hook

type Committer interface {
	CommitHook(Info) error
}

type Info struct {
	Kind hooks.Kind `yaml:"kind"`

	// RelationId identifies the relation associated with the hook. It is
	// only set when Kind indicates a relation hook.
	RelationId int `yaml:"relation-id,omitempty"`

	// RemoteUnit is the name of the unit that triggered the hook. It is only
	// set when Kind indicates a relation hook other than relation-broken.
	RemoteUnit string `yaml:"remote-unit,omitempty"`

	// ChangeVersion identifies the most recent unit settings change
	// associated with RemoteUnit. It is only set when RemoteUnit is set.
	ChangeVersion int64 `yaml:"change-version,omitempty"`

	// StorageId is the ID of the storage instance relevant to the hook.
	StorageId string `yaml:"storage-id,omitempty"`
}

type NoUpdates struct{}

type Peek interface {
	// HookInfo returns information about the hook at the head of the queue.
	HookInfo() Info
	// Consume pops the hook from the head of the queue and makes new Peeks
	// available.
	Consume()
	// Reject makes new Peeks available.
	Reject()
}

type Peeker interface {
	// Peeks returns a channel on which Peeks are delivered. The receiver of a
	// Peek must Consume or Reject the Peek before further peeks will be sent.
	Peeks() <-chan Peek
	// Stop stops the Peeker's Source, and prevents any further Peeks from
	// being delivered.
	Stop() error
}

type Sender interface {
	Stop() error
}

type Source interface {

	// Changes returns a channel sending events which must be processed
	// synchronously, and in order.
	Changes() <-chan SourceChange

	// Stop causes the Source to clean up its resources and stop sending
	// changes.
	Stop() error

	// Empty returns false if any hooks are scheduled.
	Empty() bool

	// Next returns the first scheduled hook. It will panic if no hooks are
	// scheduled.
	Next() Info

	// Pop removes the first scheduled hook, and invalidates the results of
	// previous calls to Next() and Empty(). It will panic if no hooks are
	// scheduled.
	Pop()
}

type SourceChange func() error

type Validator interface {
	ValidateHook(Info) error
}