watch

Documentation

Overview

Package watch implements better watch semantics on top of etcd. See this issue for the reasoning behind the package: https://github.com/coreos/etcd/issues/7362

Index

• func CheckType(template proto.Message, val interface{}) error
• type Event
  • func (e *Event) Unmarshal(key *string, val proto.Message) error
  • func (e *Event) UnmarshalPrev(key *string, val proto.Message) error
• type EventType
• type OpOption
  • func WithFilterPut() OpOption
  • func WithPrevKV() OpOption
• type Watcher
  • func MakeWatcher(eventCh chan *Event, done chan struct{}) Watcher
  • func NewWatcher(ctx context.Context, client *etcd.Client, trimPrefix, prefix string, ...) (Watcher, error)

Functions

func CheckType

func CheckType(template proto.Message, val interface{}) error

CheckType checks to make sure val has the same type as template, unless template is nil in which case it always returns nil.

Types

type Event

type Event struct {
	Key       []byte
	Value     []byte
	PrevKey   []byte
	PrevValue []byte
	Type      EventType
	Rev       int64
	Ver       int64
	Err       error
	Template  proto.Message
}

Event is an event that occurred to an item in etcd.

func (*Event) Unmarshal

func (e *Event) Unmarshal(key *string, val proto.Message) error

Unmarshal unmarshals the item in an event into a protobuf message.

func (*Event) UnmarshalPrev

func (e *Event) UnmarshalPrev(key *string, val proto.Message) error

UnmarshalPrev unmarshals the prev item in an event into a protobuf message.

type EventType

type EventType int

EventType is the type of event

const (
	// EventPut happens when an item is added
	EventPut EventType = iota
	// EventDelete happens when an item is removed
	EventDelete
	// EventError happens when an error occurred
	EventError
)

type OpOption

type OpOption etcd.OpOption

OpOption is a simple typedef for etcd.OpOption.

func WithFilterPut

func WithFilterPut() OpOption

WithFilterPut discards PUT events from the watcher.

func WithPrevKV

func WithPrevKV() OpOption

WithPrevKV gets the previous key-value pair before the event happens. If the previous KV is already compacted, nothing will be returned.

type Watcher

type Watcher interface {
	// Watch returns a channel that delivers events
	Watch() <-chan *Event
	// Close this channel when you are done receiving events
	Close()
}

Watcher ...

func MakeWatcher

func MakeWatcher(eventCh chan *Event, done chan struct{}) Watcher

MakeWatcher returns a Watcher that uses the given event channel and done channel internally to deliver events and signal closure, respectively.

func NewWatcher

func NewWatcher(ctx context.Context, client *etcd.Client, trimPrefix, prefix string, template proto.Message, opts ...OpOption) (Watcher, error)

NewWatcher watches a given etcd prefix for events.