memberlist

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Published: Apr 30, 2021 License: MPL-2.0 Imports: 29 Imported by: 1,065

README

memberlist GoDoc CircleCI

memberlist is a Go library that manages cluster membership and member failure detection using a gossip based protocol.

The use cases for such a library are far-reaching: all distributed systems require membership, and memberlist is a re-usable solution to managing cluster membership and node failure detection.

memberlist is eventually consistent but converges quickly on average. The speed at which it converges can be heavily tuned via various knobs on the protocol. Node failures are detected and network partitions are partially tolerated by attempting to communicate to potentially dead nodes through multiple routes.

Building

If you wish to build memberlist you'll need Go version 1.2+ installed.

Please check your installation with:

go version

Usage

Memberlist is surprisingly simple to use. An example is shown below:

/* Create the initial memberlist from a safe configuration.
   Please reference the godoc for other default config types.
   http://godoc.org/github.com/hashicorp/memberlist#Config
*/
list, err := memberlist.Create(memberlist.DefaultLocalConfig())
if err != nil {
	panic("Failed to create memberlist: " + err.Error())
}

// Join an existing cluster by specifying at least one known member.
n, err := list.Join([]string{"1.2.3.4"})
if err != nil {
	panic("Failed to join cluster: " + err.Error())
}

// Ask for members of the cluster
for _, member := range list.Members() {
	fmt.Printf("Member: %s %s\n", member.Name, member.Addr)
}

// Continue doing whatever you need, memberlist will maintain membership
// information in the background. Delegates can be used for receiving
// events when members join or leave.

The most difficult part of memberlist is configuring it since it has many available knobs in order to tune state propagation delay and convergence times. Memberlist provides a default configuration that offers a good starting point, but errs on the side of caution, choosing values that are optimized for higher convergence at the cost of higher bandwidth usage.

For complete documentation, see the associated Godoc.

Protocol

memberlist is based on "SWIM: Scalable Weakly-consistent Infection-style Process Group Membership Protocol". However, we extend the protocol in a number of ways:

  • Several extensions are made to increase propagation speed and convergence rate.
  • Another set of extensions, that we call Lifeguard, are made to make memberlist more robust in the presence of slow message processing (due to factors such as CPU starvation, and network delay or loss).

For details on all of these extensions, please read our paper "Lifeguard : SWIM-ing with Situational Awareness", along with the memberlist source. We welcome any questions related to the protocol on our issue tracker.

Documentation

Overview

memberlist is a library that manages cluster membership and member failure detection using a gossip based protocol.

The use cases for such a library are far-reaching: all distributed systems require membership, and memberlist is a re-usable solution to managing cluster membership and node failure detection.

memberlist is eventually consistent but converges quickly on average. The speed at which it converges can be heavily tuned via various knobs on the protocol. Node failures are detected and network partitions are partially tolerated by attempting to communicate to potentially dead nodes through multiple routes.

Index

Constants

View Source
const (
	ProtocolVersionMin uint8 = 1

	// Version 3 added support for TCP pings but we kept the default
	// protocol version at 2 to ease transition to this new feature.
	// A memberlist speaking version 2 of the protocol will attempt
	// to TCP ping another memberlist who understands version 3 or
	// greater.
	//
	// Version 4 added support for nacks as part of indirect probes.
	// A memberlist speaking version 2 of the protocol will expect
	// nacks from another memberlist who understands version 4 or
	// greater, and likewise nacks will be sent to memberlists who
	// understand version 4 or greater.
	ProtocolVersion2Compatible = 2

	ProtocolVersionMax = 5
)

This is the minimum and maximum protocol version that we can _understand_. We're allowed to speak at any version within this range. This range is inclusive.

View Source
const (
	MetaMaxSize = 512 // Maximum size for node meta data

)

Variables

This section is empty.

Functions

func LogAddress

func LogAddress(addr net.Addr) string

func LogConn

func LogConn(conn net.Conn) string

func LogStringAddress added in v0.2.0

func LogStringAddress(addr string) string

func ParseCIDRs added in v0.2.1

func ParseCIDRs(v []string) ([]net.IPNet, error)

ParseCIDRs return a possible empty list of all Network that have been parsed In case of error, it returns succesfully parsed CIDRs and the last error found

func ValidateKey

func ValidateKey(key []byte) error

ValidateKey will check to see if the key is valid and returns an error if not.

key should be either 16, 24, or 32 bytes to select AES-128, AES-192, or AES-256.

