116 lines
3.0 KiB
Go
116 lines
3.0 KiB
Go
/*
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Copyright The containerd Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package shutdown
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import (
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"context"
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"errors"
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"sync"
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"time"
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"golang.org/x/sync/errgroup"
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)
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// ErrShutdown is the error condition when a context has been fully shutdown
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var ErrShutdown = errors.New("shutdown")
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// Service is used to facilitate shutdown by through callback
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// registration and shutdown initiation
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type Service interface {
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// Shutdown initiates shutdown
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Shutdown()
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// RegisterCallback registers functions to be called on shutdown and before
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// the shutdown channel is closed. A callback error will propagate to the
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// context error
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RegisterCallback(func(context.Context) error)
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// Done returns a channel that's closed when all shutdown callbacks are invoked.
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Done() <-chan struct{}
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// Err returns nil if Done is not yet closed.
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// If Done is closed, Err returns first failed callback error or ErrShutdown.
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Err() error
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}
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// WithShutdown returns a context which is similar to a cancel context, but
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// with callbacks which can propagate to the context error. Unlike a cancel
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// context, the shutdown context cannot be canceled from the parent context.
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// However, future child contexes will be canceled upon shutdown.
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func WithShutdown(ctx context.Context) (context.Context, Service) {
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ss := &shutdownService{
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Context: ctx,
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doneC: make(chan struct{}),
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timeout: 30 * time.Second,
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}
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return ss, ss
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}
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type shutdownService struct {
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context.Context
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mu sync.Mutex
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isShutdown bool
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callbacks []func(context.Context) error
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doneC chan struct{}
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err error
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timeout time.Duration
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}
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func (s *shutdownService) Shutdown() {
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s.mu.Lock()
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defer s.mu.Unlock()
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if s.isShutdown {
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return
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}
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s.isShutdown = true
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go func(callbacks []func(context.Context) error) {
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ctx, cancel := context.WithTimeout(context.Background(), s.timeout)
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defer cancel()
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grp, ctx := errgroup.WithContext(ctx)
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for i := range callbacks {
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fn := callbacks[i]
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grp.Go(func() error { return fn(ctx) })
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}
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err := grp.Wait()
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if err == nil {
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err = ErrShutdown
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}
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s.mu.Lock()
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s.err = err
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close(s.doneC)
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s.mu.Unlock()
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}(s.callbacks)
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}
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func (s *shutdownService) Done() <-chan struct{} {
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return s.doneC
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}
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func (s *shutdownService) Err() error {
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s.mu.Lock()
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defer s.mu.Unlock()
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return s.err
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}
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func (s *shutdownService) RegisterCallback(fn func(context.Context) error) {
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s.mu.Lock()
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defer s.mu.Unlock()
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if s.callbacks == nil {
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s.callbacks = []func(context.Context) error{}
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}
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s.callbacks = append(s.callbacks, fn)
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}
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