// Copyright 2014 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.shell;
/**
* Implementations of this interface observe, and potentially kill,
* a {@link Killable} object. This is the mechanism by which "kill"
* functionality is exposed to callers in the
* {@link Command#execute(byte[], KillableObserver, boolean)} method.
*
*/
public interface KillableObserver {
/**
* <p>Begin observing the given {@link Killable}. This method must return
* promptly; until it returns, {@link Command#execute()} cannot complete.
* Implementations may wish to start a new {@link Thread} here to handle
* kill logic, and to interrupt or otherwise ask the thread to stop in the
* {@link #stopObserving(Killable)} method. See
* <a href="http://builder.com.com/5100-6370-5144546.html">
* Interrupting Java threads</a> for notes on how to implement this
* correctly.</p>
*
* <p>Implementations may or may not be able to observe more than
* one {@link Killable} at a time; see javadoc for details.</p>
*
* @param killable killable to observer
*/
void startObserving(Killable killable);
/**
* Stop observing the given {@link Killable}, since it is
* no longer active.
*/
void stopObserving(Killable killable);
}