hashring

Documentation

Overview

Copyright (c) 2016-2019 Uber Technologies, Inc.

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.

Copyright (c) 2016-2019 Uber Technologies, Inc.

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.

Copyright (c) 2016-2019 Uber Technologies, Inc.

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.

Copyright (c) 2016-2019 Uber Technologies, Inc.

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.

Index

• type Config
• type Option
  • func WithWatcher(w Watcher) Option
• type PassiveRing
  • func NewPassive(config Config, cluster hostlist.List, passiveFilter healthcheck.PassiveFilter, ...) PassiveRing
  • func NoopPassiveRing(hosts hostlist.List) PassiveRing
• type Ring
  • func New(config Config, cluster hostlist.List, filter healthcheck.Filter, ...) Ring
• type Watcher

Types

type Config

type Config struct {
	// MaxReplica is the max number of hosts each blob will be replicated across.
	// If MaxReplica is >= the number of hosts in the ring, every host will own
	// every blob.
	MaxReplica int `yaml:"max_replica"`

	// RefreshInterval is the interval at which membership / health information
	// is refreshed during monitoring.
	RefreshInterval time.Duration `yaml:"refresh_interval"`
}

Config defines Ring configuration.

type Option

type Option func(*ring)

Option allows setting custom parameters for ring.

func WithWatcher

func WithWatcher(w Watcher) Option

WithWatcher adds a watcher to the ring. Can be used multiple times.

type PassiveRing

type PassiveRing interface {
	Ring
	Failed(addr string)
}

PassiveRing is a wrapper around Ring which supports passive health checks. See healthcheck.PassiveFilter for passive health check documentation.

func NewPassive

func NewPassive(
	config Config,
	cluster hostlist.List,
	passiveFilter healthcheck.PassiveFilter,
	opts ...Option) PassiveRing

NewPassive creats a new PassiveRing.

func NoopPassiveRing

func NoopPassiveRing(hosts hostlist.List) PassiveRing

NoopPassiveRing returns a PassiveRing which never filters unhealthy hosts.

type Ring

type Ring interface {
	Locations(d core.Digest) []string
	Contains(addr string) bool
	Monitor(stop <-chan struct{})
	Refresh()
}

Ring is a rendezvous hashing ring which calculates an ordered replica set of healthy addresses which own any given digest.

Address membership within the ring is defined by a dynamic hostlist.List. On top of that, replica sets are filtered by the health status of their addresses. Membership and health status may be refreshed by using Monitor.

Ring maintains the invariant that it is always non-empty and can always provide locations, although in some scenarios the provided locations are not guaranteed to be healthy (see Locations).

func New

func New(
	config Config, cluster hostlist.List, filter healthcheck.Filter, opts ...Option) Ring

New creates a new Ring whose members are defined by cluster.

type Watcher

type Watcher interface {
	Notify(latest stringset.Set)
}

Watcher allows clients to watch the ring for changes. Whenever membership changes, each registered Watcher is notified with the latest hosts.