org.jgroups.protocols

Class FORK

java.lang.Object

org.jgroups.stack.Protocol

org.jgroups.protocols.FORK

public class FORK
extends Protocol

The FORK protocol; multiplexes messages to different forks in a stack (https://issues.jboss.org/browse/JGRP-1613). See doc/design/FORK.txt for details

Since:

3.4

Author:

Bela Ban

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	FORK.ForkHeader

Field Summary

Fields

Modifier and Type	Field and Description
protected java.lang.String	config
protected java.util.concurrent.ConcurrentMap<java.lang.String,Protocol>	fork_stacks
static short	ID
protected Address	local_addr
protected boolean	process_state_events

Fields inherited from class org.jgroups.stack.Protocol

after_creation_hook, down_prot, ergonomics, id, log, name, stack, stats, up_prot

Constructor Summary

Constructors

Constructor and Description
FORK()

Method Summary

Modifier and Type	Method and Description
ProtocolStack	createForkStack(java.lang.String fork_stack_id, java.util.List<Protocol> protocols, boolean initialize) Returns the fork stack for fork_stack_id (if exitstent), or creates a new fork-stack from protocols and adds it into the hashmap of fork-stack (key is fork_stack_id).
protected void	createForkStacks(java.util.Map<java.lang.String,java.util.List<ProtocolConfiguration>> protocols)
protected void	createForkStacks(java.lang.String config)
protected static java.util.List<Protocol>	createProtocols(ProtocolStack stack, java.util.List<ProtocolConfiguration> protocol_configs) Creates a fork-stack from the configuration, initializes all protocols (setting values), sets the protocol stack as top protocol, connects the protocols and calls init() on them.
java.lang.Object	down(Event evt) An event is to be sent down the stack.
Protocol	get(java.lang.String fork_stack_id)
static ForkProtocolStack	getForkStack(Protocol prot)
int	getForkStacks()
static java.io.InputStream	getForkStream(java.lang.String config)
protected void	getStateFrom(JChannel channel, Protocol prot, java.lang.String stack, java.lang.String ch, java.io.DataOutputStream out)
protected void	getStateFromMainAndForkChannels(Event evt)
UnknownForkHandler	getUnknownForkHandler()
void	init() Called after instance has been created (null constructor) and before protocol is started.
void	parse(org.w3c.dom.Node node) Called by the XML parser when subelements are found in the configuration of a protocol.
Protocol	putIfAbsent(java.lang.String fork_stack_id, Protocol prot)
void	remove(java.lang.String fork_stack_id)
protected void	setStateInMainAndForkChannels(java.io.InputStream in)
void	setUnknownForkHandler(UnknownForkHandler unknownForkHandler)
java.lang.Object	up(Event evt) An event was received from the layer below.
void	up(MessageBatch batch) Sends up a multiple messages in a MessageBatch.

Methods inherited from class org.jgroups.stack.Protocol

accept, afterCreationHook, destroy, dumpStats, enableStats, getConfigurableObjects, getDownProtocol, getDownServices, getId, getIdsAbove, getLevel, getLog, getName, getProtocolStack, getSocketFactory, getThreadFactory, getTransport, getUpProtocol, getUpServices, getValue, isErgonomics, level, printStats, providedDownServices, providedUpServices, requiredDownServices, requiredUpServices, resetStatistics, resetStats, setDownProtocol, setErgonomics, setId, setLevel, setProtocolStack, setSocketFactory, setUpProtocol, setValue, setValues, start, statsEnabled, stop

Methods inherited from class java.lang.Object

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

Field Detail

ID

public static short ID

config

protected java.lang.String config

process_state_events

protected boolean process_state_events

fork_stacks

protected final java.util.concurrent.ConcurrentMap<java.lang.String,Protocol> fork_stacks

local_addr

protected Address local_addr

Constructor Detail

FORK

public FORK()

Method Detail

setUnknownForkHandler

public void setUnknownForkHandler(UnknownForkHandler unknownForkHandler)

getUnknownForkHandler

public UnknownForkHandler getUnknownForkHandler()

get

public Protocol get(java.lang.String fork_stack_id)

putIfAbsent

public Protocol putIfAbsent(java.lang.String fork_stack_id,
                            Protocol prot)

remove

public void remove(java.lang.String fork_stack_id)

getForkStacks

public int getForkStacks()

getForkStack

public static ForkProtocolStack getForkStack(Protocol prot)

init

public void init()
          throws java.lang.Exception

Description copied from class: Protocol

Called after instance has been created (null constructor) and before protocol is started. Properties are already set. Other protocols are not yet connected and events cannot yet be sent.

