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/*
 * arcus-java-client : Arcus Java client
 * Copyright 2010-2014 NAVER Corp.
 *
 * 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.spy.memcached.internal;

import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

import net.spy.memcached.MemcachedConnection;
import net.spy.memcached.OperationTimeoutException;
import net.spy.memcached.compat.log.LoggerFactory;
import net.spy.memcached.ops.Operation;
import net.spy.memcached.ops.OperationState;
import net.spy.memcached.plugin.LocalCacheManager;

/**
 * Future for handling results from bulk gets.
 *
 * Not intended for general use.
 *
 * @param  types of objects returned from the GET
 */
public class BulkGetFuture implements BulkFuture> {
  private final Map> rvMap;
  private final Collection ops;
  private final CountDownLatch latch;
  private boolean cancelled = false;
  private boolean timeout = false;

  // FIXME right position?
  private LocalCacheManager localCacheManager;

  public BulkGetFuture(Map> m,
                       Collection getOps, CountDownLatch l) {
    super();
    rvMap = m;
    ops = getOps;
    latch = l;
  }

  public BulkGetFuture(Map> m,
                       Collection getOps, CountDownLatch l,
                       LocalCacheManager lcm) {
    super();
    rvMap = m;
    ops = getOps;
    latch = l;
    localCacheManager = lcm;
  }

  public boolean cancel(boolean ign) {
    boolean rv = false;
    for (Operation op : ops) {
      rv |= op.getState() == OperationState.WRITE_QUEUED;
      op.cancel("by application.");
    }
    for (Future v : rvMap.values()) {
      v.cancel(ign);
    }
    cancelled = true;
    return rv;
  }

  public Map get() throws InterruptedException, ExecutionException {
    try {
      return get(Long.MAX_VALUE, TimeUnit.MILLISECONDS);
    } catch (TimeoutException e) {
      throw new OperationTimeoutException(e);
    }
  }

  public Map getSome(long duration, TimeUnit units)
          throws InterruptedException, ExecutionException {
    Collection timedoutOps = new HashSet();
    Map ret = internalGet(duration, units, timedoutOps);
    if (timedoutOps.size() > 0) {
      timeout = true;
      LoggerFactory.getLogger(getClass()).warn(
              new CheckedOperationTimeoutException(duration, units, timedoutOps).getMessage());
    }
    return ret;

  }

  /*
   * get all or nothing: timeout exception is thrown if all the data could not
   * be retrieved
   *
   * @see java.util.concurrent.Future#get(long, java.util.concurrent.TimeUnit)
   */
  public Map get(long duration, TimeUnit units)
          throws InterruptedException, ExecutionException, TimeoutException {
    Collection timedoutOps = new HashSet();
    Map ret = internalGet(duration, units, timedoutOps);
    if (timedoutOps.size() > 0) {
      this.timeout = true;
      throw new CheckedOperationTimeoutException(duration, units, timedoutOps);
    }
    return ret;
  }

  /**
   * refactored code common to both get(long, TimeUnit) and getSome(long,
   * TimeUnit)
   */
  private Map internalGet(long to, TimeUnit unit,
                                     Collection timedoutOps) throws InterruptedException,
          ExecutionException {
    if (!latch.await(to, unit)) {
      for (Operation op : ops) {
        if (op.getState() != OperationState.COMPLETE) {
          MemcachedConnection.opTimedOut(op);
          timedoutOps.add(op);
        } else {
          MemcachedConnection.opSucceeded(op);
        }
      }
    }
    for (Operation op : ops) {
      if (op.isCancelled()) {
        throw new ExecutionException(new RuntimeException(op.getCancelCause()));
      }
      if (op.hasErrored()) {
        throw new ExecutionException(op.getException());
      }
    }
    Map m = new HashMap();
    for (Map.Entry> me : rvMap.entrySet()) {
      String key = me.getKey();
      Future future = me.getValue();
      T value = future.get();

      // put the key into the result map.
      m.put(key, value);

      // cache the key locally
      if (localCacheManager != null) {
        // iff it is from the remote cache.
        if (!(future instanceof LocalCacheManager.Task)) {
          localCacheManager.put(key, value);
        }
      }
    }
    return m;
  }

  public boolean isCancelled() {
    return cancelled;
  }

  public boolean isDone() {
    return latch.getCount() == 0;
  }

  /*
   * set to true if timeout was reached.
   *
   * @see net.spy.memcached.internal.BulkFuture#isTimeout()
   */
  public boolean isTimeout() {
    return timeout;
  }
}