Package net.spy.memcached

Source Code of net.spy.memcached.MemcachedClient

// Copyright (c) 2006  Dustin Sallings <dustin@spy.net>

package net.spy.memcached;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.net.URI;
import java.nio.channels.CancelledKeyException;
import java.nio.channels.ClosedSelectorException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.ConcurrentMap;
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 java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;

import net.spy.memcached.auth.AuthDescriptor;
import net.spy.memcached.auth.AuthThreadMonitor;
import net.spy.memcached.auth.PlainCallbackHandler;
import net.spy.memcached.compat.SpyThread;
import net.spy.memcached.internal.BulkFuture;
import net.spy.memcached.internal.BulkGetFuture;
import net.spy.memcached.internal.GetFuture;
import net.spy.memcached.internal.OperationFuture;
import net.spy.memcached.internal.SingleElementInfiniteIterator;
import net.spy.memcached.ops.CASOperationStatus;
import net.spy.memcached.ops.CancelledOperationStatus;
import net.spy.memcached.ops.ConcatenationType;
import net.spy.memcached.ops.DeleteOperation;
import net.spy.memcached.ops.GetAndTouchOperation;
import net.spy.memcached.ops.GetOperation;
import net.spy.memcached.ops.GetlOperation;
import net.spy.memcached.ops.GetsOperation;
import net.spy.memcached.ops.Mutator;
import net.spy.memcached.ops.Operation;
import net.spy.memcached.ops.OperationCallback;
import net.spy.memcached.ops.OperationState;
import net.spy.memcached.ops.OperationStatus;
import net.spy.memcached.ops.StatsOperation;
import net.spy.memcached.ops.StoreType;
import net.spy.memcached.transcoders.TranscodeService;
import net.spy.memcached.transcoders.Transcoder;
import net.spy.memcached.vbucket.ConfigurationException;
import net.spy.memcached.vbucket.ConfigurationProvider;
import net.spy.memcached.vbucket.ConfigurationProviderHTTP;
import net.spy.memcached.vbucket.Reconfigurable;
import net.spy.memcached.vbucket.config.Bucket;
import net.spy.memcached.vbucket.config.Config;
import net.spy.memcached.vbucket.config.ConfigType;

/**
* Client to a memcached server.
*
* <h2>Basic usage</h2>
*
* <pre>
*  MemcachedClient c=new MemcachedClient(
*    new InetSocketAddress("hostname", portNum));
*
*  // Store a value (async) for one hour
*  c.set("someKey", 3600, someObject);
*  // Retrieve a value.
*  Object myObject=c.get("someKey");
</pre>
*
<h2>Advanced Usage</h2>
*
<p>
*   MemcachedClient may be processing a great deal of asynchronous messages or
*   possibly dealing with an unreachable memcached, which may delay processing.
*   If a memcached is disabled, for example, MemcachedConnection will continue
*   to attempt to reconnect and replay pending operations until it comes back
*   up.  To prevent this from causing your application to hang, you can use
*   one of the asynchronous mechanisms to time out a request and cancel the
*   operation to the server.
</p>
*
<pre>
*      // Get a memcached client connected to several servers
*      // over the binary protocol
*      MemcachedClient c = new MemcachedClient(new BinaryConnectionFactory(),
*              AddrUtil.getAddresses("server1:11211 server2:11211"));
*
*      // Try to get a value, for up to 5 seconds, and cancel if it
*      // doesn't return
*      Object myObj = null;
*      Future&lt;Object&gt; f = c.asyncGet("someKey");
*      try {
*          myObj = f.get(5, TimeUnit.SECONDS);
*      // throws expecting InterruptedException, ExecutionException
*      // or TimeoutException
*      } catch (Exception e) {  /*  /
*          // Since we don't need this, go ahead and cancel the operation.
*          // This is not strictly necessary, but it'll save some work on
*          // the server.  It is okay to cancel it if running.
*          f.cancel(true);
*          // Do other timeout related stuff
*      }
* </pre>
*/
public class MemcachedClient extends SpyThread
  implements MemcachedClientIF, ConnectionObserver, Reconfigurable {

  private volatile boolean running=true;
  private volatile boolean shuttingDown=false;

  private final long operationTimeout;

  private final MemcachedConnection conn;
  final OperationFactory opFact;

  final Transcoder<Object> transcoder;

  final TranscodeService tcService;

  final AuthDescriptor authDescriptor;

  private final AuthThreadMonitor authMonitor = new AuthThreadMonitor();
  private volatile boolean reconfiguring = false;
  private ConfigurationProvider configurationProvider;

  /**
   * Get a memcache client operating on the specified memcached locations.
   *
   * @param ia the memcached locations
   * @throws IOException if connections cannot be established
   */
  public MemcachedClient(InetSocketAddress... ia) throws IOException {
    this(new DefaultConnectionFactory(), Arrays.asList(ia));
  }

  /**
   * Get a memcache client over the specified memcached locations.
   *
   * @param addrs the socket addrs
   * @throws IOException if connections cannot be established
   */
  public MemcachedClient(List<InetSocketAddress> addrs)
    throws IOException {
    this(new DefaultConnectionFactory(), addrs);
  }

  /**
   * Get a memcache client over the specified memcached locations.
   *
   * @param cf the connection factory to configure connections for this client
   * @param addrs the socket addresses
   * @throws IOException if connections cannot be established
   */
  public MemcachedClient(ConnectionFactory cf, List<InetSocketAddress> addrs)
    throws IOException {
    if(cf == null) {
      throw new NullPointerException("Connection factory required");
    }
    if(addrs == null) {
      throw new NullPointerException("Server list required");
    }
    if(addrs.isEmpty()) {
      throw new IllegalArgumentException(
        "You must have at least one server to connect to");
    }
    if(cf.getOperationTimeout() <= 0) {
      throw new IllegalArgumentException(
        "Operation timeout must be positive.");
    }
    tcService = new TranscodeService(cf.isDaemon());
    transcoder=cf.getDefaultTranscoder();
    opFact=cf.getOperationFactory();
    assert opFact != null : "Connection factory failed to make op factory";
    conn=cf.createConnection(addrs);
    assert conn != null : "Connection factory failed to make a connection";
    operationTimeout = cf.getOperationTimeout();
    authDescriptor = cf.getAuthDescriptor();
    if(authDescriptor != null) {
      addObserver(this);
    }
    setName("Memcached IO over " + conn);
    setDaemon(cf.isDaemon());
    start();
  }

