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errgroup.go
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/
errgroup.go
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/*
* MinIO Cloud Storage, (C) 2017 MinIO, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package errgroup
import (
"sync"
)
// A Group is a collection of goroutines working on subtasks that are part of
// the same overall task.
//
// A zero Group is valid and does not cancel on error.
type Group struct {
wg sync.WaitGroup
errs []error
}
// WithNErrs returns a new Group with length of errs slice upto nerrs,
// upon Wait() errors are returned collected from all tasks.
func WithNErrs(nerrs int) *Group {
return &Group{errs: make([]error, nerrs)}
}
// Wait blocks until all function calls from the Go method have returned, then
// returns the slice of errors from all function calls.
func (g *Group) Wait() []error {
g.wg.Wait()
return g.errs
}
// Go calls the given function in a new goroutine.
//
// The first call to return a non-nil error will be
// collected in errs slice and returned by Wait().
func (g *Group) Go(f func() error, index int) {
g.wg.Add(1)
go func() {
defer g.wg.Done()
if err := f(); err != nil {
g.errs[index] = err
}
}()
}