dendrite

package module
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 Go to latest Published: May 25, 2015 License: MIT Imports: 15 Imported by: 0

README

Dendrite

Dendrite is a Go package that implements distributed hash table (DHT) based on Chord Protocol. Included sub-package 'dtable' is built on top of dendrite and implements distributed in-memory key/value database, with replication and failover support, with query interface to Get() or Set() items with different consistency levels.

For better key distribution, dendrite allows configurable number of virtual nodes per instance (vnodes). The number of replicas in dtable is also configurable.

Calling application can bootstrap the cluster, or join existing one by connecting to any of existing nodes (must be manually specified). Node discovery is not part of the implementation. Use consul (consul.io) or something else for that purpose.

Chord protocol defines ring stabilization. In dendrite, stabilization period is configurable.

Node to node (network) communication is built on top of ZeroMQ sockets over TCP for speed, clustering and reliability. Dendrite starts configurable number of goroutines (default: 10) for load balanced serving of remote requests, but scales that number up and down depending on the load (aka prefork model).

All messages sent through dendrite are encapsulated in ChordMsg structure, where first byte indicates message type, and actual data follows. Data part is serialized with protocol buffers.

Dendrite can be extended through two interfaces:

  • TransportHook
  • DelegateHook

TransportHook allows other packages to provide additional message types, decoders and handlers, while DelegateHook can be used to capture chord events that dendrite emits:

  • EvPredecessorJoined
  • EvPredecessorLeft
  • EvReplicasChanged

Documentation

Usage

import "github.com/fastfn/dendrite"
import "github.com/fastfn/dendrite/dtable"
...
// Initialize ZMQTransport with timeout set to 5 seconds
transport, err := dendrite.InitZMQTransport("127.0.0.1:5000", 5*time.Second)
if err != nil {
	panic(err)
	return
}
config := dendrite.DefaultConfig("127.0.0.1:5000")
Bootstrap the cluster (first node)
// Start new cluster
ring, err = dendrite.CreateRing(config, transport)
if err != nil {
	panic(err)
}
table = dtable.Init(ring, transport, dtable.LogInfo)
Joining the cluster
// We join the cluster by providing the address of one of existing nodes in the cluster.
ring, err = dendrite.JoinRing(config, transport, "192.168.0.50:5000")
if err != nil {
	panic(err)
}
table = dtable.Init(ring, transport, dtable.LogInfo)
DTable Query examples
Set()
query := table.NewQuery()
err := query.Set([]byte("testkey"), []byte("testvalue"))
if err != nil {
	panic(err)
}
Set() with consistency

Consistency() is used prior to Set() to request minimum writes before operation returns success. If dtable runs with 2 replicas, user may request 2 writes (primary + 1 replica) and let dtable handle final write in the background. If requested value is larger than configured dendrite replicas, value is reset to default. Default is 1.

query := table.NewQuery()
err := query.Consistency(2).Set([]byte("testkey"), []byte("testvalue"))
if err != nil {
	panic(err)
}
Get()
query := table.NewQuery()
item, err := query.Get([]byte("testkey"))
if err != nil {
	log.Println("Got error in table Get: ", err)
} else if item == nil {
	log.Printf("item not found")
} else {
	log.Printf("Value is: %s\n", string(item.Val))
}
GetLocalKeys()

GetLocalKeys() returns the list of all keys stored on local node.

query := table.NewQuery()
for _, key := range query.GetLocalKeys() {
	log.Printf("Key: %s\n", string(key))
}

Todo

  • dtable: support SetMulti() and GetMulti() on public interface
  • dtable: support batches on replication/migration ops
  • dendrite: add some kind of security for inter communication between nodes

Documentation

Overview

Package dendrite implements a distributed hash table (DHT) based on Chord Protocol. Included sub-package 'dtable' is built on top of dendrite and implements distributed in-memory key/value database, with replication and failover support, with query interface to Get() or Set() items with different consistency levels.

For better key distribution, dendrite allows configurable number of virtual nodes per instance (vnodes). The number of replicas in dtable is also configurable.

Calling application can bootstrap the cluster, or join existing one by connecting to any of existing nodes (must be manually specified). Node discovery is not part of the implementation. Use consul (consul.io) or something else for that purpose.

Chord protocol defines ring stabilization. In dendrite, stabilization period is configurable.

Node to node (network) communication is built on top of ZeroMQ sockets over TCP for speed, clustering and reliability. Dendrite starts configurable number of goroutines (default: 10) for load balanced serving of remote requests, but scales that number up and down depending on the load (aka prefork model).

