gradle-master/subprojects/launcher/src/main/java/org/gradle/launcher/daemon/server/api/DaemonStateControl.java
/*
 * Copyright 2012 the original author or 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 org.gradle.launcher.daemon.server.api;

import org.gradle.initialization.BuildCancellationToken;

public interface DaemonStateControl {
    /**
     * <p>Requests that the daemon stop, but wait until the daemon is idle. The stop will happen asynchronously, and this method does not block.
     *
     * <p>The daemon will stop accepting new work, so that subsequent calls to {@link #runCommand} will fail with {@link DaemonUnavailableException}.
     */
    void requestStop(String reason);

    /**
     * Requests a forceful stops of the daemon. Does not wait until the daemon is idle to begin stopping. The stop will happen asynchronously, and this method does not block.
     *
     * <p>If any long running command is currently running, the blocked call to {@link #runCommand} will fail with {@link DaemonStoppedException}.</p>
     *
     * <p>The daemon will stop accepting new work, so that subsequent calls to {@link #runCommand} will failing with {@link DaemonUnavailableException}.
     */
    void requestForcefulStop(String reason);

    /**
     * Returns the current state of the daemon
     *
     * @return The current state of the daemon
     */
    State getState();

    /**
     * Requests that a running build be canceled.  Note that this method does NOT block until the operation has been cancelled.
     */
    void requestCancel();

    /**
     * Communicates a request for build cancellation. Note that this method blocks until the operation has been cancelled.
     *
     * <p>If any long running command is currently running, this method does block for certain time to give chance to perform cancellation, and if the command
     * doesn't finnish in a timely manner a request for forceful stop will be issued ({@link #requestForcefulStop(String reason)}.</p>
     */
    void cancelBuild();

    /**
     * Returns a cancellation token used to communicate cancel requests to commands processed in this daemon.
     *
     * @return Created cancellation token associated with currently running command or an arbitrary instance if no command is running.
     */
    BuildCancellationToken getCancellationToken();

    /**
     * Runs the given long running command. No more than 1 command may be running at any given time.
     *
     * @param command The command to run
     * @param commandDisplayName The command's display name, used for logging and error messages.
     *
     * @throws DaemonUnavailableException When this daemon is unable to run the command, either because it is currently executing another command
     * or is currently stopping.
     * @throws DaemonStoppedException When this daemon started executing the command but was unable to complete it because the daemon is about to stop.
     * The caller should note that the command may still be running at the time the method returns but should consider the command as abandoned.
     */
    void runCommand(Runnable command, String commandDisplayName) throws DaemonUnavailableException, DaemonStoppedException;

    enum State {Idle, Busy, Canceled, StopRequested, Stopped, Broken}
}
