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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up with different versions on classes on the class path).

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package org.jgroups.blocks;

import org.jgroups.*;
import org.jgroups.annotations.ManagedAttribute;
import org.jgroups.annotations.ManagedOperation;
import org.jgroups.logging.Log;
import org.jgroups.logging.LogFactory;
import org.jgroups.util.*;

import java.io.*;
import java.lang.reflect.Method;
import java.util.*;
import java.util.concurrent.TimeUnit;


/**
 * Cache which allows for replication factors per data items; the factor determines how many replicas
 * of a key/value we create across the cluster.

 * See doc/design/ReplCache.txt for details.
 * @author Bela Ban
 */
public class ReplCache implements Receiver, Cache.ChangeListener {

    /** The cache in which all entries are located. The value is a tuple, consisting of the replication count and the
     * actual value */
    private Cache> l2_cache=new Cache<>();

    /** The local bounded cache, to speed up access to frequently accessed entries. Can be disabled or enabled */
    private Cache l1_cache=null;

    private static final Log log=LogFactory.getLog(ReplCache.class);
    private JChannel ch=null;
    private Address local_addr;
    private View    view;
    private RpcDispatcher disp;
    @ManagedAttribute(writable=true)
    private String props="udp.xml";
    @ManagedAttribute(writable=true)
    private String cluster_name="ReplCache-Cluster";
    @ManagedAttribute(writable=true)
    private long call_timeout=1000L;
    @ManagedAttribute(writable=true)
    private long caching_time=30000L; // in milliseconds. -1 means don't cache, 0 means cache forever (or until changed)

    @ManagedAttribute
    private short default_replication_count=1; // no replication by default

    private HashFunction hash_function=null;

    private HashFunctionFactory hash_function_factory=ConsistentHashFunction::new;

    private final Set receivers=new HashSet<>();

    private final Set change_listeners=new HashSet<>();

    /** On a view change, if a member P1 detects that for any given key K, P1 is not the owner of K, then
     * it will compute the new owner P2 and transfer ownership for all Ks for which P2 is the new owner. P1
     * will then also evict those keys from its L2 cache */
    @ManagedAttribute(writable=true)
    private boolean migrate_data=true;

    private static final short PUT         = 1;
    private static final short PUT_FORCE   = 2;
    private static final short GET         = 3;
    private static final short REMOVE      = 4;
    private static final short REMOVE_MANY = 5;

    protected static final Map methods=Util.createConcurrentMap(8);
    private TimeScheduler timer;




    static {
        try {
            methods.put(PUT, ReplCache.class.getMethod("_put",
                                                       Object.class,
                                                       Object.class,
                                                       short.class,
                                                       long.class));
            methods.put(PUT_FORCE, ReplCache.class.getMethod("_put",
                                                             Object.class,
                                                             Object.class,
                                                             short.class,
                                                             long.class, boolean.class));
            methods.put(GET, ReplCache.class.getMethod("_get",
                                                       Object.class));
            methods.put(REMOVE, ReplCache.class.getMethod("_remove", Object.class));
            methods.put(REMOVE_MANY, ReplCache.class.getMethod("_removeMany", Set.class));
        }
        catch(NoSuchMethodException e) {
            throw new RuntimeException(e);
        }
    }


    public interface HashFunction {

        /**
         * Function that, given a key and a replication count, returns replication_count number of different
         * addresses of nodes.
         * @param key
         * @param replication_count
         * @return
         */
        List
 hash(K key, short replication_count);

        /**
         * When the topology changes, this method will be called. Implementations will typically cache the node list
         * @param nodes
         */
        void installNodes(List
 nodes);
    }


    public interface HashFunctionFactory {
        HashFunction create();
    }


    public ReplCache(String props, String cluster_name) {
        this.props=props;
        this.cluster_name=cluster_name;
    }

    public String getProps() {
        return props;
    }

    public void setProps(String props) {
        this.props=props;
    }

    public Address getLocalAddress() {
        return local_addr;
    }

    @ManagedAttribute
    public String getLocalAddressAsString() {
        return local_addr != null? local_addr.toString() : "null";
    }

