fixes #32 autoscale based on CPUs available

This should work on both Windows and the most common POSIX
variants.  We will create at least two threads for running
completions, but there are numerous other threads in the code.

2 files changed, 21 insertions, 0 deletions

diff --git a/src/platform/posix/posix_thread.c b/src/platform/posix/posix_thread.c
index f016ca3f..df2ee9d2 100644
--- a/src/platform/posix/posix_thread.c
+++ b/src/platform/posix/posix_thread.c
@@ -336,4 +336,16 @@ nni_plat_fini(void)
 	pthread_mutex_unlock(&nni_plat_init_lock);
 }
 
+int
+nni_plat_ncpu(void)
+{
+	// POSIX specifies sysconf exists, but not the value
+	// _SC_NPROCESSORS_ONLN.  Nonetheless, everybody implements it.
+	// If you don't we'll assume you only have a single logical CPU.
+#ifdef _SC_NPROCESSORS_ONLN
+	return (sysconf(_SC_NPROCESSORS_ONLN));
+#else
+	return (1);
+#endif
+}
 #endif // NNG_PLATFORM_POSIX
diff --git a/src/platform/windows/win_thread.c b/src/platform/windows/win_thread.c
index 2e9d58d7..a3d932aa 100644
--- a/src/platform/windows/win_thread.c
+++ b/src/platform/windows/win_thread.c
@@ -148,6 +148,15 @@ nni_plat_thr_is_self(nni_plat_thr *thr)
 static LONG plat_inited = 0;
 
 int
+nni_plat_ncpu(void)
+{
+	SYSTEM_INFO info;
+
+	GetSystemInfo(&info);
+	return ((int) (info.dwNumberOfProcessors));
+}
+
+int
 nni_plat_init(int (*helper)(void))
 {
 	int            rv   = 0;