Types

type Address added in v0.2.0

type Address struct {
	// Addr is a network address as a string, similar to Dial. This usually is
	// in the form of "host:port". This is required.
	Addr string

	// Name is the name of the node being addressed. This is optional but
	// transports may require it.
	Name string
}

func (*Address) String added in v0.2.0

func (a *Address) String() string

type AliveDelegate

type AliveDelegate interface {
	// NotifyAlive is invoked when a message about a live
	// node is received from the network.  Returning a non-nil
	// error prevents the node from being considered a peer.
	NotifyAlive(peer *Node) error
}

AliveDelegate is used to involve a client in processing a node "alive" message. When a node joins, either through a UDP gossip or TCP push/pull, we update the state of that node via an alive message. This can be used to filter a node out and prevent it from being considered a peer using application specific logic.

type Broadcast

type Broadcast interface {
	// Invalidates checks if enqueuing the current broadcast
	// invalidates a previous broadcast
	Invalidates(b Broadcast) bool

	// Returns a byte form of the message
	Message() []byte

	// Finished is invoked when the message will no longer
	// be broadcast, either due to invalidation or to the
	// transmit limit being reached
	Finished()
}

Broadcast is something that can be broadcasted via gossip to the memberlist cluster.

type ChannelEventDelegate

type ChannelEventDelegate struct {
	Ch chan<- NodeEvent
}

ChannelEventDelegate is used to enable an application to receive events about joins and leaves over a channel instead of a direct function call.

Care must be taken that events are processed in a timely manner from the channel, since this delegate will block until an event can be sent.

func (*ChannelEventDelegate) NotifyJoin

func (c *ChannelEventDelegate) NotifyJoin(n *Node)

func (*ChannelEventDelegate) NotifyLeave

func (c *ChannelEventDelegate) NotifyLeave(n *Node)

func (*ChannelEventDelegate) NotifyUpdate

func (c *ChannelEventDelegate) NotifyUpdate(n *Node)

type Config

type Config struct {
	// The name of this node. This must be unique in the cluster.
	Name string

	// Transport is a hook for providing custom code to communicate with
	// other nodes. If this is left nil, then memberlist will by default
	// make a NetTransport using BindAddr and BindPort from this structure.
	Transport Transport

	// Configuration related to what address to bind to and ports to
	// listen on. The port is used for both UDP and TCP gossip. It is
	// assumed other nodes are running on this port, but they do not need
	// to.
	BindAddr string
	BindPort int

	// Configuration related to what address to advertise to other
	// cluster members. Used for nat traversal.
	AdvertiseAddr string
	AdvertisePort int

	// ProtocolVersion is the configured protocol version that we
	// will _speak_. This must be between ProtocolVersionMin and
	// ProtocolVersionMax.
	ProtocolVersion uint8

	// TCPTimeout is the timeout for establishing a stream connection with
	// a remote node for a full state sync, and for stream read and write
	// operations. This is a legacy name for backwards compatibility, but
	// should really be called StreamTimeout now that we have generalized
	// the transport.
	TCPTimeout time.Duration

	// IndirectChecks is the number of nodes that will be asked to perform
	// an indirect probe of a node in the case a direct probe fails. Memberlist
	// waits for an ack from any single indirect node, so increasing this
	// number will increase the likelihood that an indirect probe will succeed
	// at the expense of bandwidth.
	IndirectChecks int

	// RetransmitMult is the multiplier for the number of retransmissions
	// that are attempted for messages broadcasted over gossip. The actual
	// count of retransmissions is calculated using the formula:
	//
	//   Retransmits = RetransmitMult * log(N+1)
	//
	// This allows the retransmits to scale properly with cluster size. The
	// higher the multiplier, the more likely a failed broadcast is to converge
	// at the expense of increased bandwidth.
	RetransmitMult int

	// SuspicionMult is the multiplier for determining the time an
	// inaccessible node is considered suspect before declaring it dead.
	// The actual timeout is calculated using the formula:
	//
	//   SuspicionTimeout = SuspicionMult * log(N+1) * ProbeInterval
	//
	// This allows the timeout to scale properly with expected propagation
	// delay with a larger cluster size. The higher the multiplier, the longer
	// an inaccessible node is considered part of the cluster before declaring
	// it dead, giving that suspect node more time to refute if it is indeed
	// still alive.
	SuspicionMult int

	// SuspicionMaxTimeoutMult is the multiplier applied to the
	// SuspicionTimeout used as an upper bound on detection time. This max
	// timeout is calculated using the formula:
	//
	// SuspicionMaxTimeout = SuspicionMaxTimeoutMult * SuspicionTimeout
	//
	// If everything is working properly, confirmations from other nodes will
	// accelerate suspicion timers in a manner which will cause the timeout
	// to reach the base SuspicionTimeout before that elapses, so this value
	// will typically only come into play if a node is experiencing issues
	// communicating with other nodes. It should be set to a something fairly
	// large so that a node having problems will have a lot of chances to
	// recover before falsely declaring other nodes as failed, but short
	// enough for a legitimately isolated node to still make progress marking
	// nodes failed in a reasonable amount of time.
	SuspicionMaxTimeoutMult int

	// PushPullInterval is the interval between complete state syncs.
	// Complete state syncs are done with a single node over TCP and are
	// quite expensive relative to standard gossiped messages. Setting this
	// to zero will disable state push/pull syncs completely.
	//
	// Setting this interval lower (more frequent) will increase convergence
	// speeds across larger clusters at the expense of increased bandwidth
	// usage.
	PushPullInterval time.Duration