  /**
   * Get a MemcachedClient based on the REST response from a Membase server
   * where the username is different than the bucket name.
   *
   * To connect to the "default" special bucket for a given cluster, use an
   * empty string as the password.
   *
   * If a password has not been assigned to the bucket, it is typically an
   * empty string.
   *
   * @param baseList the URI list of one or more servers from the cluster
   * @param bucketName the bucket name in the cluster you wish to use
   * @param usr the username for the bucket; this nearly always be the same
   *        as the bucket name
   * @param pwd the password for the bucket
   * @throws IOException if connections could not be made
   * @throws ConfigurationException if the configuration provided by the
   *         server has issues or is not compatible
   */
  public MemcachedClient(final List<URI> baseList,
    final String bucketName,
    final String usr, final String pwd) throws IOException, ConfigurationException {
    for (URI bu : baseList) {
      if (!bu.isAbsolute()) {
        throw new IllegalArgumentException("The base URI must be absolute");
      }
    }
    this.configurationProvider = new ConfigurationProviderHTTP(baseList, usr, pwd);
    Bucket bucket = this.configurationProvider.getBucketConfiguration(bucketName);
    Config config = bucket.getConfig();
    ConnectionFactoryBuilder cfb = new ConnectionFactoryBuilder();
    if (config.getConfigType() == ConfigType.MEMBASE) {
      cfb.setFailureMode(FailureMode.Retry)
        .setProtocol(ConnectionFactoryBuilder.Protocol.BINARY)
        .setHashAlg(HashAlgorithm.KETAMA_HASH)
        .setLocatorType(ConnectionFactoryBuilder.Locator.VBUCKET)
        .setVBucketConfig(bucket.getConfig());
    } else if (config.getConfigType() == ConfigType.MEMCACHE) {
      cfb.setFailureMode(FailureMode.Retry)
        .setProtocol(ConnectionFactoryBuilder.Protocol.BINARY)
        .setHashAlg(HashAlgorithm.KETAMA_HASH)
        .setLocatorType(ConnectionFactoryBuilder.Locator.CONSISTENT);
    } else {
      throw new ConfigurationException("Bucket type not supported or JSON response unexpected");
    }
    if (!this.configurationProvider.getAnonymousAuthBucket().equals(bucketName) && usr != null) {
      AuthDescriptor ad = new AuthDescriptor(new String[]{"PLAIN"},
        new PlainCallbackHandler(usr, pwd));
      cfb.setAuthDescriptor(ad);
    }
    ConnectionFactory cf = cfb.build();
    List<InetSocketAddress> addrs = AddrUtil.getAddresses(bucket.getConfig().getServers());
    if(cf == null) {
      throw new NullPointerException("Connection factory required");
    }
    if(addrs == null) {
      throw new NullPointerException("Server list required");
    }
    if(addrs.isEmpty()) {
      throw new IllegalArgumentException(
      "You must have at least one server to connect to");
    }
    if(cf.getOperationTimeout() <= 0) {
      throw new IllegalArgumentException(
        "Operation timeout must be positive.");
    }
    tcService = new TranscodeService(cf.isDaemon());
    transcoder=cf.getDefaultTranscoder();
    opFact=cf.getOperationFactory();
    assert opFact != null : "Connection factory failed to make op factory";
    conn=cf.createConnection(addrs);
    assert conn != null : "Connection factory failed to make a connection";
    operationTimeout = cf.getOperationTimeout();
    authDescriptor = cf.getAuthDescriptor();
    if(authDescriptor != null) {
      addObserver(this);
    }
    setName("Memcached IO over " + conn);
    setDaemon(cf.isDaemon());
    this.configurationProvider.subscribe(bucketName, this);
    start();
  }

  /**
   * Get a MemcachedClient based on the REST response from a Membase server.
   *
   * This constructor is merely a convenience for situations where the bucket
   * name is the same as the user name.  This is commonly the case.
   *
   * To connect to the "default" special bucket for a given cluster, use an
   * empty string as the password.
   *
   * If a password has not been assigned to the bucket, it is typically an
   * empty string.
   *
   * @param baseList the URI list of one or more servers from the cluster
   * @param bucketName the bucket name in the cluster you wish to use
   * @param pwd the password for the bucket
   * @throws IOException if connections could not be made
   * @throws ConfigurationException if the configuration provided by the
   *         server has issues or is not compatible
   */
  public MemcachedClient(List<URI> baseList,
    String bucketName,
    String pwd) throws IOException, ConfigurationException {
    this(baseList, bucketName, bucketName, pwd);
  }
  public void reconfigure(Bucket bucket) {
    reconfiguring = true;
    try {
      conn.reconfigure(bucket);
    } catch (IllegalArgumentException ex) {
      getLogger().warn("Failed to reconfigure client, staying with previous configuration.", ex);
    } finally {
      reconfiguring = false;
    }
  }

  /**
   * Get the addresses of available servers.
   *
   * <p>
   * This is based on a snapshot in time so shouldn't be considered
   * completely accurate, but is a useful for getting a feel for what's
   * working and what's not working.
   * </p>
   *
   * @return point-in-time view of currently available servers
   */
  public Collection<SocketAddress> getAvailableServers() {
    ArrayList<SocketAddress> rv=new ArrayList<SocketAddress>();
    for(MemcachedNode node : conn.getLocator().getAll()) {
      if(node.isActive()) {
        rv.add(node.getSocketAddress());
      }
    }
    return rv;
  }

  /**
   * Get the addresses of unavailable servers.
   *
   * <p>
   * This is based on a snapshot in time so shouldn't be considered
   * completely accurate, but is a useful for getting a feel for what's
   * working and what's not working.
   * </p>
   *
   * @return point-in-time view of currently available servers
   */
  public Collection<SocketAddress> getUnavailableServers() {
    ArrayList<SocketAddress> rv=new ArrayList<SocketAddress>();
    for(MemcachedNode node : conn.getLocator().getAll()) {
      if(!node.isActive()) {
        rv.add(node.getSocketAddress());
      }
    }
    return rv;
  }

  /**
   * Get a read-only wrapper around the node locator wrapping this instance.
   *
   * @return this instance's NodeLocator
   */
  public NodeLocator getNodeLocator() {
    return conn.getLocator().getReadonlyCopy();
  }

  /**
   * Get the default transcoder that's in use.
   *
   * @return this instance's Transcoder
   */
  public Transcoder<Object> getTranscoder() {
    return transcoder;
  }

  private void validateKey(String key) {
    byte[] keyBytes=KeyUtil.getKeyBytes(key);
    if(keyBytes.length > MAX_KEY_LENGTH) {
      throw new IllegalArgumentException("Key is too long (maxlen = "
          + MAX_KEY_LENGTH + ")");
    }
    if(keyBytes.length == 0) {
      throw new IllegalArgumentException(
        "Key must contain at least one character.");
    }
    // Validate the key
    for(byte b : keyBytes) {
      if(b == ' ' || b == '\n' || b == '\r' || b == 0) {
        throw new IllegalArgumentException(
          "Key contains invalid characters:  ``" + key + "''");
      }
    }
  }

  private void checkState() {
    if(shuttingDown) {
      throw new IllegalStateException("Shutting down");
    }
    assert isAlive() : "IO Thread is not running.";
  }

  /**
   * (internal use) Add a raw operation to a numbered connection.
   * This method is exposed for testing.
   *
   * @param which server number
   * @param op the operation to perform
   * @return the Operation
   */
  Operation addOp(final String key, final Operation op) {
    validateKey(key);
    checkState();
    conn.addOperation(key, op);
    return op;
  }

  CountDownLatch broadcastOp(final BroadcastOpFactory of) {
    return broadcastOp(of, conn.getLocator().getAll(), true);
  }

  CountDownLatch broadcastOp(final BroadcastOpFactory of,
      Collection<MemcachedNode> nodes) {
    return broadcastOp(of, nodes, true);
  }

  private CountDownLatch broadcastOp(BroadcastOpFactory of,
      Collection<MemcachedNode> nodes,
      boolean checkShuttingDown) {
    if(checkShuttingDown && shuttingDown) {
      throw new IllegalStateException("Shutting down");
    }
    return conn.broadcastOperation(of, nodes);
  }

  private <T> Future<Boolean> asyncStore(StoreType storeType, String key,
               int exp, T value, Transcoder<T> tc) {
    CachedData co=tc.encode(value);
    final CountDownLatch latch=new CountDownLatch(1);
    final OperationFuture<Boolean> rv=new OperationFuture<Boolean>(latch,
        operationTimeout);
    Operation op=opFact.store(storeType, key, co.getFlags(),
        exp, co.getData(), new OperationCallback() {
          public void receivedStatus(OperationStatus val) {
            rv.set(val.isSuccess());
          }
          public void complete() {
            latch.countDown();
          }});
    rv.setOperation(op);
    addOp(key, op);
    return rv;
  }

  private Future<Boolean> asyncStore(StoreType storeType,
      String key, int exp, Object value) {
    return asyncStore(storeType, key, exp, value, transcoder);
  }

  private <T> Future<Boolean> asyncCat(
      ConcatenationType catType, long cas, String key,
      T value, Transcoder<T> tc) {
    CachedData co=tc.encode(value);
    final CountDownLatch latch=new CountDownLatch(1);
    final OperationFuture<Boolean> rv=new OperationFuture<Boolean>(latch,
        operationTimeout);
    Operation op=opFact.cat(catType, cas, key, co.getData(),
        new OperationCallback() {
      public void receivedStatus(OperationStatus val) {
        rv.set(val.isSuccess());
      }
      public void complete() {
        latch.countDown();
      }});
    rv.setOperation(op);
    addOp(key, op);
    return rv;
  }

