code: /*
   * Copyright 2012-2018 Chronicle Map Contributors
   *
   * 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 net.openhft.chronicle.map.ipc;
  
  import net.openhft.chronicle.bytes.Byteable;
  import net.openhft.chronicle.bytes.BytesStore;
  
  /**
   *
   */
  public class StateMachineData implements Byteable {
      private BytesStore bs;
      private long offset;
  
      /**
       * c-tor
       */
      public StateMachineData() {
          this.bs = null;
          this.offset = -1;
      }
  
      // *************************************************************************
      //
      // *************************************************************************
  
      /**
       */
      public boolean stateIn(StateMachineState... states) {
          StateMachineState currentState = getState();
          for (StateMachineState state : states) {
              if (state == currentState) {
                  return true;
              }
          }
  
          return false;
      }
  
      /**
       */
      public boolean setState(StateMachineState from, StateMachineState to) {
          if (this.bs == null) throw new NullPointerException("Byteable is not set to off heap");
  
          return this.bs.compareAndSwapInt(this.offset, from.value(), to.value());
      }
  
      /**
       */
      public StateMachineState getState() {
          if (this.bs == null) throw new NullPointerException("Byteable is not set to off heap");
  
          int value = this.bs.readVolatileInt(this.offset);
          return StateMachineState.fromValue(value);
      }
  
      /**
       */
      public void setState(StateMachineState state) {
          if (this.bs == null) throw new NullPointerException("Byteable is not set to off heap");
  
          this.bs.writeInt(this.offset, state.value());
      }
  
      /**
       * Wait for a state and make a transition.
       * It spins initially (1000 iterations), then uses a Thread.yield() .
       *
       */
      public void waitForState(StateMachineState from, StateMachineState to) {
          if (this.bs == null) throw new NullPointerException("Byteable is not set to off heap");
  
          // spin
          for (int i = 0; !setState(from, to); i++) {
              if (i > 1000) {
                  Thread.yield(); // back off a little.
              }
          }
      }
  
      // *************************************************************************
      //
      // *************************************************************************
  
      /**
       */
      public int getStateData() {
          if (this.bs != null) {
              return this.bs.readVolatileInt(this.offset + 4);
          }
  
          return -1;
      }
  
      /**
       */
      public void setStateData(int data) {
          if (this.bs != null) {
              this.bs.writeInt(this.offset + 4, data);
          }
      }
  
      /**
       */
      public int incStateData() {
          if (this.bs != null) {
              return this.bs.addAndGetInt(this.offset + 4, 1);
          }
  
          return -1;
      }
  
      /**
       */
      public boolean done() {
          if (this.bs != null) {
              return getStateData() > 100;
          }
  
          return true;
      }
  
      // *************************************************************************
      //
      // *************************************************************************
  
      @Override
      public void bytesStore(BytesStore bytes, long offset, long size) {
          if (size != 16)
              throw new IllegalArgumentException();
          this.bs = bytes;
          this.offset = offset;
      }
  
      @Override
      public BytesStore bytesStore() {
          return this.bs;
      }
  
      @Override
      public long offset() {
          return this.offset;
      }
  
      @Override
      public long maxSize() {
          return 16;
      }
  }
  