	// ProbeInterval and ProbeTimeout are used to configure probing
	// behavior for memberlist.
	//
	// ProbeInterval is the interval between random node probes. Setting
	// this lower (more frequent) will cause the memberlist cluster to detect
	// failed nodes more quickly at the expense of increased bandwidth usage.
	//
	// ProbeTimeout is the timeout to wait for an ack from a probed node
	// before assuming it is unhealthy. This should be set to 99-percentile
	// of RTT (round-trip time) on your network.
	ProbeInterval time.Duration
	ProbeTimeout  time.Duration

	// DisableTcpPings will turn off the fallback TCP pings that are attempted
	// if the direct UDP ping fails. These get pipelined along with the
	// indirect UDP pings.
	DisableTcpPings bool

	// DisableTcpPingsForNode is like DisableTcpPings, but lets you control
	// whether to perform TCP pings on a node-by-node basis.
	DisableTcpPingsForNode func(nodeName string) bool

	// AwarenessMaxMultiplier will increase the probe interval if the node
	// becomes aware that it might be degraded and not meeting the soft real
	// time requirements to reliably probe other nodes.
	AwarenessMaxMultiplier int

	// GossipInterval and GossipNodes are used to configure the gossip
	// behavior of memberlist.
	//
	// GossipInterval is the interval between sending messages that need
	// to be gossiped that haven't been able to piggyback on probing messages.
	// If this is set to zero, non-piggyback gossip is disabled. By lowering
	// this value (more frequent) gossip messages are propagated across
	// the cluster more quickly at the expense of increased bandwidth.
	//
	// GossipNodes is the number of random nodes to send gossip messages to
	// per GossipInterval. Increasing this number causes the gossip messages
	// to propagate across the cluster more quickly at the expense of
	// increased bandwidth.
	//
	// GossipToTheDeadTime is the interval after which a node has died that
	// we will still try to gossip to it. This gives it a chance to refute.
	GossipInterval      time.Duration
	GossipNodes         int
	GossipToTheDeadTime time.Duration

	// GossipVerifyIncoming controls whether to enforce encryption for incoming
	// gossip. It is used for upshifting from unencrypted to encrypted gossip on
	// a running cluster.
	GossipVerifyIncoming bool

	// GossipVerifyOutgoing controls whether to enforce encryption for outgoing
	// gossip. It is used for upshifting from unencrypted to encrypted gossip on
	// a running cluster.
	GossipVerifyOutgoing bool

	// EnableCompression is used to control message compression. This can
	// be used to reduce bandwidth usage at the cost of slightly more CPU
	// utilization. This is only available starting at protocol version 1.
	EnableCompression bool

	// SecretKey is used to initialize the primary encryption key in a keyring.
	// The primary encryption key is the only key used to encrypt messages and
	// the first key used while attempting to decrypt messages. Providing a
	// value for this primary key will enable message-level encryption and
	// verification, and automatically install the key onto the keyring.
	// The value should be either 16, 24, or 32 bytes to select AES-128,
	// AES-192, or AES-256.
	SecretKey []byte

	// The keyring holds all of the encryption keys used internally. It is
	// automatically initialized using the SecretKey and SecretKeys values.
	Keyring *Keyring

	// Delegate and Events are delegates for receiving and providing
	// data to memberlist via callback mechanisms. For Delegate, see
	// the Delegate interface. For Events, see the EventDelegate interface.
	//
	// The DelegateProtocolMin/Max are used to guarantee protocol-compatibility
	// for any custom messages that the delegate might do (broadcasts,
	// local/remote state, etc.). If you don't set these, then the protocol
	// versions will just be zero, and version compliance won't be done.
	Delegate                Delegate
	DelegateProtocolVersion uint8
	DelegateProtocolMin     uint8
	DelegateProtocolMax     uint8
	Events                  EventDelegate
	Conflict                ConflictDelegate
	Merge                   MergeDelegate
	Ping                    PingDelegate
	Alive                   AliveDelegate

	// DNSConfigPath points to the system's DNS config file, usually located
	// at /etc/resolv.conf. It can be overridden via config for easier testing.
	DNSConfigPath string

	// LogOutput is the writer where logs should be sent. If this is not
	// set, logging will go to stderr by default. You cannot specify both LogOutput
	// and Logger at the same time.
	LogOutput io.Writer

	// Logger is a custom logger which you provide. If Logger is set, it will use
	// this for the internal logger. If Logger is not set, it will fall back to the
	// behavior for using LogOutput. You cannot specify both LogOutput and Logger
	// at the same time.
	Logger *log.Logger

	// Size of Memberlist's internal channel which handles UDP messages. The
	// size of this determines the size of the queue which Memberlist will keep
	// while UDP messages are handled.
	HandoffQueueDepth int