  /**
   * Touch the given key to reset its expiration time with the default
   * transcoder.
   *
   * @param key the key to fetch
   * @param exp the new expiration to set for the given key
   * @return a future that will hold the return value of whether or not
   * the fetch succeeded
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public <T> Future<Boolean> touch(final String key, final int exp) {
    return touch(key, exp, transcoder);
  }

  /**
   * Touch the given key to reset its expiration time.
   *
   * @param key the key to fetch
   * @param exp the new expiration to set for the given key
   * @param tc the transcoder to serialize and unserialize value
   * @return a future that will hold the return value of whether or not
   * the fetch succeeded
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public <T> Future<Boolean> touch(final String key, final int exp,
      final Transcoder<T> tc) {
    final CountDownLatch latch=new CountDownLatch(1);
    final OperationFuture<Boolean> rv=new OperationFuture<Boolean>(latch,
        operationTimeout);

    Operation op=opFact.touch(key, exp, new OperationCallback() {
      public void receivedStatus(OperationStatus status) {
        rv.set(status.isSuccess());
    }
      public void complete() {
        latch.countDown();
      }});
    rv.setOperation(op);
    addOp(key, op);
    return rv;
  }

  /**
   * Append to an existing value in the cache.
   *
   * <p>Note that the return will be false any time a mutation has not
   * occurred.</p>
   *
   * @param cas cas identifier (ignored in the ascii protocol)
   * @param key the key to whose value will be appended
   * @param val the value to append
   * @return a future indicating success, false if there was no change
   *         to the value
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public Future<Boolean> append(long cas, String key, Object val) {
    return append(cas, key, val, transcoder);
  }

  /**
   * Append to an existing value in the cache.
   *
   * <p>Note that the return will be false any time a mutation has not
   * occurred.</p>
   *
   * @param <T>
   * @param cas cas identifier (ignored in the ascii protocol)
   * @param key the key to whose value will be appended
   * @param val the value to append
   * @param tc the transcoder to serialize and unserialize the value
   * @return a future indicating success
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public <T> Future<Boolean> append(long cas, String key, T val,
      Transcoder<T> tc) {
    return asyncCat(ConcatenationType.append, cas, key, val, tc);
  }

  /**
   * Prepend to an existing value in the cache.
   *
   * <p>Note that the return will be false any time a mutation has not
   * occurred.</p>
   *
   * @param cas cas identifier (ignored in the ascii protocol)
   * @param key the key to whose value will be prepended
   * @param val the value to append
   * @return a future indicating success
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public Future<Boolean> prepend(long cas, String key, Object val) {
    return prepend(cas, key, val, transcoder);
  }

  /**
   * Prepend to an existing value in the cache.
   *
   * <p>Note that the return will be false any time a mutation has not
   * occurred.</p>
   *
   * @param <T>
   * @param cas cas identifier (ignored in the ascii protocol)
   * @param key the key to whose value will be prepended
   * @param val the value to append
   * @param tc the transcoder to serialize and unserialize the value
   * @return a future indicating success
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public <T> Future<Boolean> prepend(long cas, String key, T val,
      Transcoder<T> tc) {
    return asyncCat(ConcatenationType.prepend, cas, key, val, tc);
  }

  /**
     * Asynchronous CAS operation.
     *
     * @param <T>
     * @param key the key
     * @param casId the CAS identifier (from a gets operation)
     * @param value the new value
     * @param tc the transcoder to serialize and unserialize the value
     * @return a future that will indicate the status of the CAS
     * @throws IllegalStateException in the rare circumstance where queue
     *         is too full to accept any more requests
     */
    public <T> Future<CASResponse> asyncCAS(String key, long casId, T value,
            Transcoder<T> tc) {
        return asyncCAS(key, casId, 0, value, tc);
  }

  /**
   * Asynchronous CAS operation.
   *
   * @param <T>
   * @param key the key
   * @param casId the CAS identifier (from a gets operation)
   * @param exp the expiration of this object
   * @param value the new value
   * @param tc the transcoder to serialize and unserialize the value
   * @return a future that will indicate the status of the CAS
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public <T> Future<CASResponse> asyncCAS(String key, long casId, int exp, T value,
      Transcoder<T> tc) {
    CachedData co=tc.encode(value);
    final CountDownLatch latch=new CountDownLatch(1);
    final OperationFuture<CASResponse> rv=new OperationFuture<CASResponse>(
        latch, operationTimeout);
    Operation op=opFact.cas(StoreType.set, key, casId, co.getFlags(), exp,
        co.getData(), new OperationCallback() {
          public void receivedStatus(OperationStatus val) {
            if(val instanceof CASOperationStatus) {
              rv.set(((CASOperationStatus)val).getCASResponse());
            } else if(val instanceof CancelledOperationStatus) {
              // Cancelled, ignore and let it float up
            } else {
              throw new RuntimeException(
                "Unhandled state: " + val);
            }
          }
          public void complete() {
            latch.countDown();
          }});
    rv.setOperation(op);
    addOp(key, op);
    return rv;
  }

  /**
   * Asynchronous CAS operation using the default transcoder.
   *
   * @param key the key
   * @param casId the CAS identifier (from a gets operation)
   * @param value the new value
   * @return a future that will indicate the status of the CAS
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public Future<CASResponse> asyncCAS(String key, long casId, Object value) {
    return asyncCAS(key, casId, value, transcoder);
  }

  /**
     * Perform a synchronous CAS operation.
     *
     * @param <T>
     * @param key the key
     * @param casId the CAS identifier (from a gets operation)
     * @param value the new value
     * @param tc the transcoder to serialize and unserialize the value
     * @return a CASResponse
     * @throws OperationTimeoutException if global operation timeout is
     *         exceeded
     * @throws IllegalStateException in the rare circumstance where queue
     *         is too full to accept any more requests
     */
    public <T> CASResponse cas(String key, long casId, T value,
            Transcoder<T> tc) {
        return cas(key, casId, 0, value, tc);
    }

  /**
   * Perform a synchronous CAS operation.
   *
   * @param <T>
   * @param key the key
   * @param casId the CAS identifier (from a gets operation)
   * @param exp the expiration of this object
   * @param value the new value
   * @param tc the transcoder to serialize and unserialize the value
   * @return a CASResponse
   * @throws OperationTimeoutException if global operation timeout is
   *         exceeded
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public <T> CASResponse cas(String key, long casId, int exp, T value,
      Transcoder<T> tc) {
    try {
      return asyncCAS(key, casId, exp, value, tc).get(operationTimeout,
          TimeUnit.MILLISECONDS);
    } catch (InterruptedException e) {
      throw new RuntimeException("Interrupted waiting for value", e);
    } catch (ExecutionException e) {
      throw new RuntimeException("Exception waiting for value", e);
    } catch (TimeoutException e) {
      throw new OperationTimeoutException("Timeout waiting for value", e);
    }
  }

  /**
   * Perform a synchronous CAS operation with the default transcoder.
   *
   * @param key the key
   * @param casId the CAS identifier (from a gets operation)
   * @param value the new value
   * @return a CASResponse
   * @throws OperationTimeoutException if the global operation timeout is
   *       exceeded
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public CASResponse cas(String key, long casId, Object value) {
    return cas(key, casId, value, transcoder);
  }

  /**
   * Add an object to the cache iff it does not exist already.
   *
   * <p>
   * The <code>exp</code> value is passed along to memcached exactly as
   * given, and will be processed per the memcached protocol specification:
   * </p>
   *
   * <p>Note that the return will be false any time a mutation has not
   * occurred.</p>
   *
   * <blockquote>
   * <p>
   * The actual value sent may either be
   * Unix time (number of seconds since January 1, 1970, as a 32-bit
   * value), or a number of seconds starting from current time. In the
   * latter case, this number of seconds may not exceed 60*60*24*30 (number
   * of seconds in 30 days); if the number sent by a client is larger than
   * that, the server will consider it to be real Unix time value rather
   * than an offset from current time.
   * </p>
   * </blockquote>
   *
   * @param <T>
   * @param key the key under which this object should be added.
   * @param exp the expiration of this object
   * @param o the object to store
   * @param tc the transcoder to serialize and unserialize the value
   * @return a future representing the processing of this operation
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public <T> Future<Boolean> add(String key, int exp, T o, Transcoder<T> tc) {
    return asyncStore(StoreType.add, key, exp, o, tc);
  }

