content: /*
   * Copyright (c) 2013 - 2014, Allen A. George <allen dot george at gmail dot com>
   *
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *     * Redistributions of source code must retain the above copyright
   *       notice, this list of conditions and the following disclaimer.
   *     * Redistributions in binary form must reproduce the above copyright
   *       notice, this list of conditions and the following disclaimer in the
   *       documentation and/or other materials provided with the distribution.
   *     * Neither the name of libraft nor the
   *       names of its contributors may be used to endorse or promote products
   *       derived from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
   * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
   * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  package io.libraft.algorithm;
  
  import com.google.common.base.Preconditions;
  import com.google.common.collect.Maps;
  
  import javax.annotation.Nullable;
  import java.util.Map;
  
  /**
   * Implements the {@link Store} interface representing the
   * data that has to be placed in durable storage for the Raft distributed consensus
   * algorithm. This clss (obviously) does not use durable storage, and is meant
   * to be used in unit tests only.
   * <p/>
   * NOTE: This class is explicitly not final so that it can be spied upon using Mockito.
   */
  class InMemoryStore implements Store {
  
      private long currentTerm = 0;
      private long commitIndex = 0;
      private final Map<Long, String> votedFor = Maps.newHashMap();
  
      @Override
      public long getCurrentTerm() throws StorageException {
          return currentTerm;
      }
  
      @Override
      public void setCurrentTerm(long currentTerm) throws StorageException {
          if (this.currentTerm != 0 && currentTerm != 0) {
              Preconditions.checkArgument(currentTerm > this.currentTerm);
          }
  
          this.currentTerm = currentTerm;
      }
  
      @Override
      public long getCommitIndex() throws StorageException {
          return commitIndex;
      }
  
      @Override
      public void setCommitIndex(long commitIndex) throws StorageException {
          if (this.currentTerm != 0 && commitIndex != 0) {
              Preconditions.checkArgument(commitIndex > this.commitIndex);
          }
  
          this.commitIndex = commitIndex;
      }
  
      @Override
      public @Nullable String getVotedFor(long term) throws StorageException {
          return votedFor.get(term);
      }
  
      @Override
      public void setVotedFor(long term, String server) throws StorageException {
          votedFor.put(term, server);
      }
  
      @Override
      public void clearVotedFor() throws StorageException {
          votedFor.clear();
      }
  }
  