watch

Documentation

Index

• type RetryFunc
• type View
  • func NewView(config *WatcherConfig, d dep.Dependency) (*View, error)
• type Wait
  • func ParseWait(s string) (*Wait, error)
• type Watcher
  • func NewWatcher(config *WatcherConfig) (*Watcher, error)
  • func (w *Watcher) Add(d dep.Dependency) (bool, error)
  • func (w *Watcher) Remove(d dep.Dependency) bool
  • func (w *Watcher) Stop()
  • func (w *Watcher) Watching(d dep.Dependency) bool
• type WatcherConfig

Types

type RetryFunc

type RetryFunc func(time.Duration) time.Duration

RetryFunc is a function that defines the retry for a given watcher. The function parameter is the current retry (which might be nil), and the return value is the new retry. In this way, you can build complex retry functions that are based off the previous values.

var DefaultRetryFunc RetryFunc = func(t time.Duration) time.Duration {
	return t
}

DefaultRetryFunc is the default return function, which just echos whatever duration it was given.

type View

type View struct {
	// Dependency is the dependency that is associated with this View
	Dependency dep.Dependency

	// Data is the most-recently-received data from Consul for this View
	Data interface{}
	// contains filtered or unexported fields
}

View is a representation of a Dependency and the most recent data it has received from Consul.

func NewView

func NewView(config *WatcherConfig, d dep.Dependency) (*View, error)

NewView creates a new view object from the given Consul API client and Dependency. If an error occurs, it will be returned.

type Wait

type Wait struct {
	// Min and Max are the minimum and maximum time, respectively, to wait for
	// data changes before rendering a new template to disk.
	Min, Max time.Duration
}

Wait is the Min/Max duration used by the Watcher

func ParseWait

func ParseWait(s string) (*Wait, error)

ParseWait parses a string of the format `minimum(:maximum)` into a Wait struct.

type Watcher

type Watcher struct {
	sync.Mutex

	// DataCh is the chan where Views will be published.
	DataCh chan *View

	// ErrCh is the chan where any errors will be published.
	ErrCh chan error

	// FinishCh is the chan where the watcher reports it is "done".
	FinishCh chan struct{}
	// contains filtered or unexported fields
}

Watcher is a top-level manager for views that poll Consul for data.

func NewWatcher

func NewWatcher(config *WatcherConfig) (*Watcher, error)

NewWatcher creates a new watcher using the given API client.

func (*Watcher) Add

func (w *Watcher) Add(d dep.Dependency) (bool, error)

Add adds the given dependency to the list of monitored depedencies and start the associated view. If the dependency already exists, no action is taken.

If the Dependency already existed, it this function will return false. If the view was successfully created, it will return true. If an error occurs while creating the view, it will be returned here (but future errors returned by the view will happen on the channel).

func (*Watcher) Remove

func (w *Watcher) Remove(d dep.Dependency) bool

Remove removes the given dependency from the list and stops the associated View. If a View for the given dependency does not exist, this function will return false. If the View does exist, this function will return true upon successful deletion.

func (*Watcher) Stop

func (w *Watcher) Stop()

Stop halts this watcher and any currently polling views immediately. If a view was in the middle of a poll, no data will be returned.

func (*Watcher) Watching

func (w *Watcher) Watching(d dep.Dependency) bool

Watching determines if the given dependency is being watched.

type WatcherConfig

type WatcherConfig struct {
	// Client is the mechanism for communicating with the Consul API.
	Client *api.Client

	// Once is used to determine if the views should poll for data exactly once.
	Once bool

	// MaxStale is the maximum staleness of a query. If specified, Consul will
	// distribute work among all servers instead of just the leader. Specifying
	// this option assumes the use of AllowStale.
	MaxStale time.Duration

	// RetryFunc is a RetryFunc that represents the way retrys and backoffs
	// should occur.
	RetryFunc RetryFunc
}

WatcherConfig is the configuration for a particular Watcher.