Add SMT detection for mac. Fixes #963.

--
Change-Id: Ib83af0d0a04dc6b173bef1df28d17abc7a3c824d
Reviewed-on: https://bazel-review.googlesource.com/#/c/3120/
MOS_MIGRATED_REVID=119027507

1 files changed, 60 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/actions/LocalHostResourceManagerDarwin.java b/src/main/java/com/google/devtools/build/lib/actions/LocalHostResourceManagerDarwin.java
new file mode 100644
index 0000000000..1ada1bfd0c
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/actions/LocalHostResourceManagerDarwin.java
@@ -0,0 +1,60 @@
+// Copyright 2016 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.actions;
+
+import com.google.devtools.build.lib.unix.NativePosixSystem;
+
+import java.io.IOException;
+
+/**
+ * This class estimates the local host's resource capacity for Darwin.
+ */
+public class LocalHostResourceManagerDarwin {
+  private static final Boolean JNI_UNAVAILABLE =
+      "0".equals(System.getProperty("io.bazel.UnixFileSystem"));
+  private static final double EFFECTIVE_CPUS_PER_HYPERTHREADED_CPU = 0.6;
+
+  private static int getLogicalCpuCount() throws IOException {
+    return (int) NativePosixSystem.sysctlbynameGetLong("hw.logicalcpu");
+  }
+
+  private static int getPhysicalCpuCount() throws IOException {
+    return (int) NativePosixSystem.sysctlbynameGetLong("hw.physicalcpu");
+  }
+
+  private static double getMemoryInMb() throws IOException {
+    return NativePosixSystem.sysctlbynameGetLong("hw.memsize") / 1E6;
+  }
+
+  public static ResourceSet getLocalHostResources() {
+    if (JNI_UNAVAILABLE) {
+      return null;
+    }
+    try {
+      int logicalCpuCount = getLogicalCpuCount();
+      int physicalCpuCount = getPhysicalCpuCount();
+      double ramMb = getMemoryInMb();
+      boolean hyperthreading = (logicalCpuCount != physicalCpuCount);
+
+      return ResourceSet.create(
+          ramMb,
+          logicalCpuCount * (hyperthreading ? EFFECTIVE_CPUS_PER_HYPERTHREADED_CPU : 1.0),
+          1.0,
+          Integer.MAX_VALUE);
+    } catch (IOException e) {
+      return null;
+    }
+  }
+}