meterstatus

Documentation

Overview

Package meterstatus provides a worker that executes the meter-status-changed hook periodically.

Index

• func GetTriggers(wst WorkerState, status string, disconnectedAt time.Time, clk Clock, ...) (<-chan time.Time, <-chan time.Time)
• func Manifold(config ManifoldConfig) dependency.Manifold
• func NewConnectedStatusHandler(cfg ConnectedConfig) (watcher.NotifyHandler, error)
• func NewConnectedStatusWorker(cfg ConnectedConfig) (worker.Worker, error)
• func NewIsolatedStatusWorker(cfg IsolatedConfig) (worker.Worker, error)
• type Clock
• type ConnectedConfig
  • func (c ConnectedConfig) Validate() error
• type ControllerBackedState
  • func NewControllerBackedState(api UnitStateAPI) *ControllerBackedState
  • func (cbs *ControllerBackedState) Read() (*State, error)
  • func (cbs *ControllerBackedState) Write(st *State) error
• type Disconnected
  • func (d Disconnected) When() time.Time
• type DiskBackedState
  • func NewDiskBackedState(path string) *DiskBackedState
  • func (dbs *DiskBackedState) Read() (*State, error)
  • func (dbs *DiskBackedState) Write(st *State) error
• type HookRunner
  • func NewHookRunner(config HookRunnerConfig) HookRunner
• type HookRunnerConfig
• type IsolatedConfig
  • func (c IsolatedConfig) Validate() error
• type Logger
• type ManifoldConfig
• type State
• type StateReadWriter
• type TriggerCreator
• type UnitStateAPI
• type WorkerState

Functions

func GetTriggers

func GetTriggers(
	wst WorkerState,
	status string,
	disconnectedAt time.Time,
	clk Clock,
	amberGracePeriod time.Duration,
	redGracePeriod time.Duration) (<-chan time.Time, <-chan time.Time)

GetTriggers returns the signal channels for state transitions based on the current state. It controls the transitions of the inactive meter status worker.

In a simple case, the transitions are trivial:

D------------------A----------------------R--------------------->

D - disconnect time A - amber status triggered R - red status triggered

The problem arises from the fact that the lifetime of the worker can be interrupted, possibly with significant portions of the duration missing.

func Manifold

func Manifold(config ManifoldConfig) dependency.Manifold

Manifold returns a status manifold.

func NewConnectedStatusHandler

func NewConnectedStatusHandler(cfg ConnectedConfig) (watcher.NotifyHandler, error)

NewConnectedStatusHandler creates a new meter status handler for handling meter status changes as provided by the API.

func NewConnectedStatusWorker

func NewConnectedStatusWorker(cfg ConnectedConfig) (worker.Worker, error)

NewConnectedStatusWorker creates a new worker that monitors the meter status of the unit and runs the meter-status-changed hook appropriately.

func NewIsolatedStatusWorker

func NewIsolatedStatusWorker(cfg IsolatedConfig) (worker.Worker, error)

NewIsolatedStatusWorker creates a new status worker that runs without an API connection.

Types

type Clock

type Clock interface {
	Now() time.Time
	After(time.Duration) <-chan time.Time
}

Clock defines the time methods used by this package.

type ConnectedConfig

type ConnectedConfig struct {
	Runner          HookRunner
	Status          meterstatus.MeterStatusClient
	StateReadWriter StateReadWriter
	Logger          Logger
}

ConnectedConfig contains all the dependencies required to create a new connected status worker.

func (ConnectedConfig) Validate

func (c ConnectedConfig) Validate() error

Validate validates the config structure and returns an error on failure.

type ControllerBackedState

type ControllerBackedState struct {
	// contains filtered or unexported fields
}

ControllerBackedState is a StateReadWriter that uses the controller as its backing store.

func NewControllerBackedState

func NewControllerBackedState(api UnitStateAPI) *ControllerBackedState

NewControllerBackedState returns a new ControllerBackedState that uses the provided UnitStateAPI to communicate with the controller.

func (*ControllerBackedState) Read

func (cbs *ControllerBackedState) Read() (*State, error)

Read the current meter status information from the controller.

func (*ControllerBackedState) Write

func (cbs *ControllerBackedState) Write(st *State) error

Write the supplied status information to the controller.