	// Maximum number of bytes that memberlist will put in a packet (this
	// will be for UDP packets by default with a NetTransport). A safe value
	// for this is typically 1400 bytes (which is the default). However,
	// depending on your network's MTU (Maximum Transmission Unit) you may
	// be able to increase this to get more content into each gossip packet.
	// This is a legacy name for backward compatibility but should really be
	// called PacketBufferSize now that we have generalized the transport.
	UDPBufferSize int

	// DeadNodeReclaimTime controls the time before a dead node's name can be
	// reclaimed by one with a different address or port. By default, this is 0,
	// meaning nodes cannot be reclaimed this way.
	DeadNodeReclaimTime time.Duration

	// RequireNodeNames controls if the name of a node is required when sending
	// a message to that node.
	RequireNodeNames bool
	// CIDRsAllowed If nil, allow any connection (default), otherwise specify all networks
	// allowed to connect (you must specify IPv6/IPv4 separately)
	// Using [] will block all connections.
	CIDRsAllowed []net.IPNet
}

func DefaultLANConfig

func DefaultLANConfig() *Config

DefaultLANConfig returns a sane set of configurations for Memberlist. It uses the hostname as the node name, and otherwise sets very conservative values that are sane for most LAN environments. The default configuration errs on the side of caution, choosing values that are optimized for higher convergence at the cost of higher bandwidth usage. Regardless, these values are a good starting point when getting started with memberlist.

func DefaultLocalConfig

func DefaultLocalConfig() *Config

DefaultLocalConfig works like DefaultConfig, however it returns a configuration that is optimized for a local loopback environments. The default configuration is still very conservative and errs on the side of caution.

func DefaultWANConfig

func DefaultWANConfig() *Config

DefaultWANConfig works like DefaultConfig, however it returns a configuration that is optimized for most WAN environments. The default configuration is still very conservative and errs on the side of caution.

func (*Config) BuildVsnArray added in v0.1.4

func (conf *Config) BuildVsnArray() []uint8

BuildVsnArray creates the array of Vsn

func (*Config) EncryptionEnabled

func (c *Config) EncryptionEnabled() bool

Returns whether or not encryption is enabled

func (*Config) IPAllowed added in v0.2.1

func (c *Config) IPAllowed(ip net.IP) error

IPAllowed return an error if access to memberlist is denied

func (*Config) IPMustBeChecked added in v0.2.1

func (c *Config) IPMustBeChecked() bool

IPMustBeChecked return true if IPAllowed must be called

type ConflictDelegate

type ConflictDelegate interface {
	// NotifyConflict is invoked when a name conflict is detected
	NotifyConflict(existing, other *Node)
}

ConflictDelegate is a used to inform a client that a node has attempted to join which would result in a name conflict. This happens if two clients are configured with the same name but different addresses.

type Delegate

type Delegate interface {
	// NodeMeta is used to retrieve meta-data about the current node
	// when broadcasting an alive message. It's length is limited to
	// the given byte size. This metadata is available in the Node structure.
	NodeMeta(limit int) []byte

	// NotifyMsg is called when a user-data message is received.
	// Care should be taken that this method does not block, since doing
	// so would block the entire UDP packet receive loop. Additionally, the byte
	// slice may be modified after the call returns, so it should be copied if needed
	NotifyMsg([]byte)

	// GetBroadcasts is called when user data messages can be broadcast.
	// It can return a list of buffers to send. Each buffer should assume an
	// overhead as provided with a limit on the total byte size allowed.
	// The total byte size of the resulting data to send must not exceed
	// the limit. Care should be taken that this method does not block,
	// since doing so would block the entire UDP packet receive loop.
	GetBroadcasts(overhead, limit int) [][]byte

	// LocalState is used for a TCP Push/Pull. This is sent to
	// the remote side in addition to the membership information. Any
	// data can be sent here. See MergeRemoteState as well. The `join`
	// boolean indicates this is for a join instead of a push/pull.
	LocalState(join bool) []byte

	// MergeRemoteState is invoked after a TCP Push/Pull. This is the
	// state received from the remote side and is the result of the
	// remote side's LocalState call. The 'join'
	// boolean indicates this is for a join instead of a push/pull.
	MergeRemoteState(buf []byte, join bool)
}

Delegate is the interface that clients must implement if they want to hook into the gossip layer of Memberlist. All the methods must be thread-safe, as they can and generally will be called concurrently.

type EventDelegate

type EventDelegate interface {
	// NotifyJoin is invoked when a node is detected to have joined.
	// The Node argument must not be modified.
	NotifyJoin(*Node)

	// NotifyLeave is invoked when a node is detected to have left.
	// The Node argument must not be modified.
	NotifyLeave(*Node)

	// NotifyUpdate is invoked when a node is detected to have
	// updated, usually involving the meta data. The Node argument
	// must not be modified.
	NotifyUpdate(*Node)
}

EventDelegate is a simpler delegate that is used only to receive notifications about members joining and leaving. The methods in this delegate may be called by multiple goroutines, but never concurrently. This allows you to reason about ordering.

type IngestionAwareTransport deprecated added in v0.2.0

type IngestionAwareTransport interface {
	IngestPacket(conn net.Conn, addr net.Addr, now time.Time, shouldClose bool) error
	IngestStream(conn net.Conn) error
}

IngestionAwareTransport is not used.