  /**
   * Add an object to the cache (using the default transcoder)
   * iff it does not exist already.
   *
   * <p>
   * The <code>exp</code> value is passed along to memcached exactly as
   * given, and will be processed per the memcached protocol specification:
   * </p>
   *
   * <p>Note that the return will be false any time a mutation has not
   * occurred.</p>
   *
   * <blockquote>
   * <p>
   * The actual value sent may either be
   * Unix time (number of seconds since January 1, 1970, as a 32-bit
   * value), or a number of seconds starting from current time. In the
   * latter case, this number of seconds may not exceed 60*60*24*30 (number
   * of seconds in 30 days); if the number sent by a client is larger than
   * that, the server will consider it to be real Unix time value rather
   * than an offset from current time.
   * </p>
   * </blockquote>
   *
   * @param key the key under which this object should be added.
   * @param exp the expiration of this object
   * @param o the object to store
   * @return a future representing the processing of this operation
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public Future<Boolean> add(String key, int exp, Object o) {
    return asyncStore(StoreType.add, key, exp, o, transcoder);
  }

  /**
   * Set an object in the cache regardless of any existing value.
   *
   * <p>
   * The <code>exp</code> value is passed along to memcached exactly as
   * given, and will be processed per the memcached protocol specification:
   * </p>
   *
   * <p>Note that the return will be false any time a mutation has not
   * occurred.</p>
   *
   * <blockquote>
   * <p>
   * The actual value sent may either be
   * Unix time (number of seconds since January 1, 1970, as a 32-bit
   * value), or a number of seconds starting from current time. In the
   * latter case, this number of seconds may not exceed 60*60*24*30 (number
   * of seconds in 30 days); if the number sent by a client is larger than
   * that, the server will consider it to be real Unix time value rather
   * than an offset from current time.
   * </p>
   * </blockquote>
   *
   * @param <T>
   * @param key the key under which this object should be added.
   * @param exp the expiration of this object
   * @param o the object to store
   * @param tc the transcoder to serialize and unserialize the value
   * @return a future representing the processing of this operation
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public <T> Future<Boolean> set(String key, int exp, T o, Transcoder<T> tc) {
    return asyncStore(StoreType.set, key, exp, o, tc);
  }

  /**
   * Set an object in the cache (using the default transcoder)
   * regardless of any existing value.
   *
   * <p>
   * The <code>exp</code> value is passed along to memcached exactly as
   * given, and will be processed per the memcached protocol specification:
   * </p>
   *
   * <p>Note that the return will be false any time a mutation has not
   * occurred.</p>
   *
   * <blockquote>
   * <p>
   * The actual value sent may either be
   * Unix time (number of seconds since January 1, 1970, as a 32-bit
   * value), or a number of seconds starting from current time. In the
   * latter case, this number of seconds may not exceed 60*60*24*30 (number
   * of seconds in 30 days); if the number sent by a client is larger than
   * that, the server will consider it to be real Unix time value rather
   * than an offset from current time.
   * </p>
   * </blockquote>
   *
   * @param key the key under which this object should be added.
   * @param exp the expiration of this object
   * @param o the object to store
   * @return a future representing the processing of this operation
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public Future<Boolean> set(String key, int exp, Object o) {
    return asyncStore(StoreType.set, key, exp, o, transcoder);
  }

  /**
   * Replace an object with the given value iff there is already a value
   * for the given key.
   *
   * <p>
   * The <code>exp</code> value is passed along to memcached exactly as
   * given, and will be processed per the memcached protocol specification:
   * </p>
   *
   * <p>Note that the return will be false any time a mutation has not
   * occurred.</p>
   *
   * <blockquote>
   * <p>
   * The actual value sent may either be
   * Unix time (number of seconds since January 1, 1970, as a 32-bit
   * value), or a number of seconds starting from current time. In the
   * latter case, this number of seconds may not exceed 60*60*24*30 (number
   * of seconds in 30 days); if the number sent by a client is larger than
   * that, the server will consider it to be real Unix time value rather
   * than an offset from current time.
   * </p>
   * </blockquote>
   *
   * @param <T>
   * @param key the key under which this object should be added.
   * @param exp the expiration of this object
   * @param o the object to store
   * @param tc the transcoder to serialize and unserialize the value
   * @return a future representing the processing of this operation
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public <T> Future<Boolean> replace(String key, int exp, T o,
    Transcoder<T> tc) {
    return asyncStore(StoreType.replace, key, exp, o, tc);
  }

  /**
   * Replace an object with the given value (transcoded with the default
   * transcoder) iff there is already a value for the given key.
   *
   * <p>
   * The <code>exp</code> value is passed along to memcached exactly as
   * given, and will be processed per the memcached protocol specification:
   * </p>
   *
   * <p>Note that the return will be false any time a mutation has not
   * occurred.</p>
   *
   * <blockquote>
   * <p>
   * The actual value sent may either be
   * Unix time (number of seconds since January 1, 1970, as a 32-bit
   * value), or a number of seconds starting from current time. In the
   * latter case, this number of seconds may not exceed 60*60*24*30 (number
   * of seconds in 30 days); if the number sent by a client is larger than
   * that, the server will consider it to be real Unix time value rather
   * than an offset from current time.
   * </p>
   * </blockquote>
   *
   * @param key the key under which this object should be added.
   * @param exp the expiration of this object
   * @param o the object to store
   * @return a future representing the processing of this operation
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public Future<Boolean> replace(String key, int exp, Object o) {
    return asyncStore(StoreType.replace, key, exp, o, transcoder);
  }

  /**
   * Get the given key asynchronously.
   *
   * @param <T>
   * @param key the key to fetch
   * @param tc the transcoder to serialize and unserialize value
   * @return a future that will hold the return value of the fetch
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public <T> Future<T> asyncGet(final String key, final Transcoder<T> tc) {

    final CountDownLatch latch=new CountDownLatch(1);
    final GetFuture<T> rv=new GetFuture<T>(latch, operationTimeout);

    Operation op=opFact.get(key,
        new GetOperation.Callback() {
      private Future<T> val=null;
      public void receivedStatus(OperationStatus status) {
        rv.set(val);
      }
      public void gotData(String k, int flags, byte[] data) {
        assert key.equals(k) : "Wrong key returned";
        val=tcService.decode(tc,
          new CachedData(flags, data, tc.getMaxSize()));
      }
      public void complete() {
        latch.countDown();
      }});
    rv.setOperation(op);
    addOp(key, op);
    return rv;
  }

  /**
   * Get the given key asynchronously and decode with the default
   * transcoder.
   *
   * @param key the key to fetch
   * @return a future that will hold the return value of the fetch
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public Future<Object> asyncGet(final String key) {
    return asyncGet(key, transcoder);
  }

  /**
   * Gets (with CAS support) the given key asynchronously.
   *
   * @param <T>
   * @param key the key to fetch
   * @param tc the transcoder to serialize and unserialize value
   * @return a future that will hold the return value of the fetch
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public <T> Future<CASValue<T>> asyncGets(final String key,
      final Transcoder<T> tc) {

    final CountDownLatch latch=new CountDownLatch(1);
    final OperationFuture<CASValue<T>> rv=
      new OperationFuture<CASValue<T>>(latch, operationTimeout);

    Operation op=opFact.gets(key,
        new GetsOperation.Callback() {
      private CASValue<T> val=null;
      public void receivedStatus(OperationStatus status) {
        rv.set(val);
      }
      public void gotData(String k, int flags, long cas, byte[] data) {
        assert key.equals(k) : "Wrong key returned";
        assert cas > 0 : "CAS was less than zero:  " + cas;
        val=new CASValue<T>(cas, tc.decode(
          new CachedData(flags, data, tc.getMaxSize())));
      }
      public void complete() {
        latch.countDown();
      }});
    rv.setOperation(op);
    addOp(key, op);
    return rv;
  }

