CTest: Add options to control test process affinity to CPUs

In commit v2.8.0~170 (ENH: Added ctest test options PROCESSORS and
RUN_SERIAL, 2009-09-07) CTest learned to track the number of processors
allocated to running tests in order to balance it against the desired
level of parallelism.  Extend this idea by introducing a new
`PROCESSOR_AFFINITY` test property to ask that CTest run a test
with the CPU affinity mask set.  This will allow a set of tests
that are running concurrently to use disjoint CPU resources.

1 files changed, 62 insertions, 0 deletions

diff --git a/Source/cmAffinity.cxx b/Source/cmAffinity.cxx
new file mode 100644
index 0000000..bdf1f42
--- /dev/null
+++ b/Source/cmAffinity.cxx
@@ -0,0 +1,62 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#include "cmAffinity.h"
+
+#include "cm_uv.h"
+
+#ifndef CMAKE_USE_SYSTEM_LIBUV
+#ifdef _WIN32
+#define CM_HAVE_CPU_AFFINITY
+#include <windows.h>
+#elif defined(__linux__) || defined(__FreeBSD__)
+#define CM_HAVE_CPU_AFFINITY
+#include <pthread.h>
+#include <sched.h>
+#if defined(__FreeBSD__)
+#include <pthread_np.h>
+#include <sys/cpuset.h>
+#include <sys/param.h>
+#endif
+#if defined(__linux__)
+typedef cpu_set_t cm_cpuset_t;
+#else
+typedef cpuset_t cm_cpuset_t;
+#endif
+#endif
+#endif
+
+namespace cmAffinity {
+
+std::set<size_t> GetProcessorsAvailable()
+{
+  std::set<size_t> processorsAvailable;
+#ifdef CM_HAVE_CPU_AFFINITY
+  int cpumask_size = uv_cpumask_size();
+  if (cpumask_size > 0) {
+#ifdef _WIN32
+    DWORD_PTR procmask;
+    DWORD_PTR sysmask;
+    if (GetProcessAffinityMask(GetCurrentProcess(), &procmask, &sysmask) !=
+        0) {
+      for (int i = 0; i < cpumask_size; ++i) {
+        if (procmask & (((DWORD_PTR)1) << i)) {
+          processorsAvailable.insert(i);
+        }
+      }
+    }
+#else
+    cm_cpuset_t cpuset;
+    CPU_ZERO(&cpuset); // NOLINT(clang-tidy)
+    if (pthread_getaffinity_np(pthread_self(), sizeof(cpuset), &cpuset) == 0) {
+      for (int i = 0; i < cpumask_size; ++i) {
+        if (CPU_ISSET(i, &cpuset)) {
+          processorsAvailable.insert(i);
+        }
+      }
+    }
+#endif
+  }
+#endif
+  return processorsAvailable;
+}
+}