#ifndef C10_UTIL_FLAGS_H_ #define C10_UTIL_FLAGS_H_ /* Commandline flags support for C10. * * This is a portable commandline flags tool for c10, so we can optionally * choose to use gflags or a lightweight custom implementation if gflags is * not possible on a certain platform. If you have gflags installed, set the * macro C10_USE_GFLAGS will seamlessly route everything to gflags. * * To define a flag foo of type bool default to true, do the following in the * *global* namespace: * C10_DEFINE_bool(foo, true, "An example."); * * To use it in another .cc file, you can use C10_DECLARE_* as follows: * C10_DECLARE_bool(foo); * * In both cases, you can then access the flag via FLAGS_foo. * * It is recommended that you build with gflags. To learn more about the flags * usage, refer to the gflags page here: * * https://gflags.github.io/gflags/ * * Note about Python users / devs: gflags is initiated from a C++ function * ParseCommandLineFlags, and is usually done in native binaries in the main * function. As Python does not have a modifiable main function, it is usually * difficult to change the flags after Python starts. Hence, it is recommended * that one sets the default value of the flags to one that's acceptable in * general - that will allow Python to run without wrong flags. */ #include #include #include namespace c10 { /** * Sets the usage message when a commandline tool is called with "--help". */ C10_API void SetUsageMessage(const std::string& str); /** * Returns the usage message for the commandline tool set by SetUsageMessage. */ C10_API const char* UsageMessage(); /** * Parses the commandline flags. * * This command parses all the commandline arguments passed in via pargc * and argv. Once it is finished, partc and argv will contain the remaining * commandline args that c10 does not deal with. Note that following * convention, argv[0] contains the binary name and is not parsed. */ C10_API bool ParseCommandLineFlags(int* pargc, char*** pargv); /** * Checks if the commandline flags has already been passed. */ C10_API bool CommandLineFlagsHasBeenParsed(); } // namespace c10 //////////////////////////////////////////////////////////////////////////////// // Below are gflags and non-gflags specific implementations. // In general, they define the following macros for one to declare (use // C10_DECLARE) or define (use C10_DEFINE) flags: // C10_{DECLARE,DEFINE}_{int,int64,double,bool,string} //////////////////////////////////////////////////////////////////////////////// #ifdef C10_USE_GFLAGS //////////////////////////////////////////////////////////////////////////////// // Begin gflags section: most functions are basically rerouted to gflags. //////////////////////////////////////////////////////////////////////////////// #include // C10 uses hidden visibility by default. However, in gflags, it only uses // export on Windows platform (with dllexport) but not on linux/mac (with // default visibility). As a result, to ensure that we are always exporting // global variables, we will redefine the GFLAGS_DLL_DEFINE_FLAG macro if we // are building C10 as a shared library. // This has to be done after the inclusion of gflags, because some early // versions of gflags.h (e.g. 2.0 on ubuntu 14.04) directly defines the // macros, so we need to do definition after gflags is done. #ifdef GFLAGS_DLL_DEFINE_FLAG #undef GFLAGS_DLL_DEFINE_FLAG #endif // GFLAGS_DLL_DEFINE_FLAG #ifdef GFLAGS_DLL_DECLARE_FLAG #undef GFLAGS_DLL_DECLARE_FLAG #endif // GFLAGS_DLL_DECLARE_FLAG #define GFLAGS_DLL_DEFINE_FLAG C10_EXPORT #define GFLAGS_DLL_DECLARE_FLAG C10_IMPORT // gflags before 2.0 uses namespace google and after 2.1 uses namespace gflags. // Using GFLAGS_GFLAGS_H_ to capture this change. #ifndef GFLAGS_GFLAGS_H_ namespace gflags = google; #endif // GFLAGS_GFLAGS_H_ // Motivation about the gflags wrapper: // (1) We would need to make sure that the gflags version and the non-gflags // version of C10 are going to expose the same flags abstraction. One should // explicitly use FLAGS_flag_name to access the flags. // (2) For flag names, it is recommended to start with c10_ to distinguish it // from regular gflags flags. For example, do // C10_DEFINE_BOOL(c10_my_flag, true, "An example"); // to allow one to use FLAGS_c10_my_flag. // (3) Gflags has a design issue that does not properly expose the global flags, // if one builds the library with -fvisibility=hidden. The current gflags (as of // Aug 2018) only deals with the Windows case using dllexport, and not the Linux // counterparts. As a result, we will explicitly use C10_EXPORT to export