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Adding B3 propagator (#523)
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‎api/include/opentelemetry/nostd/string_view.h

+14
Original file line numberDiff line numberDiff line change
@@ -120,6 +120,20 @@ class string_view
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return substr(pos1, count1).compare(string_view(s, count2));
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};
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size_type find(char ch, size_type pos = 0) const noexcept
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{
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size_type res = npos;
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if (pos < length())
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{
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auto found = Traits::find(data() + pos, length() - pos, ch);
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if (found)
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{
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res = found - data();
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}
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}
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return res;
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}
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bool operator<(const string_view v) const noexcept { return compare(v) < 0; }
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bool operator>(const string_view v) const noexcept { return compare(v) > 0; }

‎api/include/opentelemetry/trace/propagation/b3_propagator.h

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,273 @@
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#pragma once
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#include <array>
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#include <iostream>
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#include <map>
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#include <string>
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#include "opentelemetry/common/key_value_iterable.h"
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#include "opentelemetry/context/context.h"
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#include "opentelemetry/nostd/shared_ptr.h"
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#include "opentelemetry/nostd/span.h"
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#include "opentelemetry/nostd/string_view.h"
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#include "opentelemetry/nostd/variant.h"
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#include "opentelemetry/trace/default_span.h"
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#include "opentelemetry/trace/propagation/http_text_format.h"
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#include "opentelemetry/trace/span.h"
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#include "opentelemetry/trace/span_context.h"
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OPENTELEMETRY_BEGIN_NAMESPACE
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namespace trace
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{
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namespace propagation
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{
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static const nostd::string_view kB3CombinedHeader = "b3";
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static const nostd::string_view kB3TraceIdHeader = "X-B3-TraceId";
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static const nostd::string_view kB3SpanIdHeader = "X-B3-SpanId";
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static const nostd::string_view kB3SampledHeader = "X-B3-Sampled";
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/*
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B3, single header:
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b3: 80f198ee56343ba864fe8b2a57d3eff7-e457b5a2e4d86bd1-1-05e3ac9a4f6e3b90
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^ ^ ^^^^^^^^^^^^^^^^
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0 TraceId 31 33 SpanId 48 | 52 ParentSpanId 68
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50 Debug flag
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Multiheader version: X-B3-Sampled
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X-B3-TraceId X-B3-SpanId X-B3-ParentSpanId (ignored)
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*/
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static const int kTraceIdHexStrLength = 32;
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static const int kSpanIdHexStrLength = 16;
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static const int kTraceFlagHexStrLength = 1;
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// The B3PropagatorExtractor class provides an interface that enables extracting context from
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// headers of HTTP requests. HTTP frameworks and clients can integrate with B3Propagator by
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// providing the object containing the headers, and a getter function for the extraction. Based on:
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// https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/context/api-propagators.md#b3-extract
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template <typename T>
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class B3PropagatorExtractor : public HTTPTextFormat<T>
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{
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public:
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// Rules that manages how context will be extracted from carrier.
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using Getter = nostd::string_view (*)(const T &carrier, nostd::string_view trace_type);
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// Returns the context that is stored in the HTTP header carrier with the getter as extractor.
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context::Context Extract(Getter getter,
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const T &carrier,
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context::Context &context) noexcept override
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{
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SpanContext span_context = ExtractImpl(getter, carrier);
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nostd::shared_ptr<Span> sp{new DefaultSpan(span_context)};
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return context.SetValue(kSpanKey, sp);
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}
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static SpanContext GetCurrentSpan(const context::Context &context)
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{
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context::Context ctx(context);
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context::ContextValue span = ctx.GetValue(kSpanKey);
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if (nostd::holds_alternative<nostd::shared_ptr<Span>>(span))
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{
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return nostd::get<nostd::shared_ptr<Span>>(span).get()->GetContext();
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}
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return SpanContext::GetInvalid();
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}
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static TraceId GenerateTraceIdFromString(nostd::string_view trace_id)
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{
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uint8_t buf[kTraceIdHexStrLength / 2];
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GenerateBuffFromHexStrPad0(trace_id, sizeof(buf), buf);
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return TraceId(buf);
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}
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static SpanId GenerateSpanIdFromString(nostd::string_view span_id)
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{
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uint8_t buf[kSpanIdHexStrLength / 2];
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GenerateBuffFromHexStrPad0(span_id, sizeof(buf), buf);
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return SpanId(buf);
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}
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static TraceFlags GenerateTraceFlagsFromString(nostd::string_view trace_flags)
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{
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if (trace_flags.length() != 1 || (trace_flags[0] != '1' && trace_flags[0] != 'd'))
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{ // check for invalid length of flags and treat 'd' as sampled
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return TraceFlags(0);
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}
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return TraceFlags(TraceFlags::kIsSampled);
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}
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private:
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// Converts hex numbers (string_view) into bytes stored in a buffer and pads buffer with 0.
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static void GenerateBuffFromHexStrPad0(nostd::string_view hexStr, int bufSize, uint8_t *buf)
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{ // we are doing this starting from "right" side for left-padding
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nostd::string_view::size_type posInp = hexStr.length();
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int posOut = bufSize;
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while (posOut--)
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{
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int val = 0;
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if (posInp)
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{
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int hexDigit2 = HexToInt(hexStr[--posInp]); // low nibble
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int hexDigit1 = 0;
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if (posInp)
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{
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hexDigit1 = HexToInt(hexStr[--posInp]);
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}
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if (hexDigit1 < 0 || hexDigit2 < 0)
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{ // malformed hex sequence. Fill entire buffer with zeroes.
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for (int j = 0; j < bufSize; j++)
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{
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buf[j] = 0;
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}
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return;
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}
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val = hexDigit1 * 16 + hexDigit2;
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}
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buf[posOut] = val;
