modern-trace

modern-trace is the shared C++23 trace contract for the modern_* repositories. It owns the reusable tracing surface that should not live in a domain package: W3C traceparent parsing/formatting, the shared TraceContext, PMR-aware in-memory buffering, fixed-size drain queues, logger fan-in, and background-drain coordination.

What Lives Here

• modern.trace: umbrella module for the trace contract
• modern::trace::TraceContext: shared value type for runtime and domain boundaries
• parse_traceparent() / format_traceparent(): W3C wire-format conversion
• InMemoryTraceBuffer, SpscTraceDrainQueue, TraceLogger, TraceLoggerFanIn
• TraceDrainSignal, TraceDrainPump, TraceBackgroundDrainController

modern_trace intentionally does not own schedulers, threads, timers, or domain-specific networking/file abstractions. Those stay in modern_runtime and higher-level repos.

Build

cmake -S . -B build -G Ninja -DCMAKE_CXX_COMPILER=clang++
cmake --build build
ctest --test-dir build --output-on-failure

Requirements:

• CMake 3.28+
• C++23 compiler with module support
• Clang + Ninja is the primary validated path

Consume It

Build-tree use:

add_subdirectory(modern_trace)
target_link_libraries(my_app PRIVATE modern_trace::modern_trace)

Installed package use:

find_package(modern_trace CONFIG REQUIRED)
target_link_libraries(my_app PRIVATE modern_trace::modern_trace)

Import the module you need:

import modern.trace;