diff --git a/.jules/bolt.md b/.jules/bolt.md index b2c1128..d0bea81 100644 --- a/.jules/bolt.md +++ b/.jules/bolt.md @@ -28,3 +28,6 @@ ## 2025-10-24 - Bulk Disk I/O Parallelization and Thread Pool Starvation **Learning:** Both `withTaskGroup` and `Task.detached` schedule their work on Swift's cooperative thread pool, which has only as many threads as the CPU has cores. Running synchronous blocking I/O (like `FileManager.removeItem`) directly inside such tasks ties up cooperative threads — when every thread is parked in a syscall there is nothing left to advance other Swift Concurrency work, which manifests as starvation and (with self-referential `await` chains) outright deadlock. `Task.detached` does not help here: "detached" means unstructured/independent, not "off the cooperative pool." **Action:** To parallelize bulk blocking I/O, combine a sliding-window `withThrowingTaskGroup` (e.g., `maxConcurrency` of 8) with a per-item handoff to a GCD queue: wrap the blocking call in `withCheckedThrowingContinuation` and dispatch it via `DispatchQueue.global(qos: .userInitiated).async { ... continuation.resume(...) }`. The cooperative-pool task only `await`s the continuation, so it never holds a thread while the syscall runs. +## 2024-05-29 - Short-circuiting and Lazy Filtering in SwiftUI Computed Properties +**Learning:** Checking `.isEmpty` on a property that eager-filters an array (e.g., `!items.filter { ... }.isEmpty`) forces O(N) evaluation and allocates an intermediate array every time it's accessed, which is deadly in SwiftUI computed properties. +**Action:** Always use `.contains(where:)` instead of `.filter { ... }.isEmpty` to short-circuit the evaluation. For reductions or counts, use `.lazy.filter` to skip intermediate allocations. diff --git a/Sources/Cacheout/ViewModels/CacheoutViewModel.swift b/Sources/Cacheout/ViewModels/CacheoutViewModel.swift index 27de41a..8f1b2b8 100644 --- a/Sources/Cacheout/ViewModels/CacheoutViewModel.swift +++ b/Sources/Cacheout/ViewModels/CacheoutViewModel.swift @@ -106,7 +106,7 @@ class CacheoutViewModel: ObservableObject { } var selectedSize: Int64 { - selectedResults.reduce(0) { $0 + $1.sizeBytes } + scanResults.lazy.filter(\.isSelected).reduce(0) { $0 + $1.sizeBytes } } var formattedSelectedSize: String { @@ -118,7 +118,7 @@ class CacheoutViewModel: ObservableObject { } var hasResults: Bool { !scanResults.isEmpty || !nodeModulesItems.isEmpty } - var hasSelection: Bool { !selectedResults.isEmpty || selectedNodeModulesSize > 0 } + var hasSelection: Bool { scanResults.contains(where: \.isSelected) || selectedNodeModulesSize > 0 } // MARK: - Node Modules computed properties