All messages sent through dendrite are encapsulated in ChordMsg structure, where first byte indicates message type, and actual data follows. Data part is serialized with protocol buffers.

Dendrite can be extended through two interfaces: 

TransportHook
DelegateHook

TransportHook allows other packages to provide additional message types, decoders and handlers, while DelegateHook can be used to capture chord events that dendrite emits: 

EvPredecessorJoined
EvPredecessorLeft
EvReplicasChanged

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func Between 

func Between(id1, id2, key []byte, rincl bool) bool

Between checks if key is between id1 and id2, such that:

if rincl (right-included flag) is true: 

(id1 > key >  id2)

if rincl (right-included flag) is false: 

(id1 > key >= id2)

func HashKey 

func HashKey(key []byte) []byte

HashKey generates SHA1 hash for a given []byte key

func KeyFromString 

func KeyFromString(key_str string) []byte

KeyFromString decodes hex string to []byte

func Min 

func Min(a, b int) int

Min returns lesser of two ints.

Types

type ChordMsg 

type ChordMsg struct {
	Type             MsgType
	Data             []byte
	TransportMsg     interface{}                     // unmarshalled data, depending on transport
	TransportHandler func(*ChordMsg, chan *ChordMsg) // request pointer, response channel
}

ChordMsg is lowest entity to be transmited through dendrite.

type Config 

type Config struct {
	Hostname      string
	NumVnodes     int // num of vnodes to create
	StabilizeMin  time.Duration
	StabilizeMax  time.Duration
	NumSuccessors int      // number of successor to keep in self log
	Replicas      int      // number of replicas to keep by default
	LogLevel      LogLevel // logLevel, 0 = null, 1 = info, 2 = debug
}

Config is a main ring configuration struct.

func DefaultConfig 

func DefaultConfig(hostname string) *Config

DefaultConfig returns *Config with default values.

type DelegateHook 

type DelegateHook interface {
	EmitEvent(*EventCtx)
}

DelegateHook provides interface to capture dendrite events in 3rd party packages.

type ErrHookUnknownType 

type ErrHookUnknownType string

func (ErrHookUnknownType) Error 

func (e ErrHookUnknownType) Error() string

type EventCtx 

type EventCtx struct {
	EvType        RingEventType
	Target        *Vnode
	PrimaryItem   *Vnode
	SecondaryItem *Vnode
	ItemList      []*Vnode
	ResponseCh    chan interface{}
}

EventCtx is a generic struct representing an event. Instance of EventCtx is emitted to DelegateHooks.

type LocalTransport 

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

LocalTransport implements Transport interface, but is used for communicating between local vnodes.

func (*LocalTransport) Decode 

func (lt *LocalTransport) Decode(raw []byte) (*ChordMsg, error)

Decode does nothing in local transport. Just satisfying interface.

func (*LocalTransport) Encode 

func (lt *LocalTransport) Encode(msgtype MsgType, data []byte) []byte

Encode does nothing in local transport. Just satisfying interface.

func (*LocalTransport) FindSuccessors 

func (lt *LocalTransport) FindSuccessors(vn *Vnode, limit int, key []byte) ([]*Vnode, error)

FindSuccessors implements Transport's FindSuccessors() in local transport.

func (*LocalTransport) GetPredecessor 

func (lt *LocalTransport) GetPredecessor(vn *Vnode) (*Vnode, error)

GetPredecessor implements Transport's GetPredecessor() in local transport.

func (*LocalTransport) GetVnodeHandler 

func (lt *LocalTransport) GetVnodeHandler(vnode *Vnode) (VnodeHandler, bool)

GetVnodeHandler returns registered local vnode handler, if one is found for given vnode.

func (*LocalTransport) ListVnodes 

func (lt *LocalTransport) ListVnodes(host string) ([]*Vnode, error)

ListVnodes implements Transport's ListVnodes() in local transport.

func (*LocalTransport) Notify 

func (lt *LocalTransport) Notify(dest, self *Vnode) ([]*Vnode, error)

Notify implements Transport's Notify() in local transport.

func (*LocalTransport) Ping 

func (lt *LocalTransport) Ping(vn *Vnode) (bool, error)

Ping implements Transport's Ping() in local transport.

func (*LocalTransport) Register 

func (lt *LocalTransport) Register(vnode *Vnode, handler VnodeHandler)

Register registers a VnodeHandler within local and remote transports.