    @ManagedAttribute
    public String getView() {
        return view != null? view.toString() : "null";
    }

    @ManagedAttribute
    public int getClusterSize() {
        return view != null? view.size() : 0;
    }

    @ManagedAttribute
    public boolean isL1CacheEnabled() {
        return l1_cache != null;
    }

    public String getClusterName() {
        return cluster_name;
    }

    public void setClusterName(String cluster_name) {
        this.cluster_name=cluster_name;
    }

    public long getCallTimeout() {
        return call_timeout;
    }

    public void setCallTimeout(long call_timeout) {
        this.call_timeout=call_timeout;
    }

    public long getCachingTime() {
        return caching_time;
    }

    public void setCachingTime(long caching_time) {
        this.caching_time=caching_time;
    }

    public boolean isMigrateData() {
        return migrate_data;
    }

    public void setMigrateData(boolean migrate_data) {
        this.migrate_data=migrate_data;
    }

    public short getDefaultReplicationCount() {
        return default_replication_count;
    }

    public void setDefaultReplicationCount(short default_replication_count) {
        this.default_replication_count=default_replication_count;
    }

    public HashFunction getHashFunction() {
        return hash_function;
    }

    public void setHashFunction(HashFunction hash_function) {
        this.hash_function=hash_function;
    }

    public HashFunctionFactory getHashFunctionFactory() {
        return hash_function_factory;
    }

    public void setHashFunctionFactory(HashFunctionFactory hash_function_factory) {
        this.hash_function_factory=hash_function_factory;
    }

    public void addReceiver(Receiver r) {
        receivers.add(r);
    }

    public void removeMembershipListener(Receiver r) {
        receivers.remove(r);
    }

    public void addChangeListener(ChangeListener l) {
        change_listeners.add(l);
    }

    public void removeChangeListener(ChangeListener l) {
        change_listeners.remove(l);
    }

    public Cache getL1Cache() {
        return l1_cache;
    }

    public void setL1Cache(Cache cache) {
        if(l1_cache != null)
            l1_cache.stop();
        l1_cache=cache;
    }

    public Cache> getL2Cache() {
        return l2_cache;
    }

    public void setL2Cache(Cache> cache) {
        if(cache != null) {
            l2_cache.stop();
            l2_cache=cache;
        }
    }


    @ManagedOperation
    public void start() throws Exception {
        if(hash_function_factory != null) {
            hash_function=hash_function_factory.create();
        }
        if(hash_function == null)
            hash_function=new ConsistentHashFunction<>();

        ch=new JChannel(props);
        disp=new RpcDispatcher(ch, this).setMethodLookup(methods::get).setReceiver(this);
        ch.connect(cluster_name);
        local_addr=ch.getAddress();
        view=ch.getView();
        timer=ch.getProtocolStack().getTransport().getTimer();

        l2_cache.addChangeListener(this);
    }

    @ManagedOperation
    public void stop() {
        if(l1_cache != null)
            l1_cache.stop();
        if(migrate_data) {
            List
 members_without_me=new ArrayList<>(view.getMembers());
            members_without_me.remove(local_addr);

            HashFunction tmp_hash_function=hash_function_factory.create();
            tmp_hash_function.installNodes(members_without_me);

            for(Map.Entry>> entry: l2_cache.entrySet()) {
                K key=entry.getKey();
                Cache.Value> val=entry.getValue();
                if(val == null)
                    continue;
                Value tmp=val.getValue();
                if(tmp == null)
                    continue;
                short repl_count=tmp.getReplicationCount();
                if(repl_count != 1) // we only handle keys which are not replicated and which are stored by us
                    continue;

                List
 nodes=tmp_hash_function.hash(key, repl_count);
                if(nodes == null || nodes.isEmpty())
                    continue;
                if(!nodes.contains(local_addr)) {
                    Address dest=nodes.get(0); // should only have 1 element anyway
                    move(dest, key, tmp.getVal(), repl_count, val.getTimeout(), true);
                    _remove(key);
                }
            }
        }
        l2_cache.removeChangeListener(this);
        l2_cache.stop();
        disp.stop();
        ch.close();
    }