Deprecated: IngestionAwareTransport is not used and may be removed in a future version. Define the interface locally instead of referencing this exported interface.

type Keyring

type Keyring struct {
	// contains filtered or unexported fields
}

func NewKeyring

func NewKeyring(keys [][]byte, primaryKey []byte) (*Keyring, error)

NewKeyring constructs a new container for a set of encryption keys. The keyring contains all key data used internally by memberlist.

While creating a new keyring, you must do one of:

- Omit keys and primary key, effectively disabling encryption
- Pass a set of keys plus the primary key
- Pass only a primary key

If only a primary key is passed, then it will be automatically added to the keyring. If creating a keyring with multiple keys, one key must be designated primary by passing it as the primaryKey. If the primaryKey does not exist in the list of secondary keys, it will be automatically added at position 0.

A key should be either 16, 24, or 32 bytes to select AES-128, AES-192, or AES-256.

func (*Keyring) AddKey

func (k *Keyring) AddKey(key []byte) error

AddKey will install a new key on the ring. Adding a key to the ring will make it available for use in decryption. If the key already exists on the ring, this function will just return noop.

key should be either 16, 24, or 32 bytes to select AES-128, AES-192, or AES-256.

func (*Keyring) GetKeys

func (k *Keyring) GetKeys() [][]byte

GetKeys returns the current set of keys on the ring.

func (*Keyring) GetPrimaryKey

func (k *Keyring) GetPrimaryKey() (key []byte)

GetPrimaryKey returns the key on the ring at position 0. This is the key used for encrypting messages, and is the first key tried for decrypting messages.

func (*Keyring) RemoveKey

func (k *Keyring) RemoveKey(key []byte) error

RemoveKey drops a key from the keyring. This will return an error if the key requested for removal is currently at position 0 (primary key).

func (*Keyring) UseKey

func (k *Keyring) UseKey(key []byte) error

UseKey changes the key used to encrypt messages. This is the only key used to encrypt messages, so peers should know this key before this method is called.

type Memberlist

type Memberlist struct {
	// contains filtered or unexported fields
}

func Create

func Create(conf *Config) (*Memberlist, error)

Create will create a new Memberlist using the given configuration. This will not connect to any other node (see Join) yet, but will start all the listeners to allow other nodes to join this memberlist. After creating a Memberlist, the configuration given should not be modified by the user anymore.

func (*Memberlist) GetHealthScore

func (m *Memberlist) GetHealthScore() int

GetHealthScore gives this instance's idea of how well it is meeting the soft real-time requirements of the protocol. Lower numbers are better, and zero means "totally healthy".

func (*Memberlist) Join

func (m *Memberlist) Join(existing []string) (int, error)

Join is used to take an existing Memberlist and attempt to join a cluster by contacting all the given hosts and performing a state sync. Initially, the Memberlist only contains our own state, so doing this will cause remote nodes to become aware of the existence of this node, effectively joining the cluster.

This returns the number of hosts successfully contacted and an error if none could be reached. If an error is returned, the node did not successfully join the cluster.

func (*Memberlist) Leave

func (m *Memberlist) Leave(timeout time.Duration) error

Leave will broadcast a leave message but will not shutdown the background listeners, meaning the node will continue participating in gossip and state updates.

This will block until the leave message is successfully broadcasted to a member of the cluster, if any exist or until a specified timeout is reached.

This method is safe to call multiple times, but must not be called after the cluster is already shut down.

func (*Memberlist) LocalNode

func (m *Memberlist) LocalNode() *Node

LocalNode is used to return the local Node

func (*Memberlist) Members

func (m *Memberlist) Members() []*Node

Members returns a list of all known live nodes. The node structures returned must not be modified. If you wish to modify a Node, make a copy first.

func (*Memberlist) NumMembers

func (m *Memberlist) NumMembers() (alive int)

NumMembers returns the number of alive nodes currently known. Between the time of calling this and calling Members, the number of alive nodes may have changed, so this shouldn't be used to determine how many members will be returned by Members.

func (*Memberlist) Ping

func (m *Memberlist) Ping(node string, addr net.Addr) (time.Duration, error)

Ping initiates a ping to the node with the specified name.

func (*Memberlist) ProtocolVersion

func (m *Memberlist) ProtocolVersion() uint8

ProtocolVersion returns the protocol version currently in use by this memberlist.

func (*Memberlist) SendBestEffort

func (m *Memberlist) SendBestEffort(to *Node, msg []byte) error

SendBestEffort uses the unreliable packet-oriented interface of the transport to target a user message at the given node (this does not use the gossip mechanism). The maximum size of the message depends on the configured UDPBufferSize for this memberlist instance.

