org.jgroups.util
Class ForwardQueue

java.lang.Object
  org.jgroups.util.ForwardQueue

public class ForwardQueue
extends java.lang.Object

Forwards messages in FIFO order to a destination. Uses IDs to prevent duplicates. Used by FORWARD_TO_COORD.

Since:

3.3

Author:

Bela Ban

Nested Class Summary

protected class

ForwardQueue.Flusher

Field Summary

protected Promise<java.lang.Long>	ack_promise Used for each resent message to wait until the message has been received
protected java.util.concurrent.ConcurrentMap<Address,java.util.NavigableSet<java.lang.Long>>	delivery_table
protected int	delivery_table_max_size Size of the set to store received seqnos (for duplicate checking)
protected Protocol	down_prot
protected ForwardQueue.Flusher	flusher
protected boolean	flushing Set when we block all sending threads to resend all messages from forward_table
protected java.util.NavigableMap<java.lang.Long,Message>	forward_table Maintains messages forwarded to the target which which no ack has been received yet.
protected java.util.concurrent.atomic.AtomicInteger	in_flight_sends Keeps track of the threads sending messages
protected Address	local_addr
protected Log	log
protected boolean	running
protected java.util.concurrent.locks.Condition	send_cond
protected java.util.concurrent.locks.Lock	send_lock
protected Protocol	up_prot

Constructor Summary

ForwardQueue(Log log)

Method Summary

void	ack(long id)
protected void	block()
protected boolean	canDeliver(Address sender, long seqno) Checks if seqno has already been received from sender.
int	deliveryTableSize() Total size of all queues of the delivery table
protected void	doFlush(Address new_target)
void	flush(Address new_target, java.util.List<Address> mbrs)
protected void	flushMessagesInForwardTable(Address target) Sends all messages currently in forward_table to the new target (changing the dest field).
int	getDeliveryTableMaxSize()
Protocol	getDownProt()
Address	getLocalAddr()
Protocol	getUpProt()
void	receive(long id, Message msg)
void	send(long id, Message msg)
void	setDeliveryTableMaxSize(int max_size)
void	setDownProt(Protocol down_prot)
void	setLocalAddr(Address local_addr)
void	setUpProt(Protocol up_prot)
int	size()
void	start()
protected void	startFlusher(Address new_coord)
void	stop()
protected void	stopFlusher()
protected void	unblockAll()

Methods inherited from class java.lang.Object

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

Field Detail

up_prot

protected Protocol up_prot

down_prot

protected Protocol down_prot

local_addr

protected Address local_addr

forward_table

protected final java.util.NavigableMap<java.lang.Long,Message> forward_table

Maintains messages forwarded to the target which which no ack has been received yet. Needs to be sorted so we can resend them in the right order

send_lock

protected final java.util.concurrent.locks.Lock send_lock

send_cond

protected final java.util.concurrent.locks.Condition send_cond

flushing

protected volatile boolean flushing

Set when we block all sending threads to resend all messages from forward_table

running

protected volatile boolean running

in_flight_sends

protected final java.util.concurrent.atomic.AtomicInteger in_flight_sends

Keeps track of the threads sending messages

delivery_table

protected final java.util.concurrent.ConcurrentMap<Address,java.util.NavigableSet<java.lang.Long>> delivery_table

flusher

protected volatile ForwardQueue.Flusher flusher

ack_promise

protected final Promise<java.lang.Long> ack_promise

Used for each resent message to wait until the message has been received

log

protected final Log log

delivery_table_max_size

protected int delivery_table_max_size

Size of the set to store received seqnos (for duplicate checking)

Constructor Detail

ForwardQueue

public ForwardQueue(Log log)

Method Detail

getUpProt

public Protocol getUpProt()

setUpProt

public void setUpProt(Protocol up_prot)

getDownProt

public Protocol getDownProt()

setDownProt

public void setDownProt(Protocol down_prot)

getLocalAddr

public Address getLocalAddr()

setLocalAddr

public void setLocalAddr(Address local_addr)

getDeliveryTableMaxSize

public int getDeliveryTableMaxSize()

setDeliveryTableMaxSize

public void setDeliveryTableMaxSize(int max_size)

deliveryTableSize

public int deliveryTableSize()

Total size of all queues of the delivery table

start

public void start()

stop

public void stop()

send

public void send(long id,
                 Message msg)

receive

public void receive(long id,
                    Message msg)

flush

public void flush(Address new_target,
                  java.util.List<Address> mbrs)

ack

public void ack(long id)

size

public int size()

doFlush

protected void doFlush(Address new_target)
                throws java.lang.InterruptedException

Throws:

java.lang.InterruptedException

flushMessagesInForwardTable

protected void flushMessagesInForwardTable(Address target)

Sends all messages currently in forward_table to the new target (changing the dest field). This needs to be done, so the underlying reliable unicast protocol (e.g. UNICAST) adds these messages to its retransmission mechanism
Note that we need to resend the messages in order of their seqnos ! We also need to prevent other message from being inserted until we're done, that's why there's synchronization.
Access to the forward_table doesn't need to be synchronized as there won't be any insertions during flushing (all down-threads are blocked)

canDeliver

protected boolean canDeliver(Address sender,
                             long seqno)

Checks if seqno has already been received from sender. This weeds out duplicates. Note that this method is never called concurrently for the same sender.

block

protected void block()

unblockAll

protected void unblockAll()

startFlusher

protected void startFlusher(Address new_coord)

stopFlusher

protected void stopFlusher()