func (*LocalTransport) RegisterHook 

func (lt *LocalTransport) RegisterHook(th TransportHook)

RegisterHook does nothing in local transport. Just satisfying interface.

type LogLevel 

type LogLevel int
const (
	LogNull  LogLevel = 0
	LogInfo  LogLevel = 1
	LogDebug LogLevel = 2
)

type MsgType 

type MsgType byte

MsgType represents message type for ChordMsg encoding. 

const (
	// protocol buffer messages (for definitions, see pb_defs/chord.proto)
	PbPing MsgType = iota
	PbAck
	PbErr
	PbForward
	PbJoin
	PbLeave
	PbListVnodes
	PbListVnodesResp
	PbFindSuccessors
	PbGetPredecessor
	PbProtoVnode
	PbNotify
)

type PBProtoAck 

type PBProtoAck struct {
	Version          *int64 `protobuf:"varint,1,req,name=version" json:"version,omitempty"`
	Ok               *bool  `protobuf:"varint,2,req,name=ok" json:"ok,omitempty"`
	XXX_unrecognized []byte `json:"-"`
}

PBProtoAck is generic response message with boolean 'ok' state.

func (*PBProtoAck) GetOk 

func (m *PBProtoAck) GetOk() bool

func (*PBProtoAck) GetVersion 

func (m *PBProtoAck) GetVersion() int64

func (*PBProtoAck) ProtoMessage 

func (*PBProtoAck) ProtoMessage()

func (*PBProtoAck) Reset 

func (m *PBProtoAck) Reset()

func (*PBProtoAck) String 

func (m *PBProtoAck) String() string

type PBProtoErr 

type PBProtoErr struct {
	Error            *string `protobuf:"bytes,2,req,name=error" json:"error,omitempty"`
	XXX_unrecognized []byte  `json:"-"`
}

PBProtoErr defines error message.

func (*PBProtoErr) GetError 

func (m *PBProtoErr) GetError() string

func (*PBProtoErr) ProtoMessage 

func (*PBProtoErr) ProtoMessage()

func (*PBProtoErr) Reset 

func (m *PBProtoErr) Reset()

func (*PBProtoErr) String 

func (m *PBProtoErr) String() string

type PBProtoFindSuccessors 

type PBProtoFindSuccessors struct {
	Key              []byte        `protobuf:"bytes,1,req,name=key" json:"key,omitempty"`
	Dest             *PBProtoVnode `protobuf:"bytes,2,req,name=dest" json:"dest,omitempty"`
	Limit            *int32        `protobuf:"varint,3,opt,name=limit" json:"limit,omitempty"`
	XXX_unrecognized []byte        `json:"-"`
}

PBProtoFindSuccessors is a structure to request successors for a key.

func (*PBProtoFindSuccessors) GetDest 

func (m *PBProtoFindSuccessors) GetDest() *PBProtoVnode

func (*PBProtoFindSuccessors) GetKey 

func (m *PBProtoFindSuccessors) GetKey() []byte

func (*PBProtoFindSuccessors) GetLimit 

func (m *PBProtoFindSuccessors) GetLimit() int32

func (*PBProtoFindSuccessors) ProtoMessage 

func (*PBProtoFindSuccessors) ProtoMessage()

func (*PBProtoFindSuccessors) Reset 

func (m *PBProtoFindSuccessors) Reset()

func (*PBProtoFindSuccessors) String 

func (m *PBProtoFindSuccessors) String() string

type PBProtoForward 

type PBProtoForward struct {
	Vnode            *PBProtoVnode `protobuf:"bytes,1,req,name=vnode" json:"vnode,omitempty"`
	XXX_unrecognized []byte        `json:"-"`
}

PBProtoForward is sent to caller if request should be forwarded to another vnode.

func (*PBProtoForward) GetVnode 

func (m *PBProtoForward) GetVnode() *PBProtoVnode

func (*PBProtoForward) ProtoMessage 

func (*PBProtoForward) ProtoMessage()

func (*PBProtoForward) Reset 

func (m *PBProtoForward) Reset()

func (*PBProtoForward) String 

func (m *PBProtoForward) String() string

type PBProtoGetPredecessor 

type PBProtoGetPredecessor struct {
	Dest             *PBProtoVnode `protobuf:"bytes,1,req,name=dest" json:"dest,omitempty"`
	XXX_unrecognized []byte        `json:"-"`
}

PBProtoGetPredecessor - request immediate predecessor from vnode.