func (*Memberlist) SendReliable

func (m *Memberlist) SendReliable(to *Node, msg []byte) error

SendReliable uses the reliable stream-oriented interface of the transport to target a user message at the given node (this does not use the gossip mechanism). Delivery is guaranteed if no error is returned, and there is no limit on the size of the message.

func (*Memberlist) SendTo deprecated

func (m *Memberlist) SendTo(to net.Addr, msg []byte) error

Deprecated: SendTo is deprecated in favor of SendBestEffort, which requires a node to target. If you don't have a node then use SendToAddress.

func (*Memberlist) SendToAddress added in v0.2.0

func (m *Memberlist) SendToAddress(a Address, msg []byte) error

func (*Memberlist) SendToTCP deprecated

func (m *Memberlist) SendToTCP(to *Node, msg []byte) error

Deprecated: SendToTCP is deprecated in favor of SendReliable.

func (*Memberlist) SendToUDP deprecated

func (m *Memberlist) SendToUDP(to *Node, msg []byte) error

Deprecated: SendToUDP is deprecated in favor of SendBestEffort.

func (*Memberlist) Shutdown

func (m *Memberlist) Shutdown() error

Shutdown will stop any background maintenance of network activity for this memberlist, causing it to appear "dead". A leave message will not be broadcasted prior, so the cluster being left will have to detect this node's shutdown using probing. If you wish to more gracefully exit the cluster, call Leave prior to shutting down.

This method is safe to call multiple times.

func (*Memberlist) UpdateNode

func (m *Memberlist) UpdateNode(timeout time.Duration) error

UpdateNode is used to trigger re-advertising the local node. This is primarily used with a Delegate to support dynamic updates to the local meta data. This will block until the update message is successfully broadcasted to a member of the cluster, if any exist or until a specified timeout is reached.

type MergeDelegate

type MergeDelegate interface {
	// NotifyMerge is invoked when a merge could take place.
	// Provides a list of the nodes known by the peer. If
	// the return value is non-nil, the merge is canceled.
	NotifyMerge(peers []*Node) error
}

MergeDelegate is used to involve a client in a potential cluster merge operation. Namely, when a node does a TCP push/pull (as part of a join), the delegate is involved and allowed to cancel the join based on custom logic. The merge delegate is NOT invoked as part of the push-pull anti-entropy.

type MockAddress

type MockAddress struct {
	// contains filtered or unexported fields
}

MockAddress is a wrapper which adds the net.Addr interface to our mock address scheme.

func (*MockAddress) Network

func (a *MockAddress) Network() string

See net.Addr.

func (*MockAddress) String

func (a *MockAddress) String() string

See net.Addr.

type MockNetwork

type MockNetwork struct {
	// contains filtered or unexported fields
}

MockNetwork is used as a factory that produces MockTransport instances which are uniquely addressed and wired up to talk to each other.

func (*MockNetwork) NewTransport

func (n *MockNetwork) NewTransport(name string) *MockTransport

NewTransport returns a new MockTransport with a unique address, wired up to talk to the other transports in the MockNetwork.

type MockTransport

type MockTransport struct {
	// contains filtered or unexported fields
}

MockTransport directly plumbs messages to other transports its MockNetwork.

func (*MockTransport) DialAddressTimeout added in v0.2.0

func (t *MockTransport) DialAddressTimeout(a Address, timeout time.Duration) (net.Conn, error)

See NodeAwareTransport.

func (*MockTransport) DialTimeout

func (t *MockTransport) DialTimeout(addr string, timeout time.Duration) (net.Conn, error)

See Transport.

func (*MockTransport) FinalAdvertiseAddr

func (t *MockTransport) FinalAdvertiseAddr(string, int) (net.IP, int, error)

See Transport.

func (*MockTransport) IngestPacket added in v0.2.0

func (t *MockTransport) IngestPacket(conn net.Conn, addr net.Addr, now time.Time, shouldClose bool) error

See NodeAwareTransport.

func (*MockTransport) IngestStream added in v0.2.0

func (t *MockTransport) IngestStream(conn net.Conn) error

See NodeAwareTransport.

func (*MockTransport) PacketCh

func (t *MockTransport) PacketCh() <-chan *Packet

See Transport.

func (*MockTransport) Shutdown

func (t *MockTransport) Shutdown() error

See Transport.

func (*MockTransport) StreamCh

func (t *MockTransport) StreamCh() <-chan net.Conn

See Transport.

func (*MockTransport) WriteTo

func (t *MockTransport) WriteTo(b []byte, addr string) (time.Time, error)

See Transport.

func (*MockTransport) WriteToAddress added in v0.2.0

func (t *MockTransport) WriteToAddress(b []byte, a Address) (time.Time, error)

See NodeAwareTransport.

type NamedBroadcast added in v0.1.1

type NamedBroadcast interface {
	Broadcast
	// The unique identity of this broadcast message.
	Name() string
}

NamedBroadcast is an optional extension of the Broadcast interface that gives each message a unique string name, and that is used to optimize

