go: infra/libs/* now live in luci-go.

go/src/infra/libs/parallel/parallel.go

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-package parallel
-
-import (
-        "sync"
-
-        "infra/libs/errors"
-)
-
-// FanOutIn is useful to quickly parallelize a group of tasks.
-//
-// You pass it a function which is expected to push simple `func() error`
-// closures into the provided chan. Each function will be executed in parallel
-// and their error results will be collated.
-//
-// The function blocks until all functions are executed, and an
-// errors.MultiError is returned if one or more of your fan-out tasks failed,
-// otherwise this function returns nil.
-func FanOutIn(gen func(chan<- func() error)) error {
-        funchan := make(chan func() error)
-        go func() {
-                defer close(funchan)
-                gen(funchan)
-        }()
-
-        errchan := make(chan error)
-        grp := sync.WaitGroup{}
-        for fn := range funchan {
-                grp.Add(1)
-                fn := fn
-                go func() {
-                        defer grp.Done()
-                        if err := fn(); err != nil {
-                                errchan <- err
-                        }
-                }()
-        }
-        go func() {
-                grp.Wait()
-                close(errchan)
-        }()
-        return errors.MultiErrorFromErrors(errchan)
-}