Move Runnables into lib.util so that it can be used by other packages.

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MOS_MIGRATED_REVID=110709069

src/main/java/com/google/devtools/build/lib/util/Runnables.java

diff --git a/src/main/java/com/google/devtools/build/lib/util/Runnables.java b/src/main/java/com/google/devtools/build/lib/util/Runnables.java
new file mode 100644
index 0000000..db62891
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/util/Runnables.java
@@ -0,0 +1,40 @@
+// Copyright 2015 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.util;
+
+/** Utilities for dealing with {@link Runnable}s that may call into uncontrolled code. */
+public class Runnables {
+  private Runnables() {}
+
+  /**
+   * A {@link Runnable} that terminates the jvm instead of throwing an unchecked exception in
+   * {@link Runnable#run}.
+   *
+   * <p>This is useful if the {@link Runnable} may be executed by code outside of our control, e.g.
+   * if we call into library code that silently swallows {@link RuntimeException}s from our code.
+   */
+  // TODO(bazel-team): Long-term, callers may want to handle exceptions more gracefully.
+  public abstract static class AbstractCrashTerminatingRunnable implements Runnable {
+    protected abstract void runImpl();
+
+    @Override
+    public final void run() {
+      try {
+        runImpl();
+      } catch (Throwable t) {
+        RuntimeUtils.halt(t);
+      }
+    }
+  }
+}

src/main/java/com/google/devtools/build/lib/util/RuntimeUtils.java

diff --git a/src/main/java/com/google/devtools/build/lib/util/RuntimeUtils.java b/src/main/java/com/google/devtools/build/lib/util/RuntimeUtils.java
new file mode 100644
index 0000000..c8dbb5c
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/util/RuntimeUtils.java
@@ -0,0 +1,48 @@
+// Copyright 2015 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.util;
+
+import com.google.common.base.Throwables;
+
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+
+/** Utilities for interacting with the jvm. */
+public class RuntimeUtils {
+  private static final Logger LOG = Logger.getLogger(RuntimeUtils.class.getName());
+
+  @Nullable private static volatile Throwable unprocessedThrowableInTest = null;
+
+  private RuntimeUtils() {}
+
+  /**
+   * In tests, System.exit may be disabled. Thus, the main thread should call this method whenever
+   * it is about to block on thread completion that might hang because of a failed halt below.
+   */
+  public static void maybePropagateUnprocessedThrowableIfInTest() {
+    Throwables.propagateIfPossible(unprocessedThrowableInTest);
+  }
+
+  /** Terminates the jvm with the exit code {@link ExitCode#BLAZE_INTERNAL_ERROR}. */
+  public static void halt(Throwable crash) {
+    LOG.info("About to call System#exit. Halt requested due to crash. See stderr for details.");
+    System.err.println("About to call System#exit. Halt requested due to crash");
+    crash.printStackTrace();
+    System.err.println("... called from");
+    new Exception().printStackTrace();
+    unprocessedThrowableInTest = crash;
+    System.exit(ExitCode.BLAZE_INTERNAL_ERROR.getNumericExitCode());
+  }
+}