  /**
   * Gets (with CAS support) the given key asynchronously and decode using
   * the default transcoder.
   *
   * @param key the key to fetch
   * @return a future that will hold the return value of the fetch
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public Future<CASValue<Object>> asyncGets(final String key) {
    return asyncGets(key, transcoder);
  }

  /**
   * Gets (with CAS support) with a single key.
   *
   * @param <T>
   * @param key the key to get
   * @param tc the transcoder to serialize and unserialize value
   * @return the result from the cache and CAS id (null if there is none)
   * @throws OperationTimeoutException if global operation timeout is
   *        exceeded
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public <T> CASValue<T> gets(String key, Transcoder<T> tc) {
    try {
      return asyncGets(key, tc).get(
        operationTimeout, TimeUnit.MILLISECONDS);
    } catch (InterruptedException e) {
      throw new RuntimeException("Interrupted waiting for value", e);
    } catch (ExecutionException e) {
      throw new RuntimeException("Exception waiting for value", e);
    } catch (TimeoutException e) {
      throw new OperationTimeoutException("Timeout waiting for value", e);
    }
  }

  /**
   * Get with a single key and reset its expiration.
   *
   * @param <T>
   * @param key the key to get
   * @param exp the new expiration for the key
   * @param tc the transcoder to serialize and unserialize value
   * @return the result from the cache (null if there is none)
   * @throws OperationTimeoutException if the global operation timeout is
   *       exceeded
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public <T> CASValue<T> getAndTouch(String key, int exp, Transcoder<T> tc) {
    try {
      return asyncGetAndTouch(key, exp, tc).get(operationTimeout,
          TimeUnit.MILLISECONDS);
    } catch (InterruptedException e) {
      throw new RuntimeException("Interrupted waiting for value", e);
    } catch (ExecutionException e) {
      throw new RuntimeException("Exception waiting for value", e);
    } catch (TimeoutException e) {
      throw new OperationTimeoutException("Timeout waiting for value", e);
    }
  }

  /**
   * Get a single key and reset its expiration using the default transcoder.
   *
   * @param key the key to get
   * @param exp the new expiration for the key
   * @return the result from the cache and CAS id (null if there is none)
   * @throws OperationTimeoutException if the global operation timeout is
   *       exceeded
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public CASValue<Object> getAndTouch(String key, int exp) {
    return getAndTouch(key, exp, transcoder);
  }

  /**
   * Gets (with CAS support) with a single key using the default transcoder.
   *
   * @param key the key to get
   * @return the result from the cache and CAS id (null if there is none)
   * @throws OperationTimeoutException if the global operation timeout is
   *       exceeded
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public CASValue<Object> gets(String key) {
    return gets(key, transcoder);
  }

  /**
   * Get with a single key.
   *
   * @param <T>
   * @param key the key to get
   * @param tc the transcoder to serialize and unserialize value
   * @return the result from the cache (null if there is none)
   * @throws OperationTimeoutException if the global operation timeout is
   *       exceeded
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public <T> T get(String key, Transcoder<T> tc) {
    try {
      return asyncGet(key, tc).get(
        operationTimeout, TimeUnit.MILLISECONDS);
    } catch (InterruptedException e) {
      throw new RuntimeException("Interrupted waiting for value", e);
    } catch (ExecutionException e) {
      throw new RuntimeException("Exception waiting for value", e);
    } catch (TimeoutException e) {
      throw new OperationTimeoutException("Timeout waiting for value", e);
    }
  }

  /**
   * Get with a single key and decode using the default transcoder.
   *
   * @param key the key to get
   * @return the result from the cache (null if there is none)
   * @throws OperationTimeoutException if the global operation timeout is
   *       exceeded
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public Object get(String key) {
    return get(key, transcoder);
  }

  /**
   * Gets and locks the given key asynchronously. By default the maximum allowed
   * timeout is 30 seconds. Timeouts greater than this will be set to 30 seconds.
   *
   * @param key the key to fetch and lock
   * @param exp the amount of time the lock should be valid for in seconds.
   * @param tc the transcoder to serialize and unserialize value
   * @return a future that will hold the return value of the fetch
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public <T> Future<CASValue<T>> asyncGetAndLock(final String key, int exp,
      final Transcoder<T> tc) {
    final CountDownLatch latch=new CountDownLatch(1);
    final OperationFuture<CASValue<T>> rv=
      new OperationFuture<CASValue<T>>(latch, operationTimeout);

    Operation op=opFact.getl(key, exp,
        new GetlOperation.Callback() {
      private CASValue<T> val=null;
      public void receivedStatus(OperationStatus status) {
        rv.set(val);
      }
      public void gotData(String k, int flags, long cas, byte[] data) {
        assert key.equals(k) : "Wrong key returned";
        assert cas > 0 : "CAS was less than zero:  " + cas;
        val=new CASValue<T>(cas, tc.decode(
          new CachedData(flags, data, tc.getMaxSize())));
      }
      public void complete() {
        latch.countDown();
      }});
    rv.setOperation(op);
    addOp(key, op);
    return rv;
  }

  /**
   * Get and lock the given key asynchronously and decode with the default
   * transcoder. By default the maximum allowed timeout is 30 seconds.
   * Timeouts greater than this will be set to 30 seconds.
   *
   * @param key the key to fetch and lock
   * @param exp the amount of time the lock should be valid for in seconds.
   * @return a future that will hold the return value of the fetch
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public Future<CASValue<Object>> asyncGetAndLock(final String key, int exp) {
    return asyncGetAndLock(key, exp, transcoder);
  }

  /**
   * Asynchronously get a bunch of objects from the cache.
   *
   * @param <T>
   * @param keys the keys to request
   * @param tc_iter an iterator of transcoders to serialize and
   *        unserialize values; the transcoders are matched with
   *        the keys in the same order.  The minimum of the key
   *        collection length and number of transcoders is used
   *        and no exception is thrown if they do not match
   * @return a Future result of that fetch
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public <T> BulkFuture<Map<String, T>> asyncGetBulk(Collection<String> keys,
    Iterator<Transcoder<T>> tc_iter) {
    final Map<String, Future<T>> m=new ConcurrentHashMap<String, Future<T>>();

    // This map does not need to be a ConcurrentHashMap
    // because it is fully populated when it is used and
    // used only to read the transcoder for a key.
    final Map<String, Transcoder<T>> tc_map = new HashMap<String, Transcoder<T>>();

    // Break the gets down into groups by key
    final Map<MemcachedNode, Collection<String>> chunks
      =new HashMap<MemcachedNode, Collection<String>>();
    final NodeLocator locator=conn.getLocator();
    Iterator<String> key_iter=keys.iterator();
    while (key_iter.hasNext() && tc_iter.hasNext()) {
      String key=key_iter.next();
      tc_map.put(key, tc_iter.next());
      validateKey(key);
      final MemcachedNode primaryNode=locator.getPrimary(key);
      MemcachedNode node=null;
      if(primaryNode.isActive()) {
        node=primaryNode;
      } else {
        for(Iterator<MemcachedNode> i=locator.getSequence(key);
          node == null && i.hasNext();) {
          MemcachedNode n=i.next();
          if(n.isActive()) {
            node=n;
          }
        }
        if(node == null) {
          node=primaryNode;
        }
      }
      assert node != null : "Didn't find a node for " + key;
      Collection<String> ks=chunks.get(node);
      if(ks == null) {
        ks=new ArrayList<String>();
        chunks.put(node, ks);
      }
      ks.add(key);
    }

    final CountDownLatch latch=new CountDownLatch(chunks.size());
    final Collection<Operation> ops=new ArrayList<Operation>(chunks.size());

    GetOperation.Callback cb=new GetOperation.Callback() {
        @SuppressWarnings("synthetic-access")
        public void receivedStatus(OperationStatus status) {
          if(!status.isSuccess()) {
            getLogger().warn("Unsuccessful get:  %s", status);
          }
        }
        public void gotData(String k, int flags, byte[] data) {
          Transcoder<T> tc = tc_map.get(k);
          m.put(k, tcService.decode(tc,
              new CachedData(flags, data, tc.getMaxSize())));
        }
        public void complete() {
          latch.countDown();
        }
    };

