Initial Jack import.

Change-Id: I953cf0a520195a7187d791b2885848ad0d5a9b43

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diff --git a/guava/src/com/google/common/util/concurrent/Service.java b/guava/src/com/google/common/util/concurrent/Service.java
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+/*
+ * Copyright (C) 2009 The Guava Authors
+ *
+ * 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.common.util.concurrent;
+
+import com.google.common.annotations.Beta;
+
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Executor;
+
+/**
+ * An object with an operational state, plus asynchronous {@link #start()} and {@link #stop()}
+ * lifecycle methods to transition between states. Example services include webservers, RPC servers
+ * and timers.
+ *
+ * <p>The normal lifecycle of a service is:
+ * <ul>
+ *   <li>{@linkplain State#NEW NEW} -&gt;
+ *   <li>{@linkplain State#STARTING STARTING} -&gt;
+ *   <li>{@linkplain State#RUNNING RUNNING} -&gt;
+ *   <li>{@linkplain State#STOPPING STOPPING} -&gt;
+ *   <li>{@linkplain State#TERMINATED TERMINATED}
+ * </ul>
+ *
+ * <p>There are deviations from this if there are failures or if {@link Service#stop} is called
+ * before the {@link Service} reaches the {@linkplain State#RUNNING RUNNING} state. The set of legal
+ * transitions form a <a href="http://en.wikipedia.org/wiki/Directed_acyclic_graph">DAG</a>,
+ * therefore every method of the listener will be called at most once. N.B. The {@link State#FAILED}
+ * and {@link State#TERMINATED} states are terminal states, once a service enters either of these
+ * states it cannot ever leave them.
+ *
+ * <p>Implementors of this interface are strongly encouraged to extend one of the abstract classes
+ * in this package which implement this interface and make the threading and state management
+ * easier.
+ *
+ * @author Jesse Wilson
+ * @author Luke Sandberg
+ * @since 9.0 (in 1.0 as {@code com.google.common.base.Service})
+ */
+@Beta
+public interface Service {
+  /**
+   * If the service state is {@link State#NEW}, this initiates service startup and returns
+   * immediately. If the service has already been started, this method returns immediately without
+   * taking action. A stopped service may not be restarted.
+   *
+   * @return a future for the startup result, regardless of whether this call initiated startup.
+   *         Calling {@link ListenableFuture#get} will block until the service has finished
+   *         starting, and returns one of {@link State#RUNNING}, {@link State#STOPPING} or
+   *         {@link State#TERMINATED}. If the service fails to start, {@link ListenableFuture#get}
+   *         will throw an {@link ExecutionException}, and the service's state will be
+   *         {@link State#FAILED}. If it has already finished starting, {@link ListenableFuture#get}
+   *         returns immediately. Cancelling this future has no effect on the service.
+   */
+  ListenableFuture<State> start();
+
+  /**
+   * Initiates service startup (if necessary), returning once the service has finished starting.
+   * Unlike calling {@code start().get()}, this method throws no checked exceptions, and it cannot
+   * be {@linkplain Thread#interrupt interrupted}.
+   *
+   * @throws UncheckedExecutionException if startup failed
+   * @return the state of the service when startup finished.
+   */
+  State startAndWait();
+
+  /**
+   * Returns {@code true} if this service is {@linkplain State#RUNNING running}.
+   */
+  boolean isRunning();
+
+  /**
+   * Returns the lifecycle state of the service.
+   */
+  State state();
+
+  /**
+   * If the service is {@linkplain State#STARTING starting} or {@linkplain State#RUNNING running},
+   * this initiates service shutdown and returns immediately. If the service is
+   * {@linkplain State#NEW new}, it is {@linkplain State#TERMINATED terminated} without having been
+   * started nor stopped. If the service has already been stopped, this method returns immediately
+   * without taking action.
+   *
+   * @return a future for the shutdown result, regardless of whether this call initiated shutdown.
+   *         Calling {@link ListenableFuture#get} will block until the service has finished shutting
+   *         down, and either returns {@link State#TERMINATED} or throws an
+   *         {@link ExecutionException}. If it has already finished stopping,
+   *         {@link ListenableFuture#get} returns immediately. Cancelling this future has no effect
+   *         on the service.
+   */
+  ListenableFuture<State> stop();
+
+  /**
+   * Initiates service shutdown (if necessary), returning once the service has finished stopping. If
+   * this is {@link State#STARTING}, startup will be cancelled. If this is {@link State#NEW}, it is
+   * {@link State#TERMINATED terminated} without having been started nor stopped. Unlike calling
+   * {@code stop().get()}, this method throws no checked exceptions.
