ceph/src/jaegertracing/opentelemetry-cpp/api/include/opentelemetry/context/propagation/composite_propagator.h

   1 // Copyright The OpenTelemetry Authors
   2 // SPDX-License-Identifier: Apache-2.0
   3
   4 #pragma once
   5
   6 #include <initializer_list>
   7 #include <memory>
   8 #include <vector>
   9 #include "opentelemetry/context/propagation/text_map_propagator.h"
  10
  11 OPENTELEMETRY_BEGIN_NAMESPACE
  12 namespace context
  13 {
  14 namespace propagation
  15 {
  16
  17 class CompositePropagator : public TextMapPropagator
  18 {
  19 public:
  20   CompositePropagator(std::vector<std::unique_ptr<TextMapPropagator>> propagators)
  21       : propagators_(std::move(propagators))
  22   {}
  23
  24   /**
  25    * Run each of the configured propagators with the given context and carrier.
  26    * Propagators are run in the order they are configured, so if multiple
  27    * propagators write the same carrier key, the propagator later in the list
  28    * will "win".
  29    *
  30    * @param carrier Carrier into which context will be injected
  31    * @param context Context to inject
  32    *
  33    */
  34
  35   void Inject(TextMapCarrier &carrier, const context::Context &context) noexcept override
  36   {
  37     for (auto &p : propagators_)
  38     {
  39       p->Inject(carrier, context);
  40     }
  41   }
  42
  43   /**
  44    * Run each of the configured propagators with the given context and carrier.
  45    * Propagators are run in the order they are configured, so if multiple
  46    * propagators write the same context key, the propagator later in the list
  47    * will "win".
  48    *
  49    * @param carrier Carrier from which to extract context
  50    * @param context Context to add values to
  51    */
  52   context::Context Extract(const TextMapCarrier &carrier,
  53                            context::Context &context) noexcept override
  54   {
  55     auto first = true;
  56     context::Context tmp_context;
  57     for (auto &p : propagators_)
  58     {
  59       if (first)
  60       {
  61         tmp_context = p->Extract(carrier, context);
  62         first       = false;
  63       }
  64       else
  65       {
  66         tmp_context = p->Extract(carrier, tmp_context);
  67       }
  68     }
  69     return propagators_.size() ? tmp_context : context;
  70   }
  71
  72   /**
  73    * Invoke callback with  fields set to carrier by `inject` method for all the
  74    * configured propagators
  75    * Returns true if all invocation return true
  76    */
  77   bool Fields(nostd::function_ref<bool(nostd::string_view)> callback) const noexcept override
  78   {
  79     bool status = true;
  80     for (auto &p : propagators_)
  81     {
  82       status = status && p->Fields(callback);
  83     }
  84     return status;
  85   }
  86
  87 private:
  88   std::vector<std::unique_ptr<TextMapPropagator>> propagators_;
  89 };
  90 }  // namespace propagation
  91 }  // namespace context
  92 OPENTELEMETRY_END_NAMESPACE;