    // Now that we know how many servers it breaks down into, and the latch
    // is all set up, convert all of these strings collections to operations
    final Map<MemcachedNode, Operation> mops=
      new HashMap<MemcachedNode, Operation>();

    for(Map.Entry<MemcachedNode, Collection<String>> me
        : chunks.entrySet()) {
      Operation op=opFact.get(me.getValue(), cb);
      mops.put(me.getKey(), op);
      ops.add(op);
    }
    assert mops.size() == chunks.size();
    checkState();
    conn.addOperations(mops);
    return new BulkGetFuture<T>(m, ops, latch);
  }

  /**
   * Asynchronously get a bunch of objects from the cache.
   *
   * @param <T>
   * @param keys the keys to request
   * @param tc the transcoder to serialize and unserialize values
   * @return a Future result of that fetch
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public <T> BulkFuture<Map<String, T>> asyncGetBulk(Collection<String> keys,
    Transcoder<T> tc) {
    return asyncGetBulk(keys, new SingleElementInfiniteIterator(tc));
  }

  /**
   * Asynchronously get a bunch of objects from the cache and decode them
   * with the given transcoder.
   *
   * @param keys the keys to request
   * @return a Future result of that fetch
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public BulkFuture<Map<String, Object>> asyncGetBulk(Collection<String> keys) {
    return asyncGetBulk(keys, transcoder);
  }

  /**
   * Varargs wrapper for asynchronous bulk gets.
   *
   * @param <T>
   * @param tc the transcoder to serialize and unserialize value
   * @param keys one more more keys to get
   * @return the future values of those keys
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public <T> BulkFuture<Map<String, T>> asyncGetBulk(Transcoder<T> tc,
    String... keys) {
    return asyncGetBulk(Arrays.asList(keys), tc);
  }

  /**
   * Varargs wrapper for asynchronous bulk gets with the default transcoder.
   *
   * @param keys one more more keys to get
   * @return the future values of those keys
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public BulkFuture<Map<String, Object>> asyncGetBulk(String... keys) {
    return asyncGetBulk(Arrays.asList(keys), transcoder);
  }

  /**
   * Get the given key to reset its expiration time.
   *
   * @param key the key to fetch
   * @param exp the new expiration to set for the given key
   * @return a future that will hold the return value of the fetch
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public Future<CASValue<Object>> asyncGetAndTouch(final String key, final int exp) {
    return asyncGetAndTouch(key, exp, transcoder);
  }

  /**
   * Get the given key to reset its expiration time.
   *
   * @param key the key to fetch
   * @param exp the new expiration to set for the given key
   * @param tc the transcoder to serialize and unserialize value
   * @return a future that will hold the return value of the fetch
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public <T> Future<CASValue<T>> asyncGetAndTouch(final String key, final int exp,
      final Transcoder<T> tc) {
    final CountDownLatch latch=new CountDownLatch(1);
    final OperationFuture<CASValue<T>> rv=new OperationFuture<CASValue<T>>(latch,
        operationTimeout);

    Operation op=opFact.getAndTouch(key, exp, new GetAndTouchOperation.Callback() {
      private CASValue<T> val=null;
      public void receivedStatus(OperationStatus status) {
        rv.set(val);
      }
      public void complete() {
        latch.countDown();
      }
      public void gotData(String key, int flags, long cas, byte[] data) {
        assert key.equals(key) : "Wrong key returned";
        assert cas > 0 : "CAS was less than zero:  " + cas;
        val=new CASValue<T>(cas, tc.decode(
          new CachedData(flags, data, tc.getMaxSize())));
      }});
    rv.setOperation(op);
    addOp(key, op);
    return rv;
  }

  /**
   * Get the values for multiple keys from the cache.
   *
   * @param <T>
   * @param keys the keys
   * @param tc the transcoder to serialize and unserialize value
   * @return a map of the values (for each value that exists)
   * @throws OperationTimeoutException if the global operation timeout is
   *       exceeded
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public <T> Map<String, T> getBulk(Collection<String> keys,
      Transcoder<T> tc) {
    try {
      return asyncGetBulk(keys, tc).get(
        operationTimeout, TimeUnit.MILLISECONDS);
    } catch (InterruptedException e) {
      throw new RuntimeException("Interrupted getting bulk values", e);
    } catch (ExecutionException e) {
      throw new RuntimeException("Failed getting bulk values", e);
    } catch (TimeoutException e) {
      throw new OperationTimeoutException(
        "Timeout waiting for bulkvalues", e);
    }
  }

  /**
   * Get the values for multiple keys from the cache.
   *
   * @param keys the keys
   * @return a map of the values (for each value that exists)
   * @throws OperationTimeoutException if the global operation timeout is
   *       exceeded
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public Map<String, Object> getBulk(Collection<String> keys) {
    return getBulk(keys, transcoder);
  }

  /**
   * Get the values for multiple keys from the cache.
   *
   * @param <T>
   * @param tc the transcoder to serialize and unserialize value
   * @param keys the keys
   * @return a map of the values (for each value that exists)
   * @throws OperationTimeoutException if the global operation timeout is
   *       exceeded
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public <T> Map<String, T> getBulk(Transcoder<T> tc, String... keys) {
    return getBulk(Arrays.asList(keys), tc);
  }

  /**
   * Get the values for multiple keys from the cache.
   *
   * @param keys the keys
   * @return a map of the values (for each value that exists)
   * @throws OperationTimeoutException if the global operation timeout is
   *       exceeded
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public Map<String, Object> getBulk(String... keys) {
    return getBulk(Arrays.asList(keys), transcoder);
  }

  /**
   * Get the versions of all of the connected memcacheds.
   *
   * @return a Map of SocketAddress to String for connected servers
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public Map<SocketAddress, String> getVersions() {
    final Map<SocketAddress, String>rv=
      new ConcurrentHashMap<SocketAddress, String>();

    CountDownLatch blatch = broadcastOp(new BroadcastOpFactory(){
      public Operation newOp(final MemcachedNode n,
          final CountDownLatch latch) {
        final SocketAddress sa=n.getSocketAddress();
        return opFact.version(
            new OperationCallback() {
              public void receivedStatus(OperationStatus s) {
                rv.put(sa, s.getMessage());
              }
              public void complete() {
                latch.countDown();
              }
            });
      }});
    try {
      blatch.await(operationTimeout, TimeUnit.MILLISECONDS);
    } catch (InterruptedException e) {
      throw new RuntimeException("Interrupted waiting for versions", e);
    }
    return rv;
  }

  /**
   * Get all of the stats from all of the connections.
   *
   * @return a Map of a Map of stats replies by SocketAddress
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public Map<SocketAddress, Map<String, String>> getStats() {
    return getStats(null);
  }

  /**
   * Get a set of stats from all connections.
   *
   * @param arg which stats to get
   * @return a Map of the server SocketAddress to a map of String stat
   *       keys to String stat values.
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public Map<SocketAddress, Map<String, String>> getStats(final String arg) {
    final Map<SocketAddress, Map<String, String>> rv
      =new HashMap<SocketAddress, Map<String, String>>();

