Update from Google.

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MOE_MIGRATED_REVID=85702957

1 files changed, 60 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/shell/SimpleKillableObserver.java b/src/main/java/com/google/devtools/build/lib/shell/SimpleKillableObserver.java
new file mode 100644
index 0000000000..85794b8387
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/shell/SimpleKillableObserver.java
@@ -0,0 +1,60 @@
+// Copyright 2014 Google Inc. 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.shell;
+
+/**
+ * <p>A simple implementation of {@link KillableObserver} which can be told
+ * explicitly to kill its {@link Killable} by calling {@link #kill()}. This
+ * is the sort of functionality that callers might expect to find available
+ * on the {@link Command} class.</p>
+ *
+ * <p>Note that this class can only observe one {@link Killable} at a time;
+ * multiple instances should be used for concurrent calls to
+ * {@link Command#execute(byte[], KillableObserver, boolean)}.</p>
+ */
+public final class SimpleKillableObserver implements KillableObserver {
+
+  private Killable killable;
+
+  /**
+   * Does nothing except store a reference to the given {@link Killable}.
+   *
+   * @param killable {@link Killable} to kill
+   */
+  public synchronized void startObserving(final Killable killable) {
+    this.killable = killable;
+  }
+
+  /**
+   * Forgets reference to {@link Killable} provided to
+   * {@link #startObserving(Killable)}
+   */
+  public synchronized void stopObserving(final Killable killable) {
+    if (!this.killable.equals(killable)) {
+      throw new IllegalStateException("start/stopObservering called with " +
+                                      "different Killables");
+    }
+    this.killable = null;
+  }
+
+  /**
+   * Calls {@link Killable#kill()} on the saved {@link Killable}.
+   */
+  public synchronized void kill() {
+    if (killable != null) {
+      killable.kill();
+    }
+  }
+}