diff --git a/pkg/syncutil/group.go b/pkg/syncutil/group.go new file mode 100644 index 000000000..6426310e9 --- /dev/null +++ b/pkg/syncutil/group.go @@ -0,0 +1,64 @@ +/* +Copyright 2013 Google 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 syncutil + +import "sync" + +// A Group is like a sync.WaitGroup and coordinates doing +// multiple things at once. Its zero value is ready to use. +type Group struct { + wg sync.WaitGroup + mu sync.Mutex // guards errs + errs []error +} + +// Go runs fn in its own goroutine, but does not wait for it to complete. +// Call Err or Errs to wait for all the goroutines to complete. +func (g *Group) Go(fn func() error) { + g.wg.Add(1) + go func() { + defer g.wg.Done() + err := fn() + if err != nil { + g.mu.Lock() + defer g.mu.Unlock() + g.errs = append(g.errs, err) + } + }() +} + +// Wait waits for all the previous calls to Go to complete. +func (g *Group) Wait() { + g.wg.Wait() +} + +// Err waits for all previous calls to Go to complete and returns the +// first non-nil error, or nil. +func (g *Group) Err() error { + g.wg.Wait() + if len(g.errs) > 0 { + return g.errs[0] + } + return nil +} + +// Err waits for all previous calls to Go to complete and returns the +// first non-nil error, or nil. +func (g *Group) Errs() []error { + g.wg.Wait() + return g.errs +}