Implement parallelism singleton (#901)

Makefile

@@ -75,7 +75,7 @@ $(O)/tests/test_BuildConfig: $(O)/tests/test_BuildConfig.o \
   $(O)/Logger.o $(O)/TermColor.o $(O)/Manifest.o \
   $(O)/Semver.o $(O)/Algos.o $(O)/VersionReq.o $(O)/Git2/Repository.o \
   $(O)/Git2/Object.o $(O)/Git2/Oid.o $(O)/Git2/Global.o $(O)/Git2/Config.o \
-  $(O)/Git2/Exception.o $(O)/Git2/Commit.o $(O)/Git2/Time.o
+  $(O)/Git2/Exception.o $(O)/Git2/Commit.o $(O)/Git2/Time.o $(O)/Parallel.o
 	$(CXX) $(CXXFLAGS) $^ $(LIBS) -o $@
 
 $(O)/tests/test_Algos: $(O)/tests/test_Algos.o $(O)/Logger.o \

src/BuildConfig.cc

@@ -5,6 +5,7 @@
 #include "Git2.hpp"
 #include "Logger.hpp"
 #include "Manifest.hpp"
+#include "Parallel.hpp"
 #include "TermColor.hpp"
 
 #include <algorithm>
@@ -641,12 +642,10 @@ processSrc(
 }
 
 static HashSet<String>
-processSources(
-    BuildConfig& config, const Vec<Path>& sourceFilePaths, const bool isParallel
-) {
+processSources(BuildConfig& config, const Vec<Path>& sourceFilePaths) {
   HashSet<String> buildObjTargets;
 
-  if (isParallel) {
+  if (isParallel()) {
     tbb::spin_mutex mtx;
     tbb::parallel_for(
         tbb::blocked_range<usize>(0, sourceFilePaths.size()),
@@ -721,7 +720,7 @@ processTestSrc(
 }
 
 static BuildConfig
-configureBuild(const bool isDebug, const bool isParallel) {
+configureBuild(const bool isDebug) {
   if (!fs::exists("src")) {
     throw PoacError("src directory not found");
   }
@@ -755,7 +754,7 @@ configureBuild(const bool isDebug, const bool isParallel) {
 
   // Source Pass
   const HashSet<String> buildObjTargets =
-      processSources(config, sourceFilePaths, isParallel);
+      processSources(config, sourceFilePaths);
 
   // Project binary target.
   const String mainObjTarget = config.buildOutDir / "main.o";
@@ -770,7 +769,7 @@ configureBuild(const bool isDebug, const bool isParallel) {
   // Test Pass
   Vec<String> testCommands;
   HashSet<String> testTargets;
-  if (isParallel) {
+  if (isParallel()) {
     tbb::spin_mutex mtx;
     tbb::parallel_for(
         tbb::blocked_range<usize>(0, sourceFilePaths.size()),
@@ -815,7 +814,7 @@ configureBuild(const bool isDebug, const bool isParallel) {
 
 /// @returns the directory where the Makefile is generated.
 String
-emitMakefile(const bool isDebug, const bool isParallel) {
+emitMakefile(const bool isDebug) {
   setOutDir(isDebug);
 
   // When emitting Makefile, we also build the project.  So, we need to
@@ -830,15 +829,15 @@ emitMakefile(const bool isDebug, const bool isParallel) {
   }
   Logger::debug("Makefile is NOT up to date");
 
-  const BuildConfig config = configureBuild(isDebug, isParallel);
+  const BuildConfig config = configureBuild(isDebug);
   std::ofstream ofs(makefilePath);
   config.emitMakefile(ofs);
   return outDir;
 }
 
 /// @returns the directory where the compilation database is generated.
 String
-emitCompdb(const bool isDebug, const bool isParallel) {
+emitCompdb(const bool isDebug) {
   setOutDir(isDebug);
 
   // compile_commands.json also needs INCLUDES, but not LIBS.
@@ -852,7 +851,7 @@ emitCompdb(const bool isDebug, const bool isParallel) {
   }
   Logger::debug("compile_commands.json is NOT up to date");
 
-  const BuildConfig config = configureBuild(isDebug, isParallel);
+  const BuildConfig config = configureBuild(isDebug);
   std::ofstream ofs(compdbPath);
   config.emitCompdb(outDir, ofs);
   return outDir;
@@ -864,15 +863,15 @@ modeString(const bool isDebug) {
 }
 
