feat: add multi-GPU backend abstraction layer (gpu_backend)

CMakeLists.txt

@@ -1,5 +1,42 @@
 cmake_minimum_required(VERSION 3.10)
-project(MainProject VERSION 1.0)
+
+find_package(Git QUIET)
+
+if(GIT_FOUND)
+    execute_process(
+        COMMAND ${GIT_EXECUTABLE} describe --tags --long --match "v*"
+        WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+        OUTPUT_VARIABLE GIT_DESCRIBE_OUTPUT
+        ERROR_QUIET
+        OUTPUT_STRIP_TRAILING_WHITESPACE
+    )
+    if(GIT_DESCRIBE_OUTPUT MATCHES "^v([0-9]+\\.[0-9]+\\.[0-9]+)-([0-9]+)-g([0-9a-f]+)$")
+        set(GIT_VERSION "${CMAKE_MATCH_1}")
+        set(GIT_DISTANCE "${CMAKE_MATCH_2}")
+        set(GIT_HASH "${CMAKE_MATCH_3}")
+        if(GIT_DISTANCE STREQUAL "0")
+            set(DETECTED_VERSION "${GIT_VERSION}")
+        else()
+            set(DETECTED_VERSION "${GIT_VERSION}+git${GIT_HASH}")
+        endif()
+        message(STATUS "Version from git tag: ${DETECTED_VERSION}")
+    endif()
+endif()
+
+if(NOT DEFINED DETECTED_VERSION OR DETECTED_VERSION STREQUAL "")
+    set(DETECTED_VERSION "0.0.0")
+    message(WARNING "Could not detect version from git tag, using fallback: ${DETECTED_VERSION}")
+endif()
+
+# Strip +gitXXXXXXX suffix for CMake project VERSION (must be numeric X.Y.Z)
+if(DETECTED_VERSION MATCHES "^([0-9]+\\.[0-9]+\\.[0-9]+)")
+    set(NUMERIC_VERSION "${CMAKE_MATCH_1}")
+else()
+    set(NUMERIC_VERSION "0.0.0")
+endif()
+
+project(MainProject VERSION ${NUMERIC_VERSION})
+message(STATUS "Project version: ${PROJECT_VERSION} (full: ${DETECTED_VERSION})")
 
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
@@ -30,10 +67,20 @@ target_include_directories(xxhash PUBLIC
 install(FILES ${XXHASH_HEADERS} DESTINATION include)
 
 # ==================== prometheus-cpp Library ====================
-# Option to enable/disable monitoring (env FLEXKV_ENABLE_METRICS=0 or -DFLEXKV_ENABLE_MONITORING=OFF)
-set(_FLEXKV_MONITORING_DEFAULT ON)
+# Step 1: Auto-detect default from directory existence
+if(IS_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/third_party/prometheus-cpp")
+    set(_FLEXKV_MONITORING_DEFAULT ON)
+else()
+    set(_FLEXKV_MONITORING_DEFAULT OFF)
+    message(STATUS "third_party/prometheus-cpp not found, Prometheus monitoring defaults to OFF")
+endif()
+
+# Step 2: Environment variable override (FLEXKV_ENABLE_METRICS=1/0)
 if(DEFINED ENV{FLEXKV_ENABLE_METRICS})
-  if("$ENV{FLEXKV_ENABLE_METRICS}" STREQUAL "0" OR "$ENV{FLEXKV_ENABLE_METRICS}" STREQUAL "OFF"
+  if("$ENV{FLEXKV_ENABLE_METRICS}" STREQUAL "1" OR "$ENV{FLEXKV_ENABLE_METRICS}" STREQUAL "ON"
+      OR "$ENV{FLEXKV_ENABLE_METRICS}" STREQUAL "YES" OR "$ENV{FLEXKV_ENABLE_METRICS}" STREQUAL "TRUE")
+    set(_FLEXKV_MONITORING_DEFAULT ON)
+  elseif("$ENV{FLEXKV_ENABLE_METRICS}" STREQUAL "0" OR "$ENV{FLEXKV_ENABLE_METRICS}" STREQUAL "OFF"
       OR "$ENV{FLEXKV_ENABLE_METRICS}" STREQUAL "NO" OR "$ENV{FLEXKV_ENABLE_METRICS}" STREQUAL "FALSE")
     set(_FLEXKV_MONITORING_DEFAULT OFF)
   endif()