add otel instrumentation (#581)

this change adds OTEL tracing to a few places

* Top-level application lifecycle (config/init/cleanup, main loop)
* http.sys requests

it also brings some otlptrace optimizations and dynamic configuration of tracing. OTLP tracing is currently always disabled

1 files changed, 33 insertions, 8 deletions

diff --git a/src/zentelemetry/include/zentelemetry/otlptrace.h b/src/zentelemetry/include/zentelemetry/otlptrace.h
index ebecff91a..f191241ed 100644
--- a/src/zentelemetry/include/zentelemetry/otlptrace.h
+++ b/src/zentelemetry/include/zentelemetry/otlptrace.h
@@ -3,6 +3,7 @@
 #pragma once
 
 #include <zenbase/refcount.h>
+#include <zencore/memcmp.h>
 #include <zencore/uid.h>
 
 #include <span>
@@ -30,8 +31,6 @@ using AttributeList = std::span<std::pair<std::string, std::string>>;
 
 class Tracer;
 
-Tracer& GetTracer();
-
 // OLTP Span ID
 
 struct SpanId
@@ -42,8 +41,16 @@ struct SpanId
 	explicit SpanId(const std::span<const uint8_t, 8> Bytes) noexcept { std::copy(Bytes.begin(), Bytes.end(), Id); }
 	explicit SpanId(const Oid& InId) noexcept { memcpy(Id, reinterpret_cast<const uint8_t*>(InId.OidBits), sizeof Id); }
 
-	auto   operator<=>(const SpanId& Rhs) const = default;
-	inline operator bool() const { return *this != SpanId(); }
+	std::strong_ordering operator<=>(const SpanId& Rhs) const noexcept
+	{
+		int cmp = MemCmpFixed<kSize>(Id, Rhs.Id);
+		if (cmp < 0)
+			return std::strong_ordering::less;
+		if (cmp > 0)
+			return std::strong_ordering::greater;
+		return std::strong_ordering::equal;
+	}
+	inline operator bool() const { return *reinterpret_cast<const uint64_t*>(Id) != 0; }
 
 	static SpanId NewSpanId();
 
@@ -64,8 +71,19 @@ struct TraceId
 	inline TraceId() noexcept : Id{0} {}
 	explicit TraceId(const std::span<const uint8_t, kSize> Bytes) noexcept { std::copy(Bytes.begin(), Bytes.end(), Id); }
 
-	auto   operator<=>(const TraceId& Rhs) const = default;
-	inline operator bool() const { return *this != TraceId(); }
+	std::strong_ordering operator<=>(const TraceId& Rhs) const noexcept
+	{
+		int cmp = MemCmpFixed<kSize>(Id, Rhs.Id);
+		if (cmp < 0)
+			return std::strong_ordering::less;
+		if (cmp > 0)
+			return std::strong_ordering::greater;
+		return std::strong_ordering::equal;
+	}
+	inline operator bool() const
+	{
+		return !(reinterpret_cast<const uint64_t*>(Id)[0] == 0 && reinterpret_cast<const uint64_t*>(Id)[1] == 0);
+	}
 
 	static TraceId NewTraceId();
 
@@ -194,7 +212,6 @@ private:
 	uint64_t	   m_StartTime = 0;
 	uint64_t	   m_EndTime   = 0;
 	Kind		   m_Kind	   = Kind::kInternal;
-	bool		   m_Ended	   = false;
 
 	Span(MemoryArena& Arena, std::string_view Name, Span* SpanChain);
 	~Span();
@@ -209,6 +226,13 @@ class ScopedSpan final
 {
 public:
 	ScopedSpan(std::string_view Name);
+	ScopedSpan(std::string_view Name, std::invocable<Span&> auto&& InitializerFunction) : ScopedSpan(Name)
+	{
+		if (m_Span)
+		{
+			InitializerFunction(*m_Span);
+		}
+	}
 	ScopedSpan() = delete;
 	~ScopedSpan();
 
@@ -217,7 +241,8 @@ public:
 	ScopedSpan(ScopedSpan&& Rhs)				 = default;
 	ScopedSpan(const ScopedSpan& Rhs)			 = default;
 
-	Span* operator->() const { return m_Span.Get(); }
+		 operator bool() const { return !!m_Span; }
+	void WithSpan(auto Func) const { Func(*m_Span); }
 
 private:
 	ScopedSpan(Span* InSpan, Tracer* InTracer);