Overrides:

init in class Protocol

Throws:

java.lang.Exception - Thrown if protocol cannot be initialized successfully. This will cause the ProtocolStack to fail, so the channel constructor will throw an exception

down

public java.lang.Object down(Event evt)

Description copied from class: Protocol

An event is to be sent down the stack. The layer may want to examine its type and perform some action on it, depending on the event's type. If the event is a message MSG, then the layer may need to add a header to it (or do nothing at all) before sending it down the stack using down_prot.down(). In case of a GET_ADDRESS event (which tries to retrieve the stack's address from one of the bottom layers), the layer may need to send a new response event back up the stack using up_prot.up().

Overrides:

down in class Protocol

up

public java.lang.Object up(Event evt)

Description copied from class: Protocol

An event was received from the layer below. Usually the current layer will want to examine the event type and - depending on its type - perform some computation (e.g. removing headers from a MSG event type, or updating the internal membership list when receiving a VIEW_CHANGE event). Finally the event is either a) discarded, or b) an event is sent down the stack using down_prot.down() or c) the event (or another event) is sent up the stack using up_prot.up().

Overrides:

up in class Protocol

up

public void up(MessageBatch batch)

Description copied from class: Protocol

Sends up a multiple messages in a MessageBatch. The sender of the batch is always the same, and so is the destination (null == multicast messages). Messages in a batch can be OOB messages, regular messages, or mixed messages, although the transport itself will create initial MessageBatches that contain only either OOB or regular messages.

The default processing below sends messages up the stack individually, based on a matching criteria (calling Protocol.accept(org.jgroups.Message)), and - if true - calls Protocol.up(org.jgroups.Event) for that message and removes the message. If the batch is not empty, it is passed up, or else it is dropped.

Subclasses should check if there are any messages destined for them (e.g. using MessageBatch.getMatchingMessages(short,boolean)), then possibly remove and process them and finally pass the batch up to the next protocol. Protocols can also modify messages in place, e.g. ENCRYPT could decrypt all encrypted messages in the batch, not remove them, and pass the batch up when done.

Overrides:

up in class Protocol

Parameters:

batch - The message batch

getStateFromMainAndForkChannels

protected void getStateFromMainAndForkChannels(Event evt)

getStateFrom

protected void getStateFrom(JChannel channel,
                            Protocol prot,
                            java.lang.String stack,
                            java.lang.String ch,
                            java.io.DataOutputStream out)
                     throws java.lang.Exception

Throws:

java.lang.Exception

setStateInMainAndForkChannels

protected void setStateInMainAndForkChannels(java.io.InputStream in)

createForkStacks

protected void createForkStacks(java.lang.String config)
                         throws java.lang.Exception

Throws:

java.lang.Exception

createForkStacks

protected void createForkStacks(java.util.Map<java.lang.String,java.util.List<ProtocolConfiguration>> protocols)
                         throws java.lang.Exception

Throws:

java.lang.Exception

parse

public void parse(org.w3c.dom.Node node)
           throws java.lang.Exception

Description copied from class: Protocol

Called by the XML parser when subelements are found in the configuration of a protocol. This allows a protocol to define protocol-specific information and to parse it

Overrides:

parse in class Protocol

Throws:

java.lang.Exception

createForkStack

public ProtocolStack createForkStack(java.lang.String fork_stack_id,
                                     java.util.List<Protocol> protocols,
                                     boolean initialize)
                              throws java.lang.Exception

Returns the fork stack for fork_stack_id (if exitstent), or creates a new fork-stack from protocols and adds it into the hashmap of fork-stack (key is fork_stack_id). Method init() will be called on each protocol, from bottom to top.

Parameters:

fork_stack_id - The key under which the new fork-stack should be added to the fork-stacks hashmap

protocols - A list of protocols from bottom to top to be inserted. They will be sandwiched between ForkProtocolStack (top) and ForkProtocol (bottom). The list can be empty (or null) in which case we won't create any protocols, but still have a separate fork-stack inserted.

initialize - If false, the ref count 'inits' will not get incremented and init() won't be called. This is needed when creating a fork stack from an XML config inside of the FORK protocol. The protocols in the fork stack will only get initialized on the first ForkChannel creation

Returns:

The new ForkProtocolStack, or the existing stack (if present)

Throws:

java.lang.Exception

createProtocols

protected static java.util.List<Protocol> createProtocols(ProtocolStack stack,
                                                          java.util.List<ProtocolConfiguration> protocol_configs)
                                                   throws java.lang.Exception

Creates a fork-stack from the configuration, initializes all protocols (setting values), sets the protocol stack as top protocol, connects the protocols and calls init() on them. Returns the protocols in a list, from bottom to top

Throws:

java.lang.Exception

getForkStream

public static java.io.InputStream getForkStream(java.lang.String config)
                                         throws java.io.IOException

Throws:

java.io.IOException