Package org.jgroups.protocols
Class BARRIER
- java.lang.Object
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- org.jgroups.stack.Protocol
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- org.jgroups.protocols.BARRIER
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public class BARRIER extends Protocol
All messages up the stack have to go through a barrier (read lock, RL). By default, the barrier is open. When a CLOSE_BARRIER event is received, we close the barrier by acquiring a write lock (WL). This succeeds when all previous messages have completed (by releasing their RLs). Thus, when we have acquired the WL, we know that there are no pending messages processed.
When an OPEN_BARRIER event is received, we simply open the barrier again and let all messages pass in the up direction. This is done by releasing the WL.- Author:
- Bela Ban
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Field Summary
Fields Modifier and Type Field Description protected java.util.concurrent.atomic.AtomicBoolean
barrier_closed
protected java.util.concurrent.Future<?>
barrier_opener_future
protected long
flush_timeout
protected java.util.Set<Address>
holes
protected java.util.Map<java.lang.Thread,java.lang.Object>
in_flight_threads
protected Address
local_addr
protected java.util.concurrent.locks.Lock
lock
protected long
max_close_time
protected java.util.Map<Address,Message>
mcast_queue
protected java.util.concurrent.locks.Condition
no_pending_threads
signals to waiting threads that the barrier is open againprotected static java.lang.Object
NULL
protected TimeScheduler
timer
protected TP
transport
protected java.util.Map<Address,Message>
ucast_queue
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Fields inherited from class org.jgroups.stack.Protocol
after_creation_hook, down_prot, ergonomics, id, log, stack, stats, up_prot
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Constructor Summary
Constructors Constructor Description BARRIER()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description protected void
cancelBarrierOpener()
void
closeBarrier()
Close the barrier.void
destroy()
This method is called on aJChannel.close()
.java.lang.Object
down(Event evt)
An event is to be sent down the stack.protected void
flushQueue(java.util.Map<Address,Message> queue)
java.lang.String
getHoles()
int
getInFlightThreadsCount()
int
getNumberOfInFlightThreads()
void
init()
Called after instance has been created (null constructor) and before protocol is started.boolean
isClosed()
boolean
isOpenerScheduled()
void
openBarrier()
protected java.lang.String
printInFlightThreads()
protected void
scheduleBarrierOpener()
void
stop()
This method is called on aJChannel.disconnect()
.protected void
unblock(java.lang.Thread current_thread)
java.lang.Object
up(Event evt)
An event was received from the protocol below.java.lang.Object
up(Message msg)
A single message was received.void
up(MessageBatch batch)
Sends up a multiple messages in aMessageBatch
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Methods inherited from class org.jgroups.stack.Protocol
accept, afterCreationHook, down, enableStats, getConfigurableObjects, getDownProtocol, getDownServices, getId, getIdsAbove, getLevel, getLog, getName, getProtocolStack, getSocketFactory, getThreadFactory, getTransport, getUpProtocol, getUpServices, getValue, isErgonomics, level, parse, providedDownServices, providedUpServices, requiredDownServices, requiredUpServices, resetStatistics, resetStats, setDownProtocol, setErgonomics, setId, setLevel, setProtocolStack, setSocketFactory, setUpProtocol, setValue, start, statsEnabled
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Field Detail
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max_close_time
protected long max_close_time
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flush_timeout
protected long flush_timeout
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lock
protected final java.util.concurrent.locks.Lock lock
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barrier_closed
protected final java.util.concurrent.atomic.AtomicBoolean barrier_closed
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no_pending_threads
protected java.util.concurrent.locks.Condition no_pending_threads
signals to waiting threads that the barrier is open again
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in_flight_threads
protected java.util.Map<java.lang.Thread,java.lang.Object> in_flight_threads
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barrier_opener_future
protected volatile java.util.concurrent.Future<?> barrier_opener_future
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timer
protected TimeScheduler timer
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local_addr
protected Address local_addr
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holes
protected final java.util.Set<Address> holes
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transport
protected TP transport
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NULL
protected static final java.lang.Object NULL
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Method Detail
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isClosed
public boolean isClosed()
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getHoles
public java.lang.String getHoles()
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getNumberOfInFlightThreads
public int getNumberOfInFlightThreads()
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getInFlightThreadsCount
public int getInFlightThreadsCount()
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isOpenerScheduled
public boolean isOpenerScheduled()
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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.
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stop
public void stop()
Description copied from class:Protocol
This method is called on aJChannel.disconnect()
. Stops work (e.g. by closing multicast socket). Will be called from top to bottom. This means that at the time of the method invocation the neighbor protocol below is still working. This method will replace the STOP, STOP_OK, CLEANUP and CLEANUP_OK events. The ProtocolStack guarantees that when this method is called all messages in the down queue will have been flushed
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destroy
public void destroy()
Description copied from class:Protocol
This method is called on aJChannel.close()
. Does some cleanup; after the call the VM will terminate
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down
public java.lang.Object down(Event evt)
Description copied from class:Protocol
An event is to be sent down the stack. A protocol 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 protocol may need to add a header to it (or do nothing at all) before sending it down the stack usingdown_prot.down()
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up
public java.lang.Object up(Event evt)
Description copied from class:Protocol
An event was received from the protocol below. Usually the current protocol 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 usingdown_prot.down()
or c) the event (or another event) is sent up the stack usingup_prot.up()
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up
public java.lang.Object up(Message msg)
Description copied from class:Protocol
A single message was received. Protocols may examine the message and do something (e.g. add a header) with it before passing it up.
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up
public void up(MessageBatch batch)
Description copied from class:Protocol
Sends up a multiple messages in aMessageBatch
. 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 (callingProtocol.accept(org.jgroups.Message)
), and - if true - callsProtocol.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. usingMessageBatch.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.
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unblock
protected void unblock(java.lang.Thread current_thread)
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closeBarrier
public void closeBarrier() throws java.util.concurrent.TimeoutException
Close the barrier. Temporarily remove all threads which are waiting or blocked, re-insert them after the call- Throws:
java.util.concurrent.TimeoutException
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openBarrier
public void openBarrier()
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printInFlightThreads
protected java.lang.String printInFlightThreads()
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scheduleBarrierOpener
protected void scheduleBarrierOpener()
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cancelBarrierOpener
protected void cancelBarrierOpener()
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