* Implement the join to seed nodes process
When a new node is started started it sends a message to all
seed nodes and then sends join command to the one that answers
first.
* Configuration of seed-nodes and auto-join
* New JoinSeedNodeSpec that verifies the auto join to seed nodes
* In tests seed nodes are configured by overriding seedNodes
function, since addresses are not known before start
* Deputy nodes are the live members of the seed nodes (not sure if
that will be the final solution, see ticket 2252
* Updated cluster.rst with latest info about deputy and seed nodes
- introducing RepointableActorRef, which starts out with an
UnstartedActorCell which can cheaply be created; the Supervise()
message will trigger child.activate() in the supervisor, which means
that the actual creation (now with normal ActorCell) happens exactly
in the right place and with the right semantics. Messages which were
enqueued to the dummy cell are transferred atomically into the
ActorCell (using normal .tell()), so message sends keep working
exactly as they used to
- this enables getting rid of the brittle synchronization around
RoutedActorRef by replacing that one with a RepointableActorRef
subclass which creates RoutedActorCells upon activate(), with the nice
benefit that there is no hurry then to get it right because the new
cell is constructed “on the side”
misc fixes:
- InvalidMessageException is now actually enforced when trying to send
“null”
- Mailboxes may be created without having an ActorCell, which can come
in handy later, because the cell is only needed when this mailbox is
going to be scheduled on some executor
- remove occurrences of Props(), which is equivalent to Props[Nothing],
which is equivalent to «bug»
- add test case which verifies that context.actorOf is still synchronous
- plus all the stuff I have forgotten.
* Added implementation of the LEAVE command for a cluster node
* Changed the meaning of Member.isUnavailable to only DOWN and REMOVED
* Removed EXIT and UP as user commands
* Fixed Cluster.self to fall back to checking for itself in the gossip.overview.unreachable set.
* Added Leader action transitioning from LEAVING -> EXITING
* Improved comments
Signed-off-by: Jonas Bonér <jonas@jonasboner.com>
* Uses finite state machine for three states: Closed, Open, Half-Open
* Closed state allows calls through, and on sequential failures exceeding the max# set - transitions to Open state. Intervening successes cause the failure count to reset to 0
* Open state throws a CircuitOpenException on every call until the reset timeout is reached which causes a transition to Half-Open state
* Half-Open state will allow the next single call through, if it succeeds - transition to Closed state, if it fails - transition back to Open state, starting the reset timer again
* Allow configuration for the call and reset timeouts, as well as the maximum number of sequential failures before opening
* Supports async or synchronous call protection
* Callbacks are supported for state entry into Closed, Open, Half-Open. These are run in the supplied execution context
* Both thrown exceptions and calls exceeding max call time are considered failures
* Uses akka scheduler for timer events
* Integrated into File-Based durable mailbox
* Sample documented for other durable mailboxes
