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go/src/infra/libs/infra_util/errors.go

+// Copyright 2014 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 infra_util
+
+import (
+        "bytes"
+        "fmt"
+        "sync"
+)
+
+type MultiError []error
+
+func FanOutIn(hint int, producer func(chan<- func() error)) error {
+        funcChan := make(chan func() error, hint)
+        errChan := make(chan error)
+        go func() {
+                go func() {
+                        defer close(funcChan)
+                        producer(funcChan)
+                }()
+                grp := sync.WaitGroup{}
+                for f := range funcChan {
+                        grp.Add(1)
+                        f := f
+                        go func() { defer grp.Done(); errChan <- f() }()
+                }
+                go func() { defer close(errChan); grp.Wait() }()
+        }()
+        return MultiErrorFromChan(errChan)
+}
+
+func MultiErrorFromChan(in <-chan error) error {
+        ret := MultiError{}
+        for err := range in {
+                if err != nil {
+                        ret = append(ret, err)
+                }
+        }
+        if len(ret) != 0 {
+                return &ret
+        }
+        return nil
+}
+
+func (m *MultiError) Error() string {
+        if m == nil {
+                return "ME[]"
+        }
+        buf := &bytes.Buffer{}
+        fmt.Fprintf(buf, "ME[")
+        first := true
+        for _, e := range *m {
+                if !first {
+                        fmt.Fprint(buf, ",")
+                }
+                first = false
+                fmt.Fprintf(buf, "%#v", e.Error())
+        }
+        fmt.Fprintf(buf, "]")
+        return buf.String()
+}
+
+func (m *MultiError) ErrorStrings() StringSet {
+        ret := make(StringSet, len(*m))
+        for _, e := range *m {
+                ret.Add(e.Error())
+        }
+        return ret
+}