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| 1 | import Foundation |
| 2 | |
| 3 | // 🤖 A two-generation memo: the fix for the bubble caches' `removeAll()` |
| 4 | // eviction. The old crude cap wiped the ENTIRE memo whenever it filled, so |
| 5 | // after a while of normal multi-space use every thread open re-parsed and |
| 6 | // re-built every visible message on the main actor — measured on device |
| 7 | // 2026-07-20 as 1–3s opens (worst on markdown-heavy bot threads; issue |
| 8 | // #1210). Rotation keeps the hot set instead: when the hot generation |
| 9 | // fills it becomes the cold one (dropping the previous cold — the actually |
| 10 | // stale half), and a cold hit promotes back to hot. O(1), no timestamps, |
| 11 | // worst-case memory two generations. |
| 12 | struct Memo<Key: Hashable, Value> { |
| 13 | private var hot: [Key: Value] = [:] |
| 14 | private var cold: [Key: Value] = [:] |
| 15 | private let cap: Int |
| 16 | |
| 17 | init(cap: Int = 600) { self.cap = cap } |
| 18 | |
| 19 | mutating func get(_ key: Key, _ build: () -> Value) -> Value { |
| 20 | if let v = hot[key] { return v } |
| 21 | if let v = cold[key] { |
| 22 | promote(key, v) |
| 23 | return v |
| 24 | } |
| 25 | let v = build() |
| 26 | promote(key, v) |
| 27 | return v |
| 28 | } |
| 29 | |
| 30 | private mutating func promote(_ key: Key, _ v: Value) { |
| 31 | if hot.count >= cap { |
| 32 | cold = hot |
| 33 | hot = [:] |
| 34 | } |
| 35 | hot[key] = v |
| 36 | } |
| 37 | } |
| 38 | |
amadan