jschoubben
ac3422f914
Discovery, the finding writer and the vault login names read it; no fixed name. Builds: design 47 G §527, §634 (A-149)
62 lines
1.5 KiB
Go
62 lines
1.5 KiB
Go
package link
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import (
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"context"
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"errors"
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"sync"
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)
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// OwnName is the module that is this node-engine: the module whose catalog entry claims the seat node-engine, which the
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// engine learns first from its applied record of the build whose fingerprint is its own and, on a first start with no such
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// record, from its first composing (design 47 G §527, §634, A-149). Its discovery, its finding writer and its login names
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// in the vault read it here and fix none.
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type OwnName struct {
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mu sync.Mutex
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name string
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ready chan struct{}
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}
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// NewOwnName makes an own name not yet known.
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func NewOwnName() *OwnName { return &OwnName{ready: make(chan struct{})} }
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// Set keeps the name; an empty one changes nothing. The first name opens Wait for everyone.
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func (o *OwnName) Set(name string) {
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if o == nil || name == "" {
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return
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}
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o.mu.Lock()
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defer o.mu.Unlock()
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if o.name == "" {
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close(o.ready)
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}
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o.name = name
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}
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// Get is the name, "" while it is not known.
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func (o *OwnName) Get() string {
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if o == nil {
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return ""
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}
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o.mu.Lock()
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defer o.mu.Unlock()
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return o.name
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}
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// Wait returns the name once it is known, or ctx's error.
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func (o *OwnName) Wait(ctx context.Context) (string, error) {
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if o == nil {
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return "", errors.New("this session names no own module")
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}
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select {
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case <-o.ready:
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return o.Get(), nil
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case <-ctx.Done():
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return "", ctx.Err()
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}
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}
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// OwnNamed is a link that reads the node-engine's own module from an OwnName when it serves its seat.
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type OwnNamed interface {
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UseOwnName(*OwnName)
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}
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