    /**
     * Places a key/value pair into one or several nodes in the cluster.
     * @param key The key, needs to be serializable
     * @param val The value, needs to be serializable
     * @param repl_count Number of replicas. The total number of times a data item should be present in a cluster.
     * Needs to be > 0
     * 
    
     * 
  • -1: create key/val in all the nodes in the cluster
     * 
  • 1: create key/val only in one node in the cluster, picked by computing the consistent hash of KEY
     * 
  • K > 1: create key/val in those nodes in the cluster which match the consistent hashes created for KEY
     * 

     * @param timeout Expiration time for key/value.
     * 
    
     * 
  • -1: don't cache at all in the L1 cache
     * 
  • 0: cache forever, until removed or evicted because we need space for newer elements
     * 
  • > 0: number of milliseconds to keep an idle element in the cache. An element is idle when not accessed.
     * 

     * @param synchronous Whether or not to block until all cluster nodes have applied the change
     */
    @ManagedOperation
    public void put(K key, V val, short repl_count, long timeout, boolean synchronous) {
        if(repl_count == 0) {
            if(log.isWarnEnabled())
                log.warn("repl_count of 0 is invalid, data will not be stored in the cluster");
            return;
        }
        mcastPut(key, val, repl_count, timeout, synchronous);
        if(l1_cache != null && timeout >= 0)
            l1_cache.put(key, val, timeout);
    }

    
    /**
     * Places a key/value pair into one or several nodes in the cluster.
     * @param key The key, needs to be serializable
     * @param val The value, needs to be serializable
     * @param repl_count Number of replicas. The total number of times a data item should be present in a cluster.
     * Needs to be > 0
     * 
    
     * 
  • -1: create key/val in all the nodes in the cluster
     * 
  • 1: create key/val only in one node in the cluster, picked by computing the consistent hash of KEY
     * 
  • K > 1: create key/val in those nodes in the cluster which match the consistent hashes created for KEY
     * 

     * @param timeout Expiration time for key/value.
     * 
    
     * 
  • -1: don't cache at all in the L1 cache
     * 
  • 0: cache forever, until removed or evicted because we need space for newer elements
     * 
  • > 0: number of milliseconds to keep an idle element in the cache. An element is idle when not accessed.
     * 

     */
    @ManagedOperation
    public void put(K key, V val, short repl_count, long timeout) {
        put(key, val, repl_count, timeout, false); // don't block (asynchronous put) by default
    }



    @ManagedOperation
    public void put(K key, V val) {
        put(key, val, default_replication_count, caching_time);
    }


    
    /**
     * Returns the value associated with key
     * @param key The key, has to be serializable
     * @return The value associated with key, or null
     */
    @ManagedOperation
    public V get(K key) {

        // 1. Try the L1 cache first
        if(l1_cache != null) {
            V val=l1_cache.get(key);
            if(val != null) {
                if(log.isTraceEnabled())
                    log.trace("returned value " + val + " for " + key + " from L1 cache");
                return val;
            }
        }

        // 2. Try the local cache
        Cache.Value> val=l2_cache.getEntry(key);
        Value tmp;
        if(val != null) {
            tmp=val.getValue();
            if(tmp !=null) {
                V real_value=tmp.getVal();
                if(real_value != null && l1_cache != null && val.getTimeout() >= 0)
                    l1_cache.put(key, real_value, val.getTimeout());
                return tmp.getVal();
            }
        }

