brave.propagation.tracecontext.TraceContextInjector Maven / Gradle / Ivy

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/*
 * Copyright 2020 The OpenZipkin 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 brave.propagation.tracecontext;

import brave.propagation.B3SingleFormat;
import brave.propagation.Propagation.Setter;
import brave.propagation.TraceContext;
import brave.propagation.TraceContext.Injector;

import static brave.propagation.tracecontext.TraceContextPropagation.TRACEPARENT;
import static brave.propagation.tracecontext.TraceContextPropagation.TRACESTATE;

final class TraceContextInjector implements Injector {
  final Setter setter;
  final TraceparentFormat traceparentFormat;
  final String tracestateKey;

  TraceContextInjector(TraceContextPropagation propagation, Setter setter) {
    this.setter = setter;
    this.traceparentFormat = propagation.traceparentFormat;
    this.tracestateKey = propagation.tracestateKey;
  }

  @Override public void inject(TraceContext context, R request) {
    setter.put(request, TRACEPARENT, traceparentFormat.write(context));
    Tracestate tracestate = context.findExtra(Tracestate.class);

    // TODO: char buffer to reduce allocations in tracestate.stateString
    String b3 = B3SingleFormat.writeB3SingleFormat(context);
    if (tracestate != null) {
      setter.put(request, TRACESTATE, tracestate.stateString(tracestateKey, b3));
    } else {
      setter.put(request, TRACESTATE, tracestateKey + "=" + b3);
    }
  }
}