type Disconnected

type Disconnected struct {
	Disconnected int64       `yaml:"disconnected-at,omitempty"`
	State        WorkerState `yaml:"disconnected-state,omitempty"`
}

Disconnected stores the information relevant to the inactive meter status worker.

func (Disconnected) When

func (d Disconnected) When() time.Time

When returns the time when the unit was disconnected.

type DiskBackedState

type DiskBackedState struct {
	// contains filtered or unexported fields
}

DiskBackedState stores the meter status on disk.

func NewDiskBackedState

func NewDiskBackedState(path string) *DiskBackedState

NewDiskBackedState creates a DiskBackedState instance that uses path for reading/writing the meter status state.

func (*DiskBackedState) Read

func (dbs *DiskBackedState) Read() (*State, error)

Read the current meter status information from disk.

func (*DiskBackedState) Write

func (dbs *DiskBackedState) Write(st *State) error

Write the supplied status information to disk.

type HookRunner

type HookRunner interface {
	RunHook(string, string, <-chan struct{})
}

HookRunner implements the functionality necessary to run a meter-status-changed hook.

func NewHookRunner

func NewHookRunner(config HookRunnerConfig) HookRunner

type HookRunnerConfig

type HookRunnerConfig struct {
	MachineLock machinelock.Lock
	AgentConfig agent.Config
	Tag         names.UnitTag
	Clock       Clock
	Logger      Logger
}

HookRunnerConfig is just an argument struct for NewHookRunner.

type IsolatedConfig

type IsolatedConfig struct {
	Runner           HookRunner
	StateReadWriter  StateReadWriter
	Clock            Clock
	Logger           Logger
	AmberGracePeriod time.Duration
	RedGracePeriod   time.Duration
	TriggerFactory   TriggerCreator
}

IsolatedConfig stores all the dependencies required to create an isolated meter status worker.

func (IsolatedConfig) Validate

func (c IsolatedConfig) Validate() error

Validate validates the config structure and returns an error on failure.

type Logger

type Logger interface {
	Errorf(string, ...interface{})
	Warningf(string, ...interface{})
	Infof(string, ...interface{})
	Debugf(string, ...interface{})
	Tracef(string, ...interface{})

	Root() loggo.Logger
}

Logger represents the logging methods used in this package.

type ManifoldConfig

type ManifoldConfig struct {
	AgentName     string
	APICallerName string
	MachineLock   machinelock.Lock
	Clock         Clock
	Logger        Logger

	NewHookRunner           func(HookRunnerConfig) HookRunner
	NewMeterStatusAPIClient func(base.APICaller, names.UnitTag) meterstatus.MeterStatusClient
	NewUniterStateAPIClient func(base.FacadeCaller, names.UnitTag) *common.UnitStateAPI

	NewConnectedStatusWorker func(ConnectedConfig) (worker.Worker, error)
	NewIsolatedStatusWorker  func(IsolatedConfig) (worker.Worker, error)
}

ManifoldConfig identifies the resource names upon which the status manifold depends.

type State

type State struct {
	Code         string        `yaml:"status-code"`
	Info         string        `yaml:"status-info"`
	Disconnected *Disconnected `yaml:"disconnected,omitempty"`
}

State represents the worker's internal state.

type StateReadWriter

type StateReadWriter interface {
	Read() (*State, error)
	Write(*State) error
}

StateReadWriter is implemented by types that can read and write the meter worker's internal state.

type TriggerCreator

type TriggerCreator func(WorkerState, string, time.Time, Clock, time.Duration, time.Duration) (<-chan time.Time, <-chan time.Time)

type UnitStateAPI

type UnitStateAPI interface {
	State() (params.UnitStateResult, error)
	SetState(params.SetUnitStateArg) error
}

UnitStateAPI describes the API for reading/writing unit state data from/to the controller.

type WorkerState

type WorkerState int

workerState defines all the possible states the isolatedStatusWorker can be in.

const (
	Uninitialized WorkerState = iota
	WaitingAmber              // Waiting for a signal to switch to AMBER status.
	WaitingRed                // Waiting for a signal to switch to RED status.
	Done                      // No more transitions to perform.
)