...
When a client connects to the server with subscription enabled flag, an HARegionQueue for that client-proxy is created on the server side.
Class Diagrams
PlantUML |
---|
skinparam dpi 80
@startuml
hide empty members
title Server to Client Queues - Class Diagram
class CacheClientNotifier {
Singleton for a Cache.
}
class CacheClientProxy {
One for each client. |
...
Keeps track of a the subscriptions for the client.
}
class MessageDispatcher {
Thread that reads events from the queue.
}
class HARegionQueue {
Holds the list of events to |
...
dispatch to a single client. } class HAContainerMap { Holds the actual values for events to dispatch. Used to store only a single copy of each value across all queues. } interface HAContainerMap CacheClientNotifier "1 " o-- "*" CacheClientProxy CacheClientProxy o-- MessageDispatcher CacheClientNotifier o-- HAContainerMap MessageDispatcher o-- HARegionQueue HARegionQueue "*" --> "1" HAContainerMap HARegionQueue o-- HARegion @enduml |
This next diagram focuses on cardinality:
- between
HARegionQueue
andDACE
(DispatchedAndCurrentEvents
) objects (through the mis-namedHARegionQueue.eventsMap
) - between
HARegion
and the two kinds of entries it holds:<Position,Conflatable>
and<ThreadIdentifier,SequenceID>
In both cases, the Java Map
s are depicted as associations in the diagram (the Map
objects are not shown explicitly). So, for instance HARegionQueue.eventsMap
is a Map
. It's depicted as a 1-to-(0..1 per Position)
association from HARegionQueue
to Position
. Similarly for HARegion
to Conflatable
and HARegion
to SequenceID
.
The diagram introduces two types not actually present in the Java code. Both are depicted as subtypes of Long
: SequenceID
to stand for an event's sequence id; and Position
to stand for a position in a queue. In the source code these are both just Long
s.
PlantUML |
---|
@startuml title HARegionQueue—Class Diagram\nHARegion and DACE Cardinalities class SequenceID <<design class>> Long <|-- SequenceID class Position <<design class>> Long <|-- Position class HARegionQueue { Position tailKey } class DispatchedAndCurrentEvents { SequenceID lastDispatchedSequenceID } ' these are together because I want to highlight the similarity (potential subtype relationship) together { ' putting this first causes it to be layed out to the right of ThreadIdentifier, making the ' association (line) from Conflatable shorter class EventID { byte[] membershipId long threadId SequenceID sequenceId int bucketId } class ThreadIdentifier { byte[] membershipId long threadId } } interface Conflatable ' these subtypes of Conflatable are grouped together together { interface ClientMessage class HAEventWrapper class ConflatableObject } Conflatable <|-- HAEventWrapper Conflatable <|-- ConflatableObject Conflatable <|-- ClientMessage interface ClientUpdateMessage ClientMessage <|-- ClientUpdateMessage ClientUpdateMessage <|-- ClientUpdateMessageImpl ClientUpdateMessageImpl <|-- ClientInstantiatorMessage ClientMessage <|-- ClientMarkerMessageImpl Conflatable --> EventID interface RegionQueue RegionQueue <|-- HARegionQueue HARegionQueue <|-- BlockingHARegionQueue BlockingHARegionQueue <|-- DurableHARegionQueue DistributedRegion <|-- HARegion ' while method signatures in HARegionQueue take Object, there's downcasting to Conflatable HARegion "*" *-- "0..1 per Position" Conflatable HARegion "*" *-- "0..1 per ThreadIdentifier" SequenceID HARegionQueue *-- HARegion HARegionQueue "1" *-- "0..1 per ThreadIdentifier" DispatchedAndCurrentEvents DispatchedAndCurrentEvents "1" *-- "0..1 per Position" Position ' this hidden assoc changes layout such that cardinality text on SequenceID and Position isn't overlapping as much ConflatableObject -[hidden]- HARegion @enduml |
Sequence Diagrams
PlantUML |
---|
skinparam dpi 80
title Put into Queue (for Partitioned Regions)
actor user
user -> "PR Primary" : put
"PR Primary" -> "PR Secondary" : UpdateMessage
"PR Primary" -> "Adjunct Receiver": PutMessage
note right
The primary notifies all members that have
clients with interest
end note
"PR Primary" -> CacheClientNotifier: notifyClients()
"Adjunct Receiver" -> CacheClientNotifier: notifyClients()
note right
All members with interest
call notifyClients locally
end note
"PR Secondary" -> CacheClientNotifier: notifyClients()
CacheClientNotifier -> CacheClientProxy: deliverMessage()
CacheClientProxy -> MessageDispatcher : enqueueMessage()
MessageDispatcher -> HARegionQueue: basicPut()
|
...
Adding events to HARegionQueue:
...
Based on the interest satisfied by the client, the ClientMessage is created and added to the HARegionQueue of the interested client (“CacheClientProxy.enqueueMessage()”). Once the event is added to the HARegionQueue the cache operation thread returns to the caller.
There are cases where the events are not simply added to the HARegionQueue. Specifically, there currently are two cases where the event is put into a temporary queue.
1. The server is providing an initial image to a performed (see HARegionQueue.giiQueue)
2. A client is in the process of registering and its message dispatcher/queue are not fully created and initialized
After these operations are completed, the temporary queues are drained and the event is added to the HARegionQueue. The diagrams below show the different put paths in detail.
These diagrams show more detail around the special handling during client queue initialization or providing an initial image.
Delivering/Dispatching Events to Client:
...
After the events are delivered and removed from the primary queue (node), it sends the “QueueRemovalMessage” to secondary queues (nodes); as part of message processing each secondary queue removes events from its queue(“QueueRemovalMessage.process().removeDispatchedEvents()”.
The diagram below shows a simplified view of the queue removal logic.
Memory Optimization:
...
This is done at the end of “HARegionQueue.putObject()”.