func (*PBProtoGetPredecessor) GetDest 

func (m *PBProtoGetPredecessor) GetDest() *PBProtoVnode

func (*PBProtoGetPredecessor) ProtoMessage 

func (*PBProtoGetPredecessor) ProtoMessage()

func (*PBProtoGetPredecessor) Reset 

func (m *PBProtoGetPredecessor) Reset()

func (*PBProtoGetPredecessor) String 

func (m *PBProtoGetPredecessor) String() string

type PBProtoLeave 

type PBProtoLeave struct {
	Source           *PBProtoVnode `protobuf:"bytes,1,req,name=source" json:"source,omitempty"`
	Dest             *PBProtoVnode `protobuf:"bytes,2,req,name=dest" json:"dest,omitempty"`
	XXX_unrecognized []byte        `json:"-"`
}

PBProtoLeave (not used)

func (*PBProtoLeave) GetDest 

func (m *PBProtoLeave) GetDest() *PBProtoVnode

func (*PBProtoLeave) GetSource 

func (m *PBProtoLeave) GetSource() *PBProtoVnode

func (*PBProtoLeave) ProtoMessage 

func (*PBProtoLeave) ProtoMessage()

func (*PBProtoLeave) Reset 

func (m *PBProtoLeave) Reset()

func (*PBProtoLeave) String 

func (m *PBProtoLeave) String() string

type PBProtoListVnodes 

type PBProtoListVnodes struct {
	XXX_unrecognized []byte `json:"-"`
}

PBProtoListVnodes - request the list of vnodes from remote vnode.

func (*PBProtoListVnodes) ProtoMessage 

func (*PBProtoListVnodes) ProtoMessage()

func (*PBProtoListVnodes) Reset 

func (m *PBProtoListVnodes) Reset()

func (*PBProtoListVnodes) String 

func (m *PBProtoListVnodes) String() string

type PBProtoListVnodesResp 

type PBProtoListVnodesResp struct {
	Vnodes           []*PBProtoVnode `protobuf:"bytes,1,rep,name=vnodes" json:"vnodes,omitempty"`
	XXX_unrecognized []byte          `json:"-"`
}

PBProtoListVnodesResp is a structure for returning multiple vnodes to a caller.

func (*PBProtoListVnodesResp) GetVnodes 

func (m *PBProtoListVnodesResp) GetVnodes() []*PBProtoVnode

func (*PBProtoListVnodesResp) ProtoMessage 

func (*PBProtoListVnodesResp) ProtoMessage()

func (*PBProtoListVnodesResp) Reset 

func (m *PBProtoListVnodesResp) Reset()

func (*PBProtoListVnodesResp) String 

func (m *PBProtoListVnodesResp) String() string

type PBProtoNotify 

type PBProtoNotify struct {
	Dest             *PBProtoVnode `protobuf:"bytes,1,req,name=dest" json:"dest,omitempty"`
	Vnode            *PBProtoVnode `protobuf:"bytes,2,req,name=vnode" json:"vnode,omitempty"`
	XXX_unrecognized []byte        `json:"-"`
}

PBProtoNotify is a message to notify the remote vnode of origin's existence.

func (*PBProtoNotify) GetDest 

func (m *PBProtoNotify) GetDest() *PBProtoVnode

func (*PBProtoNotify) GetVnode 

func (m *PBProtoNotify) GetVnode() *PBProtoVnode

func (*PBProtoNotify) ProtoMessage 

func (*PBProtoNotify) ProtoMessage()

func (*PBProtoNotify) Reset 

func (m *PBProtoNotify) Reset()

func (*PBProtoNotify) String 

func (m *PBProtoNotify) String() string

type PBProtoPing 

type PBProtoPing struct {
	Version          *int64 `protobuf:"varint,1,req,name=version" json:"version,omitempty"`
	XXX_unrecognized []byte `json:"-"`
}

PBProtoPing is simple structure for pinging remote vnodes.

func (*PBProtoPing) GetVersion 

func (m *PBProtoPing) GetVersion() int64

func (*PBProtoPing) ProtoMessage 

func (*PBProtoPing) ProtoMessage()

func (*PBProtoPing) Reset 

func (m *PBProtoPing) Reset()

func (*PBProtoPing) String 

func (m *PBProtoPing) String() string

type PBProtoVnode 

type PBProtoVnode struct {
	Id               []byte  `protobuf:"bytes,1,req,name=id" json:"id,omitempty"`
	Host             *string `protobuf:"bytes,2,req,name=host" json:"host,omitempty"`
	XXX_unrecognized []byte  `json:"-"`
}