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}
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}
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// Converts a single character to a corresponding integer (e.g. '1' to 1), return -1
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// if the character is not a valid number in hex.
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static int8_t HexToInt(char c)
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{
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if (c >= '0' && c <= '9')
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{
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return (int8_t)(c - '0');
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}
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else if (c >= 'a' && c <= 'f')
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{
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return (int8_t)(c - 'a' + 10);
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}
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else if (c >= 'A' && c <= 'F')
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{
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return (int8_t)(c - 'A' + 10);
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}
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else
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{
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return -1;
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}
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}
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static SpanContext ExtractImpl(Getter getter, const T &carrier)
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{
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// all these are hex values
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nostd::string_view trace_id;
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nostd::string_view span_id;
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nostd::string_view trace_flags;
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// first let's try a single-header variant
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auto singleB3Header = getter(carrier, kB3CombinedHeader);
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if (!singleB3Header.empty())
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{
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// From: https://github.com/openzipkin/b3-propagation/blob/master/RATIONALE.md
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// trace_id can be 16 or 32 chars
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auto firstSep = singleB3Header.find('-');
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trace_id = singleB3Header.substr(0, firstSep);
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if (firstSep != nostd::string_view::npos)
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{ // at least two fields are required
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auto secondSep = singleB3Header.find('-', firstSep + 1);
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if (secondSep != nostd::string_view::npos)
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{ // more than two fields - check also trace_flags
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span_id = singleB3Header.substr(firstSep + 1, secondSep - firstSep - 1);
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if (secondSep + 1 < singleB3Header.size())
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{
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trace_flags = singleB3Header.substr(secondSep + 1, kTraceFlagHexStrLength);
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}
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}
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else
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{
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span_id = singleB3Header.substr(firstSep + 1);
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}
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}
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}
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else
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{
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trace_id = getter(carrier, kB3TraceIdHeader);
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span_id = getter(carrier, kB3SpanIdHeader);
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trace_flags = getter(carrier, kB3SampledHeader);
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}
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// now convert hex to objects
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TraceId trace_id_obj = GenerateTraceIdFromString(trace_id);
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SpanId span_id_obj = GenerateSpanIdFromString(span_id);
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if (!trace_id_obj.IsValid() || !span_id_obj.IsValid())
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{
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return SpanContext(false, false);
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}
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TraceFlags trace_flags_obj = GenerateTraceFlagsFromString(trace_flags);
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return SpanContext(trace_id_obj, span_id_obj, trace_flags_obj, true);
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}
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};
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// The B3Propagator class provides interface that enables extracting and injecting context into
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// single header of HTTP Request.
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template <typename T>
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class B3Propagator : public B3PropagatorExtractor<T>
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{
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public:
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// Rules that manages how context will be injected to carrier.
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using Setter = void (*)(T &carrier,
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nostd::string_view trace_type,
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nostd::string_view trace_description);
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// Sets the context for a HTTP header carrier with self defined rules.
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void Inject(Setter setter, T &carrier, const context::Context &context) noexcept override
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{
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SpanContext span_context = B3PropagatorExtractor<T>::GetCurrentSpan(context);
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if (!span_context.IsValid())
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{
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return;
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}
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char trace_id[kTraceIdHexStrLength];
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TraceId(span_context.trace_id()).ToLowerBase16(trace_id);
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char span_id[kSpanIdHexStrLength];
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SpanId(span_context.span_id()).ToLowerBase16(span_id);
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char trace_flags[2];
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TraceFlags(span_context.trace_flags()).ToLowerBase16(trace_flags);
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// Note: This is only temporary replacement for appendable string
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std::string hex_string = "";
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for (int i = 0; i < 32; i++)
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{
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hex_string.push_back(trace_id[i]);
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}
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hex_string.push_back('-');
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for (int i = 0; i < 16; i++)
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{
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hex_string.push_back(span_id[i]);
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}
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hex_string.push_back('-');
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hex_string.push_back(trace_flags[1]);
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setter(carrier, kB3CombinedHeader, hex_string);
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}
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};
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template <typename T>
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class B3PropagatorMultiHeader : public B3PropagatorExtractor<T>
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{
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public:
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// Rules that manages how context will be injected to carrier.
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using Setter = void (*)(T &carrier,
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nostd::string_view trace_type,
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nostd::string_view trace_description);
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void Inject(Setter setter, T &carrier, const context::Context &context) noexcept override
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{
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SpanContext span_context = B3PropagatorExtractor<T>::GetCurrentSpan(context);
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if (!span_context.IsValid())
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{
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return;
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}
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char trace_id[32];
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TraceId(span_context.trace_id()).ToLowerBase16(trace_id);
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char span_id[16];
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SpanId(span_context.span_id()).ToLowerBase16(span_id);
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char trace_flags[2];
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TraceFlags(span_context.trace_flags()).ToLowerBase16(trace_flags);
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setter(carrier, kB3TraceIdHeader, nostd::string_view(trace_id, sizeof(trace_id)));
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setter(carrier, kB3SpanIdHeader, nostd::string_view(span_id, sizeof(span_id)));
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setter(carrier, kB3SampledHeader, nostd::string_view(trace_flags + 1, 1));
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}
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};
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} // namespace propagation
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} // namespace trace
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OPENTELEMETRY_END_NAMESPACE

