Since heap is already sorted, we can just check first element
to see if anything is expiry, rather than popping and pushing
it back. If nothing is expiry, pop operation is unnecessary.
Signed-off-by: Gyuho Lee <gyuhox@gmail.com>
This adds a heap acting as a priority queue to keep track of lease
exiprations. Previously the whole lease map had to be iterated through
each time.
The queue allows us to check only those leases which might be expired.
When the expiration changes, we add an additional entry. If we check an
entry that isn't expired, it means that the lease got extended.
If we find a entry in the heap that doesn't have a corresponding entry in
the map, we know that the lease has already been expired or revoked.
The golang/time package tracks monotonic time in each time.Time
returned by time.Now function for Go 1.9.
Use time.Time to measure whether a lease is expired and remove
previous pkg/monotime. Use zero time.Time to mean forever. No
expiration when expiry.IsZero() is true.
Instead of unconditionally randomizing, extend leases on promotion
if too many leases expire within the same time span. If the server
has few leases or spread out expires, there will be no extension.
Randomize the very first expiry on lease recovery
to prevent recovered leases from expiring all at
the same time.
Address https://github.com/coreos/etcd/issues/8096.
Signed-off-by: Gyu-Ho Lee <gyuhox@gmail.com>
Demote was racing on expiry when LeaseTimeToLive called Remaining. Replace
with intrinsics since the ordering isn't important, but torn writes are
bad.
The new leader needs to refresh with an extened TTL to gracefully handle
the potential concurrent leader issue. Clients might still send keep alive
to old leader until the old leader itself gives up leadership at most after
an election timeout.
When raft broadcasts a Grant to all nodes, all nodes must
agree on the same lease ID. Otherwise, attaching a key to
a lease will fail since the lease ID is node-dependent.