 String
-getMakeCommand(const bool isParallel) {
+getMakeCommand() {
   String makeCommand;
   if (isVerbose()) {
     makeCommand = "make";
   } else {
     makeCommand = "make -s --no-print-directory Q=@";
   }
 
-  if (isParallel) {
+  if (isParallel()) {
     const unsigned int numThreads = std::thread::hardware_concurrency();
     if (numThreads > 1) {
       makeCommand += " -j" + std::to_string(numThreads);

src/BuildConfig.hpp

@@ -11,7 +11,7 @@ inline const HashSet<String> HEADER_FILE_EXTS{
 };
 // clang-format on
 
-String emitMakefile(bool isDebug, bool isParallel);
-String emitCompdb(bool isDebug, bool isParallel);
+String emitMakefile(bool isDebug);
+String emitCompdb(bool isDebug);
 String modeString(bool isDebug);
-String getMakeCommand(bool isParallel);
+String getMakeCommand();

src/Cmd/Build.cc

@@ -3,6 +3,7 @@
 #include "../Algos.hpp"
 #include "../BuildConfig.hpp"
 #include "../Logger.hpp"
+#include "../Parallel.hpp"
 
 #include <chrono>
 #include <cstdlib>
@@ -27,11 +28,11 @@ const Subcmd BUILD_CMD =
         .setMainFn(buildMain);
 
 int
-buildImpl(String& outDir, const bool isDebug, const bool isParallel) {
+buildImpl(String& outDir, const bool isDebug) {
   const auto start = std::chrono::steady_clock::now();
 
-  outDir = emitMakefile(isDebug, isParallel);
-  const String makeCommand = getMakeCommand(isParallel) + " -C " + outDir;
+  outDir = emitMakefile(isDebug);
+  const String makeCommand = getMakeCommand() + " -C " + outDir;
   const int exitCode = execCmd(makeCommand);
 
   const auto end = std::chrono::steady_clock::now();
@@ -50,7 +51,6 @@ buildMain(const std::span<const StringRef> args) {
   // Parse args
   bool isDebug = true;
   bool buildCompdb = false;
-  bool isParallel = true;
   for (usize i = 0; i < args.size(); ++i) {
     const StringRef arg = args[i];
     HANDLE_GLOBAL_OPTS({ { "build" } }) // workaround for std::span until C++26
@@ -65,7 +65,7 @@ buildMain(const std::span<const StringRef> args) {
       buildCompdb = true;
     }
     else if (arg == "--no-parallel") {
-      isParallel = false;
+      setParallel(false);
     }
     else {
       return BUILD_CMD.noSuchArg(arg);
@@ -74,11 +74,11 @@ buildMain(const std::span<const StringRef> args) {
 
   if (!buildCompdb) {
     String outDir;
-    return buildImpl(outDir, isDebug, isParallel);
+    return buildImpl(outDir, isDebug);
   }
 
   // Build compilation database
-  const String outDir = emitCompdb(isDebug, isParallel);
+  const String outDir = emitCompdb(isDebug);
   Logger::info("Generated", outDir, "/compile_commands.json");
   return EXIT_SUCCESS;
 }

src/Cmd/Build.hpp

@@ -4,4 +4,4 @@
 #include "../Rustify.hpp"
 
 extern const Subcmd BUILD_CMD;
-int buildImpl(String& outDir, bool isDebug, bool isParallel);
+int buildImpl(String& outDir, bool isDebug);

src/Cmd/Run.cc

@@ -5,6 +5,7 @@
 #include "../Cli.hpp"
 #include "../Logger.hpp"
 #include "../Manifest.hpp"
+#include "../Parallel.hpp"
 #include "../Rustify.hpp"
 #include "Build.hpp"
 
@@ -34,7 +35,6 @@ static int
 runMain(const std::span<const StringRef> args) {
   // Parse args
   bool isDebug = true;
-  bool isParallel = true;
   usize i = 0;
   for (i = 0; i < args.size(); ++i) {
     const StringRef arg = args[i];
@@ -47,7 +47,7 @@ runMain(const std::span<const StringRef> args) {
       isDebug = false;
     }
     else if (arg == "--no-parallel") {
-      isParallel = false;
+      setParallel(false);
     }
     else {
       break;
@@ -60,7 +60,7 @@ runMain(const std::span<const StringRef> args) {
   }
 
