34 lines
457 B
V
34 lines
457 B
V
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module sync
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import sync.atomic2
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pub struct Once {
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mut:
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m RwMutex
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pub:
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count u64
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}
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// new_once return a new Once struct.
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pub fn new_once() &Once {
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mut once := &Once{}
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once.m.init()
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return once
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}
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// do execute the function only once.
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pub fn (mut o Once) do(f fn ()) {
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if atomic2.load_u64(&o.count) < 1 {
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o.do_slow(f)
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}
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}
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fn (mut o Once) do_slow(f fn ()) {
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o.m.@lock()
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if o.count < 1 {
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atomic2.store_u64(&o.count, 1)
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f()
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}
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o.m.unlock()
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}
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