the // flags defined in C10. This is done via a global reference, so the flag // itself is not duplicated - under the hood it is the same global gflags flag. #define C10_GFLAGS_DEF_WRAPPER(type, real_type, name, default_value, help_str) \ DEFINE_##type(name, default_value, help_str); #define C10_DEFINE_int(name, default_value, help_str) \ C10_GFLAGS_DEF_WRAPPER(int32, gflags::int32, name, default_value, help_str) #define C10_DEFINE_int32(name, default_value, help_str) \ C10_DEFINE_int(name, default_value, help_str) #define C10_DEFINE_int64(name, default_value, help_str) \ C10_GFLAGS_DEF_WRAPPER(int64, gflags::int64, name, default_value, help_str) #define C10_DEFINE_double(name, default_value, help_str) \ C10_GFLAGS_DEF_WRAPPER(double, double, name, default_value, help_str) #define C10_DEFINE_bool(name, default_value, help_str) \ C10_GFLAGS_DEF_WRAPPER(bool, bool, name, default_value, help_str) #define C10_DEFINE_string(name, default_value, help_str) \ C10_GFLAGS_DEF_WRAPPER(string, ::fLS::clstring, name, default_value, help_str) // DECLARE_typed_var should be used in header files and in the global namespace. #define C10_GFLAGS_DECLARE_WRAPPER(type, real_type, name) DECLARE_##type(name); #define C10_DECLARE_int(name) \ C10_GFLAGS_DECLARE_WRAPPER(int32, gflags::int32, name) #define C10_DECLARE_int32(name) C10_DECLARE_int(name) #define C10_DECLARE_int64(name) \ C10_GFLAGS_DECLARE_WRAPPER(int64, gflags::int64, name) #define C10_DECLARE_double(name) \ C10_GFLAGS_DECLARE_WRAPPER(double, double, name) #define C10_DECLARE_bool(name) C10_GFLAGS_DECLARE_WRAPPER(bool, bool, name) #define C10_DECLARE_string(name) \ C10_GFLAGS_DECLARE_WRAPPER(string, ::fLS::clstring, name) //////////////////////////////////////////////////////////////////////////////// // End gflags section. //////////////////////////////////////////////////////////////////////////////// #else // C10_USE_GFLAGS //////////////////////////////////////////////////////////////////////////////// // Begin non-gflags section: providing equivalent functionality. //////////////////////////////////////////////////////////////////////////////// namespace c10 { class C10_API C10FlagParser { public: bool success() { return success_; } protected: template bool Parse(const std::string& content, T* value); bool success_{false}; }; C10_DECLARE_REGISTRY(C10FlagsRegistry, C10FlagParser, const std::string&); } // namespace c10 // The macros are defined outside the c10 namespace. In your code, you should // write the C10_DEFINE_* and C10_DECLARE_* macros outside any namespace // as well. #define C10_DEFINE_typed_var(type, name, default_value, help_str) \ C10_EXPORT type FLAGS_##name = default_value; \ namespace c10 { \ namespace { \ class C10FlagParser_##name : public C10FlagParser { \ public: \ explicit C10FlagParser_##name(const std::string& content) { \ success_ = C10FlagParser::Parse(content, &FLAGS_##name); \ } \ }; \ } \ RegistererC10FlagsRegistry g_C10FlagsRegistry_##name( \ #name, \ C10FlagsRegistry(), \ RegistererC10FlagsRegistry::DefaultCreator, \ "(" #type ", default " #default_value ") " help_str); \ } #define C10_DEFINE_int(name, default_value, help_str) \ C10_DEFINE_typed_var(int, name, default_value, help_str) #define C10_DEFINE_int32(name, default_value, help_str) \ C10_DEFINE_int(name, default_value, help_str) #define C10_DEFINE_int64(name, default_value, help_str) \ C10_DEFINE_typed_var(int64_t, name, default_value, help_str) #define C10_DEFINE_double(name, default_value, help_str) \ C10_DEFINE_typed_var(double, name, default_value, help_str) #define C10_DEFINE_bool(name, default_value, help_str) \ C10_DEFINE_typed_var(bool, name, default_value, help_str) #define C10_DEFINE_string(name, default_value, help_str) \ C10_DEFINE_typed_var(std::string, name, default_value, help_str) // DECLARE_typed_var should be used in header files and in the global namespace. #define C10_DECLARE_typed_var(type, name) C10_API extern type FLAGS_##name #define C10_DECLARE_int(name) C10_DECLARE_typed_var(int, name) #define C10_DECLARE_int32(name) C10_DECLARE_int(name) #define C10_DECLARE_int64(name) C10_DECLARE_typed_var(int64_t, name) #define C10_DECLARE_double(name) C10_DECLARE_typed_var(double, name) #define C10_DECLARE_bool(name) C10_DECLARE_typed_var(bool, name) #define C10_DECLARE_string(name) C10_DECLARE_typed_var(std::string, name) //////////////////////////////////////////////////////////////////////////////// // End non-gflags section. //////////////////////////////////////////////////////////////////////////////// #endif // C10_USE_GFLAGS #endif // C10_UTIL_FLAGS_H_