PBProtoVnode represents Vnode structure.

func (*PBProtoVnode) GetHost 

func (m *PBProtoVnode) GetHost() string

func (*PBProtoVnode) GetId 

func (m *PBProtoVnode) GetId() []byte

func (*PBProtoVnode) ProtoMessage 

func (*PBProtoVnode) ProtoMessage()

func (*PBProtoVnode) Reset 

func (m *PBProtoVnode) Reset()

func (*PBProtoVnode) String 

func (m *PBProtoVnode) String() string

type Ring 

type Ring struct {
	Stabilizations int
	// contains filtered or unexported fields
}

Ring is the main chord ring object.

func CreateRing 

func CreateRing(config *Config, transport Transport) (*Ring, error)

CreateRing bootstraps the ring with given config and local transport.

func JoinRing 

func JoinRing(config *Config, transport Transport, existing string) (*Ring, error)

JoinRing joins existing dendrite network.

func (*Ring) Len 

func (r *Ring) Len() int

Len implements sort.Interface Len() - used to sort ring.vnodes.

func (*Ring) Less 

func (r *Ring) Less(i, j int) bool

Less implements sort.Interface Less() - used to sort ring.vnodes.

func (*Ring) Logf 

func (r *Ring) Logf(level LogLevel, format string, v ...interface{})

Logf wraps log.Printf

func (*Ring) Logln 

func (r *Ring) Logln(level LogLevel, v ...interface{})

Logln wraps log.Println

func (*Ring) Lookup 

func (r *Ring) Lookup(n int, keyHash []byte) ([]*Vnode, error)

Lookup. For given key hash, it finds N successors in the ring.

func (*Ring) MaxStabilize 

func (r *Ring) MaxStabilize() time.Duration

MaxStabilize returns ring.config.StabilizeMax duration.

func (*Ring) MyVnodes 

func (r *Ring) MyVnodes() []*Vnode

MyVnodes returns slice of local Vnodes

func (*Ring) RegisterDelegateHook 

func (r *Ring) RegisterDelegateHook(dh DelegateHook)

RegisterDelegateHook registers DelegateHook for emitting ring events.

func (*Ring) Replicas 

func (r *Ring) Replicas() int

Replicas returns ring.config.Replicas.

func (*Ring) Swap 

func (r *Ring) Swap(i, j int)

Swap implements sort.Interface Swap() - used to sort ring.vnodes.

type RingEventType 

type RingEventType int
var (
	EvPredecessorJoined RingEventType = 1
	EvPredecessorLeft   RingEventType = 2
	EvReplicasChanged   RingEventType = 3
)

type Transport 

type Transport interface {
	// ListVnodes returns list of local vnodes from remote host.
	ListVnodes(string) ([]*Vnode, error)

	// Ping sends ping message to a vnode.
	Ping(*Vnode) (bool, error)

	// GetPredecessor is a request to get vnode's predecessor.
	GetPredecessor(*Vnode) (*Vnode, error)

	// Notify our successor of ourselves.
	Notify(dest, self *Vnode) ([]*Vnode, error)

	// FindSuccessors sends request to a vnode, requesting the list of successors for given key.
	FindSuccessors(*Vnode, int, []byte) ([]*Vnode, error)

	// GetVnodeHandler returns VnodeHandler interface if requested vnode is local
	GetVnodeHandler(*Vnode) (VnodeHandler, bool)

	// Register registers local vnode handlers
	Register(*Vnode, VnodeHandler)

	// Encode encodes dendrite msg into two frame byte stream. First frame is a single byte representing
	// message type, and another frame is protobuf data.
	Encode(MsgType, []byte) []byte

	// RegisterHook registers a TransportHook within the transport.
	RegisterHook(TransportHook)

	TransportHook
}

Transport interface defines methods for communication between vnodes.

func InitLocalTransport 

func InitLocalTransport(remote Transport) Transport

InitLocalTransport initializes LocalTransport.

func InitZMQTransport 

func InitZMQTransport(hostname string, timeout time.Duration) (Transport, error)

InitZMQTransport creates ZeroMQ transport.

