74 lines
1.9 KiB
Go
74 lines
1.9 KiB
Go
package m
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import (
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"context"
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"sync"
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)
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type ctxKey int
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const (
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ctxStateKey ctxKey = iota
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)
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type ctxState struct {
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path []string
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l sync.RWMutex
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children map[string]context.Context
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}
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func newCtxState() *ctxState {
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return &ctxState{
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children: map[string]context.Context{},
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}
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}
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// Ctx returns a new context which can be used as the root context for all
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// purposes in this framework.
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func Ctx() context.Context {
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return context.WithValue(context.Background(), ctxStateKey, newCtxState())
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}
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func getCtxState(ctx context.Context) *ctxState {
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s, _ := ctx.Value(ctxStateKey).(*ctxState)
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if s == nil {
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panic("non-conforming context used")
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}
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return s
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}
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// Path returns the sequence of names which were used to produce this context
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// via the ChildOf function.
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func Path(ctx context.Context) []string {
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return getCtxState(ctx).path
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}
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// Children returns all children of this context which have been created by
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// ChildOf, mapped by their name.
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func Children(ctx context.Context) map[string]context.Context {
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s := getCtxState(ctx)
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out := map[string]context.Context{}
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s.l.RLock()
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defer s.l.RUnlock()
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for name, childCtx := range s.children {
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out[name] = childCtx
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}
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return out
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}
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// ChildOf creates a child of the given context with the given name and returns
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// it. The Path of the returned context will be the path of the parent with its
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// name appended to it. The Children function can be called on the parent to
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// retrieve all children which have been made using this function.
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func ChildOf(ctx context.Context, name string) context.Context {
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s, childS := getCtxState(ctx), newCtxState()
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s.l.Lock()
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defer s.l.Unlock()
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childS.path = make([]string, 0, len(s.path)+1)
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childS.path = append(childS.path, s.path...)
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childS.path = append(childS.path, name)
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childCtx := context.WithValue(ctx, ctxStateKey, childS)
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s.children[name] = childCtx
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return childCtx
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}
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