Make it easier to disable process executor

By adding a DISALLOW_PROCESS_EXECUTOR build option it's possible
to conveniently disable the usage of fork() on non-Window platforms
that either don't have fork(), or have an incomplete or inefficient
implementation that is to be considered a last resort only. In the
same commit the DISALLOW_THREAD_EXECUTOR is used for conditionally
compiling the thread executor so that both executors are treated in
the same way.

Author: sodero

cli/processexecutor.cpp

@@ -22,7 +22,7 @@
 
 #include "processexecutor.h"
 
-#if !defined(WIN32) && !defined(__MINGW32__)
+#if !defined(DISALLOW_PROCESS_EXECUTOR) && !defined(WIN32) && !defined(__MINGW32__)
 
 #include "cppcheck.h"
 #include "errorlogger.h"
@@ -471,4 +471,4 @@ void ProcessExecutor::reportInternalChildErr(const std::string &childname, const
         mErrorLogger.reportErr(errmsg);
 }
 
-#endif // !WIN32
+#endif // !DISALLOW_PROCESS_EXECUTOR && !WIN32 && !__MINGW32__

cli/threadexecutor.cpp

@@ -18,6 +18,8 @@
 
 #include "threadexecutor.h"
 
+#if !defined(DISALLOW_THREAD_EXECUTOR)
+
 #include "config.h"
 #include "cppcheck.h"
 #include "errorlogger.h"
@@ -219,3 +221,5 @@ unsigned int ThreadExecutor::check()
 
     return result;
 }
+
+#endif // !DISALLOW_THREAD_EXECUTOR

cmake/compilerDefinitions.cmake

@@ -52,6 +52,10 @@ if(DISALLOW_THREAD_EXECUTOR)
     add_definitions(-DDISALLOW_THREAD_EXECUTOR)
 endif()
 
+if(DISALLOW_PROCESS_EXECUTOR)
+    add_definitions(-DDISALLOW_PROCESS_EXECUTOR)
+endif()
+
 if(MSVC AND DISABLE_CRTDBG_MAP_ALLOC)
     add_definitions(-DDISABLE_CRTDBG_MAP_ALLOC)
 endif()

cmake/options.cmake

@@ -92,6 +92,10 @@ option(DISALLOW_THREAD_EXECUTOR "Disallow usage of ThreadExecutor for -j"
 if(DISALLOW_THREAD_EXECUTOR AND WIN32)
     message(FATAL_ERROR "Cannot disable usage of ThreadExecutor on Windows as no other executor implementation is currently available")
 endif()
+option(DISALLOW_PROCESS_EXECUTOR "Disallow usage of ProcessExecutor for -j"                   OFF)
+if(DISALLOW_THREAD_EXECUTOR AND DISALLOW_PROCESS_EXECUTOR)
+    message(FATAL_ERROR "Cannot disable both ThreadExecutor and ProcessExecutor")
+endif()
 set(USE_BOOST "Auto" CACHE STRING "Usage of Boost")
 set_property(CACHE USE_BOOST PROPERTY STRINGS Auto Off On)
 option(USE_BOOST_INT128     "Usage of Boost.Multiprecision 128-bit integer for Mathlib"     OFF)

cmake/printInfo.cmake

@@ -78,6 +78,7 @@ if(HAVE_RULES)
 endif()
 message(STATUS)
 message(STATUS "DISALLOW_THREAD_EXECUTOR = ${DISALLOW_THREAD_EXECUTOR}")
+message(STATUS "DISALLOW_PROCESS_EXECUTOR = ${DISALLOW_PROCESS_EXECUTOR}")
 message(STATUS "CMAKE_THREAD_LIBS_INIT = ${CMAKE_THREAD_LIBS_INIT}")
 message(STATUS)
 message(STATUS "USE_BUNDLED_TINYXML2 =  ${USE_BUNDLED_TINYXML2}")

lib/config.h

@@ -164,12 +164,16 @@ static const std::string emptyString;
 #define HAS_THREADING_MODEL_THREAD
 #define STDCALL __stdcall
 #elif ((defined(__GNUC__) || defined(__sun)) && !defined(__MINGW32__)) || defined(__CPPCHECK__)
+#if !defined(DISALLOW_PROCESS_EXECUTOR)
 #define HAS_THREADING_MODEL_FORK
+#endif
 #if !defined(DISALLOW_THREAD_EXECUTOR)
 #define HAS_THREADING_MODEL_THREAD
 #endif
 #define STDCALL
-#else
+#endif
+
+#if !defined(HAS_THREADING_MODEL_FORK) && !defined(HAS_THREADING_MODEL_THREAD)
 #error "No threading model defined"
 #endif