Release v0.3.2: Fix ODR violation in profiling

Author: networmix

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.3.2] - 2025-12-12
+
+### Fixed
+
+- **Profiling**: Fix ODR violation that caused empty stats when profiling was enabled. Moved `profiling_enabled()` and `ProfilingStats::instance()` definitions from inline header to `profiling.cpp` to ensure a single instance when static library is linked into the Python module.
+
 ## [0.3.1] - 2025-12-08
 
 ### Added

CMakeLists.txt

@@ -79,6 +79,7 @@ add_library(netgraph_core STATIC
   src/flow_graph.cpp
   src/flow_policy.cpp
   src/cpu_backend.cpp
+  src/profiling.cpp
 )
 target_include_directories(netgraph_core PUBLIC
   $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>

include/netgraph/core/profiling.hpp

@@ -24,7 +24,6 @@ From Python:
 
 #include <chrono>
 #include <cstdint>
-#include <cstdlib>
 #include <iostream>
 #include <mutex>
 #include <string>
@@ -33,21 +32,14 @@ From Python:
 namespace netgraph::core {
 
 // Check once at startup, cache result. Returns true if NGRAPH_CORE_PROFILE=1.
-inline bool profiling_enabled() noexcept {
-    static const bool enabled = [] {
-        const char* env = std::getenv("NGRAPH_CORE_PROFILE");
-        return env && env[0] == '1';
-    }();
-    return enabled;
-}
+// Defined in profiling.cpp to avoid ODR violations with static library linking.
+bool profiling_enabled() noexcept;
 
 // Singleton collecting profiling statistics.
 class ProfilingStats {
 public:
-    static ProfilingStats& instance() {
-        static ProfilingStats inst;
-        return inst;
-    }
+    // Defined in profiling.cpp to avoid ODR violations with static library linking.
+    static ProfilingStats& instance();
 
     void record(const char* name, double micros) {
         std::lock_guard<std::mutex> lock(mutex_);

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "scikit_build_core.build"
 
 [project]
 name = "netgraph-core"
-version = "0.3.1"
+version = "0.3.2"
 description = "C++ implementation of graph algorithms for network flow analysis and traffic engineering with Python bindings"
 readme = "README.md"
 requires-python = ">=3.11"

python/netgraph_core/_version.py

@@ -2,4 +2,4 @@
 
 __all__ = ["__version__"]
 
-__version__ = "0.3.1"
+__version__ = "0.3.2"

src/profiling.cpp

@@ -0,0 +1,29 @@
+/*
+  Profiling implementation - singleton definitions.
+
+  These are defined in a .cpp file (not inline in the header) to avoid ODR
+  violations when linking a static library into a shared library (Python module).
+  With inline definitions, separate static variable instances can exist in each
+  translation unit, causing profiling data to be recorded in one instance while
+  being read from another.
+*/
+#include "netgraph/core/profiling.hpp"
+
+#include <cstdlib>
+
+namespace netgraph::core {
+
+bool profiling_enabled() noexcept {
+    static const bool enabled = [] {
+        const char* env = std::getenv("NGRAPH_CORE_PROFILE");
+        return env && env[0] == '1';
+    }();
+    return enabled;
+}
+
+ProfilingStats& ProfilingStats::instance() {
+    static ProfilingStats inst;
+    return inst;
+}
+
+} // namespace netgraph::core