func (r *Replica) leasePostApply(
ctx context.Context,
newLease *roachpb.Lease,
replicaID roachpb.ReplicaID,
prevLease *roachpb.Lease,
) {
iAmTheLeaseHolder := newLease.Replica.ReplicaID == replicaID
leaseChangingHands := prevLease.Replica.StoreID != newLease.Replica.StoreID
if leaseChangingHands && iAmTheLeaseHolder {
// If this replica is a new holder of the lease, update the low water
// mark of the timestamp cache. Note that clock offset scenarios are
// handled via a stasis period inherent in the lease which is documented
// in on the Lease struct.
//
// The introduction of lease transfers implies that the previous lease
// may have been shortened and we are now applying a formally overlapping
// lease (since the old lease holder has promised not to serve any more
// requests, this is kosher). This means that we don't use the old
// lease's expiration but instead use the new lease's start to initialize
// the timestamp cache low water.
if log.V(1) {
log.Infof(ctx, "new range lease %s following %s [physicalTime=%s]",
newLease, prevLease, r.store.Clock().PhysicalTime())
}
r.mu.Lock()
r.mu.tsCache.SetLowWater(newLease.Start)
r.mu.Unlock()
// Gossip the first range whenever its lease is acquired. We check to
// make sure the lease is active so that a trailing replica won't process
// an old lease request and attempt to gossip the first range.
if r.IsFirstRange() && r.IsLeaseValid(newLease, r.store.Clock().Now()) {
r.gossipFirstRange(ctx)
}
}
if leaseChangingHands && !iAmTheLeaseHolder {
// We're not the lease holder, reset our timestamp cache, releasing
// anything currently cached. The timestamp cache is only used by the
// lease holder. Note that we'll call SetLowWater when we next acquire
// the lease.
r.mu.Lock()
r.mu.tsCache.Clear(r.store.Clock().Now())
r.mu.Unlock()
}
if !iAmTheLeaseHolder && r.IsLeaseValid(newLease, r.store.Clock().Now()) {
// If this replica is the raft leader but it is not the new lease holder,
// then try to transfer the raft leadership to match the lease. We like it
// when leases and raft leadership are collocated because that facilitates
// quick command application (requests generally need to make it to both the
// lease holder and the raft leader before being applied by other replicas).
// Note that this condition is also checked periodically when computing
// replica metrics.
r.maybeTransferRaftLeadership(ctx, newLease.Replica.ReplicaID)
}
// Notify the store that a lease change occurred and it may need to
// gossip the updated store descriptor (with updated capacity).
if leaseChangingHands && (prevLease.OwnedBy(r.store.StoreID()) ||
newLease.OwnedBy(r.store.StoreID())) {
r.store.maybeGossipOnCapacityChange(ctx, leaseChangeEvent)
}
}
