Add compiler/platform agnostic thread-local storage

It doesn't cover all cases, but we can work on those as
we go along. For now, gcc, MSVC++, Intel C/C++, IBM XL C/C++,
Sun Studio C/C++ and Borland C++ Builder are the supported
compilers (although we boldly assume that they all are of
a recent enough version to support thread-local storage).

This is intended to be used in upcoming patches that implement
graceful (but TLS-dependant) error-handling in the library.

As an added bonus, we also bring the online_cpus() function
from git.git to detect the number of usable cpu's.

Signed-off-by: Andreas Ericsson <ae@op5.se>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

1 files changed, 48 insertions, 0 deletions

diff --git a/src/thread-utils.c b/src/thread-utils.c
new file mode 100644
index 000000000..c945829d4
--- /dev/null
+++ b/src/thread-utils.c
@@ -0,0 +1,48 @@
+#include "thread-utils.h"
+
+#ifdef _WIN32
+#  define WIN32_LEAN_AND_MEAN
+#  include <windows.h>
+#elif defined(hpux) || defined(__hpux) || defined(_hpux)
+#  include <sys/pstat.h>
+#endif
+
+/*
+ * By doing this in two steps we can at least get
+ * the function to be somewhat coherent, even
+ * with this disgusting nest of #ifdefs.
+ */
+#ifndef _SC_NPROCESSORS_ONLN
+#  ifdef _SC_NPROC_ONLN
+#    define _SC_NPROCESSORS_ONLN _SC_NPROC_ONLN
+#  elif defined _SC_CRAY_NCPU
+#    define _SC_NPROCESSORS_ONLN _SC_CRAY_NCPU
+#  endif
+#endif
+
+int git_online_cpus(void)
+{
+#ifdef _SC_NPROCESSORS_ONLN
+	long ncpus;
+#endif
+
+#ifdef _WIN32
+	SYSTEM_INFO info;
+	GetSystemInfo(&info);
+
+	if ((int)info.dwNumberOfProcessors > 0)
+		return (int)info.dwNumberOfProcessors;
+#elif defined(hpux) || defined(__hpux) || defined(_hpux)
+	struct pst_dynamic psd;
+
+	if (!pstat_getdynamic(&psd, sizeof(psd), (size_t)1, 0))
+		return (int)psd.psd_proc_cnt;
+#endif
+
+#ifdef _SC_NPROCESSORS_ONLN
+	if ((ncpus = (long)sysconf(_SC_NPROCESSORS_ONLN)) > 0)
+		return (int)ncpus;
+#endif
+
+	return 1;
+}