RTC include directory detection. (#387)

* RTC will now attempt to auto find the include dir if variable is not set.
* CMake configure step auto generates a version file which is used for ensuring header version matches library build version.
(Might wish to make the version file generation behaviour different in future if this ends up too aggressive)
Partially addresses #253 
Co-authored-by: Peter Heywood <peethwd@gmail.com>

.gitignore

@@ -3,6 +3,9 @@
 *.json
 *.bin
 
+# dynamically generated version file
+include/flamegpu/version.h
+
 # GoogleTest directories (handled by CMake)
 googletest-build/
 googletest-download/

cmake/common.cmake

@@ -127,6 +127,11 @@ if(Jitify_FOUND)
     set(FLAMEGPU_DEPENDENCY_INCLUDE_DIRECTORIES ${FLAMEGPU_DEPENDENCY_INCLUDE_DIRECTORIES} "${Jitify_INCLUDE_DIRS}")
 endif()
 
+# If gcc, need to add linker flag for std::experimental::filesystem pre c++17
+if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+    set(FLAMEGPU_DEPENDENCY_LINK_LIBRARIES ${FLAMEGPU_DEPENDENCY_LINK_LIBRARIES} "-lstdc++fs")
+endif()
+
 # Logging for jitify compilation
 set(CMAKE_CUDA_FLAGS "${CMAKE_CUDA_FLAGS} -DJITIFY_PRINT_LOG")
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DJITIFY_PRINT_LOG")
@@ -401,6 +406,9 @@ endfunction()
 
 # Function to mask some of the flag setting for the static library
 function(add_flamegpu_library NAME SRC FLAMEGPU_ROOT)
+    # Generate version file
+    GET_COMMIT_HASH()
+
     # Define which source files are required for the target executable
     add_library(${NAME} STATIC ${SRC})
 
@@ -498,3 +506,57 @@ macro(CMAKE_SET_TARGET_FOLDER tgt folder)
     set_property(GLOBAL PROPERTY USE_FOLDERS OFF)
   endif()
 endmacro()
+
+#-----------------------------------------------------------------------
+# Generate files that act as informal version numbers
+# ${CMAKE_CURRENT_BINARY_DIR}/short_hash.txt - File only contains git short hash for use by CMake
+# ${FLAMEGPU_ROOT}/include/flamegpu/version.h - Programatically accessible version
+#
+# Based on https://cmake.org/pipermail/cmake/2018-October/068388.html
+#-----------------------------------------------------------------------
+macro(GET_COMMIT_HASH)
+# If git changes, we reconfigure
+# This is a very aggressive version
+# Might be better to simply make generation of the file a pre-build script
+# That would be cheaper than re-configure
+set_property(
+  DIRECTORY 
+  APPEND 
+  PROPERTY CMAKE_CONFIGURE_DEPENDS 
+  "${FLAMEGPU_ROOT}/.git/index"
+)
+set(SHORT_HASH_FILE ${CMAKE_CURRENT_BINARY_DIR}/short_hash.txt)
+find_package(Git)
+if(Git_FOUND)
+    execute_process(
+        COMMAND
+            ${GIT_EXECUTABLE} rev-parse --short HEAD
+        WORKING_DIRECTORY
+            ${FLAMEGPU_ROOT}
+        RESULT_VARIABLE
+            SHORT_HASH_RESULT
+        OUTPUT_VARIABLE
+            SHORT_HASH
+        OUTPUT_STRIP_TRAILING_WHITESPACE)
+else()
+    set(SHORT_HASH "GitHash") # Placeholder, though its unlikely to be required
+endif()
+
+file(WRITE ${SHORT_HASH_FILE} ${SHORT_HASH})
+# Also create version.h
+configure_file(${FLAMEGPU_ROOT}/cmake/version.h ${FLAMEGPU_ROOT}/include/flamegpu/version.h)
+
+# The trick here is to make sure short_hash.txt is listed as a byproduct
+add_custom_target(
+    git_short_hash
+    BYPRODUCTS
+        ${SHORT_HASH_FILE}
+    COMMAND
+        ${CMAKE_COMMAND}
+        "-DSHORT_HASH_FILE=${SHORT_HASH_FILE}"
+        "-P" "${CMAKE_CURRENT_LIST_FILE}"
+    COMMENT
+        "Re-checking short hash..."
+    VERBATIM
+    USES_TERMINAL)
+endmacro()

