Documentation
¶
Index ¶
- Variables
- type Closer
- type CloserFn
- type Option
- type Stopper
- func (s *Stopper) AddCloser(c Closer)
- func (s *Stopper) IsStopped() <-chan struct{}
- func (s *Stopper) NumTasks() int
- func (s *Stopper) Quiesce()
- func (s *Stopper) Recover()
- func (s *Stopper) RunAsyncTask(ctx context.Context, f func(context.Context)) error
- func (s *Stopper) RunLimitedAsyncTask(ctx context.Context, sem chan struct{}, wait bool, f func(context.Context)) error
- func (s *Stopper) RunTask(f func()) error
- func (s *Stopper) RunTaskWithErr(f func() error) error
- func (s *Stopper) RunWorker(f func())
- func (s *Stopper) RunningTasks() TaskMap
- func (s *Stopper) ShouldQuiesce() <-chan struct{}
- func (s *Stopper) ShouldStop() <-chan struct{}
- func (s *Stopper) Stop()
- func (s *Stopper) WithCancel(ctx context.Context) context.Context
- type TaskMap
Constants ¶
This section is empty.
Variables ¶
var ErrThrottled = errors.New("throttled on async limiting semaphore")
ErrThrottled is returned from RunLimitedAsyncTask in the event that there is no more capacity for async tasks, as limited by the semaphore.
Functions ¶
This section is empty.
Types ¶
type Closer ¶
type Closer interface {
Close()
}
Closer is an interface for objects to attach to the stopper to be closed once the stopper completes.
type Option ¶
type Option interface {
// contains filtered or unexported methods
}
An Option can be passed to NewStopper.
func OnPanic ¶
func OnPanic(handler func(interface{})) Option
OnPanic is an option which lets the Stopper recover from all panics using the provided panic handler.
When Stop() is invoked during stack unwinding, OnPanic is also invoked, but Stop() may not have carried out its duties.
func TrackTasks ¶
TrackTasks is an option which allows tracking of tasks to be disabled.
type Stopper ¶
type Stopper struct {
// contains filtered or unexported fields
}
A Stopper provides a channel-based mechanism to stop an arbitrary array of workers. Each worker is registered with the stopper via the RunWorker() method. The system further allows execution of functions through RunTask() and RunAsyncTask().
Stopping occurs in two phases: the first is the request to stop, which moves the stopper into a quiescing phase. While quiescing, calls to RunTask() & RunAsyncTask() don't execute the function passed in and return errUnavailable. When all outstanding tasks have been completed, the stopper closes its stopper channel, which signals all live workers that it's safe to shut down. When all workers have shutdown, the stopper is complete.
An arbitrary list of objects implementing the Closer interface may be added to the stopper via AddCloser(), to be closed after the stopper has stopped.
func NewStopper ¶
NewStopper returns an instance of Stopper.
func (*Stopper) IsStopped ¶
func (s *Stopper) IsStopped() <-chan struct{}
IsStopped returns a channel which will be closed after Stop() has been invoked to full completion, meaning all workers have completed and all closers have been closed.
func (*Stopper) Quiesce ¶
func (s *Stopper) Quiesce()
Quiesce moves the stopper to state quiescing and waits until all tasks complete. This is used from Stop() and unittests.
func (*Stopper) Recover ¶
func (s *Stopper) Recover()
Recover is used internally by Stopper to provide a hook for recovery of panics on goroutines started by the Stopper. It can also be invoked explicitly (via "defer s.Recover()") on goroutines that are created outside of Stopper.
func (*Stopper) RunAsyncTask ¶
RunAsyncTask runs function f in a goroutine. It returns an error when the Stopper is quiescing, in which case the function is not executed.
func (*Stopper) RunLimitedAsyncTask ¶
func (s *Stopper) RunLimitedAsyncTask( ctx context.Context, sem chan struct{}, wait bool, f func(context.Context), ) error
RunLimitedAsyncTask runs function f in a goroutine, using the given channel as a semaphore to limit the number of tasks that are run concurrently to the channel's capacity. If wait is true, blocks until the semaphore is available in order to push back on callers that may be trying to create many tasks. If wait is false, returns immediately with an error if the semaphore is not available. Returns an error if the Stopper is quiescing, in which case the function is not executed.
func (*Stopper) RunTask ¶
RunTask adds one to the count of tasks left to quiesce in the system. Any worker which is a "first mover" when starting tasks must call this method before starting work on a new task. First movers include goroutines launched to do periodic work and the kv/db.go gateway which accepts external client requests.
Returns an error to indicate that the system is currently quiescing and function f was not called.
func (*Stopper) RunTaskWithErr ¶
RunTaskWithErr adds one to the count of tasks left to quiesce in the system. Any worker which is a "first mover" when starting tasks must call this method before starting work on a new task. First movers include goroutines launched to do periodic work and the kv/db.go gateway which accepts external client requests.
If the system is currently quiescing and function f was not called, returns an error indicating this condition. Otherwise, returns whatever f returns.
func (*Stopper) RunWorker ¶
func (s *Stopper) RunWorker(f func())
RunWorker runs the supplied function as a "worker" to be stopped by the stopper. The function <f> is run in a goroutine.
func (*Stopper) RunningTasks ¶
RunningTasks returns a map containing the count of running tasks keyed by call site.
func (*Stopper) ShouldQuiesce ¶
func (s *Stopper) ShouldQuiesce() <-chan struct{}
ShouldQuiesce returns a channel which will be closed when Stop() has been invoked and outstanding tasks should begin to quiesce.
func (*Stopper) ShouldStop ¶
func (s *Stopper) ShouldStop() <-chan struct{}
ShouldStop returns a channel which will be closed when Stop() has been invoked and outstanding tasks have quiesced.
Source Files