        // 3. Execute a cluster wide GET
        try {
            RspList rsps=disp.callRemoteMethods(null,
                                                new MethodCall(GET, key),
                                                new RequestOptions(ResponseMode.GET_ALL, call_timeout));
            for(Rsp rsp: rsps.values()) {
                Object obj=rsp.getValue();
                if(obj == null || obj instanceof Throwable)
                    continue;
                val=(Cache.Value>)rsp.getValue();
                if(val != null) {
                    tmp=val.getValue();
                    if(tmp != null) {
                        V real_value=tmp.getVal();
                        if(real_value != null && l1_cache != null && val.getTimeout() >= 0)
                            l1_cache.put(key, real_value, val.getTimeout());
                        return real_value;
                    }
                }
            }
            return null;
        }
        catch(Throwable t) {
            if(log.isWarnEnabled())
                log.warn("get() failed", t);
            return null;
        }
    }

    /**
     * Removes key in all nodes in the cluster, both from their local hashmaps and L1 caches
     * @param key The key, needs to be serializable
     */
    @ManagedOperation
    public void remove(K key) {
        remove(key, false); // by default we use asynchronous removals
    }


    /**
     * Removes key in all nodes in the cluster, both from their local hashmaps and L1 caches
     * @param key The key, needs to be serializable
     */
    @ManagedOperation
    public void remove(K key, boolean synchronous) {
        try {
            disp.callRemoteMethods(null, new MethodCall(REMOVE, key),
                                   new RequestOptions(synchronous? ResponseMode.GET_ALL : ResponseMode.GET_NONE, call_timeout));
            if(l1_cache != null)
                l1_cache.remove(key);
        }
        catch(Throwable t) {
            if(log.isWarnEnabled())
                log.warn("remove() failed", t);
        }
    }


    /**
     * Removes all keys and values in the L2 and L1 caches
     */
    @ManagedOperation
    public void clear() {
        Set keys=new HashSet<>(l2_cache.getInternalMap().keySet());
        mcastClear(keys, false);
    }

    public V _put(K key, V val, short repl_count, long timeout) {
        return _put(key, val, repl_count, timeout, false);
    }

    /**
     *
     * @param key
     * @param val
     * @param repl_count
     * @param timeout
     * @param force Skips acceptance checking and simply adds the key/value
     * @return
     */
    public V _put(K key, V val, short repl_count, long timeout, boolean force) {

        if(!force) {

            // check if we need to host the data
            boolean accept=repl_count == -1;

            if(!accept) {
                if(view != null && repl_count >= view.size()) {
                    accept=true;
                }
                else {
                    List
 selected_hosts=hash_function != null? hash_function.hash(key, repl_count) : null;
                    if(selected_hosts != null) {
                        if(log.isTraceEnabled())
                            log.trace("local=" + local_addr + ", hosts=" + selected_hosts);
                        for(Address addr: selected_hosts) {
                            if(addr.equals(local_addr)) {
                                accept=true;
                                break;
                            }
                        }
                    }
                    if(!accept)
                        return null;
                }
            }
        }

        if(log.isTraceEnabled())
            log.trace("_put(" + key + ", " + val + ", " + repl_count + ", " + timeout + ")");

        Value value=new Value<>(val, repl_count);
        Value retval=l2_cache.put(key, value, timeout);

        if(l1_cache != null)
            l1_cache.remove(key);

        notifyChangeListeners();

        return retval != null? retval.getVal() : null;
    }

    public Cache.Value> _get(K key) {
        if(log.isTraceEnabled())
            log.trace("_get(" + key + ")");
        return l2_cache.getEntry(key);
    }

    public V _remove(K key) {
        if(log.isTraceEnabled())
            log.trace("_remove(" + key + ")");
        Value retval=l2_cache.remove(key);
        if(l1_cache != null)
            l1_cache.remove(key);
        notifyChangeListeners();
        return retval != null? retval.getVal() : null;
    }


    public void _removeMany(Set keys) {
        if(log.isTraceEnabled())
            log.trace("_removeMany(): " + keys.size() + " entries");
        keys.forEach(this::_remove);
    }





    public void viewAccepted(final View new_view) {
        final List
 old_nodes=this.view != null? new ArrayList<>(this.view.getMembers()) : null;

        this.view=new_view;
        if(log.isDebugEnabled())
            log.debug("new view: " + new_view);