cmake/version.h

@@ -0,0 +1,15 @@
+/**${SHORT_HASH}
+ * This file is automatically generated at CMake configure time, do not modify
+ */
+#ifndef INCLUDE_FLAMEGPU_VERSION_H_
+#define INCLUDE_FLAMEGPU_VERSION_H_
+
+#include <string>
+
+namespace flamegpu_internal {
+std::string getCommitHash() {
+    return "${SHORT_HASH}";
+}
+}  // namespace flamegpu_internal
+
+#endif  // INCLUDE_FLAMEGPU_VERSION_H_

include/flamegpu/exception/FGPUException.h

@@ -411,5 +411,9 @@ DERIVED_FGPUException(ExpiredWeakPtr, "Unable to convert weak pointer to shared
  * Defines an error reported from cuda device code (agent functions and agent function conditions)
  */
 DERIVED_FGPUException(DeviceError, "Error reported from device code");
+/**
+ * Defines an error reported when versions do not match
+ */
+DERIVED_FGPUException(VersionMismatch, "Versions do not match");
 
 #endif  // INCLUDE_FLAMEGPU_EXCEPTION_FGPUEXCEPTION_H_

src/CMakeLists.txt

@@ -65,7 +65,11 @@ endif()
 
 # Specify source files for the static library
 # Can't do this automatically, as CMake wouldn't know when to regen (as CMakeLists.txt would be unchanged)
+# version.h is automatically generated so does not exist prior to configure time
 SET(SRC_INCLUDE
+    ${FLAMEGPU_ROOT}/include/flamegpu/version.h
+    ${FLAMEGPU_ROOT}/include/flamegpu/defines.h
+    ${FLAMEGPU_ROOT}/include/flamegpu/flame_api.h
     ${FLAMEGPU_ROOT}/include/flamegpu/io/statereader.h
     ${FLAMEGPU_ROOT}/include/flamegpu/io/statewriter.h
     ${FLAMEGPU_ROOT}/include/flamegpu/io/jsonReader.h
@@ -91,7 +95,6 @@ SET(SRC_INCLUDE
     ${FLAMEGPU_ROOT}/include/flamegpu/pop/AgentPopulation.h
     ${FLAMEGPU_ROOT}/include/flamegpu/pop/MemoryVector.h
     ${FLAMEGPU_ROOT}/include/flamegpu/pop/AgentStateMemory.h
-    ${FLAMEGPU_ROOT}/include/flamegpu/defines.h
     ${FLAMEGPU_ROOT}/include/flamegpu/gpu/CUDAScanCompaction.h
     ${FLAMEGPU_ROOT}/include/flamegpu/gpu/CUDAErrorChecking.h
     ${FLAMEGPU_ROOT}/include/flamegpu/gpu/CUDAMessageList.h
@@ -102,7 +105,6 @@ SET(SRC_INCLUDE
     ${FLAMEGPU_ROOT}/include/flamegpu/gpu/CUDAFatAgent.h
     ${FLAMEGPU_ROOT}/include/flamegpu/gpu/CUDAFatAgentStateList.h
     ${FLAMEGPU_ROOT}/include/flamegpu/gpu/CUDAScatter.h
-    ${FLAMEGPU_ROOT}/include/flamegpu/flame_api.h
     ${FLAMEGPU_ROOT}/include/flamegpu/sim/AgentInterface.h
     ${FLAMEGPU_ROOT}/include/flamegpu/sim/Simulation.h
     ${FLAMEGPU_ROOT}/include/flamegpu/runtime/AgentFunction.h

src/flamegpu/gpu/CUDAAgent.cu

@@ -3,6 +3,23 @@
 #include <cuda_runtime.h>
 #include <device_launch_parameters.h>
 