You shoud ensure that Invalidates() checks the same uniqueness as the example below:

func (b *foo) Invalidates(other Broadcast) bool {

nb, ok := other.(NamedBroadcast)
if !ok {
	return false
}
return b.Name() == nb.Name()

}

Invalidates() isn't currently used for NamedBroadcasts, but that may change in the future.

type NetTransport

type NetTransport struct {
	// contains filtered or unexported fields
}

NetTransport is a Transport implementation that uses connectionless UDP for packet operations, and ad-hoc TCP connections for stream operations.

func NewNetTransport

func NewNetTransport(config *NetTransportConfig) (*NetTransport, error)

NewNetTransport returns a net transport with the given configuration. On success all the network listeners will be created and listening.

func (*NetTransport) DialAddressTimeout added in v0.2.0

func (t *NetTransport) DialAddressTimeout(a Address, timeout time.Duration) (net.Conn, error)

See NodeAwareTransport.

func (*NetTransport) DialTimeout

func (t *NetTransport) DialTimeout(addr string, timeout time.Duration) (net.Conn, error)

See Transport.

func (*NetTransport) FinalAdvertiseAddr

func (t *NetTransport) FinalAdvertiseAddr(ip string, port int) (net.IP, int, error)

See Transport.

func (*NetTransport) GetAutoBindPort

func (t *NetTransport) GetAutoBindPort() int

GetAutoBindPort returns the bind port that was automatically given by the kernel, if a bind port of 0 was given.

func (*NetTransport) IngestPacket added in v0.2.0

func (t *NetTransport) IngestPacket(conn net.Conn, addr net.Addr, now time.Time, shouldClose bool) error

See IngestionAwareTransport.

func (*NetTransport) IngestStream added in v0.2.0

func (t *NetTransport) IngestStream(conn net.Conn) error

See IngestionAwareTransport.

func (*NetTransport) PacketCh

func (t *NetTransport) PacketCh() <-chan *Packet

See Transport.

func (*NetTransport) Shutdown

func (t *NetTransport) Shutdown() error

See Transport.

func (*NetTransport) StreamCh

func (t *NetTransport) StreamCh() <-chan net.Conn

See Transport.

func (*NetTransport) WriteTo

func (t *NetTransport) WriteTo(b []byte, addr string) (time.Time, error)

See Transport.

func (*NetTransport) WriteToAddress added in v0.2.0

func (t *NetTransport) WriteToAddress(b []byte, a Address) (time.Time, error)

See NodeAwareTransport.

type NetTransportConfig

type NetTransportConfig struct {
	// BindAddrs is a list of addresses to bind to for both TCP and UDP
	// communications.
	BindAddrs []string

	// BindPort is the port to listen on, for each address above.
	BindPort int

	// Logger is a logger for operator messages.
	Logger *log.Logger
}

NetTransportConfig is used to configure a net transport.

type NoPingResponseError

type NoPingResponseError struct {
	// contains filtered or unexported fields
}

NoPingResponseError is used to indicate a 'ping' packet was successfully issued but no response was received

func (NoPingResponseError) Error

func (f NoPingResponseError) Error() string

type Node

type Node struct {
	Name  string
	Addr  net.IP
	Port  uint16
	Meta  []byte        // Metadata from the delegate for this node.
	State NodeStateType // State of the node.
	PMin  uint8         // Minimum protocol version this understands
	PMax  uint8         // Maximum protocol version this understands
	PCur  uint8         // Current version node is speaking
	DMin  uint8         // Min protocol version for the delegate to understand
	DMax  uint8         // Max protocol version for the delegate to understand
	DCur  uint8         // Current version delegate is speaking
}

Node represents a node in the cluster.

func (*Node) Address

func (n *Node) Address() string

Address returns the host:port form of a node's address, suitable for use with a transport.

func (*Node) FullAddress added in v0.2.0

func (n *Node) FullAddress() Address

FullAddress returns the node name and host:port form of a node's address, suitable for use with a transport.

func (*Node) String added in v0.1.1

func (n *Node) String() string

String returns the node name

type NodeAwareTransport added in v0.2.0

type NodeAwareTransport interface {
	Transport
	WriteToAddress(b []byte, addr Address) (time.Time, error)
	DialAddressTimeout(addr Address, timeout time.Duration) (net.Conn, error)
}

type NodeEvent

type NodeEvent struct {
	Event NodeEventType
	Node  *Node
}

NodeEvent is a single event related to node activity in the memberlist. The Node member of this struct must not be directly modified. It is passed as a pointer to avoid unnecessary copies. If you wish to modify the node, make a copy first.

type NodeEventType

type NodeEventType int

NodeEventType are the types of events that can be sent from the ChannelEventDelegate.

const (
	NodeJoin NodeEventType = iota
	NodeLeave
	NodeUpdate
)

type NodeStateType added in v0.2.1

type NodeStateType int
const (
	StateAlive NodeStateType = iota
	StateSuspect
	StateDead
	StateLeft
)

type Packet

type Packet struct {
	// Buf has the raw contents of the packet.
	Buf []byte

	// From has the address of the peer. This is an actual net.Addr so we
	// can expose some concrete details about incoming packets.
	From net.Addr

