concurrency

Documentation

Index

• type AllErrorAggregator
• type AllErrorRecorder
  • func (aer *AllErrorRecorder) AggrError(aggr AllErrorAggregator) error
  • func (aer *AllErrorRecorder) Error() error
  • func (aer *AllErrorRecorder) ErrorStrings() []string
  • func (aer *AllErrorRecorder) GetErrors() []error
  • func (aer *AllErrorRecorder) HasErrors() bool
  • func (aer *AllErrorRecorder) RecordError(err error)
• type ErrorGroup
  • func (eg ErrorGroup) Wait(cancel context.CancelFunc, errors chan error) *AllErrorRecorder
• type ErrorRecorder
• type FirstErrorRecorder
  • func (fer *FirstErrorRecorder) Error() error
  • func (fer *FirstErrorRecorder) HasErrors() bool
  • func (fer *FirstErrorRecorder) RecordError(err error)

Types

type AllErrorAggregator

type AllErrorAggregator func(errors []error) error

AllErrorAggregator aggregates errors.

type AllErrorRecorder

type AllErrorRecorder struct {
	Errors []error
	// contains filtered or unexported fields
}

AllErrorRecorder records all the errors.

func (*AllErrorRecorder) AggrError

func (aer *AllErrorRecorder) AggrError(aggr AllErrorAggregator) error

AggrError runs the provided aggregator over all errors and returns the error from aggregator.

func (*AllErrorRecorder) Error

func (aer *AllErrorRecorder) Error() error

Error returns an aggregate of all errors by concatenation.

func (*AllErrorRecorder) ErrorStrings

func (aer *AllErrorRecorder) ErrorStrings() []string

ErrorStrings returns all errors as string array.

func (*AllErrorRecorder) GetErrors

func (aer *AllErrorRecorder) GetErrors() []error

GetErrors returns a reference to the internal errors array.

Note that the array is not copied, so this should only be used once the recording is complete.

func (*AllErrorRecorder) HasErrors

func (aer *AllErrorRecorder) HasErrors() bool

HasErrors returns true if we ever recorded an error

func (*AllErrorRecorder) RecordError

func (aer *AllErrorRecorder) RecordError(err error)

RecordError records a possible error: - does nothing if err is nil

type ErrorGroup

type ErrorGroup struct {
	NumGoroutines        int
	NumRequiredSuccesses int
	NumAllowedErrors     int
}

ErrorGroup provides a function for waiting for N goroutines to complete with at least X successes and no more than Y failures, and cancelling the rest.

It should be used as follows:

errCh := make(chan error)
errgroupCtx, errgroupCancel := context.WithCancel(ctx)

for _, arg := range args {
	arg := arg

	go func() {
		err := doWork(errGroupCtx, arg)
		errCh <- err
	}()
}

errgroup := concurrency.ErrorGroup{
	NumGoroutines: len(args),
	NumRequiredSuccess: 5, // need at least 5 to respond with nil error before cancelling the rest
	NumAllowedErrors: 1, // if more than 1 responds with non-nil error, cancel the rest
}
errRec := errgroup.Wait(errgroupCancel, errCh)

if errRec.HasErrors() {
	// ...
}

func (ErrorGroup) Wait

func (eg ErrorGroup) Wait(cancel context.CancelFunc, errors chan error) *AllErrorRecorder

Wait waits for a group of goroutines that are sending errors to the given error channel, and are cancellable by the given cancel function.

Wait will cancel any outstanding goroutines under the following conditions:

(1) More than NumAllowedErrors non-nil results have been consumed on the error channel.

(2) At least NumRequiredSuccesses nil results have been consumed on the error channel.

After the cancellation condition is triggered, Wait will continue to consume results off the error channel so as to not permanently block any of those cancelled goroutines.

When finished consuming results from all goroutines, cancelled or otherwise, Wait returns an AllErrorRecorder that contains all errors returned by any of those goroutines. It does not close the error channel.

type ErrorRecorder

type ErrorRecorder interface {
	RecordError(error)
	HasErrors() bool
	Error() error
}

ErrorRecorder offers a way to record errors during complex asynchronous operations. Various implementation will offer different services.

type FirstErrorRecorder

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

FirstErrorRecorder records the first error, logs the others. Error() will return the first recorded error or nil.

func (*FirstErrorRecorder) Error

func (fer *FirstErrorRecorder) Error() error

Error returns the first error we saw, or nil

func (*FirstErrorRecorder) HasErrors

func (fer *FirstErrorRecorder) HasErrors() bool

HasErrors returns true if we ever recorded an error

func (*FirstErrorRecorder) RecordError

func (fer *FirstErrorRecorder) RecordError(err error)

RecordError records a possible error: - does nothing if err is nil - only records the first error reported - the rest is just logged