+#include <iostream>
+#include <fstream>
+#include <string>
+// If MSVC earlier than VS 2019
+#if defined(_MSC_VER) && _MSC_VER < 1920
+#include <filesystem>
+using std::tr2::sys::exists;
+using std::tr2::sys::path;
+#else
+// VS2019 requires this macro, as building pre c++17 cant use std::filesystem
+#define _SILENCE_EXPERIMENTAL_FILESYSTEM_DEPRECATION_WARNING
+#include <experimental/filesystem>
+using std::experimental::filesystem::v1::exists;
+using std::experimental::filesystem::v1::path;
+#endif
+
+#include "flamegpu/version.h"
 #include "flamegpu/gpu/CUDAFatAgent.h"
 #include "flamegpu/gpu/CUDAAgentStateList.h"
 #include "flamegpu/gpu/CUDAErrorChecking.h"
@@ -419,11 +436,51 @@ void CUDAAgent::clearFunctionCondition(const std::string &state) {
 
 void CUDAAgent::addInstantitateRTCFunction(jitify::JitCache &kernel_cache, const AgentFunctionData& func, bool function_condition) {
     // get header location for fgpu
-    const char* env_inc_fgp2 = std::getenv("FLAMEGPU2_INC_DIR");
-    if (!env_inc_fgp2) {
-        THROW InvalidAgentFunc("Error compiling runtime agent function ('%s'): FLAMEGPU2_INC_DIR environment variable does not exist, "
-            "in CUDAAgent::addInstantitateRTCFunction().",
-            func.name.c_str());
+    static std::string env_inc_fgp2 = std::getenv("FLAMEGPU2_INC_DIR") ? std::getenv("FLAMEGPU2_INC_DIR") : "";
+    static bool header_version_confirmed = false;
+    if (env_inc_fgp2.empty()) {
+        // Var is not set, attempt to use default arrangement
+        path test_include("");
+        // Try 5 levels of directory, to see if we can find flame_api.h
+        for (int i = 0; i < 5; ++i) {
+            path check_file = test_include;
+            check_file/= "include/flamegpu/version.h";
+            if (exists(check_file)) {
+                test_include/= "include";
+                env_inc_fgp2 = test_include.string();
+                break;
+            }
+            // Go up a level for next iteration
+            test_include/= "..";
+        }
+        if (env_inc_fgp2.empty()) {
+            THROW InvalidAgentFunc("Error compiling runtime agent function ('%s'): Unable to automatically determine include directory and FLAMEGPU2_INC_DIR environment variable does not exist, "
+                "in CUDAAgent::addInstantitateRTCFunction().",
+                func.name.c_str());
+        }
+    }
+
+    if (!header_version_confirmed) {
+        std::string fileHash;
+        // Open version.h
+        path version_file = env_inc_fgp2;
+        version_file/= "flamegpu/version.h";
+        std::ifstream vFile(version_file);
+        if (vFile.is_open()) {
+            // Read the first line
+            std::string line;
+            if (getline(vFile, line)) {
+                // If characters 3-9 match programatic hash we have success, else fail
+                fileHash = line.substr(3, 7);
+            }
+            vFile.close();
+        }
+        if (fileHash == flamegpu_internal::getCommitHash()) {
+            header_version_confirmed = true;
+        } else {
+            THROW VersionMismatch("RTC header version (%s) does not match version flamegpu2 library was built with (%s). Set the environment variable FLAMEGPU2_INC_DIR to the correct include directory.\n",
+                fileHash.c_str(), flamegpu_internal::getCommitHash().c_str());
+        }
     }
 
     // get the cuda path