43 lines
914 B
Go
43 lines
914 B
Go
package convert
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import "sync"
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// singleflightGroup deduplicates concurrent calls keyed by string. If N
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// goroutines call Do(key, fn) before the first one returns, fn runs once
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// and all callers receive the same (val, err).
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//
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// Copy of internal/apps/singleflight.go so this package has no internal
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// cross-imports. If a third caller appears, lift to internal/sf/.
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type singleflightGroup struct {
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mu sync.Mutex
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m map[string]*sfCall
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}
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type sfCall struct {
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done chan struct{}
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val any
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err error
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}
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func (g *singleflightGroup) Do(key string, fn func() (any, error)) (any, error) {
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g.mu.Lock()
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if g.m == nil {
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g.m = make(map[string]*sfCall)
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}
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if c, ok := g.m[key]; ok {
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g.mu.Unlock()
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<-c.done
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return c.val, c.err
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}
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c := &sfCall{done: make(chan struct{})}
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g.m[key] = c
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g.mu.Unlock()
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c.val, c.err = fn()
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close(c.done)
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g.mu.Lock()
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delete(g.m, key)
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g.mu.Unlock()
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return c.val, c.err
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}
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