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
• type EventType
• type OpOption
  • func WithFilterDelete() OpOption
  • func WithFilterPut() OpOption
  • func WithSort(sortBy etcd.SortTarget, sortOrder etcd.SortOrder) 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
	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.

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 struct {
	Get   etcd.OpOption
	Watch etcd.OpOption
}

OpOption is a simple typedef for etcd.OpOption.

func WithFilterDelete

func WithFilterDelete() OpOption

WithFilterDelete discards DELETE events from the watcher.

func WithFilterPut

func WithFilterPut() OpOption

WithFilterPut discards PUT events from the watcher.

func WithSort

func WithSort(sortBy etcd.SortTarget, sortOrder etcd.SortOrder) OpOption

WithSort specifies the sort to use for the watcher

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.