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Fix endianness of Jaeger IDs for transmission #832

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merged 4 commits into from
Jun 10, 2021
Merged

Fix endianness of Jaeger IDs for transmission #832

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1923f05
Fix endianess of Jaeger IDs for transmission
ThomsonTan Jun 7, 2021
2965d0b
Fix naming conflict
ThomsonTan Jun 7, 2021
b89ca2c
Merge branch 'main' into FixJaegerIds
lalitb Jun 8, 2021
dfe421b
Merge branch 'main' into FixJaegerIds
lalitb Jun 10, 2021
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34 changes: 34 additions & 0 deletions exporters/jaeger/include/opentelemetry/exporters/jaeger/recordable.h
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Original file line number Diff line number Diff line change
Expand Up @@ -7,12 +7,46 @@
#include <opentelemetry/sdk/trace/recordable.h>
#include <opentelemetry/version.h>

#if (defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && \
__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)
# define JAEGER_IS_LITTLE_ENDIAN 1
#elif defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && \
__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
# define JAEGER_IS_LITTLE_ENDIAN 0
#elif defined(_WIN32)
# define JAEGER_IS_LITTLE_ENDIAN 1
#else
# error "Endian detection needs to be set up for your compiler"
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@lalitb lalitb Jun 8, 2021 •
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how about using run-time determination if it's not set by compiler, something like:

    const int value { 0x01 };
    bool isLittleEndian = ( *(static_cast<const unsigned char *>(static_cast<const void *>(&value))) == 0x01);

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I'd like to avoid the runtime check as it is a static property known at compile time. I think our current definition should cover most real cases if not all.

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For a reference implementation see https://github.com/abseil/abseil-cpp/blob/master/absl/base/internal/endian.h I think you can use that code (not directly if avoiding dependency is needed) but is a good implementation.

#endif

OPENTELEMETRY_BEGIN_NAMESPACE
namespace exporter
{
namespace jaeger
{

#if JAEGER_IS_LITTLE_ENDIAN == 1

# if defined(__clang__) || \
(defined(__GNUC__) && ((__GNUC__ == 4 && __GNUC_MINOR__ >= 8) || __GNUC__ >= 5))
inline uint64_t bswap_64(uint64_t host_int)
{
return __builtin_bswap64(host_int);
}

# elif defined(_MSC_VER)
inline uint64_t bswap_64(uint64_t host_int)
{
return _byteswap_uint64(host_int);
}

# else
# error "Port need to support endianess conversion"

# endif

#endif

using namespace jaegertracing;

class Recordable final : public sdk::trace::Recordable
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13 changes: 13 additions & 0 deletions exporters/jaeger/src/recordable.cc
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Expand Up @@ -39,12 +39,25 @@ void Recordable::PopulateAttribute(nostd::string_view key, const common::Attribu
void Recordable::SetIdentity(const trace::SpanContext &span_context,
trace::SpanId parent_span_id) noexcept
{
// IDs should be converted to big endian before transmission.
// https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/sdk_exporters/jaeger.md#ids
#if JAEGER_IS_LITTLE_ENDIAN == 1
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I'm wondering if this is something that should be handled by htons?

https://docs.microsoft.com/en-us/windows/win32/api/winsock/nf-winsock-htons
https://linux.die.net/man/3/htons

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Or, to be more precise, something like this?

#define htonll(x) ((1==htonl(1)) ? (x) : ((uint64_t)htonl((x) & 0xFFFFFFFF) << 32) | htonl((x) >> 32))
#define ntohll(x) ((1==ntohl(1)) ? (x) : ((uint64_t)ntohl((x) & 0xFFFFFFFF) << 32) | ntohl((x) >> 32))

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@lalitb lalitb Jun 8, 2021 •
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nicely done. this will check the endianness too before performing conversion

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Thanks. I considered htonl as the first option, but I'd like to avoid the runtime check on endianness and preferred the compiler intrinsic to perform byte order swap for simplicity and slight perf win.

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I could change the function name to to_big_endian and define it as as direct return for big endian host. In this way, we don't need check the endianness at callsite of this function.

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Second thought, leave the JAEGER_IS_LITTLE_ENDIAN in the callsite could save us to create bswap_128.

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I was wondering if it's something you can move into a separate static inline utility function, then it can be reused elsewhere? I think it might be common requirement, to transmit the buffer in big endian, not unique to Jaeger?

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So far I only saw the requirement in Jaeger. I'd be happen to move this to common utility if it is used in other places.

span_->__set_traceIdHigh(
bswap_64(*(reinterpret_cast<const int64_t *>(span_context.trace_id().Id().data()))));
span_->__set_traceIdLow(
bswap_64(*(reinterpret_cast<const int64_t *>(span_context.trace_id().Id().data()) + 1)));
span_->__set_spanId(
bswap_64(*(reinterpret_cast<const int64_t *>(span_context.span_id().Id().data()))));
span_->__set_parentSpanId(
bswap_64(*(reinterpret_cast<const int64_t *>(parent_span_id.Id().data()))));
#else
span_->__set_traceIdLow(
*(reinterpret_cast<const int64_t *>(span_context.trace_id().Id().data())));
span_->__set_traceIdHigh(
*(reinterpret_cast<const int64_t *>(span_context.trace_id().Id().data()) + 1));
span_->__set_spanId(*(reinterpret_cast<const int64_t *>(span_context.span_id().Id().data())));
span_->__set_parentSpanId(*(reinterpret_cast<const int64_t *>(parent_span_id.Id().data())));
#endif

// TODO: set trace_state.
}
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8 changes: 8 additions & 0 deletions exporters/jaeger/test/jaeger_recordable_test.cc
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Expand Up @@ -14,6 +14,7 @@ namespace nostd = opentelemetry::nostd;
namespace sdktrace = opentelemetry::sdk::trace;

using namespace jaegertracing;
using namespace opentelemetry::exporter::jaeger;

TEST(JaegerSpanRecordable, SetIdentity)
{
Expand All @@ -39,10 +40,17 @@ TEST(JaegerSpanRecordable, SetIdentity)

std::unique_ptr<thrift::Span> span{rec.Span()};

#if JAEGER_IS_LITTLE_ENDIAN == 1
EXPECT_EQ(span->traceIdLow, opentelemetry::exporter::jaeger::bswap_64(trace_id_val[1]));
EXPECT_EQ(span->traceIdHigh, opentelemetry::exporter::jaeger::bswap_64(trace_id_val[0]));
EXPECT_EQ(span->spanId, opentelemetry::exporter::jaeger::bswap_64(span_id_val));
EXPECT_EQ(span->parentSpanId, opentelemetry::exporter::jaeger::bswap_64(parent_span_id_val));
#else
EXPECT_EQ(span->traceIdLow, trace_id_val[0]);
EXPECT_EQ(span->traceIdHigh, trace_id_val[1]);
EXPECT_EQ(span->spanId, span_id_val);
EXPECT_EQ(span->parentSpanId, parent_span_id_val);
#endif
}

TEST(JaegerSpanRecordable, SetName)
Expand Down