+   *
+   * @throws UncheckedExecutionException if the service has failed or fails during shutdown
+   * @return the state of the service when shutdown finished.
+   */
+  State stopAndWait();
+
+  /**
+   * Registers a {@link Listener} to be {@linkplain Executor#execute executed} on the given
+   * executor.  The listener will have the corresponding transition method called whenever the
+   * service changes state. The listener will not have previous state changes replayed, so it is
+   * suggested that listeners are added before the service starts.
+   *
+   * <p>There is no guaranteed ordering of execution of listeners, but any listener added through
+   * this method is guaranteed to be called whenever there is a state change.
+   *
+   * <p>Exceptions thrown by a listener will be propagated up to the executor. Any exception thrown
+   * during {@code Executor.execute} (e.g., a {@code RejectedExecutionException} or an exception
+   * thrown by {@linkplain MoreExecutors#sameThreadExecutor inline execution}) will be caught and
+   * logged.
+   *
+   * @param listener the listener to run when the service changes state is complete
+   * @param executor the executor in which the the listeners callback methods will be run. For fast,
+   *     lightweight listeners that would be safe to execute in any thread, consider
+   *     {@link MoreExecutors#sameThreadExecutor}.
+   * @since 13.0
+   */
+  void addListener(Listener listener, Executor executor);
+
+  /**
+   * The lifecycle states of a service.
+   *
+   * @since 9.0 (in 1.0 as {@code com.google.common.base.Service.State})
+   */
+  @Beta // should come out of Beta when Service does
+  enum State {
+    /**
+     * A service in this state is inactive. It does minimal work and consumes
+     * minimal resources.
+     */
+    NEW,
+
+    /**
+     * A service in this state is transitioning to {@link #RUNNING}.
+     */
+    STARTING,
+
+    /**
+     * A service in this state is operational.
+     */
+    RUNNING,
+
+    /**
+     * A service in this state is transitioning to {@link #TERMINATED}.
+     */
+    STOPPING,
+
+    /**
+     * A service in this state has completed execution normally. It does minimal work and consumes
+     * minimal resources.
+     */
+    TERMINATED,
+
+    /**
+     * A service in this state has encountered a problem and may not be operational. It cannot be
+     * started nor stopped.
+     */
+    FAILED
+  }
+
+  /**
+   * A listener for the various state changes that a {@link Service} goes through in its lifecycle.
+   *
+   * @author Luke Sandberg
+   * @since 13.0
+   */
+  @Beta // should come out of Beta when Service does
+  interface Listener {
+    /**
+     * Called when the service transitions from {@linkplain State#NEW NEW} to
+     * {@linkplain State#STARTING STARTING}. This occurs when {@link Service#start} or
+     * {@link Service#startAndWait} is called the first time.
+     */
+    void starting();
+
+    /**
+     * Called when the service transitions from {@linkplain State#STARTING STARTING} to
+     * {@linkplain State#RUNNING RUNNING}. This occurs when a service has successfully started.
+     */
+    void running();
+
+    /**
+     * Called when the service transitions to the {@linkplain State#STOPPING STOPPING} state. The
+     * only valid values for {@code from} are {@linkplain State#STARTING STARTING} or
+     * {@linkplain State#RUNNING RUNNING}.  This occurs when {@link Service#stop} is called.
+     *
+     * @param from The previous state that is being transitioned from.
+     */
+    void stopping(State from);
+
+    /**
+     * Called when the service transitions to the {@linkplain State#TERMINATED TERMINATED} state.
+     * The {@linkplain State#TERMINATED TERMINATED} state is a terminal state in the transition
+     * diagram.  Therefore, if this method is called, no other methods will be called on the
+     * {@link Listener}.
+     *
+     * @param from The previous state that is being transitioned from.  The only valid values for
+     *     this are {@linkplain State#NEW NEW}, {@linkplain State#RUNNING RUNNING} or
+     *     {@linkplain State#STOPPING STOPPING}.
+     */
+    void terminated(State from);
+
+    /**
+     * Called when the service transitions to the {@linkplain State#FAILED FAILED} state. The
+     * {@linkplain State#FAILED FAILED} state is a terminal state in the transition diagram.
+     * Therefore, if this method is called, no other methods will be called on the {@link Listener}.
+     *
+     * @param from The previous state that is being transitioned from.  Failure can occur in any
+     *     state with the exception of {@linkplain State#NEW NEW} or
+     *     {@linkplain State#TERMINATED TERMINATED}.
+     * @param failure The exception that caused the failure.
+     */
+    void failed(State from, Throwable failure);
+  }
+}