/
B3Propagator.ts
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/
B3Propagator.ts
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/*
* Copyright The OpenTelemetry 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
*
* https://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.
*/
import {
Context,
TextMapGetter,
TextMapPropagator,
TextMapSetter,
} from '@opentelemetry/api';
import { isTracingSuppressed } from '@opentelemetry/core';
import { B3MultiPropagator } from './B3MultiPropagator';
import { B3SinglePropagator } from './B3SinglePropagator';
import { B3_CONTEXT_HEADER } from './constants';
import { B3InjectEncoding, B3PropagatorConfig } from './types';
/**
* Propagator that extracts B3 context in both single and multi-header variants,
* with configurable injection format defaulting to B3 single-header. Due to
* the asymmetry in injection and extraction formats this is not suitable to
* be implemented as a composite propagator.
* Based on: https://github.com/openzipkin/b3-propagation
*/
export class B3Propagator implements TextMapPropagator {
private readonly _b3MultiPropagator: B3MultiPropagator = new B3MultiPropagator();
private readonly _b3SinglePropagator: B3SinglePropagator = new B3SinglePropagator();
private readonly _inject: (
context: Context,
carrier: unknown,
setter: TextMapSetter
) => void;
public readonly _fields: string[];
constructor(config: B3PropagatorConfig = {}) {
if (config.injectEncoding === B3InjectEncoding.MULTI_HEADER) {
this._inject = this._b3MultiPropagator.inject;
this._fields = this._b3MultiPropagator.fields();
} else {
this._inject = this._b3SinglePropagator.inject;
this._fields = this._b3SinglePropagator.fields();
}
}
inject(context: Context, carrier: unknown, setter: TextMapSetter) {
if (isTracingSuppressed(context)) {
return;
}
this._inject(context, carrier, setter);
}
extract(context: Context, carrier: unknown, getter: TextMapGetter): Context {
const header = getter.get(carrier, B3_CONTEXT_HEADER);
const b3Context = Array.isArray(header) ? header[0] : header;
if (b3Context) {
return this._b3SinglePropagator.extract(context, carrier, getter);
} else {
return this._b3MultiPropagator.extract(context, carrier, getter);
}
}
fields(): string[] {
return this._fields;
}
}