Program Listing for File text_map_propagator.h¶
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#pragma once
#include <cstdint>
#include "opentelemetry/context/context.h"
#include "opentelemetry/nostd/string_view.h"
#include "opentelemetry/version.h"
OPENTELEMETRY_BEGIN_NAMESPACE
namespace trace
{
namespace propagation
{
// The TextMapPropagator class provides an interface that enables extracting and injecting
// context into carriers that travel in-band across process boundaries. HTTP frameworks and clients
// can integrate with TextMapPropagator by providing the object containing the
// headers, and a getter and setter function for the extraction and
// injection of values, respectively.
template <typename T>
class TextMapPropagator
{
public:
// Rules that manages how context will be extracted from carrier.
using Getter = nostd::string_view (*)(const T &carrier, nostd::string_view trace_type);
// Rules that manages how context will be injected to carrier.
using Setter = void (*)(T &carrier,
nostd::string_view trace_type,
nostd::string_view trace_description);
// Returns the context that is stored in the carrier with the getter as extractor.
virtual context::Context Extract(Getter get_from_carrier,
const T &carrier,
context::Context &context) noexcept = 0;
// Sets the context for carrier with self defined rules.
virtual void Inject(Setter set_from_carrier,
T &carrier,
const context::Context &context) noexcept = 0;
};
} // namespace propagation
} // namespace trace
OPENTELEMETRY_END_NAMESPACE