        if(hash_function != null)
            hash_function.installNodes(new_view.getMembers());

        for(Receiver r: receivers)
            r.viewAccepted(new_view);

        if(old_nodes != null) {
            timer.schedule(() -> rebalance(old_nodes, new ArrayList<>(new_view.getMembers())), 100, TimeUnit.MILLISECONDS);
        }
    }


    public void changed() {
        notifyChangeListeners();
    }

    public String toString() {
        StringBuilder sb=new StringBuilder();
        if(l1_cache != null)
            sb.append("L1 cache: " + l1_cache.getSize() + " entries");
        sb.append("\nL2 cache: " + l2_cache.getSize() + " entries()");
        return sb.toString();
    }


    @ManagedOperation
    public String dump() {
        StringBuilder sb=new StringBuilder();
        if(l1_cache != null) {
            sb.append("L1 cache:\n").append(l1_cache.dump());
        }
        sb.append("\nL2 cache:\n").append(l2_cache.dump());

        return sb.toString();
    }

    private void notifyChangeListeners() {
        for(ChangeListener l: change_listeners) {
            try {
                l.changed();
            }
            catch(Throwable t) {
                if(log.isErrorEnabled())
                    log.error("failed notifying change listener", t);
            }
        }
    }



    private void rebalance(List
 old_nodes, List
 new_nodes) {
        HashFunction old_func=hash_function_factory.create();
        old_func.installNodes(old_nodes);

        HashFunction new_func=hash_function_factory.create();
        new_func.installNodes(new_nodes);

        boolean is_coord=Util.isCoordinator(ch);

        List keys=new ArrayList<>(l2_cache.getInternalMap().keySet());

        for(K key: keys) {
            Cache.Value> val=l2_cache.getEntry(key);
            if(log.isTraceEnabled())
                log.trace("==== rebalancing " + key);
            if(val == null) {
                if(log.isWarnEnabled())
                    log.warn(key + " has no value associated; ignoring");
                continue;
            }
            Value tmp=val.getValue();
            if(tmp == null) {
                if(log.isWarnEnabled())
                    log.warn(key + " has no value associated; ignoring");
                continue;
            }
            V real_value=tmp.getVal();
            short repl_count=tmp.getReplicationCount();
            List
 new_mbrs=Util.newMembers(old_nodes, new_nodes);

            if(repl_count == -1) {
                if(is_coord) {
                    for(Address new_mbr: new_mbrs) {
                        move(new_mbr, key, real_value, repl_count, val.getTimeout(), false);
                    }
                }
            }
            else if(repl_count == 1) {
                List
 tmp_nodes=new_func.hash(key, repl_count);
                if(!tmp_nodes.isEmpty()) {
                    Address mbr=tmp_nodes.get(0);
                    if(!mbr.equals(local_addr)) {
                        move(mbr, key, real_value, repl_count, val.getTimeout(), false);
                        _remove(key);
                    }
                }
            }
            else if(repl_count > 1) {
                List
 tmp_old=old_func.hash(key, repl_count);
                List
 tmp_new=new_func.hash(key, repl_count);

                if(log.isTraceEnabled())
                    log.trace("old nodes: " + tmp_old + "\nnew nodes: " + tmp_new);
                if(Objects.equals(tmp_old, tmp_new))
                    continue;
                mcastPut(key, real_value, repl_count, val.getTimeout(), false);
                if(tmp_new != null && !tmp_new.contains(local_addr)) {
                    _remove(key);
                }
            }
            else {
                throw new IllegalStateException("replication count is invalid (" + repl_count + ")");
            }
        }
    }

    public void mcastEntries() {
        for(Map.Entry>> entry: l2_cache.entrySet()) {
            K key=entry.getKey();
            Cache.Value> val=entry.getValue();
            if(val == null) {
                if(log.isWarnEnabled())
                    log.warn(key + " has no value associated; ignoring");
                continue;
            }
            Value tmp=val.getValue();
            if(tmp == null) {
                if(log.isWarnEnabled())
                    log.warn(key + " has no value associated; ignoring");
                continue;
            }
            V real_value=tmp.getVal();
            short repl_count=tmp.getReplicationCount();

