drain

Documentation

Index

• Constants
• Variables
• type Cancel
  • func (c *Cancel) ServeHTTP(response http.ResponseWriter, request *http.Request)
• type Interface
  • func New(options ...Option) Interface
• type Job
  • func (j Job) ToMap() map[string]interface{}
• type Option
  • func WithConnector(c device.Connector) Option
  • func WithDrainCounter(a xmetrics.Adder) Option
  • func WithLogger(l log.Logger) Option
  • func WithManager(m device.Manager) Option
  • func WithRegistry(r device.Registry) Option
  • func WithStateGauge(s xmetrics.Setter) Option
• type Progress
• type Start
  • func (s *Start) ServeHTTP(response http.ResponseWriter, request *http.Request)
• type Status
  • func (s *Status) ServeHTTP(response http.ResponseWriter, request *http.Request)

Constants

const (
	StateNotActive uint32 = 0
	StateActive    uint32 = 1

	MetricNotDraining float64 = 0.0
	MetricDraining    float64 = 1.0

	Drained = "drained"
)

Variables

var (
	ErrActive    error = errors.New("A drain operation is already running")
	ErrNotActive error = errors.New("No drain operation is running")
)

Types

type Cancel

type Cancel struct {
	Drainer Interface
}

Cancel is an HTTP handler that allows cancellation of drain jobs

func (*Cancel) ServeHTTP

func (c *Cancel) ServeHTTP(response http.ResponseWriter, request *http.Request)

type Interface

type Interface interface {
	// Start attempts to begin draining devices.  The supplied Job describes how the drain will proceed.
	// The returned channel can be used to wait for the drain job to complete.  The returned Job will be
	// the result of applying defaults and will represent the actual Job being executed.  For example, if Job.Rate
	// is set but Job.Tick is not, the returned Job will reflect the default of 1 second for Job.Tick.
	Start(Job) (<-chan struct{}, Job, error)

	// Status returns information about the current drain job, if any.  The boolean return indicates whether
	// the job is currently active, while the returned Job describes the actual options used in starting the drainer.
	// This returned Job instance will not necessarily be the same as that passed to Start, as certain fields
	// may be computed or defaulted.
	Status() (bool, Job, Progress)

	// Cancel asynchronously halts any running drain job.  The returned channel can be used to wait for the job to actually exit.
	// If no job is running, an error is returned along with a nil channel.
	Cancel() (<-chan struct{}, error)
}

Interface describes the behavior of a component which can execute a Job to drain devices. Only (1) drain Job is allowed to run at any time.

func New

func New(options ...Option) Interface

New constructs a drainer using the supplied options

type Job

type Job struct {
	// Count is the total number of devices to disconnect.  If this field is nonpositive and percent is unset,
	// the count of connected devices at the start of job execution is used.  If Percent is set, this field's
	// original value is ignored and it is set to that percentage of total devices connected at the time the
	// job starts.
	Count int `json:"count" schema:"count"`

	// Percent is the fraction of devices to drain.  If this field is set, Count's original value is ignored
	// and set to the computed percentage of connected devices at the time the job starts.
	Percent int `json:"percent,omitempty" schema:"percent"`

	// Rate is the number of devices per tick to disconnect.  If this field is nonpositive,
	// devices are disconnected as fast as possible.
	Rate int `json:"rate,omitempty" schema:"rate"`

	// Tick is the time unit for the Rate field.  If Rate is set but this field is not set,
	// a tick of 1 second is used as the default.
	Tick time.Duration `json:"tick,omitempty" schema:"tick"`
}

func (Job) ToMap

func (j Job) ToMap() map[string]interface{}

ToMap returns a map representation of this Job appropriate for marshaling to formats like JSON. This method makes things a bit prettier, like the Tick.

type Option

type Option func(*drainer)

func WithConnector

func WithConnector(c device.Connector) Option

func WithDrainCounter

func WithDrainCounter(a xmetrics.Adder) Option

func WithLogger

func WithLogger(l log.Logger) Option

func WithManager

func WithManager(m device.Manager) Option

func WithRegistry

func WithRegistry(r device.Registry) Option

func WithStateGauge

func WithStateGauge(s xmetrics.Setter) Option

type Progress

type Progress struct {
	// Visited is the number of devices handled so far.  This value will not
	// exceed the Job.Count value.
	Visited int `json:"visited"`

	// Drained is the count of visited devices that have actually been disconnected
	// due to the drain.  Devices can disconnect or be disconnected outside a drain job,
	// so this value can be lower than Visited, even in a job that has finished.
	Drained int `json:"drained"`

	// Started is the UTC system time at which the drain job was started.
	Started time.Time `json:"started"`

	// Finished is the UTC system time at which the drain job finished or was canceled.
	// If the job is running, this field will be nil.
	Finished *time.Time `json:"finished,omitempty"`
}

Progress represents a snapshot of what a drain job has done so far.

type Start

type Start struct {
	Drainer Interface
}

func (*Start) ServeHTTP

func (s *Start) ServeHTTP(response http.ResponseWriter, request *http.Request)

type Status

type Status struct {
	Drainer Interface
}

Status returns a JSON message describing the status of the drain job

func (*Status) ServeHTTP

func (s *Status) ServeHTTP(response http.ResponseWriter, request *http.Request)