‎api/test/nostd/string_view_test.cc

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@@ -75,6 +75,24 @@ TEST(StringViewTest, SubstrOutOfRange)
7575
#endif
7676
}
7777

78+
TEST(StringViewTest, FindSingleCharacter)
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{
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string_view s = "abc";
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// starting from 0-th position (default)
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EXPECT_EQ(s.find('a'), 0);
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EXPECT_EQ(s.find('b'), 1);
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EXPECT_EQ(s.find('c'), 2);
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EXPECT_EQ(s.find('d'), -1); // FIXME: string_view:npos - problem with linker
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// starting from given index
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EXPECT_EQ(s.find('a', 1), -1);
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EXPECT_EQ(s.find('b', 1), 1);
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// out of index
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EXPECT_EQ(s.find('a', 10), -1);
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}
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7896
TEST(StringViewTest, Compare)
7997
{
8098
string_view s1 = "aaa";

‎api/test/trace/propagation/CMakeLists.txt

+1-1
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@@ -1,4 +1,4 @@
1-
foreach(testname http_text_format_test)
1+
foreach(testname http_text_format_test b3_propagation_test)
22
add_executable(${testname} "${testname}.cc")
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target_link_libraries(
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${testname} ${GTEST_BOTH_LIBRARIES} ${CORE_RUNTIME_LIBS}

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