1 files changed, 102 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/shell/TimeoutKillableObserver.java b/src/main/java/com/google/devtools/build/lib/shell/TimeoutKillableObserver.java
new file mode 100644
index 0000000000..c2ed033fed
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+++ b/src/main/java/com/google/devtools/build/lib/shell/TimeoutKillableObserver.java
@@ -0,0 +1,102 @@
+// 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;
+
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+/**
+ * <p>{@link KillableObserver} implementation which will kill its observed
+ * {@link Killable} if it is still being observed after a given amount
+ * of time has elapsed.</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 TimeoutKillableObserver implements KillableObserver {
+
+  private static final Logger log =
+      Logger.getLogger(TimeoutKillableObserver.class.getCanonicalName());
+
+  private final long timeoutMS;
+  private Killable killable;
+  private SleeperThread sleeperThread;
+  private boolean timedOut;
+
+  // TODO(bazel-team): I'd like to use ThreadPool2, but it doesn't currently
+  // provide a way to interrupt a thread
+
+  public TimeoutKillableObserver(final long timeoutMS) {
+    this.timeoutMS = timeoutMS;
+  }
+
+  /**
+   * Starts a new {@link Thread} to wait for the timeout period. This is
+   * interrupted by the {@link #stopObserving(Killable)} method.
+   *
+   * @param killable killable to kill when the timeout period expires
+   */
+  @Override
+  public synchronized void startObserving(final Killable killable) {
+    this.timedOut = false;
+    this.killable = killable;
+    this.sleeperThread = new SleeperThread();
+    this.sleeperThread.start();
+  }
+
+  @Override
+  public synchronized void stopObserving(final Killable killable) {
+    if (!this.killable.equals(killable)) {
+      throw new IllegalStateException("start/stopObservering called with " +
+                                      "different Killables");
+    }
+    if (sleeperThread.isAlive()) {
+      sleeperThread.interrupt();
+    }
+    this.killable = null;
+    sleeperThread = null;
+  }
+
+  private final class SleeperThread extends Thread {
+    @Override public void run() {
+      try {
+        if (log.isLoggable(Level.FINE)) {
+          log.fine("Waiting for " + timeoutMS + "ms to kill process");
+        }
+        Thread.sleep(timeoutMS);
+        // timeout expired; kill it
+        synchronized (TimeoutKillableObserver.this) {
+          if (killable != null) {
+            log.fine("Killing process");
+            killable.kill();
+            timedOut = true;
+          }
+        }
+      } catch (InterruptedException ie) {
+        // continue -- process finished before timeout
+        log.fine("Wait interrupted since process finished; continuing...");
+      }
+    }
+  }
+
+  /**
+   * Returns true if the observed process was killed by this observer.
+   */
+  public synchronized boolean hasTimedOut() {
+    // synchronized needed for memory model visibility.
+    return timedOut;
+  }
+}