Merge pull request #89452 from Riteo/name-a-better-duo

SCons: Enable the experimental Ninja backend and minimize timestamp changes to generated code

.gitignore

@@ -35,6 +35,10 @@ bin
 compile_commands.json
 platform/windows/godot_res.res
 
+# Ninja build files
+build.ninja
+.ninja
+
 # Generated by Godot binary
 .import/
 /gdextension_interface.h

SConstruct

@@ -203,6 +203,7 @@ opts.Add(BoolVariable("custom_modules_recursive", "Detect custom modules recursi
 opts.Add(BoolVariable("dev_mode", "Alias for dev options: verbose=yes warnings=extra werror=yes tests=yes", False))
 opts.Add(BoolVariable("tests", "Build the unit tests", False))
 opts.Add(BoolVariable("fast_unsafe", "Enable unsafe options for faster rebuilds", False))
+opts.Add(BoolVariable("ninja", "Use the ninja backend for faster rebuilds", False))
 opts.Add(BoolVariable("compiledb", "Generate compilation DB (`compile_commands.json`) for external tools", False))
 opts.Add(BoolVariable("verbose", "Enable verbose output for the compilation", False))
 opts.Add(BoolVariable("progress", "Show a progress indicator during compilation", True))
@@ -956,7 +957,8 @@ if selected_platform in platform_list:
         env.vs_incs = []
         env.vs_srcs = []
 
-    # CompileDB
+    # CompileDB and Ninja are only available with certain SCons versions which
+    # not everybody might have yet, so we have to check.
     from SCons import __version__ as scons_raw_version
 
     scons_ver = env._get_major_minor_revision(scons_raw_version)
@@ -968,6 +970,20 @@ if selected_platform in platform_list:
         env.Tool("compilation_db")
         env.Alias("compiledb", env.CompilationDatabase())
 
+    if env["ninja"]:
+        if scons_ver < (4, 2, 0):
+            print("The `ninja=yes` option requires SCons 4.2 or later, but your version is %s." % scons_raw_version)
+            Exit(255)
+
+        SetOption("experimental", "ninja")
+
+        # By setting this we allow the user to run ninja by themselves with all
+        # the flags they need, as apparently automatically running from scons
+        # is way slower.
+        SetOption("disable_execute_ninja", True)
+
+        env.Tool("ninja")
+
     # Threads
     if env["threads"]:
         env.Append(CPPDEFINES=["THREADS_ENABLED"])
@@ -1041,9 +1057,10 @@ atexit.register(print_elapsed_time)
 
 
 def purge_flaky_files():
+    paths_to_keep = ["ninja.build"]
     for build_failure in GetBuildFailures():
-        path = build_failure.node.abspath
+        path = build_failure.node.path
-        if os.path.isfile(path):
+        if os.path.isfile(path) and path not in paths_to_keep:
             os.remove(path)
 
 

core/SCsub

@@ -3,6 +3,7 @@
 Import("env")
 
 import core_builders
+import methods
 
 env.core_sources = []
 
@@ -35,10 +36,12 @@ if "SCRIPT_AES256_ENCRYPTION_KEY" in os.environ:
         )
         Exit(255)
 
-# NOTE: It is safe to generate this file here, since this is still executed serially
-with open("script_encryption_key.gen.cpp", "w", encoding="utf-8", newline="\n") as f:
-    f.write('#include "core/config/project_settings.h"\nuint8_t script_encryption_key[32]={' + txt + "};\n")
 
+script_encryption_key_contents = (
+    '#include "core/config/project_settings.h"\nuint8_t script_encryption_key[32]={' + txt + "};\n"
+)
+
+methods.write_file_if_needed("script_encryption_key.gen.cpp", script_encryption_key_contents)
 
