48 lines
711 B
Go
48 lines
711 B
Go
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package promise
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import (
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"context"
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"sync"
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)
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type Promise[T any] struct {
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val T
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done chan struct{}
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mu sync.Mutex
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}
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func (p *Promise[T]) Set(val T) {
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p.mu.Lock()
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defer p.mu.Unlock()
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// Set value
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p.val = val
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// Initialize the done channel if it hasn't been initialized
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if p.done == nil {
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p.done = make(chan struct{})
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}
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// Signal that the value is set
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close(p.done)
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}
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func (p *Promise[T]) Val(ctx context.Context) T {
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p.mu.Lock()
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// Initialize the done channel if it hasn't been initialized
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if p.done == nil {
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p.done = make(chan struct{})
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}
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p.mu.Unlock()
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select {
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case <-ctx.Done():
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return *new(T)
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case <-p.done:
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p.mu.Lock()
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val := p.val
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p.mu.Unlock()
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return val
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}
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}
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