org.jgroups.blocks
Class PartitionedHashMap<K,V>

java.lang.Object
  org.jgroups.blocks.PartitionedHashMap<K,V>

All Implemented Interfaces:

MembershipListener

public class PartitionedHashMap<K,V>
extends java.lang.Object
implements MembershipListener

Hashmap which distributes its keys and values across the cluster. A PUT/GET/REMOVE computes the cluster node to which or from which to get/set the key/value from a hash of the key and then forwards the request to the remote cluster node. We also maintain a local cache (L1 cache) which is a bounded cache that caches retrieved keys/values.
Todos:

1. Use MarshalledValue to keep track of byte[] buffers, and be able to compute the exact size of the cache. This is good for maintaining a bounded cache (rather than using the number of entries)
2. Provide a better consistent hashing algorithm than ConsistentHashFunction as default
3. GUI (showing at least the topology and L1 and L2 caches)
4. Notifications (puts, removes, gets etc)
5. Invalidation of L1 caches (if used) on removal/put of item
6. Benchmarks, comparison to memcached
7. Documentation, comparison to memcached

Author:

Bela Ban

Nested Class Summary

static class	PartitionedHashMap.ConsistentHashFunction<K>
static interface	PartitionedHashMap.HashFunction<K>

Field Summary

protected static java.util.Map<java.lang.Short,java.lang.reflect.Method>

methods

Constructor Summary

PartitionedHashMap(java.lang.String props, java.lang.String cluster_name)

Method Summary

Cache.Value<V>	_get(K key)
V	_put(K key, V val, long caching_time)
V	_remove(K key)
void	addMembershipListener(MembershipListener l)
void	block() Called (usually by the FLUSH protocol), as an indication that the member should stop sending messages.
java.lang.String	dump()
V	get(K key)
long	getCachingTime()
long	getCallTimeout()
java.lang.String	getClusterName()
PartitionedHashMap.HashFunction	getHashFunction()
Cache<K,V>	getL1Cache()
Cache<K,V>	getL2Cache()
Address	getLocalAddress()
java.lang.String	getLocalAddressAsString()
java.lang.String	getProps()
java.lang.String	getView()
boolean	isL1CacheEnabled()
boolean	isMigrateData()
void	put(K key, V val)
void	put(K key, V val, long caching_time) Adds a key/value to the cache, replacing a previous item if there was one
void	remove(K key)
void	removeMembershipListener(MembershipListener l)
void	setCachingTime(long caching_time)
void	setCallTimeout(long call_timeout)
void	setClusterName(java.lang.String cluster_name)
void	setHashFunction(PartitionedHashMap.HashFunction<K> hash_function)
void	setL1Cache(Cache<K,V> cache)
void	setL2Cache(Cache<K,V> cache)
void	setMigrateData(boolean migrate_data)
void	setProps(java.lang.String props)
void	start()
void	stop()
void	suspect(Address suspected_mbr) Called whenever a member is suspected of having crashed, but has not yet been excluded.
java.lang.String	toString()
void	unblock() Called after the FLUSH protocol has unblocked previously blocked senders, and messages can be sent again.
void	viewAccepted(View new_view) Called when a change in membership has occurred.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

methods

protected static final java.util.Map<java.lang.Short,java.lang.reflect.Method> methods

Constructor Detail

PartitionedHashMap

public PartitionedHashMap(java.lang.String props,
                          java.lang.String cluster_name)

Method Detail

getProps

public java.lang.String getProps()

setProps

public void setProps(java.lang.String props)

getLocalAddress

public Address getLocalAddress()

getLocalAddressAsString

public java.lang.String getLocalAddressAsString()

getView

public java.lang.String getView()

isL1CacheEnabled

public boolean isL1CacheEnabled()

getClusterName

public java.lang.String getClusterName()

setClusterName

public void setClusterName(java.lang.String cluster_name)

getCallTimeout

public long getCallTimeout()

setCallTimeout

public void setCallTimeout(long call_timeout)

getCachingTime

public long getCachingTime()

setCachingTime

public void setCachingTime(long caching_time)

isMigrateData

public boolean isMigrateData()

setMigrateData

public void setMigrateData(boolean migrate_data)

getHashFunction

public PartitionedHashMap.HashFunction getHashFunction()

setHashFunction

public void setHashFunction(PartitionedHashMap.HashFunction<K> hash_function)

addMembershipListener

public void addMembershipListener(MembershipListener l)

removeMembershipListener

public void removeMembershipListener(MembershipListener l)

getL1Cache

public Cache<K,V> getL1Cache()

setL1Cache

public void setL1Cache(Cache<K,V> cache)

getL2Cache

public Cache<K,V> getL2Cache()

setL2Cache

public void setL2Cache(Cache<K,V> cache)

start

public void start()
           throws java.lang.Exception

Throws:

java.lang.Exception

stop

public void stop()

put

public void put(K key,
                V val)

put

public void put(K key,
                V val,
                long caching_time)

Adds a key/value to the cache, replacing a previous item if there was one

Parameters:

key - The key

val - The value

caching_time - Time to live. -1 means never cache, 0 means cache forever. All other (positive) values are the number of milliseconds to cache the item

get

public V get(K key)

remove

public void remove(K key)

_put

public V _put(K key,
              V val,
              long caching_time)

_get

public Cache.Value<V> _get(K key)

_remove

public V _remove(K key)

viewAccepted

public void viewAccepted(View new_view)

Description copied from interface: MembershipListener

Called when a change in membership has occurred. No long running actions, sending of messages or anything that could block should be done in this callback. If some long running action needs to be performed, it should be done in a separate thread.

Note that on reception of the first view (a new member just joined), the channel will not yet be in the connected state. This only happens when Channel.connect(String) returns.

Specified by:

viewAccepted in interface MembershipListener

suspect

public void suspect(Address suspected_mbr)

Description copied from interface: MembershipListener

Called whenever a member is suspected of having crashed, but has not yet been excluded.

Specified by:

suspect in interface MembershipListener

block

public void block()

Description copied from interface: MembershipListener

Called (usually by the FLUSH protocol), as an indication that the member should stop sending messages. Any messages sent after returning from this callback might get blocked by the FLUSH protocol. When the FLUSH protocol is done, and messages can be sent again, the FLUSH protocol will simply unblock all pending messages. If a callback for unblocking is desired, implement MembershipListener.unblock(). Note that block() is the equivalent of reception of a BlockEvent in the pull mode.

Specified by:

block in interface MembershipListener

unblock

public void unblock()

Description copied from interface: MembershipListener

Called after the FLUSH protocol has unblocked previously blocked senders, and messages can be sent again. This callback only needs to be implemented if we require a notification of that.

Note that during new view installation we provide guarantee that unblock invocation strictly follows view installation at some node A belonging to that view . However, some other message M may squeeze in between view and unblock callbacks. For more details see https://jira.jboss.org/jira/browse/JGRP-986

Specified by:

unblock in interface MembershipListener

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

dump

public java.lang.String dump()