code execution isn't affected. If possible, catch implementation specific
* exceptions and log more meaningful information.
*
* @param carrier input that you extract Span information from, usually {@link
* io.opentracing.propagation.TextMap}.
* @return {@link JaegerSpanContext} or {@code null} if carrier doesn't contain tracing information, it
* is not valid or is incomplete
* @see B3TextMapCodec
* @see TextMapCodec
*/
JaegerSpanContext extract(T carrier);
}