 # Add required thirdparty code.
 

editor/SCsub

@@ -7,19 +7,24 @@ env.editor_sources = []
 import os
 import glob
 import editor_builders
+import methods
 
 
 def _make_doc_data_class_path(to_path):
-    # NOTE: It is safe to generate this file here, since this is still executed serially
+    file_path = os.path.join(to_path, "doc_data_class_path.gen.h")
-    with open(os.path.join(to_path, "doc_data_class_path.gen.h"), "w", encoding="utf-8", newline="\n") as g:
-        g.write("static const int _doc_data_class_path_count = " + str(len(env.doc_class_path)) + ";\n")
-        g.write("struct _DocDataClassPath { const char* name; const char* path; };\n")
 
-        g.write("static const _DocDataClassPath _doc_data_class_paths[" + str(len(env.doc_class_path) + 1) + "] = {\n")
+    class_path_data = ""
-        for c in sorted(env.doc_class_path):
+    class_path_data += "static const int _doc_data_class_path_count = " + str(len(env.doc_class_path)) + ";\n"
-            g.write('\t{"' + c + '", "' + env.doc_class_path[c] + '"},\n')
+    class_path_data += "struct _DocDataClassPath { const char* name; const char* path; };\n"
-        g.write("\t{nullptr, nullptr}\n")
+    class_path_data += (
-        g.write("};\n")
+        "static const _DocDataClassPath _doc_data_class_paths[" + str(len(env.doc_class_path) + 1) + "] = {\n"
+    )
+    for c in sorted(env.doc_class_path):
+        class_path_data += '\t{"' + c + '", "' + env.doc_class_path[c] + '"},\n'
+    class_path_data += "\t{nullptr, nullptr}\n"
+    class_path_data += "};\n"
+
+    methods.write_file_if_needed(file_path, class_path_data)
 
 
 if env.editor_build:
@@ -38,10 +43,7 @@ if env.editor_build:
         reg_exporters += "\tregister_" + e + "_exporter_types();\n"
     reg_exporters += "}\n"
 
-    # NOTE: It is safe to generate this file here, since this is still executed serially
+    methods.write_file_if_needed("register_exporters.gen.cpp", reg_exporters_inc + reg_exporters)
-    with open("register_exporters.gen.cpp", "w", encoding="utf-8", newline="\n") as f:
-        f.write(reg_exporters_inc)
-        f.write(reg_exporters)
 
     # Core API documentation.
     docs = []

methods.py

@@ -228,14 +228,22 @@ def get_version_info(module_version_string="", silent=False):
     return version_info
 
 
+def write_file_if_needed(path, string):
+    try:
+        with open(path, "r", encoding="utf-8", newline="\n") as f:
+            if f.read() == string:
+                return
+    except FileNotFoundError:
+        pass
+
+    with open(path, "w", encoding="utf-8", newline="\n") as f:
+        f.write(string)
+
+
 def generate_version_header(module_version_string=""):
     version_info = get_version_info(module_version_string)
 
-    # NOTE: It is safe to generate these files here, since this is still executed serially.
+    version_info_header = """\
-
-    with open("core/version_generated.gen.h", "w", encoding="utf-8", newline="\n") as f:
-        f.write(
-            """\
 /* THIS FILE IS GENERATED DO NOT EDIT */
 #ifndef VERSION_GENERATED_GEN_H
 #define VERSION_GENERATED_GEN_H
@@ -252,21 +260,20 @@ def generate_version_header(module_version_string=""):
 #define VERSION_DOCS_URL "https://docs.godotengine.org/en/" VERSION_DOCS_BRANCH
 #endif // VERSION_GENERATED_GEN_H
 """.format(
-                **version_info
+        **version_info
-            )
+    )
-        )
 
