forked from TrueCloudLab/restic
74 lines
1.8 KiB
Go
74 lines
1.8 KiB
Go
// +build !go1.7
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package tomb
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import (
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"golang.org/x/net/context"
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)
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// WithContext returns a new tomb that is killed when the provided parent
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// context is canceled, and a copy of parent with a replaced Done channel
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// that is closed when either the tomb is dying or the parent is canceled.
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// The returned context may also be obtained via the tomb's Context method.
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func WithContext(parent context.Context) (*Tomb, context.Context) {
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var t Tomb
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t.init()
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if parent.Done() != nil {
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go func() {
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select {
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case <-t.Dying():
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case <-parent.Done():
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t.Kill(parent.Err())
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}
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}()
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}
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t.parent = parent
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child, cancel := context.WithCancel(parent)
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t.addChild(parent, child, cancel)
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return &t, child
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}
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// Context returns a context that is a copy of the provided parent context with
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// a replaced Done channel that is closed when either the tomb is dying or the
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// parent is cancelled.
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//
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// If parent is nil, it defaults to the parent provided via WithContext, or an
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// empty background parent if the tomb wasn't created via WithContext.
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func (t *Tomb) Context(parent context.Context) context.Context {
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t.init()
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t.m.Lock()
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defer t.m.Unlock()
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if parent == nil {
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if t.parent == nil {
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t.parent = context.Background()
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}
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parent = t.parent.(context.Context)
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}
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if child, ok := t.child[parent]; ok {
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return child.context.(context.Context)
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}
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child, cancel := context.WithCancel(parent)
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t.addChild(parent, child, cancel)
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return child
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}
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func (t *Tomb) addChild(parent context.Context, child context.Context, cancel func()) {
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if t.reason != ErrStillAlive {
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cancel()
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return
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}
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if t.child == nil {
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t.child = make(map[interface{}]childContext)
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}
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t.child[parent] = childContext{child, cancel, child.Done()}
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for parent, child := range t.child {
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select {
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case <-child.done:
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delete(t.child, parent)
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default:
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}
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}
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}
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