The previous logic was not properly handling the case of a node
that was failing and oining back in short period of time.
The issue was in the handling of the network messages.
When a node joins it sync with other nodes, these are passing
the whole list of nodes that at best of their knowledge are part
of a network. At this point if the node receives that node A is part
of the network it saves it before having received the notification
that node A is actually alive (coming from memberlist).
If node A failed the source node will receive the notification
while the new joined node won't because memberlist never advertise
node A as available. In this case the new node will never purge
node A from its state but also worse, will accept any table notification
where node A is the owner and so will end up in a out of sync state
with the rest of the cluster.
This commit contains also some code cleanup around the area of node
management
Signed-off-by: Flavio Crisciani <flavio.crisciani@docker.com>
- Create a test to verify that a node that joins
in an async way is not going to extend the life
of a already deleted object
Signed-off-by: Flavio Crisciani <flavio.crisciani@docker.com>
The comparison was against the wrong constant value.
As described in the comment the check is there to guarantee
to not propagate events realted to stale deleted elements
Signed-off-by: Flavio Crisciani <flavio.crisciani@docker.com>
Separate the hostname from the node identifier. All the messages
that are exchanged on the network are containing a nodeName field
that today was hostname-uniqueid. Now being encoded as strings in
the protobuf without any length restriction they plays a role
on the effieciency of protocol itself. If the hostname is very long
the overhead will increase and will degradate the performance of
the database itself that each single cycle by default allows 1400
bytes payload
Signed-off-by: Flavio Crisciani <flavio.crisciani@docker.com>
Make sure that the network is garbage collected after
the entries. Entries to be deleted requires that the network
is present.
Signed-off-by: Flavio Crisciani <flavio.crisciani@docker.com>
- Changed the loop per network. Previous implementation was taking a
ReadLock to update the reapTime but now with the residualReapTime
also the bulkSync is using the same ReadLock creating possible
issues in concurrent read and update of the value.
The new logic fetches the list of networks and proceed to the
cleanup network by network locking the database and releasing it
after each network. This should ensure a fair locking avoiding
to keep the database blocked for too much time.
Note: The ticker does not guarantee that the reap logic runs
precisely every reapTimePeriod, actually documentation says that
if the routine is too long will skip ticks. In case of slowdown
of the process itself it is possible that the lifetime of the
deleted entries increases, it still should not be a huge problem
because now the residual reaptime is propagated among all the nodes
a slower node will let the deleted entry being repropagate multiple
times but the state will still remain consistent.
Signed-off-by: Flavio Crisciani <flavio.crisciani@docker.com>
- Added remainingReapTime field in the table event.
Wihtout it a node that did not have a state for the element
was marking the element for deletion setting the max reapTime.
This was creating the possibility to keep the entry being resync
between nodes forever avoding the purpose of the reap time
itself.
- On broadcast of the table event the node owner was rewritten
with the local node name, this was not correct because the owner
should continue to remain the original one of the message
Signed-off-by: Flavio Crisciani <flavio.crisciani@docker.com>
join/leave fixes:
- when a node leaves the network will deletes all the other nodes entries but will keep track of its
to make sure that other nodes if they are tcp syncing will be aware of them being deleted. (a node that
did not yet receive the network leave will potentially tcp/sync)
add network reapTime, was not being set locally
Signed-off-by: Flavio Crisciani <flavio.crisciani@docker.com>
- Diagnose framework that exposes REST API for db interaction
- Dockerfile to build the test image
- Periodic print of stats regarding queue size
- Client and server side for integration with testkit
- Added write-delete-leave-join
- Added test write-delete-wait-leave-join
- Added write-wait-leave-join
Signed-off-by: Flavio Crisciani <flavio.crisciani@docker.com>
A rapid (within networkReapTime 30min) leave/join network
can corrupt the list of nodes per network with multiple copies
of the same nodes.
The fix makes sure that each node is present only once
Signed-off-by: Flavio Crisciani <flavio.crisciani@docker.com>
Commit ca9a768d80
added a number of debugging messages for node join/leave
events.
This patch checks if a node already was listed,
and otherwise skips the logging to make the logs a bit
less noisy.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Once the bulksync ack channel is closed remove it from the ack table
right away. There is no reason to keep it in the ack table and later
delete it in the ack waiter. Ack waiter anyways has reference to the
channel on which it is waiting.
Signed-off-by: Jana Radhakrishnan <mrjana@docker.com>
Since the node name randomization fix, we need to make sure that we
purge the old node with the same prefix and same IP from the nodes
database if it still present. This causes unnecessary reconnect
attempts.
Also added a change to avoid unnecessary update of local lamport time
and only do it of we are ready to do a push pull on a join. Join should
happen only when the node is bootstrapped or when trying to reconnect
with a failed node.
Signed-off-by: Jana Radhakrishnan <mrjana@docker.com>
Currently if there is any transient gossip failure in any node the
recoevry process depends on other nodes propogating the information
indirectly. In cases if these transient failures affects all the nodes
that this node has in its memberlist then this node will be permenantly
cutoff from the the gossip channel. Added node state management code in
networkdb to address these problems by trying to rejoin the cluster via
the failed nodes when there is a failure. This also necessitates the
need to add new messages called node event messages to differentiate
between node leave and node failure.
Signed-off-by: Jana Radhakrishnan <mrjana@docker.com>
In cases a node left the cluster and quickly rejoined before the node
entry is expired by other nodes in the cluster, when the node rejoins we
fail to add it to the quick lookup database. Fixed it.
Signed-off-by: Jana Radhakrishnan <mrjana@docker.com>
In networkdb we should ignore delete events for entries which doesn't
exist in the db. This is always true because if the entry did not exist
then the entry has been removed way earlier and got purged after the
reap timer and this notification is very stale.
Also there were duplicate delete notifications being sent to the
clients. One when the actual delete event was received from gossip and
later when the entry was getting reaped. The second notification is
unnecessary and may cause issues with the clients if they are not
coded for idempotency.
Signed-off-by: Jana Radhakrishnan <mrjana@docker.com>
When deleting entries or when learning about deleted entries remember
then for a longer time to avoid excessive delete duplicates in the
gossip cluster. Also added code changes to ignore event messages
originated from the source node so that it doesn't get added into the
rebroadcast queue.
Signed-off-by: Jana Radhakrishnan <mrjana@docker.com>
Convert all networkdb core message types from go message types to
protobuf message types. This faciliates future modification of the
message structure without breaking backward compatibility.
Signed-off-by: Jana Radhakrishnan <mrjana@docker.com>
Network DB is a network scoped gossip database built
on top of hashicorp/memberlist providing an eventually
consistent state store.
It limits the scope of the gossip and periodic bulk syncing
for table entries to only the nodes which participate in the
network to which the gossip belongs. This designs make the
gossip layer scale better and only consumes resources for the
network state that the node participates in.
Since the complete state for a network is maintained by all nodes
participating in the network, all nodes will eventually converge
to the same state.
NetworkDB also provides facilities for the users of the package to
watch on any table (or all tables) and get notified if there are
state changes of interest that happened anywhere in the cluster when
that state change eventually finds it's way to the watcher's node.
Signed-off-by: Jana Radhakrishnan <mrjana@docker.com>
Flavio Crisciani