    CountDownLatch blatch = broadcastOp(new BroadcastOpFactory(){
      public Operation newOp(final MemcachedNode n,
        final CountDownLatch latch) {
        final SocketAddress sa=n.getSocketAddress();
        rv.put(sa, new HashMap<String, String>());
        return opFact.stats(arg,
            new StatsOperation.Callback() {
          public void gotStat(String name, String val) {
            rv.get(sa).put(name, val);
          }
          @SuppressWarnings("synthetic-access") // getLogger()
          public void receivedStatus(OperationStatus status) {
            if(!status.isSuccess()) {
              getLogger().warn("Unsuccessful stat fetch:  %s",
                  status);
            }
          }
          public void complete() {
            latch.countDown();
          }});
      }});
    try {
      blatch.await(operationTimeout, TimeUnit.MILLISECONDS);
    } catch (InterruptedException e) {
      throw new RuntimeException("Interrupted waiting for stats", e);
    }
    return rv;
  }

  private long mutate(Mutator m, String key, int by, long def, int exp) {
    final AtomicLong rv=new AtomicLong();
    final CountDownLatch latch=new CountDownLatch(1);
    addOp(key, opFact.mutate(m, key, by, def, exp, new OperationCallback() {
          public void receivedStatus(OperationStatus s) {
            // XXX:  Potential abstraction leak.
            // The handling of incr/decr in the binary protocol
            // Allows us to avoid string processing.
            rv.set(new Long(s.isSuccess()?s.getMessage():"-1"));
          }
          public void complete() {
            latch.countDown();
          }}));
    try {
      if (!latch.await(operationTimeout, TimeUnit.MILLISECONDS)) {
        throw new OperationTimeoutException(
          "Mutate operation timed out, unable to modify counter ["
            + key + "]");
      }
    } catch (InterruptedException e) {
      throw new RuntimeException("Interrupted", e);
    }
    getLogger().debug("Mutation returned %s", rv);
    return rv.get();
  }

  /**
   * Getl with a single key. By default the maximum allowed timeout is 30
   * seconds. Timeouts greater than this will be set to 30 seconds.
   *
   * @param key the key to get and lock
   * @param exp the amount of time the lock should be valid for in seconds.
   * @param tc the transcoder to serialize and unserialize value
   * @return the result from the cache (null if there is none)
   * @throws OperationTimeoutException if the global operation timeout is
   *       exceeded
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public <T> CASValue<T> getAndLock(String key, int exp, Transcoder<T> tc) {
    try {
      return asyncGetAndLock(key, exp, tc).get(
          operationTimeout, TimeUnit.MILLISECONDS);
    } catch (InterruptedException e) {
      throw new RuntimeException("Interrupted waiting for value", e);
    } catch (ExecutionException e) {
      throw new RuntimeException("Exception waiting for value", e);
    } catch (TimeoutException e) {
      throw new OperationTimeoutException("Timeout waiting for value", e);
    }
  }

  /**
   * Get and lock with a single key and decode using the default transcoder.
   * By default the maximum allowed timeout is 30 seconds. Timeouts greater
   * than this will be set to 30 seconds.
   * @param key the key to get and lock
   * @param exp the amount of time the lock should be valid for in seconds.
   * @return the result from the cache (null if there is none)
   * @throws OperationTimeoutException if the global operation timeout is
   *       exceeded
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public CASValue<Object> getAndLock(String key, int exp) {
    return getAndLock(key, exp, transcoder);
  }

  /**
   * Increment the given key by the given amount.
   *
   * Due to the way the memcached server operates on items, incremented
   * and decremented items will be returned as Strings with any
   * operations that return a value.
   *
   * @param key the key
   * @param by the amount to increment
   * @return the new value (-1 if the key doesn't exist)
   * @throws OperationTimeoutException if the global operation timeout is
   *       exceeded
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public long incr(String key, int by) {
    return mutate(Mutator.incr, key, by, 0, -1);
  }

  /**
   * Decrement the given key by the given value.
   *
   * Due to the way the memcached server operates on items, incremented
   * and decremented items will be returned as Strings with any
   * operations that return a value.
   *
   * @param key the key
   * @param by the value
   * @return the new value (-1 if the key doesn't exist)
   * @throws OperationTimeoutException if the global operation timeout is
   *       exceeded
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public long decr(String key, int by) {
    return mutate(Mutator.decr, key, by, 0, -1);
  }

  /**
   * Increment the given counter, returning the new value.
   *
   * Due to the way the memcached server operates on items, incremented
   * and decremented items will be returned as Strings with any
   * operations that return a value.
   *
   * @param key the key
   * @param by the amount to increment
   * @param def the default value (if the counter does not exist)
   * @param exp the expiration of this object
   * @return the new value, or -1 if we were unable to increment or add
   * @throws OperationTimeoutException if the global operation timeout is
   *       exceeded
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public long incr(String key, int by, long def, int exp) {
    return mutateWithDefault(Mutator.incr, key, by, def, exp);
  }

  /**
   * Decrement the given counter, returning the new value.
   *
   * Due to the way the memcached server operates on items, incremented
   * and decremented items will be returned as Strings with any
   * operations that return a value.
   *
   * @param key the key
   * @param by the amount to decrement
   * @param def the default value (if the counter does not exist)
   * @param exp the expiration of this object
   * @return the new value, or -1 if we were unable to decrement or add
   * @throws OperationTimeoutException if the global operation timeout is
   *       exceeded
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public long decr(String key, int by, long def, int exp) {
    return mutateWithDefault(Mutator.decr, key, by, def, exp);
  }


  private long mutateWithDefault(Mutator t, String key,
      int by, long def, int exp) {
    long rv=mutate(t, key, by, def, exp);
    // The ascii protocol doesn't support defaults, so I added them
    // manually here.
    if(rv == -1) {
      Future<Boolean> f=asyncStore(StoreType.add,
          key, exp, String.valueOf(def));
      try {
        if(f.get(operationTimeout, TimeUnit.MILLISECONDS)) {
          rv=def;
        } else {
          rv=mutate(t, key, by, 0, exp);
          assert rv != -1 : "Failed to mutate or init value";
        }
      } catch (InterruptedException e) {
        throw new RuntimeException("Interrupted waiting for store", e);
      } catch (ExecutionException e) {
        throw new RuntimeException("Failed waiting for store", e);
      } catch (TimeoutException e) {
        throw new OperationTimeoutException(
          "Timeout waiting to mutate or init value", e);
      }
    }
    return rv;
  }

  private Future<Long> asyncMutate(Mutator m, String key, int by, long def,
      int exp) {
    final CountDownLatch latch = new CountDownLatch(1);
    final OperationFuture<Long> rv = new OperationFuture<Long>(
        latch, operationTimeout);
    Operation op = addOp(key, opFact.mutate(m, key, by, def, exp,
        new OperationCallback() {
      public void receivedStatus(OperationStatus s) {
        rv.set(new Long(s.isSuccess() ? s.getMessage() : "-1"));
      }
      public void complete() {
        latch.countDown();
      }
    }));
    rv.setOperation(op);
    return rv;
  }

  /**
   * Asychronous increment.
   *
   * @param key key to increment
   * @param by the amount to increment the value by
   * @return a future with the incremented value, or -1 if the
   *       increment failed.
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public Future<Long> asyncIncr(String key, int by) {
    return asyncMutate(Mutator.incr, key, by, 0, -1);
  }

  /**
   * Asynchronous decrement.
   *
   * @param key key to increment
   * @param by the amount to increment the value by
   * @return a future with the decremented value, or -1 if the
   *       increment failed.
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public Future<Long> asyncDecr(String key, int by) {
    return asyncMutate(Mutator.decr, key, by, 0, -1);
  }

  /**
   * Increment the given counter, returning the new value.
   *
   * @param key the key
   * @param by the amount to increment
   * @param def the default value (if the counter does not exist)
   * @return the new value, or -1 if we were unable to increment or add
   * @throws OperationTimeoutException if the global operation timeout is
   *       exceeded
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public long incr(String key, int by, long def) {
    return mutateWithDefault(Mutator.incr, key, by, def, 0);
  }

  /**
   * Decrement the given counter, returning the new value.
   *
   * @param key the key
   * @param by the amount to decrement
   * @param def the default value (if the counter does not exist)
   * @return the new value, or -1 if we were unable to decrement or add
   * @throws OperationTimeoutException if the global operation timeout is
   *       exceeded
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public long decr(String key, int by, long def) {
    return mutateWithDefault(Mutator.decr, key, by, def, 0);
  }

  /**
   * Delete the given key from the cache.
   *
   * <p>
   * The hold argument specifies the amount of time in seconds (or Unix time
   * until which) the client wishes the server to refuse "add" and "replace"
   * commands with this key. For this amount of item, the item is put into a
   * delete queue, which means that it won't possible to retrieve it by the
   * "get" command, but "add" and "replace" command with this key will also
   * fail (the "set" command will succeed, however). After the time passes,
   * the item is finally deleted from server memory.
   * </p>
   *
   * @param key the key to delete
   * @param hold how long the key should be unavailable to add commands
   *
   * @return whether or not the operation was performed
   * @deprecated Hold values are no longer honored.
   */
  @Deprecated
  public Future<Boolean> delete(String key, int hold) {
    return delete(key);
  }

