filter

Documentation

Index

• type Filter
  • func NewFilter(st *uniter.State, unitTag names.UnitTag) (Filter, error)

Types

type Filter

type Filter interface {

	// Stop shuts down the filter and returns any error encountered in the process.
	Stop() error

	// Dead returns a channel that will close when the filter has shut down.
	Dead() <-chan struct{}

	// Wait blocks until the filter has shut down, and returns any error
	// encountered in the process.
	Wait() error

	// UnitDying returns a channel which is closed when the Unit enters a Dying state.
	UnitDying() <-chan struct{}

	// UpgradeEvents returns a channel that will receive a new charm URL whenever an
	// upgrade is indicated. Events should not be read until the baseline state
	// has been specified by calling WantUpgradeEvent.
	UpgradeEvents() <-chan *charm.URL

	// ResolvedEvents returns a channel that may receive a ResolvedMode when the
	// unit's Resolved value changes, or when an event is explicitly requested.
	// A ResolvedNone state will never generate events, but ResolvedRetryHooks and
	// ResolvedNoHooks will always be delivered as described.
	ResolvedEvents() <-chan params.ResolvedMode

	// MeterStatusEvents returns a channel that will receive a signal when the unit's
	// meter status changes.
	MeterStatusEvents() <-chan struct{}

	// ConfigEvents returns a channel that will receive a signal whenever the service's
	// configuration changes, or when an event is explicitly requested.
	ConfigEvents() <-chan struct{}

	// ActionEvents returns a channel that will receive a signal whenever the unit
	// receives new Actions.
	ActionEvents() <-chan *hook.Info

	// RelationsEvents returns a channel that will receive the ids of all the service's
	// relations whose Life status has changed.
	RelationsEvents() <-chan []int

	// WantUpgradeEvent controls whether the filter will generate upgrade
	// events for unforced service charm changes.
	WantUpgradeEvent(mustForce bool)

	// SetCharm notifies the filter that the unit is running a new
	// charm. It causes the unit's charm URL to be set in state, and the
	// following changes to the filter's behaviour:
	//
	// * Upgrade events will only be generated for charms different to
	//   that supplied;
	// * A fresh relations event will be generated containing every relation
	//   the service is participating in;
	// * A fresh configuration event will be generated, and subsequent
	//   events will only be sent in response to changes in the version
	//   of the service's settings that is specific to that charm.
	//
	// SetCharm blocks until the charm URL is set in state, returning any
	// error that occurred.
	SetCharm(curl *charm.URL) error

	// WantResolvedEvent indicates that the filter should send a resolved event
	// if one is available.
	WantResolvedEvent()

	// ClearResolved notifies the filter that a resolved event has been handled
	// and should not be reported again.
	ClearResolved() error

	// DiscardConfigEvent indicates that the filter should discard any pending
	// config event.
	DiscardConfigEvent()
}

Filter is responsible for delivering events relevant to a unit agent in a form that can be consumed conveniently.

func NewFilter

func NewFilter(st *uniter.State, unitTag names.UnitTag) (Filter, error)

NewFilter returns a filter that handles state changes pertaining to the supplied unit.