-    with open("core/version_hash.gen.cpp", "w", encoding="utf-8", newline="\n") as fhash:
+    version_hash_data = """\
-        fhash.write(
-            """\
 /* THIS FILE IS GENERATED DO NOT EDIT */
 #include "core/version.h"
 const char *const VERSION_HASH = "{git_hash}";
 const uint64_t VERSION_TIMESTAMP = {git_timestamp};
 """.format(
-                **version_info
+        **version_info
-            )
+    )
-        )
+
+    write_file_if_needed("core/version_generated.gen.h", version_info_header)
+    write_file_if_needed("core/version_hash.gen.cpp", version_hash_data)
 
 
 def parse_cg_file(fname, uniforms, sizes, conditionals):
@@ -385,15 +392,18 @@ def is_module(path):
 
 
 def write_disabled_classes(class_list):
-    with open("core/disabled_classes.gen.h", "w", encoding="utf-8", newline="\n") as f:
+    file_contents = ""
-        f.write("/* THIS FILE IS GENERATED DO NOT EDIT */\n")
+
-        f.write("#ifndef DISABLED_CLASSES_GEN_H\n")
+    file_contents += "/* THIS FILE IS GENERATED DO NOT EDIT */\n"
-        f.write("#define DISABLED_CLASSES_GEN_H\n\n")
+    file_contents += "#ifndef DISABLED_CLASSES_GEN_H\n"
-        for c in class_list:
+    file_contents += "#define DISABLED_CLASSES_GEN_H\n\n"
-            cs = c.strip()
+    for c in class_list:
-            if cs != "":
+        cs = c.strip()
-                f.write("#define ClassDB_Disable_" + cs + " 1\n")
+        if cs != "":
-        f.write("\n#endif\n")
+            file_contents += "#define ClassDB_Disable_" + cs + " 1\n"
+    file_contents += "\n#endif\n"
+
+    write_file_if_needed("core/disabled_classes.gen.h", file_contents)
 
 
 def write_modules(modules):
@@ -435,9 +445,7 @@ void uninitialize_modules(ModuleInitializationLevel p_level) {
         uninitialize_cpp,
     )
 
-    # NOTE: It is safe to generate this file here, since this is still executed serially
+    write_file_if_needed("modules/register_module_types.gen.cpp", modules_cpp)
-    with open("modules/register_module_types.gen.cpp", "w", encoding="utf-8", newline="\n") as f:
-        f.write(modules_cpp)
 
 
 def convert_custom_modules_path(path):

platform/SCsub

@@ -1,5 +1,7 @@
 #!/usr/bin/env python
 
+import methods
+
 Import("env")
 
 env.platform_sources = []
@@ -18,12 +20,7 @@ reg_apis_inc += "\n"
 reg_apis += "}\n\n"
 unreg_apis += "}\n"
 
-# NOTE: It is safe to generate this file here, since this is still execute serially
+methods.write_file_if_needed("register_platform_apis.gen.cpp", reg_apis_inc + reg_apis + unreg_apis)
-with open("register_platform_apis.gen.cpp", "w", encoding="utf-8", newline="\n") as f:
-    f.write(reg_apis_inc)
-    f.write(reg_apis)
-    f.write(unreg_apis)
-
 env.add_source_files(env.platform_sources, "register_platform_apis.gen.cpp")
 
 lib = env.add_library("platform", env.platform_sources)

platform_methods.py

@@ -5,6 +5,7 @@ import platform
 import uuid
 import functools
 import subprocess
+import methods
 
 # NOTE: The multiprocessing module is not compatible with SCons due to conflict on cPickle
 
@@ -65,10 +66,9 @@ def generate_export_icons(platform_path, platform_name):
 
             svg_str += '";\n'
 
-        # NOTE: It is safe to generate this file here, since this is still executed serially.
         wf = export_path + "/" + name + "_svg.gen.h"
-        with open(wf, "w", encoding="utf-8", newline="\n") as svgw:
+
-            svgw.write(svg_str)
+        methods.write_file_if_needed(wf, svg_str)
 
 
 def get_build_version(short):

scu_builders.py

@@ -13,9 +13,9 @@ _scu_folders = set()
 _max_includes_per_scu = 1024
 
 
-def clear_out_existing_files(output_folder, extension):
+def clear_out_stale_files(output_folder, extension, fresh_files):
     output_folder = os.path.abspath(output_folder)
-    # print("clear_out_existing_files from folder: " + output_folder)
+    # print("clear_out_stale_files from folder: " + output_folder)
 
