forked from cockroachdb/cockroach
/
replicate_queue.go
171 lines (153 loc) · 5.24 KB
/
replicate_queue.go
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// Copyright 2015 The Cockroach Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
// implied. See the License for the specific language governing
// permissions and limitations under the License.
//
// Author: Ben Darnell
package storage
import (
"time"
"github.com/cockroachdb/cockroach/config"
"github.com/cockroachdb/cockroach/gossip"
"github.com/cockroachdb/cockroach/roachpb"
"github.com/cockroachdb/cockroach/util"
"github.com/cockroachdb/cockroach/util/hlc"
"github.com/cockroachdb/cockroach/util/log"
)
const (
// replicateQueueMaxSize is the max size of the replicate queue.
replicateQueueMaxSize = 100
// replicateQueueTimerDuration is the duration between replication of queued
// replicas.
replicateQueueTimerDuration = 0 // zero duration to process replication greedily
)
// replicateQueue manages a queue of replicas which may need to add an
// additional replica to their range.
type replicateQueue struct {
baseQueue
allocator Allocator
clock *hlc.Clock
}
// newReplicateQueue returns a new instance of replicateQueue.
func newReplicateQueue(gossip *gossip.Gossip, allocator Allocator, clock *hlc.Clock,
options AllocatorOptions) *replicateQueue {
rq := &replicateQueue{
allocator: allocator,
clock: clock,
}
rq.baseQueue = makeBaseQueue("replicate", rq, gossip, replicateQueueMaxSize)
return rq
}
func (*replicateQueue) needsLeaderLease() bool {
return true
}
// acceptsUnsplitRanges is false because the proper replication
// policy cannot be determined for ranges that span zone configs.
func (*replicateQueue) acceptsUnsplitRanges() bool {
return false
}
func (rq *replicateQueue) shouldQueue(now roachpb.Timestamp, repl *Replica,
sysCfg *config.SystemConfig) (shouldQ bool, priority float64) {
desc := repl.Desc()
if len(sysCfg.ComputeSplitKeys(desc.StartKey, desc.EndKey)) > 0 {
// If the replica's range needs splitting, wait until done.
return
}
// Find the zone config for this range.
zone, err := sysCfg.GetZoneConfigForKey(desc.StartKey)
if err != nil {
log.Error(err)
return
}
action, priority := rq.allocator.ComputeAction(*zone, desc)
if action != AllocatorNoop {
return true, priority
}
// See if there is a rebalancing opportunity present.
shouldRebalance := rq.allocator.ShouldRebalance(repl.store.StoreID())
return shouldRebalance, 0
}
func (rq *replicateQueue) process(now roachpb.Timestamp, repl *Replica, sysCfg *config.SystemConfig) error {
desc := repl.Desc()
// Find the zone config for this range.
zone, err := sysCfg.GetZoneConfigForKey(desc.StartKey)
if err != nil {
return err
}
action, _ := rq.allocator.ComputeAction(*zone, desc)
// Avoid taking action if the range has too many dead replicas to make
// quorum.
deadReplicas := rq.allocator.storePool.deadReplicas(desc.Replicas)
quorum := computeQuorum(len(desc.Replicas))
liveReplicaCount := len(desc.Replicas) - len(deadReplicas)
if liveReplicaCount < quorum {
return util.Errorf("range requires a replication change, but lacks a quorum of live nodes.")
}
switch action {
case AllocatorAdd:
newStore, err := rq.allocator.AllocateTarget(zone.ReplicaAttrs[0], desc.Replicas, true, nil)
if err != nil {
return err
}
newReplica := roachpb.ReplicaDescriptor{
NodeID: newStore.Node.NodeID,
StoreID: newStore.StoreID,
}
if err = repl.ChangeReplicas(roachpb.ADD_REPLICA, newReplica, desc); err != nil {
return err
}
case AllocatorRemove:
removeReplica, err := rq.allocator.RemoveTarget(desc.Replicas)
if err != nil {
return err
}
if err = repl.ChangeReplicas(roachpb.REMOVE_REPLICA, removeReplica, desc); err != nil {
return err
}
// Do not requeue if we removed ourselves.
if removeReplica.StoreID == repl.store.StoreID() {
return nil
}
case AllocatorRemoveDead:
if len(deadReplicas) == 0 {
if log.V(1) {
log.Warningf("Range of replica %s was identified as having dead replicas, but no dead replicas were found.", repl)
}
break
}
if err = repl.ChangeReplicas(roachpb.REMOVE_REPLICA, deadReplicas[0], desc); err != nil {
return err
}
case AllocatorNoop:
// The Noop case will result if this replica was queued in order to
// rebalance. Attempt to find a rebalancing target.
rebalanceStore := rq.allocator.RebalanceTarget(repl.store.StoreID(), zone.ReplicaAttrs[0], desc.Replicas)
if rebalanceStore == nil {
// No action was necessary and no rebalance target was found. Return
// without re-queueing this replica.
return nil
}
rebalanceReplica := roachpb.ReplicaDescriptor{
NodeID: rebalanceStore.Node.NodeID,
StoreID: rebalanceStore.StoreID,
}
if err = repl.ChangeReplicas(roachpb.ADD_REPLICA, rebalanceReplica, desc); err != nil {
return err
}
}
// Enqueue this replica again to see if there are more changes to be made.
rq.MaybeAdd(repl, rq.clock.Now())
return nil
}
func (*replicateQueue) timer() time.Duration {
return replicateQueueTimerDuration
}