feat: don't detect cpu if -j set

1 files changed, 20 insertions, 1 deletions

diff --git a/src/ninja.cc b/src/ninja.cc
index 3e5c971..2d43b1d 100644
--- a/src/ninja.cc
+++ b/src/ninja.cc
@@ -1305,11 +1305,28 @@ int ExceptionFilter(unsigned int code, struct _EXCEPTION_POINTERS *ep) {
 
 #endif  // _MSC_VER
 
+class DeferGuessParallelism {
+ public:
+  bool needGuess;
+  BuildConfig* config;
+
+  DeferGuessParallelism(BuildConfig* config)
+      : config(config), needGuess(true) {}
+
+  void Refresh() {
+    if (needGuess) {
+      needGuess = false;
+      config->parallelism = GuessParallelism();
+    }
+  }
+  ~DeferGuessParallelism() { Refresh(); }
+};
+
 /// Parse argv for command-line options.
 /// Returns an exit code, or -1 if Ninja should continue.
 int ReadFlags(int* argc, char*** argv,
               Options* options, BuildConfig* config) {
-  config->parallelism = GuessParallelism();
+  DeferGuessParallelism deferGuessParallelism(config);
 
   enum { OPT_VERSION = 1, OPT_QUIET = 2 };
   const option kLongOptions[] = {
@@ -1341,6 +1358,7 @@ int ReadFlags(int* argc, char*** argv,
         // We want to run N jobs in parallel. For N = 0, INT_MAX
         // is close enough to infinite for most sane builds.
         config->parallelism = value > 0 ? value : INT_MAX;
+        deferGuessParallelism.needGuess = false;
         break;
       }
       case 'k': {
@@ -1389,6 +1407,7 @@ int ReadFlags(int* argc, char*** argv,
         return 0;
       case 'h':
       default:
+        deferGuessParallelism.Refresh();
         Usage(*config);
         return 1;
     }