     if not os.path.isdir(output_folder):
         # folder does not exist or has not been created yet,
@@ -23,8 +23,9 @@ def clear_out_existing_files(output_folder, extension):
         return
 
     for file in glob.glob(output_folder + "/*." + extension):
-        # print("removed pre-existing file: " + file)
+        if not file in fresh_files:
-        os.remove(file)
+            # print("removed stale file: " + file)
+            os.remove(file)
 
 
 def folder_not_found(folder):
@@ -87,11 +88,16 @@ def write_output_file(file_count, include_list, start_line, end_line, output_fol
 
     short_filename = output_filename_prefix + num_string + ".gen." + extension
     output_filename = output_folder + "/" + short_filename
-    if _verbose:
-        print("SCU: Generating: %s" % short_filename)
-
     output_path = Path(output_filename)
-    output_path.write_text(file_text, encoding="utf8")
+
+    if not output_path.exists() or output_path.read_text() != file_text:
+        if _verbose:
+            print("SCU: Generating: %s" % short_filename)
+        output_path.write_text(file_text, encoding="utf8")
+    elif _verbose:
+        print("SCU: Generation not needed for: " + short_filename)
+
+    return output_filename
 
 
 def write_exception_output_file(file_count, exception_string, output_folder, output_filename_prefix, extension):
@@ -109,11 +115,16 @@ def write_exception_output_file(file_count, exception_string, output_folder, out
     short_filename = output_filename_prefix + "_exception" + num_string + ".gen." + extension
     output_filename = output_folder + "/" + short_filename
 
-    if _verbose:
-        print("SCU: Generating: " + short_filename)
-
     output_path = Path(output_filename)
-    output_path.write_text(file_text, encoding="utf8")
+
+    if not output_path.exists() or output_path.read_text() != file_text:
+        if _verbose:
+            print("SCU: Generating: " + short_filename)
+        output_path.write_text(file_text, encoding="utf8")
+    elif _verbose:
+        print("SCU: Generation not needed for: " + short_filename)
+
+    return output_filename
 
 
 def find_section_name(sub_folder):
@@ -214,10 +225,7 @@ def process_folder(folders, sought_exceptions=[], includes_per_scu=0, extension=
     output_folder = abs_main_folder + "/scu/"
     output_filename_prefix = "scu_" + out_filename
 
-    # Clear out any existing files (usually we will be overwriting,
+    fresh_files = set()
-    # but we want to remove any that are pre-existing that will not be
-    # overwritten, so as to not compile anything stale)
-    clear_out_existing_files(output_folder, extension)
 
     for file_count in range(0, num_output_files):
         end_line = start_line + lines_per_file
@@ -226,19 +234,28 @@ def process_folder(folders, sought_exceptions=[], includes_per_scu=0, extension=
         if file_count == (num_output_files - 1):
             end_line = len(found_includes)
 
-        write_output_file(
+        fresh_file = write_output_file(
             file_count, found_includes, start_line, end_line, output_folder, output_filename_prefix, extension
         )
 
+        fresh_files.add(fresh_file)
+
         start_line = end_line
 
     # Write the exceptions each in their own scu gen file,
     # so they can effectively compile in "old style / normal build".
     for exception_count in range(len(found_exceptions)):
-        write_exception_output_file(
+        fresh_file = write_exception_output_file(
             exception_count, found_exceptions[exception_count], output_folder, output_filename_prefix, extension
         )
 
+        fresh_files.add(fresh_file)
+
+    # Clear out any stale file (usually we will be overwriting if necessary,
+    # but we want to remove any that are pre-existing that will not be
+    # overwritten, so as to not compile anything stale).
+    clear_out_stale_files(output_folder, extension, fresh_files)
+
 
 def generate_scu_files(max_includes_per_scu):
     print("=============================")