It multiplexes incoming connections which are then processed in separate go routines (workers). Multiplexer spawns go routines as needed, but 10 worker routines are created on startup. Every request times out after provided timeout duration. ZMQ pattern is: 

zmq.ROUTER(incoming) -> proxy -> zmq.DEALER -> [zmq.REP(worker), zmq.REP...]

type TransportHook 

type TransportHook interface {
	Decode([]byte) (*ChordMsg, error) // decodes bytes to ChordMsg
}

TransportHook provides interface to build additional message types, decoders and handlers through 3rd party packages that can register their hooks and leverage existing transport architecture and capabilities.

type Vnode 

type Vnode struct {
	Id   []byte
	Host string // ip:port
}

Vnode is basic virtual node structure.

func VnodeFromProtobuf 

func VnodeFromProtobuf(pb *PBProtoVnode) *Vnode

VnodeFromProtobuf is helper method that creates *Vnode from PBProtoVnode message.

func (*Vnode) String 

func (vn *Vnode) String() string

String returns string representation (hex encoded) of vnode's Id.

func (*Vnode) ToProtobuf 

func (vn *Vnode) ToProtobuf() *PBProtoVnode

ToProtobuf is a helper method which returns PBProtoVnode message from a *Vnode.

type VnodeHandler 

type VnodeHandler interface {
	FindSuccessors([]byte, int) ([]*Vnode, *Vnode, error) // args: key, limit # returns: succs, forward, error
	FindRemoteSuccessors(int) ([]*Vnode, error)
	GetPredecessor() (*Vnode, error)
	Notify(*Vnode) ([]*Vnode, error)
}

VnodeHandler interface defines methods (from Transport interface) that are to be called in vnode context. Transports use this interface to avoid duplicate implementations. localVnode implements this interface.

type ZMQTransport 

type ZMQTransport struct {
	ClientTimeout time.Duration

	ZMQContext *zmq.Context
	// contains filtered or unexported fields
}

ZMQTransport implements Transport interface using ZeroMQ for communication.

func (*ZMQTransport) Decode 

func (transport *ZMQTransport) Decode(data []byte) (*ChordMsg, error)

Decode implements Transport's Decode() in ZMQTransport. For request messages it also sets their respective handler to be called when such request comes in. If message type is unknown to this transport, Decode() also checks for registered TransportHooks and runs their Decode() implementation.

func (*ZMQTransport) Encode 

func (transport *ZMQTransport) Encode(mt MsgType, data []byte) []byte

Encode implement's Transport's Encode() in ZMQTransport.

func (*ZMQTransport) FindSuccessors 

func (transport *ZMQTransport) FindSuccessors(remote *Vnode, limit int, key []byte) ([]*Vnode, error)

FindSuccessors - client request. Implements Transport's FindSuccessors() in ZQMTransport.

func (*ZMQTransport) GetPredecessor 

func (transport *ZMQTransport) GetPredecessor(remote *Vnode) (*Vnode, error)

GetPredecessor - client request. Implements Transport's GetPredecessor() in ZQMTransport.

func (*ZMQTransport) GetVnodeHandler 

func (transport *ZMQTransport) GetVnodeHandler(vnode *Vnode) (VnodeHandler, bool)

GetVnodeHandler returns registered local vnode handler, if one is found for given vnode.

func (*ZMQTransport) ListVnodes 

func (transport *ZMQTransport) ListVnodes(host string) ([]*Vnode, error)

ListVnodes - client request. Implements Transport's ListVnodes() in ZQMTransport.

func (*ZMQTransport) NewErrorMsg 

func (transport *ZMQTransport) NewErrorMsg(msg string) *ChordMsg

NewErrorMsg is a helper to create encoded *ChordMsg (PBProtoErr) with error in it.

func (*ZMQTransport) Notify 

func (transport *ZMQTransport) Notify(remote, self *Vnode) ([]*Vnode, error)

Notify - client request. Implements Transport's Notify() in ZQMTransport.

func (*ZMQTransport) Ping 

func (transport *ZMQTransport) Ping(remote_vn *Vnode) (bool, error)

Ping - client request. Implements Transport's Ping() in ZQMTransport.

func (*ZMQTransport) Register 

func (transport *ZMQTransport) Register(vnode *Vnode, handler VnodeHandler)

Register registers a VnodeHandler within ZMQTransport.

func (*ZMQTransport) RegisterHook 

func (t *ZMQTransport) RegisterHook(h TransportHook)

RegisterHook registers TransportHook within ZMQTransport.

Source Files

View all Source files

Directories

Path Synopsis
Package dtable implements highly available, distributed in-memory key/value datastore.
 Package dtable implements highly available, distributed in-memory key/value datastore.

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