   String outDir;
-  if (buildImpl(outDir, isDebug, isParallel) != EXIT_SUCCESS) {
+  if (buildImpl(outDir, isDebug) != EXIT_SUCCESS) {
     return EXIT_FAILURE;
   }
 

src/Cmd/Test.cc

@@ -4,6 +4,7 @@
 #include "../BuildConfig.hpp"
 #include "../Cli.hpp"
 #include "../Logger.hpp"
+#include "../Parallel.hpp"
 #include "../Rustify.hpp"
 
 #include <chrono>
@@ -30,7 +31,6 @@ static int
 testMain(const std::span<const StringRef> args) {
   // Parse args
   bool isDebug = true;
-  bool isParallel = true;
   for (usize i = 0; i < args.size(); ++i) {
     const StringRef arg = args[i];
     HANDLE_GLOBAL_OPTS({ { "test" } })
@@ -46,7 +46,7 @@ testMain(const std::span<const StringRef> args) {
       isDebug = false;
     }
     else if (arg == "--no-parallel") {
-      isParallel = false;
+      setParallel(false);
     }
     else {
       return TEST_CMD.noSuchArg(arg);
@@ -55,9 +55,8 @@ testMain(const std::span<const StringRef> args) {
 
   const auto start = std::chrono::steady_clock::now();
 
-  const String outDir = emitMakefile(isDebug, isParallel);
-  const int exitCode =
-      execCmd(getMakeCommand(isParallel) + " -C " + outDir + " test");
+  const String outDir = emitMakefile(isDebug);
+  const int exitCode = execCmd(getMakeCommand() + " -C " + outDir + " test");
 
   const auto end = std::chrono::steady_clock::now();
   const std::chrono::duration<double> elapsed = end - start;

src/Cmd/Tidy.cc

@@ -4,6 +4,7 @@
 #include "../BuildConfig.hpp"
 #include "../Cli.hpp"
 #include "../Logger.hpp"
+#include "../Parallel.hpp"
 #include "../Rustify.hpp"
 
 #include <chrono>
@@ -39,7 +40,6 @@ static int
 tidyMain(const std::span<const StringRef> args) {
   // Parse args
   bool fix = false;
-  bool isParallel = true;
   for (usize i = 0; i < args.size(); ++i) {
     const StringRef arg = args[i];
     HANDLE_GLOBAL_OPTS({ { "tidy" } })
@@ -48,7 +48,7 @@ tidyMain(const std::span<const StringRef> args) {
       fix = true;
     }
     else if (arg == "--no-parallel") {
-      isParallel = false;
+      setParallel(false);
     }
     else {
       return TIDY_CMD.noSuchArg(arg);
@@ -60,7 +60,7 @@ tidyMain(const std::span<const StringRef> args) {
     return EXIT_FAILURE;
   }
 
-  const Path outDir = emitMakefile(true /* isDebug */, isParallel);
+  const Path outDir = emitMakefile(true /* isDebug */);
 
   String tidyFlags = " POAC_TIDY_FLAGS='";
   if (!isVerbose()) {
@@ -75,7 +75,7 @@ tidyMain(const std::span<const StringRef> args) {
   }
   tidyFlags += '\'';
 
-  String makeCmd = getMakeCommand(isParallel);
+  String makeCmd = getMakeCommand();
   makeCmd += " -C ";
   makeCmd += outDir.string();
   makeCmd += tidyFlags;

src/Parallel.cc

@@ -0,0 +1,37 @@
+#include "Parallel.hpp"
+
+struct ParallelState {
+  // ParallelState is a singleton
+  ParallelState(const ParallelState&) = delete;
+  ParallelState& operator=(const ParallelState&) = delete;
+  ParallelState(ParallelState&&) noexcept = delete;
+  ParallelState& operator=(ParallelState&&) noexcept = delete;
+  ~ParallelState() noexcept = default;
+
+  void set(const bool isParallel) noexcept {
+    state = isParallel;
+  }
+  bool get() const noexcept {
+    return state;
+  }
+
+  static ParallelState& instance() noexcept {
+    static ParallelState INSTANCE;
+    return INSTANCE;
+  }
+
+private:
+  bool state = true;
+
+  ParallelState() noexcept = default;
+};
+
+void
+setParallel(const bool isParallel) noexcept {
+  ParallelState::instance().set(isParallel);
+}
+
+bool
+isParallel() noexcept {
+  return ParallelState::instance().get();
+}

src/Parallel.hpp

@@ -0,0 +1,4 @@
+#pragma once
+
+void setParallel(bool isParallel) noexcept;
+bool isParallel() noexcept;