io.gravitee.common.component.Lifecycle Maven / Gradle / Ivy

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/**
 * Copyright (C) 2015 The Gravitee team (http://gravitee.io)
 *
 * 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 io.gravitee.common.component;

/**
 * @author David BRASSELY (brasseld at gmail.com)
 */
public class Lifecycle {

  public static enum State {
    INITIALIZED,
    STOPPED,
    STARTED,
    CLOSED
  }

  private volatile State state = State.INITIALIZED;

  public State state() {
    return this.state;
  }

  /**
   * Returns true if the state is initialized.
   */
  public boolean initialized() {
    return state == State.INITIALIZED;
  }

  /**
   * Returns true if the state is started.
   */
  public boolean started() {
    return state == State.STARTED;
  }

  /**
   * Returns true if the state is stopped.
   */
  public boolean stopped() {
    return state == State.STOPPED;
  }

  /**
   * Returns true if the state is closed.
   */
  public boolean closed() {
    return state == State.CLOSED;
  }

  public boolean moveToStarted() {
    State localState = this.state;
    if (localState == State.INITIALIZED || localState == State.STOPPED) {
      state = State.STARTED;
      return true;
    }
    if (localState == State.STARTED) {
      return false;
    }
    if (localState == State.CLOSED) {
      throw new IllegalStateException("Can't move to started state when closed");
    }
    throw new IllegalStateException("Can't move to started with unknown state");
  }

  public boolean moveToStopped() {
    State localState = state;
    if (localState == State.STARTED) {
      state = State.STOPPED;
      return true;
    }
    if (localState == State.INITIALIZED || localState == State.STOPPED) {
      return false;
    }
    if (localState == State.CLOSED) {
      throw new IllegalStateException("Can't move to started state when closed");
    }
    throw new IllegalStateException("Can't move to started with unknown state");
  }

  @Override
  public String toString() {
    return state.toString();
  }
}