            if(repl_count > 1) {
                _remove(key);
                mcastPut(key, real_value, repl_count, val.getTimeout(), false);
            }
        }
    }

    private void mcastPut(K key, V val, short repl_count, long caching_time, boolean synchronous) {
        try {
            ResponseMode mode=synchronous? ResponseMode.GET_ALL : ResponseMode.GET_NONE;
            disp.callRemoteMethods(null, new MethodCall(PUT, key, val, repl_count, caching_time),
                                   new RequestOptions(mode, call_timeout));
        }
        catch(Throwable t) {
            if(log.isWarnEnabled())
                log.warn("put() failed", t);
        }
    }

    private void mcastClear(Set keys, boolean synchronous) {
        try {
            ResponseMode mode=synchronous? ResponseMode.GET_ALL : ResponseMode.GET_NONE;
            disp.callRemoteMethods(null, new MethodCall(REMOVE_MANY, keys), new RequestOptions(mode, call_timeout));
        }
        catch(Throwable t) {
            if(log.isWarnEnabled())
                log.warn("clear() failed", t);
        }
    }


    private void move(Address dest, K key, V val, short repl_count, long caching_time, boolean synchronous) {
        try {
            ResponseMode mode=synchronous? ResponseMode.GET_ALL : ResponseMode.GET_NONE;
            disp.callRemoteMethod(dest, new MethodCall(PUT_FORCE, key, val, repl_count, caching_time, true),
                                  new RequestOptions(mode, call_timeout));
        }
        catch(Throwable t) {
            if(log.isWarnEnabled())
                log.warn("move() failed", t);
        }
    }


    public interface ChangeListener {
        void changed();
    }
    
    public static class ConsistentHashFunction implements HashFunction {
        private final SortedMap nodes=new TreeMap<>();
        private final static int HASH_SPACE=2048; // must be > max number of nodes in a cluster and a power of 2
        private final static int FACTOR=3737; // to better spread the node out across the space

        public List
 hash(K key, short replication_count) {
            int index=Math.abs(key.hashCode() & (HASH_SPACE - 1));
            
            Set
 results=new LinkedHashSet<>();

            SortedMap tailmap=nodes.tailMap((short)index);
            int count=0;

            for(Map.Entry entry: tailmap.entrySet()) {
                Address val=entry.getValue();
                results.add(val);
                if(++count >= replication_count)
                    break;
            }

            if(count < replication_count) {
                for(Map.Entry entry: nodes.entrySet()) {
                    Address val=entry.getValue();
                    results.add(val);
                    if(++count >= replication_count)
                        break;
                }
            }
            return new ArrayList<>(results);
        }

        public void installNodes(List
 new_nodes) {
            nodes.clear();
            for(Address node: new_nodes) {
                int hash=Math.abs((node.hashCode() * FACTOR) & (HASH_SPACE - 1));
                for(int i=hash; i < hash + HASH_SPACE; i++) {
                    short new_index=(short)(i & (HASH_SPACE - 1));
                    if(!nodes.containsKey(new_index)) {
                        nodes.put(new_index, node);
                        break;
                    }
                }
            }

            if(log.isTraceEnabled()) {
                StringBuilder sb=new StringBuilder("node mappings:\n");
                for(Map.Entry entry: nodes.entrySet()) {
                    sb.append(entry.getKey() + ": " + entry.getValue()).append("\n");
                }
                log.trace(sb);
            }
        }

    }




    public static class Value implements Serializable {
        private final V val;
        private final short replication_count;
        private static final long serialVersionUID=-2892941069742740027L;


        public Value(V val, short replication_count) {
            this.val=val;
            this.replication_count=replication_count;
        }

        public V getVal() {
            return val;
        }


        public short getReplicationCount() {
            return replication_count;
        }

        public String toString() {
            return val + " (" + replication_count + ")";
        }
    }

}
    

    

    

            

    

            



    
    






    
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