	// Timestamp is the time when the packet was received. This should be
	// taken as close as possible to the actual receipt time to help make an
	// accurate RTT measurement during probes.
	Timestamp time.Time
}

Packet is used to provide some metadata about incoming packets from peers over a packet connection, as well as the packet payload.

type PingDelegate

type PingDelegate interface {
	// AckPayload is invoked when an ack is being sent; the returned bytes will be appended to the ack
	AckPayload() []byte
	// NotifyPing is invoked when an ack for a ping is received
	NotifyPingComplete(other *Node, rtt time.Duration, payload []byte)
}

PingDelegate is used to notify an observer how long it took for a ping message to complete a round trip. It can also be used for writing arbitrary byte slices into ack messages. Note that in order to be meaningful for RTT estimates, this delegate does not apply to indirect pings, nor fallback pings sent over TCP.

type TransmitLimitedQueue

type TransmitLimitedQueue struct {
	// NumNodes returns the number of nodes in the cluster. This is
	// used to determine the retransmit count, which is calculated
	// based on the log of this.
	NumNodes func() int

	// RetransmitMult is the multiplier used to determine the maximum
	// number of retransmissions attempted.
	RetransmitMult int
	// contains filtered or unexported fields
}

TransmitLimitedQueue is used to queue messages to broadcast to the cluster (via gossip) but limits the number of transmits per message. It also prioritizes messages with lower transmit counts (hence newer messages).

func (*TransmitLimitedQueue) GetBroadcasts

func (q *TransmitLimitedQueue) GetBroadcasts(overhead, limit int) [][]byte

GetBroadcasts is used to get a number of broadcasts, up to a byte limit and applying a per-message overhead as provided.

func (*TransmitLimitedQueue) NumQueued

func (q *TransmitLimitedQueue) NumQueued() int

NumQueued returns the number of queued messages

func (*TransmitLimitedQueue) Prune

func (q *TransmitLimitedQueue) Prune(maxRetain int)

Prune will retain the maxRetain latest messages, and the rest will be discarded. This can be used to prevent unbounded queue sizes

func (*TransmitLimitedQueue) QueueBroadcast

func (q *TransmitLimitedQueue) QueueBroadcast(b Broadcast)

QueueBroadcast is used to enqueue a broadcast

func (*TransmitLimitedQueue) Reset

func (q *TransmitLimitedQueue) Reset()

Reset clears all the queued messages. Should only be used for tests.

type Transport

type Transport interface {
	// FinalAdvertiseAddr is given the user's configured values (which
	// might be empty) and returns the desired IP and port to advertise to
	// the rest of the cluster.
	FinalAdvertiseAddr(ip string, port int) (net.IP, int, error)

	// WriteTo is a packet-oriented interface that fires off the given
	// payload to the given address in a connectionless fashion. This should
	// return a time stamp that's as close as possible to when the packet
	// was transmitted to help make accurate RTT measurements during probes.
	//
	// This is similar to net.PacketConn, though we didn't want to expose
	// that full set of required methods to keep assumptions about the
	// underlying plumbing to a minimum. We also treat the address here as a
	// string, similar to Dial, so it's network neutral, so this usually is
	// in the form of "host:port".
	WriteTo(b []byte, addr string) (time.Time, error)

	// PacketCh returns a channel that can be read to receive incoming
	// packets from other peers. How this is set up for listening is left as
	// an exercise for the concrete transport implementations.
	PacketCh() <-chan *Packet

	// DialTimeout is used to create a connection that allows us to perform
	// two-way communication with a peer. This is generally more expensive
	// than packet connections so is used for more infrequent operations
	// such as anti-entropy or fallback probes if the packet-oriented probe
	// failed.
	DialTimeout(addr string, timeout time.Duration) (net.Conn, error)

	// StreamCh returns a channel that can be read to handle incoming stream
	// connections from other peers. How this is set up for listening is
	// left as an exercise for the concrete transport implementations.
	StreamCh() <-chan net.Conn

	// Shutdown is called when memberlist is shutting down; this gives the
	// transport a chance to clean up any listeners.
	Shutdown() error
}

Transport is used to abstract over communicating with other peers. The packet interface is assumed to be best-effort and the stream interface is assumed to be reliable.

type UniqueBroadcast added in v0.1.1

type UniqueBroadcast interface {
	Broadcast
	// UniqueBroadcast is just a marker method for this interface.
	UniqueBroadcast()
}

UniqueBroadcast is an optional interface that indicates that each message is intrinsically unique and there is no need to scan the broadcast queue for duplicates.

You should ensure that Invalidates() always returns false if implementing this interface. Invalidates() isn't currently used for UniqueBroadcasts, but that may change in the future.

Directories

Path Synopsis
internal
retry
Package retry provides support for repeating operations in tests.
Package retry provides support for repeating operations in tests.

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