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sem.go
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sem.go
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// Package semerrgroup wraps an error group with a semaphore with configurable
// size, so you can control the number of tasks being executed simultaneously.
package semerrgroup
import (
"sync"
"github.com/goreleaser/goreleaser/internal/pipe"
"github.com/hashicorp/go-multierror"
"golang.org/x/sync/errgroup"
)
// Group is the Semaphore ErrorGroup itself.
type Group interface {
Go(func() error)
Wait() error
}
// New returns a new Group of a given size.
func New(size int) Group {
var g errgroup.Group
g.SetLimit(size)
return &g
}
var _ Group = &skipAwareGroup{}
// NewSkipAware returns a new Group of a given size and aware of pipe skips.
func NewSkipAware(g Group) Group {
return &skipAwareGroup{g: g}
}
type skipAwareGroup struct {
g Group
skipErr *multierror.Error
l sync.Mutex
}
// Go execs runs `fn` and saves the result if no error has been encountered.
func (s *skipAwareGroup) Go(fn func() error) {
s.g.Go(func() error {
err := fn()
// if the err is a skip, set it for later, but return nil for now so the
// group proceeds.
if pipe.IsSkip(err) {
s.l.Lock()
defer s.l.Unlock()
s.skipErr = multierror.Append(s.skipErr, err)
return nil
}
return err
})
}
// Wait waits for Go to complete and returns the first error encountered.
func (s *skipAwareGroup) Wait() error {
// if we got a "real error", return it, otherwise return skipErr or nil.
if err := s.g.Wait(); err != nil {
return err
}
if s.skipErr == nil {
return nil
}
if s.skipErr.Len() == 1 {
return s.skipErr.Errors[0]
}
return s.skipErr
}