24 lines
826 B
Go
24 lines
826 B
Go
package memory
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import (
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"math"
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"time"
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)
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// decayFactor computes the decay multiplier for a single item: the stored
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// decay_weight scaled by a time-decay that halves every recencyHalfLife days
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// (design §2 衰减: 久未使用的记忆降权). A freshly touched item keeps its full
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// decay_weight; an item unused for N half-lives is scaled to
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// decay_weight * 0.5^N, so it ranks progressively lower unless it stays relevant.
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//
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// age is measured from UpdatedAt; a future timestamp (clock skew) is clamped to
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// zero, so a just-recorded item is never scored above its base weight.
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func (r *Retriever) decayFactor(it MemoryItem, now time.Time) float64 {
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age := now.Sub(it.UpdatedAt)
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if age < 0 {
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age = 0
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}
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halfLives := float64(age) / float64(r.recencyHalfLife)
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return it.DecayWeight * math.Pow(0.5, halfLives)
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}
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