  /**
   * Delete the given key from the cache.
   *
   * @param key the key to delete
   * @return whether or not the operation was performed
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public Future<Boolean> delete(String key) {
    final CountDownLatch latch=new CountDownLatch(1);
    final OperationFuture<Boolean> rv=new OperationFuture<Boolean>(latch,
      operationTimeout);
    DeleteOperation op=opFact.delete(key,
        new OperationCallback() {
          public void receivedStatus(OperationStatus s) {
            rv.set(s.isSuccess());
          }
          public void complete() {
            latch.countDown();
          }});
    rv.setOperation(op);
    addOp(key, op);
    return rv;
  }

  /**
   * Flush all caches from all servers with a delay of application.
   * @param delay the period of time to delay, in seconds
   * @return whether or not the operation was accepted
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public Future<Boolean> flush(final int delay) {
    final AtomicReference<Boolean> flushResult=
      new AtomicReference<Boolean>(null);
    final ConcurrentLinkedQueue<Operation> ops=
      new ConcurrentLinkedQueue<Operation>();
    CountDownLatch blatch = broadcastOp(new BroadcastOpFactory(){
      public Operation newOp(final MemcachedNode n,
          final CountDownLatch latch) {
        Operation op=opFact.flush(delay, new OperationCallback(){
          public void receivedStatus(OperationStatus s) {
            flushResult.set(s.isSuccess());
          }
          public void complete() {
            latch.countDown();
          }});
        ops.add(op);
        return op;
      }});
    return new OperationFuture<Boolean>(blatch, flushResult,
        operationTimeout) {
      @Override
      public boolean cancel(boolean ign) {
        boolean rv=false;
        for(Operation op : ops) {
          op.cancel();
          rv |= op.getState() == OperationState.WRITING;
        }
        return rv;
      }
      @Override
      public boolean isCancelled() {
        boolean rv=false;
        for(Operation op : ops) {
          rv |= op.isCancelled();
        }
        return rv;
      }
      @Override
      public boolean isDone() {
        boolean rv=true;
        for(Operation op : ops) {
          rv &= op.getState() == OperationState.COMPLETE;
        }
        return rv || isCancelled();
      }
    };
  }

  /**
   * Flush all caches from all servers immediately.
   * @return whether or not the operation was performed
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public Future<Boolean> flush() {
    return flush(-1);
  }

  public Set<String> listSaslMechanisms() {
    final ConcurrentMap<String, String> rv
      = new ConcurrentHashMap<String, String>();

    CountDownLatch blatch = broadcastOp(new BroadcastOpFactory() {
      public Operation newOp(MemcachedNode n,
          final CountDownLatch latch) {
        return opFact.saslMechs(new OperationCallback() {
          public void receivedStatus(OperationStatus status) {
            for(String s : status.getMessage().split(" ")) {
              rv.put(s, s);
            }
          }
          public void complete() {
            latch.countDown();
          }
        });
      }
    });

    try {
      blatch.await();
    } catch(InterruptedException e) {
      Thread.currentThread().interrupt();
    }

    return rv.keySet();
  }

  private void logRunException(Exception e) {
    if(shuttingDown) {
      // There are a couple types of errors that occur during the
      // shutdown sequence that are considered OK.  Log at debug.
      getLogger().debug("Exception occurred during shutdown", e);
    } else {
      getLogger().warn("Problem handling memcached IO", e);
    }
  }

  /**
   * Infinitely loop processing IO.
   */
  @Override
  public void run() {
    while(running) {
            if (!reconfiguring) {
                try {
                    conn.handleIO();
                } catch (IOException e) {
                    logRunException(e);
                } catch (CancelledKeyException e) {
                    logRunException(e);
                } catch (ClosedSelectorException e) {
                    logRunException(e);
                } catch (IllegalStateException e) {
                    logRunException(e);
                }
      }
    }
    getLogger().info("Shut down memcached client");
  }

  /**
   * Shut down immediately.
   */
  public void shutdown() {
    shutdown(-1, TimeUnit.MILLISECONDS);
  }

  /**
   * Shut down this client gracefully.
   *
   * @param timeout the amount of time time for shutdown
   * @param unit the TimeUnit for the timeout
   * @return result of the shutdown request
   */
  public boolean shutdown(long timeout, TimeUnit unit) {
    // Guard against double shutdowns (bug 8).
    if(shuttingDown) {
      getLogger().info("Suppressing duplicate attempt to shut down");
      return false;
    }
    shuttingDown=true;
    String baseName=getName();
    setName(baseName + " - SHUTTING DOWN");
    boolean rv=false;
    try {
      // Conditionally wait
      if(timeout > 0) {
        setName(baseName + " - SHUTTING DOWN (waiting)");
        rv=waitForQueues(timeout, unit);
      }
    } finally {
      // But always begin the shutdown sequence
      try {
        setName(baseName + " - SHUTTING DOWN (telling client)");
        running=false;
        conn.shutdown();
        setName(baseName + " - SHUTTING DOWN (informed client)");
        tcService.shutdown();
                if (configurationProvider != null) {
                    configurationProvider.shutdown();
                }
      } catch (IOException e) {
        getLogger().warn("exception while shutting down configuration provider", e);
      }
    }
    return rv;
  }

  /**
   * Wait for the queues to die down.
   *
   * @param timeout the amount of time time for shutdown
   * @param unit the TimeUnit for the timeout
   * @return result of the request for the wait
   * @throws IllegalStateException in the rare circumstance where queue
   *         is too full to accept any more requests
   */
  public boolean waitForQueues(long timeout, TimeUnit unit) {
    CountDownLatch blatch = broadcastOp(new BroadcastOpFactory(){
      public Operation newOp(final MemcachedNode n,
          final CountDownLatch latch) {
        return opFact.noop(
            new OperationCallback() {
              public void complete() {
                latch.countDown();
              }
              public void receivedStatus(OperationStatus s) {
                // Nothing special when receiving status, only
                // necessary to complete the interface
              }
            });
      }}, conn.getLocator().getAll(), false);
    try {
      // XXX:  Perhaps IllegalStateException should be caught here
      // and the check retried.
      return blatch.await(timeout, unit);
    } catch (InterruptedException e) {
      throw new RuntimeException("Interrupted waiting for queues", e);
    }
  }

  /**
   * Add a connection observer.
   *
   * If connections are already established, your observer will be called
   * with the address and -1.
   *
   * @param obs the ConnectionObserver you wish to add
   * @return true if the observer was added.
   */
  public boolean addObserver(ConnectionObserver obs) {
    boolean rv = conn.addObserver(obs);
    if(rv) {
      for(MemcachedNode node : conn.getLocator().getAll()) {
        if(node.isActive()) {
          obs.connectionEstablished(node.getSocketAddress(), -1);
        }
      }
    }
    return rv;
  }

  /**
   * Remove a connection observer.
   *
   * @param obs the ConnectionObserver you wish to add
   * @return true if the observer existed, but no longer does
   */
  public boolean removeObserver(ConnectionObserver obs) {
    return conn.removeObserver(obs);
  }

  public void connectionEstablished(SocketAddress sa, int reconnectCount) {
    if(authDescriptor != null) {
                    if (authDescriptor.authThresholdReached()) {
                        this.shutdown();
                    }
      authMonitor.authConnection(conn, opFact, authDescriptor, findNode(sa));
    }
  }

  private MemcachedNode findNode(SocketAddress sa) {
    MemcachedNode node = null;
    for(MemcachedNode n : conn.getLocator().getAll()) {
      if(n.getSocketAddress().equals(sa)) {
        node = n;
      }
    }
    assert node != null : "Couldn't find node connected to " + sa;
    return node;
  }

  public void connectionLost(SocketAddress sa) {
    // Don't care.
  }

}
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